The NHBS Introduction to Habitats: Sand Dunes

Sand dunes in New Brighton, Merseyside, UK by Andrew Mason via Flickr

Coastal sand dunes are habitats created by sand, seashell fragments and other sediments that are moved by wave and wind action along a coastline or beach until they become trapped above the strandline. This usually occurs where vegetation is growing as their roots and leaves help to bind the sand together, preventing the sand from being blown away by the wind. There are several different types of sand dunes, categorised by their position on the shoreline, age, morphology and stability:

  • Embryo dunes: The youngest dunes at their earliest stage of development, usually closest to the shore and may still be covered by high tides. This area usually has high salinity and is a very dry environment with rapid drainage and a lot of exposure. 
  • Mobile dunes: These are dunes that are no longer covered by the highest tide but are still affected by wind; sand gets blown from the beach onto, over and away from these areas. 
  • Semi-fixed dunes: This is where vegetation cover has become more continuous with fewer areas of bare sand.
  • Fixed dunes: These are dunes that have very limited free space, with few areas of bare sand and almost continuous vegetation. 
  • Dune slack: The low-lying depressions between sand dunes. These areas can often become filled with fresh or brackish water, creating small wetlands known as interdunal wetlands or interdunal ponds. These areas can warm quickly as they’re often very shallow, providing an ideal habitat for many invertebrates. 
  • Dune scrub: A later successional stage, where a stable dune has been colonised with scrub species. These areas can continue to develop into dune-heath and older woodland. 

Sand dunes can be rich in wildlife and are important habitats for birds, reptiles, invertebrates, a variety of plant species, lichens and fungi. This is particularly the case in older, more stable dune habitats. They are classified as UK BAP Priority Habitat and several Priority List species have been recorded utilising sand dunes.

What species can you find here?
Flora

Differences in flora diversity can be found depending on the position, age, morphology and stability of the dunes. Sand dunes that are still inundated at high tide can be dominated by halophilic (salt-tolerant) plants, whereas dune slack areas may be filled with fresh groundwater, allowing them to support several freshwater plant species. Areas of low stability will most likely see lower plant diversity, with the community present dominated by pioneer species. More stable dunes are generally dominated by woody plants and have higher diversity.

Sea sandwort (Honckenya peploides)

S. Rae via Flickr

This is one of several pioneer species usually found in embryo dunes, as it is highly stress-tolerant. These plants allow sand to begin to accumulate, raising the top of the dune above the high tide level, while also adding organic matter to the sand through dying and decaying. This allows the sand dune to better retain water, allowing other plants to colonise the area.

Marram grass (Ammophila arenaria)

Jeremy Halls via Flickr

This is a dune building grass as it is tall and robust, with matted roots, therefore it is very effective at trapping and stabilising sand. It can help to form very high mobile dunes as it grows at a rate of 1m per year. It is usually the dominant plant on mobile dunes and is a familiar sight on many of our coasts. By stabilising the sand and adding nutrients through its dead leaves, this plant can allow sand dunes to be colonised by many other plant species.

Harebell (Campanula rotundifolia)

Aecole2010 via Flickr

As sand dunes become more fixed and vegetation cover becomes more continuous, the area can be very species-rich. Many wildflowers, including harebells, can be found there, providing a food source for species such as invertebrates. Due to the wide range of environmental factors in these habitats, such as wind, salinity levels and availability of shelter and fresh water, there is often a huge variety of wildflowers.

Harebells, also called bluebells of Scotland, are tough and resilient plants, living in dry, open areas such as sand dunes.  While their flowering period can vary, it’s usually from July to November in the British Isles, providing a vital source of nectar for bees during the autumn.

For more examples of wildflowers, check out our guide to UK wild flower identification.

Silver birch (Betula pendula)

Andrew Gustar via Flickr

The final successional stages of sand dunes include colonisation by woody plants, creating dune scrubs and, finally, deciduous woodland. These woodland are often lower in species diversity, as woody species out-compete others, but the habitat will remain stable for extended periods, barring any disturbance. The type of vegetation present in the climax stage is determined by a number of factors, such as climate, exposure, soil pH, grazing level and management type. Birch trees are one of the woody species that can colonise sand dunes, particularly acidic dunes with open areas for young birch trees to grow.

Fungi

While fungi are usually associated with damper habitats, there is a variety that can be found in sand dune habitats, such as the earthtongue fungus (Glutinoglossum glutinosum), dune stinkhorn (Phallus hadriani) and several puffball species. There are also rare species that can only be found in sand dunes.

Dune waxcap (Hygrocybe conicoides)

Lukas Large via Flickr

This species of waxcap occurs mainly on short grass in coastal sand dune habitats, such as on the edges of dune slacks. Waxcaps, fungi in the genus of agarics, or gilled fungi, are usually brightly coloured fungi with dry to waxy caps. They are mainly associated with unimproved grasslands, though outside of Europe they are more commonly found in woodland. Dune waxcaps resemble the blackening waxcap (Hygrocybe conica) when young, but older dune waxcaps only darken slightly, usually just on their stem, unlike the blackening waxcap.

Collared Earthstar (Geastrum triplex)

Yankech gary via Flickr

While collared earthstars are most likely found in woodlands, particularly those with a high level of leaf litter, they can also be found on sand dunes. This star-shaped fungus initially looks like a ball, similar to a puffball, before splitting open. Other earthstars, including the dwarf earthstar (Geastrum schmidelii), can also be found in sand dune habitats, particularly mature sand dune systems. They’re often found in colonies with several fruitbodies growing together.

Fauna

Sand dunes support a diverse range of fauna species, many of which are specifically adapted to live in these dynamic habitats. Similarly to shingle beaches, which will be covered in another article, this area is a key habitat for several ground-nesting birds, such as the Ringed Plover and Skylarks, grazing species such as rabbits, and invertebrates such as bees, digger wasps and other insects.

The red-banded sand wasp (Ammophila sabulosa)

Volkmar Becher via Flickr

Sand wasps reproduce by hunting caterpillars, paralysing them using their sting and burying them in burrows with the sand wasp’s egg. The females dig their burrows in sandy ground, with a nearby area of vegetation that would support their prey. Areas of sand dunes can be rich in invertebrate species, particularly where diverse vegetation is present.

Northern Dune Tiger Beetle (Cicindela hybrida)

David Tyler via Flickr

This rare beetle hunts on bare sand, preying on ants, spiders, moth larvae and flies. As they need areas of open, moving sand, they are less likely to be found in older, more stabilised sand dunes. Therefore, lack of management allowing succession and reduced sediment deposition due to development or flood defences reduce the availability of suitable habitats. Conservation efforts to restore mobile sands and remove areas of scrub are helping to provide more habitats for the northern dune tiger beetle. 

Sand lizard (Lacerta agilis)

xulescu_g via Flickr

Sand dunes support a variety of vertebrate species, including the sand lizard, one of the UK’s rarest reptiles. Their distribution is restricted to a small number of sites, such as protected heathlands and sand dunes. They require sunny habitats with vegetation for shelter and undisturbed, open sand to lay their eggs. Their numbers are impacted by habitat loss but there are several conservation efforts working towards increasing their populations. These involve a combination of habitat restoration, monitoring, reintroduction and encouraging beneficial policies and practices.

Sparrowhawk (Accipiter nisus)

Female. Andy Morffew via Flickr
Male. Caroline legg via Flickr

Several birds of prey use sand dune habitats as hunting grounds due to the presence of ground-nesting birds, lizards and some grazing species such as rabbits. Sparrowhawks can be found across Britain and Ireland, mainly in gardens, woodland and urban settings, but they can also be found on sand dunes, particularly if woodland is close by. They prey mainly on small birds, but they have also been recorded taking bats.

Chough (Pyrrhocorax pyrrhocorax)

gailhampshire via Flickr

Once extinct in Britain, Choughs now have a growing population on the Cornish and Welsh coasts, as well as a few other spots around the UK. They hunt invertebrates and larvae in the exposed sandy soils of sand dunes, using their long, curved bills. With only a small population in the UK, it is important to maintain suitable areas of habitats, therefore a number of projects are reintroducing grazing species to dunes. These species help to maintain areas of open ground and short grass, preventing sand dunes from becoming scrubland.

For more information on other species that may occur in sand dune habitats, including reptiles, coastal birds, waders and other mammal and bird species, check out some of our other guides to UK species identification.

Threats

The main threats to coastal sand dunes are development, recreational use, flood defences, falling water tables, climate change, invasive species and poor management. The development of housing, industry and areas such as golf courses can result in the damage or destruction of sand dune habitats. This, along with recreational use, such as excessive pedestrian and vehicular use, can increase levels of erosion and modify vegetation. Fragile sand dune habitats can be altered, reducing their stability and their ability to support diverse wildlife.

Poor management allows encroachment by shrubs and trees that, if left unchecked, could turn sand dune habitats into woodland areas, which can impact their suitability for specialist species. Flood defences can impact the natural processes of sediment removal and deposition, which can prevent sand dunes from developing or growing. These areas can become depleted if there is not enough sediment deposited to replace the amount removed by wind or wave action. The creation of harbours and other coastal structures can also disrupt natural sediment processes. Alternatively, these structures can also prevent sediment removal, causing a build-up of sediment.

Further threats include invasive species, such as cordgrass (Spartina anglica), which can dominate sand dunes, reducing the abundance and diversity of native plant species and reducing the number of animals that the area can support. Climate change can also threaten this habitat, as increasing intensity and frequency of storms can impact how sand dunes are formed. Sea-level rise, in combination with development, can also reduce the amount of area available for this habitat to form; this is termed coastal squeeze.

While grazing is used as a method for controlling over-stabilisation and succession, overgrazing can also impact sand dunes. It can reduce the development and spread of vegetation, preventing sand stabilisation and, therefore, reducing the diversity and abundance of the species the habitat can support. This also allows sand dunes to become depleted by wave or wind action, particularly where structures such as flood defences and development have reduced sediment deposition.

Conservation

To manage the impacts of these threats, many sand dune areas have been given Site of Special Scientific Interest (SSSI) designations, which control the amount of development that can occur. Soft engineering approaches to flood defences including beach replenishment, the restoration of stabilised sand dunes and managed realignment, where areas are allowed to be inundated by the sea, can often be a more natural approach to reducing the impacts of waves compared to hard engineerings, such as sea walls and breakwaters. These can allow the natural process of sediment removal and deposition, facilitating the development of new sand dune environments.

As mentioned, sand dunes are subject to natural habitat succession, often ending in a stable deciduous woodland habitat. To maintain sand dune habitats, encroachment by woody species must be controlled and areas of open, mobile sand should be created as this prevents soil development and, therefore, over-stabilisation.

Areas of significance

Lindisfarne National Nature Reserve, Northumberland

Braunton Burrows, North Devon

Holkham NNR, North Norfolk

Kenfig NNR, Glamorgan, South Wales

Forvie NNR, Aberdeenshire, Scotland

Further reading

The Biology of Coastal Sand Dunes

Coastal zones are becoming increasingly topical as they face relentless pressure from a number of threats. This book provides a comprehensive introduction to the formation, dynamics, maintenance and perpetuation of coastal sand dune systems.

 

Sand Dune Conservation, Management and Restoration

This book deals with the development of temperate coastal sand dunes and the way these have been influenced by human activity. Options for management are considered and the likely consequences of taking a particular course of action highlighted.

 

Field Guide to Coastal Wildflowers of Britain, Ireland and Northwest Europe

This field guide covers more than 600 species of wildflowers and other coastal flora found in Britain and Ireland, and coastal mainland north-west Europe. Detailed species accounts describe the wildflowers, grasses, sedges and rushes that occur on the coast or in abundance within sight of the sea.

 

Wildflowers of the Sefton Coast

This book describes the typical wildflowers associated with each of the Sefton Coast’s main habitats from the saltmarshes and ‘green beaches’ to the sand-dunes; the latter showing a sequence of successional stages running inland, from the newly-formed strandline and embryo dunes, through mobile and fixed-dunes to older woodland and dune-heath.

 

Beaches and Coasts

A new edition of a unique textbook that provides an exhaustive treatment of the world’s different coasts, with a focus on climate change sea-level rise. Seeking to better educate students and readers about the sustainability of coasts and coastal environment, this exciting book offers enlightening coverage of coastal geology, processes and environments.

Beach and Dune Restoration

This new edition continues the theme of the first edition: the need to restore the biodiversity, ecosystem health, and ecosystem services provided by coastal landforms and habitats, especially in the light of climate change. This will be valuable for coastal scientists, engineers, planners, and managers, as well as shorefront residents

 

Sea of Sand: A History of Great Sand Dunes National Park and Preserve

The Great Sand Dunes sprawl along the eastern fringes of the vast San Luis Valley of south-central Colorado. Sea of Sands is the definitive history of the natural, cultural, and political forces that helped shape this incomparable landscape.

This Week in Biodiversity News – 5th September 2022

Climate change

This summer was England’s hottest on record, tied with 2018. The average temperature in June, July and August was 17.1°C. Four out of the five warmest summers have occurred since 2003, with records stretching back to 1884. Hot and dry conditions are causing river levels to drop, crop damage and wildfires across England.

East Yorkshire has launched a climate change consultation, inviting residents and those who work in the area to contribute to the local authority’s response. Attendees will get a first look at the draft Climate Change Strategy developed by East Riding of Yorkshire Council, which will highlight opportunities for future action. A survey has also been created to gather people’s views on climate change from across the authority area.

Research

Ecologists are using the latest dental scanning technology to study young coral, monitoring coral size and growth. This method is said to have reduced surveying time by 99%. Dr Kate Quigley, a senior research scientist, has developed a new non-destructive method for rapidly and safely scanning coral, using an ITero Element 5D Flex dental scanner. Because coral and teeth are both calcium-based, the scanner works effectively, allowing scientists to measure thousands of tiny coral quickly, accurately and without any negative impacts on the health of the coral.

Conservation

A flock of European bee-eaters have migrated south for the winter after successfully hatching chicks in the UK. The arrival of the breeding colony in Trimingham, Norfolk, in June was described by the RSPB as a “red alert for global warming,” as they are more commonly found in the southern Mediterranean and northern Africa. Nesting bee-eaters are occurring in the UK as hotter, drier summers become more common. While they eat a variety of flying insects, including many bee species, this small colony is not expected to have had any impact on local bee populations.

European Bee-eater by Francesco Veronesi via Flickr

Water voles have been reintroduced into the New Forest, two decades after they became locally extinct. In 1998, 7000 American Mink were released from a fur farm by animal rights activists, inadvertently resulting in the loss of the local population of endangered water voles. The Environment Agency released 50 captive-bred water voles into an area near Ringwood, joining a few wild voles relocated from Salisbury. Another 50 will be introduced to the same area next spring, with the hope that the population will reach 1,000 by 2027.

A rare sea slug, Babakina anadoni, has been spotted in Cornwall, marking only the second time this species has been seen in UK waters. The first sighting was made by a Seasearch volunteer just a few weeks ago off the Isles of Scilly. Their larval stage is thought to have drifted in on ocean currents, with the adults surviving due to favourable conditions. Only a few individuals have been spotted around the world, mostly in warm waters off the west coast of Spain, as well as Portugal, France, Brazil and the Caribbean.

Babakina anadoni by Carlos Fernandez-Cid via Flickr

Policy

A ban on offshore oil and gas exploration by Shell has been upheld by a South African court. Due to the loud shock waves that would occur every 10 seconds for the five-month period, it is thought that the seismic waves used to explore the Indian Ocean coast for oil and gas would have a negative impact on whales and other marine life in the area. These surveys have been found to disrupt marine communication, navigation and eating habits, which are essential to the survival of marine life. They also damage fish air bladders, marine eggs and larvae and can cause species to temporarily migrate away from the affected area. This may have knock-on effects on local fisheries.

Pollution

A grounded ship that collided with a gas tanker off the coast of Gibraltar has begun to leak fuel oil into the sea. A significant leak was discovered, though 80% of the ship’s diesel fuel has now been removed. Booms have been deployed to limit the spread of the oil, and skimmers are being used to recover the oil from the surface. Spanish authorities believe that a full clean-up can be achieved.

River water testing fell to a 10-year low last year, with only 41,519 samples tested compared to 100,000 in 2012. Experts warn that this is causing a ‘vacuum of knowledge’ about river pollution and its effects. The decrease in monitoring has coincided with repeated cuts to the Environment Agency budget. Pollution risks increase with low-flowing rivers, such as the conditions brought on by recent droughts, because the concentration of pollutants increases.

This Week in Biodiversity News – 17th August 2022

Climate change

There is widespread drought and water shortages across parts of Europe, including areas of England and Germany (where water levels in the Rhine River have dropped significantly), as well as France, Italy, Spain, Netherlands and Belgium. This is Europe’s most severe drought in decades, with high temperatures and reduced rainfall testing infrastructure and water supplies. England experienced the driest July since 1935, with only 35% of average rainfall for the month falling. Other rivers such as the Danube and the Po have been impacted, threatening wildlife.

Research

Most sharks killed for fins are at risk of extinction. A new study has found that more than two-thirds of sharks hunted and used in the global fin trade are at risk of extinction. By studying 9,820 shark fin trimmings from markets in Hong Kong between 2014 to 2018 using DNA analysis, the researchers found 86 different species. Of these, 61 are threatened with extinction. The majority of fins came from blue sharks which are classified as “near threatened” by the IUCN, with the other top species including silky sharks, hammerheads, makos and threshers. 

Self-pollinating plants are showing rapid loss of genetic variation. Flowering species that can self-pollinate lost genetic diversity within only nine generations without bumblebees. A new study has found that monkeyflower plants lost between 13–24% of their genetic variation compared to a group that was propagated by bumblebees. Reducing genetic diversity can limit a species’ ability to adapt to environmental changes, like those brought on by climate change. This study highlights the importance of pollinator species in combating the impacts of the climate crisis.

Conservation

Derbyshire conservationists aim to save Swifts by pushing housebuilders to install nesting bricks. These hollow bricks provide a nesting area for one of the UK’s most endangered birds, whose population has dropped by 65% in the last 25 years. The Derbyshire Swift Conservation Project, run by Derbyshire Wildlife Trust, aims to raise awareness of Swifts. This aim is now increasingly being included in planning applications for new housing. 

Cornish Choughs have had a bumper year, 20 years since the first Cornish-born Choughs were seen once again. Over 70 youngsters are being raised by 25 pairs, bringing the total population to around 200 birds. Just a single pair successfully fledged young in 2002 and now Choughs can be seen all over Cornwall.

Critically endangered Albatrosses are being plagued by mice on Gough Island. This small British overseas territory in the South Atlantic is home to the Triston Albatross, along with 21 other seabird species. Mice were introduced to the island accidentally over two hundred years ago. With no existing predators, the mouse population exploded, leading to a decline in seeds and insects. In response to this drop in food supply, some mice began to prey on seabird chicks. Last year, there was an attempt to eradicate this invasive species by dropping poisoned mouse bait all over the island but this attempt failed. The mice are now once again spreading across the island.

In brighter news, the saiga antelope population has increased 10-fold after a mass die-off in 2015. A fatal bacterial disease killed around half of the population, leaving only 130,000 animals. Now, an estimated 1.3 million saiga are living in the steppe grasslands of Kazakhstan. After being hunted to the brink of extinction, numbers were down to less than 40,000 in 2005. This new increase is the result of land protections and hunting bans, which have allowed the species to begin recovering.

Policy

The US Senate has passed a sweeping climate, tax and healthcare package, which will increase corporate tax, lower the cost of some medicines and, importantly for the fight against climate change, reduce carbon emissions. The $700bn (£577bn) economic package includes $369bn (£305bn) dedicated to climate action, the largest climate investment in US history. This will be split into multiple projects, including speeding up the production of clean technology, providing tax credits for those who buy an electric car and funding for communities that have suffered the most from fossil fuel pollution.

Endangered species breeding programmes are under threat due to new EU regulations. The EU Animal Health Regulation came into force in April 2021, after being agreed in 2016, creating new controls on the import of animals and plants into the EU. These new sanitary and phytosanitary checks must be carried out at border control posts, but few exist at airports in the EU and none at French ports. Before December 2020, there were an average of 1,400 transfers of species between the UK and other EU countries in order for breeding programmes to keep the gene pool as broad as possible. But since Brexit, there were just 56 in 2021, and so far this year, there have only been 84. The lack of checking posts has effectively banned the import of any large animal, potentially preventing the breeding of certain endangered species, such as the black rhino.

This Week in Biodiversity News – 3rd August 2022

Climate change

The Mediterranean ecosystem is suffering the equivalent of a marine wildfire as temperatures in the area are more than 6°C warmer than normal. It is feared that the area is being permanently altered by global heating, with cooler deep water no longer rising to the surface. One study found that these marine heatwaves have already destroyed almost 90% of coral populations around parts of the Mediterranean. This decline has knock-on impacts on biodiversity within the marine ecosystems of the area.

Research

New research on great white sharks looking into beneficial bacteria specific to the species may help to produce new antibiotics. Researchers swabbed the nostrils, teeth, gums, dorsal fins, cuts and wounds of great white sharks, before adding the samples to agar dishes, where USCB professor Kim Ritchie can study the bacterial cultures. As their wounds heal quickly, Ritchie is interested to see whether the bacteria on and around them may help humans who are resistant to current antibiotic treatments.

Great white shark by Elias Levy via Flickr

A new project is looking at the genetic differences between bee species. ‘Beenome100’ will look to answer questions on which genetic differences make some species more vulnerable to climate change or more susceptible to different pesticides. By creating a digital repository of the complete set of genes present in 100 US bee species, scientists can link specific genes to bee functions.

Between 1986 and 2020, invasive herpetofauna cost the world $17 billion, $16.3 billion of which were associated mainly with just two species, the brown tree snake (Boiga irregularis) and the American bullfrog (Lithobates catesbeianus). This cost mainly comes from ruined farm crops and triggered power outages. The study’s researchers are hoping that their findings will encourage investment in preventing the spread of invasive species in the future.

Brown tree snake by Pavel Kirillov via Flickr

New discoveries

Scientists have recorded more than 30 potentially new species from the abyssal plains of the central Pacific. Researchers from the Natural History Museum used a remote-operated vehicle to reach depths of between 3,095 and 4,125 metres and collect over 55 specimens. These specimens include segmented worms and coral, as well as species from the same families as centipedes and jellyfish. The study highlights the potential implications of deep-sea mining for biodiversity.

Conservation

UK wild salmon stocks are reaching a crisis point, with the lowest number on record in England. A government report urges action to remove barriers in waterways and improve water quality. 42 rivers in England are considered ‘salmon rivers’ as they are traditional breeding grounds for the fish. Of these, 37 have been classified as at risk or probably at risk. Warming sea temperatures due to climate change are being blamed, along with poor water quality in rivers and estuaries, with every waterway in England failing pollution tests in 2020. The main sources of pollution are thought to be sewage outflows and agricultural runoff.

Water voles have been reintroduced to the River Beane in Hertfordshire after being locally extinct for more than 20 years. Threatened by habitat loss and predation by the invasive American mink, the species has seen a 90% drop in population over the last five decades. Herts and Middlesex Wildlife Trust, in partnership with the Woodhall Estate and with the support of the River Beane Restoration Association, reintroduced 138 water voles to the river near Watton-at-Stone. Herts and Middlesex Wildlife Trust aim to reintroduce water voles to all Hertfordshire rivers by 2030, through these reintroduction programmes and by improving habitats.

Water vole by Peter Trimming via Flickr

Pollution

A new Antarctic study has shown that the levels of ‘forever chemicals’ that are reaching this remote continent have been increasing. These chemicals include perfluorocarboxylic acid (PFCAs) and are termed forever chemicals as they do not break down naturally in the environment. They’re used in a variety of ways, such as in non-stick coating for pans and as water-repellents for clothing. The ice cores taken provide a record between 1957 and 2017 and show evidence that levels of these chemicals in Antarctic snow have increased over the last few decades, particularly between 2000 and 2017. There is ongoing research, however, into the clean-up of these forever chemicals, including a new study into bioremediation using a plant-derived material to absorb PFAs, disposing of them by allowing microbial fungi to eat them.  

Deforestation

A new study has found that over 60% of global forest area has been lost. Using a global land use dataset, the team of researchers found that global forest area declined by 81.7 million hectares (ha) between 1960 and 2019. Gross forest loss was 437.3 million ha, outweighing gross forest gain during this time, which was 355.6 million ha. The loss of forests, both in the net area and through replacement by new growth/plantations, has a significant impact on the integrity of forest ecosystems, reducing their ability to sustain biodiversity.

Climate Challenges: 7. Ocean Warming

In the lead up to the 26th UN Climate Change Conference of the Parties (COP26) in November of last year, and in the months that have followed, we have been writing a series of articles looking at some of the toughest global climate crisis challenges that we are currently facing. This blog looks at the causes of ocean warming and its impacts on marine ecosystems.

Dead coral at Lisianski overgrown with algae after a coral bleaching event in 2015. Image by John Burns via Flickr.
What causes ocean warming?

The ocean acts as a heat sink, absorbing large amounts of heat from our atmosphere and storing it over long periods; the ocean has a central role in stabilising our climate system. This heat is moved and mixed by tides, currents and wave action, allowing the ocean to soak up large amounts of heat without significant increases in temperature. This is changing, however, due to increasing concentrations of atmospheric greenhouse gases. IPCC data published in 2013 suggested that the ocean has absorbed over 90% of the excess heat generated by greenhouse gas emissions since the 1970s. This is resulting in increased ocean temperatures, with the greatest warming occurring in the southern hemisphere and in the upper 75m of the oceans surface. Average global ocean surface temperatures increased by 0.11°C per decade from 1971 to 2010. This heat sink process has helped limit the rise of global average temperatures but it has serious environmental consequences.

What are the impacts of ocean warming?

Ocean warming has a wide range of impacts on ocean chemistry, habitats, ecosystems and biodiversity, the severity and type of which can vary between habitats depending on their resilience and present biodiversity levels. Combined with other stressors such as pollution, acidification and increased nutrient input, ocean warming can increase the vulnerability of habitats and marine life to other threats such as parasites and disease outbreaks.

Water temperature is a significant environmental stressor, particularly in shallow or nearshore habitats, as they often act as nursery areas for many species. If water temperatures within nursery habitats rise above tolerable levels, they will no longer be suitable, impacting the survivorship, growth and recruitment of the species that use them.

Fishing net tangled on a reef. Image by Tim Sheerman-Chase via Flickr

Deoxygenation

Oxygen solubility varies depending on the temperature of the water; warmer ocean water holds less oxygen compared to colder water. Warmer water is also less dense, and rising ocean temperatures leads to increasing ocean stratification, where water is separated into layers. This can act like a barrier and prevents the mixing of water, slowing down ocean circulation and reducing the amount of oxygen reaching deeper waters. It is thought that dissolved oxygen levels have fallen by 2% since the 1950s due to the combined threats of ocean warming and excessive algae growth caused by anthropogenic nutrient input. Areas of low oxygen concentrations have expanded worldwide, with hundreds of new sites reported to be affected and anoxic ocean waters quadrupling in volume since the 1960s. 

Ocean deoxygenation has serious consequences for marine ecosystems and biodiversity, as oxygen is necessary to sustain life for almost all organisms in the ocean. Deoxygenation could lead to a decline in species numbers, diversity and individual growth, resulting in major ramifications throughout the food chain. In ecosystems already vulnerable due to other pressures such as overfishing, deoxygenation could lead to extinctions and even deadzones. Hundreds of millions of people rely on the oceans as a source of food and livelihood; they could be severely affected by a reduction or collapse in fish stocks. 

Warmer waters also increase the oxygen requirement of fish, exacerbating the effects of deoxygenation. There will likely be a shift in the structure of marine ecosystems as more hypoxia-tolerant species, such as jellyfish, will be favoured over less tolerant species, such as large fish and marine mammals. 

Coral bleaching

Corals are marine invertebrates that often have a hard calcium carbonate skeleton. They live in a mutualistic symbiotic relationship with photosynthetic unicellular dinoflagellates called zooxanthellae (endosymbionts), which live in their tissues. They rely on these endosymbionts for up to 95% of their energy requirements. Under certain physiological stresses, such as increasing water temperatures, these endosymbionts can be expelled and the corals turn white without the pigment from the zooxanthellae – this phenomenon is known as ‘coral bleaching’. If the stress continues over an extended period and the coral is not recolonised, the coral will eventually die. Increasing ocean temperatures over the last few decades have resulted in large-scale loss of coral across the world. This has led to degraded coral reef habitats, impacting the ecosystem and species that rely on them. Coral reefs provide food, shelter and spawning grounds for thousands of marine species, therefore the degradation of coral reefs has wide-reaching consequences. 

Bent sea rod bleaching. Image by Kelsey Roberts, U.S. Geological Survey via Flickr

Habitat loss and range shifting

All species have a thermal tolerance range. Some more generalist species are able to tolerate a broader range, but specialist species occupy a much narrower thermal niche and are therefore more vulnerable to temperature change. Temperature changes can trigger a knock-on effect on ecosystem structures as species migrate into more suitable habitats. The general trends in these shifts are a movement to higher latitudes and deeper locations. 

Many factors affect a species’ capacity to adapt to rising temperatures, including their dispersal ability, thermal tolerances, habitat or resource needs and the community composition of the new potential habitat. If the new area has high levels of pressure from competition, predation or lack of resources, or the species’ dispersal ability is limited (e.g. the species is sessile), successful establishment is unlikely.

Commercial fishing boat. Image by Gary Leavens via Flickr

Changes in community structure can negatively impact biodiversity, as the loss of whole populations from initial habitats can trigger a cascade of consequences on predator and prey populations, potentially altering entire ecosystems. These range shifts can also impact the communities already present, as new species could lead to increased competition for resources or the arrival of a novel predator that prey species are not adapted to avoid. There will also likely be socio-economic impacts on local fisheries if species move away from traditional fishing grounds.

Range shifting has been recorded in zooplankton, where warm-water species are extending their ranges poleward at a rate of up to to more than 230km per decade. There has also been a corresponding decline in the abundance of cold-water species in these areas. Zooplankton play a key role in many food chains as they are an intermediary species, transporting energy from the primary producers (phytoplankton) they consume to their predators, such as fish and decapods. Therefore, these changes in zooplankton community composition impact whole marine food webs, especially as warm-water species are generally smaller and less energy-rich.

Radiolarian zooplankton stack images, composed of dozens of single photographs taken using a microscope at different focus levels. Images 1, 2, and 3 by Picturepest via Flickr.

Temperature-dependent sex determination

Some marine species exhibit environmental sex determination, where certain environmental factors can influence the sex of offspring during embryonic or early juvenile development. With increasing ocean temperatures, the proportion of males to females being born could be altered in certain species, leading to biased sex ratios. This can affect reproduction, genetic diversity and potentially population numbers. 

Many fisheries are female-dependant, as female fish tend to grow larger, therefore are more likely to grow to harvestable sizes and can produce a larger yield. Southern flounder (Paralichthys lethostigma) exhibits sex reversal to males during early juvenile development at both 18°C and 28°C, with the optimal temperature for female development being 23°C. Southern habitats consistently have higher temperatures of over 27°C, therefore producing more male-biased sex ratios, potentially impacting the viability of fisheries operating out of these locations.

Other impacts

Warming ocean temperatures are also thought to be impacting breeding patterns, with many species reproducing earlier. This could lead to an uncoupling of certain predator and prey interactions if migrating predators arrive too late to feed during spawning events. Some species have been found to breed for a shorter duration, such as black sea bass (Centropristis striata) whose spawning season is starting later and ending earlier in the northern parts of their range. This suggests that there may be lower reproduction and recruitment in newly occupied ranges, demonstrating the potential future impact of warming ocean waters on species experiencing poleward-driven range shifts. Migration patterns have also been noted to be affected, with similar potential results.

Ocean warming also reduces the amount of sea ice. The implications of this, such as sea-level rise, coastal flooding and erosion, will be covered in more depth in a future blog post.

Coral spawning. Images 1 and 2 by Pei Yan via Flickr
What can be done?

As the main driver for increasing ocean temperatures is the increase in atmospheric greenhouse gases, particularly carbon dioxide, the solution is to reduce our greenhouse gas emissions. Beyond this, we need to protect and restore our marine and coastal ecosystems and manage the other stressors that are exacerbating the impacts of ocean warming. By creating protected areas and restoring degraded habitats, we can create refuges for species and improve biodiversity, which has been shown to increase ecosystem resilience against the impacts of climate change.

By working with fisheries, governments could introduce further policies that work towards sustainability, such as by improving quota limits and reducing by-catch. Many governments and fisheries are already working towards this, but scientific research and accurate data are needed to ensure that population estimates are accurate to prevent overfishing. Steps like these will help to reduce the pressures we place on the marine realm, allowing ecosystems to be more resilient to the effects of ocean warming. 

Scientific research into monitoring ocean warming is also important. Up-to-date and accurate measurements, with local and global monitoring of the rates, trends and effects can help policymakers make rapid and correct decisions to mitigate the worst impacts. Many of the policies signed at COP26 may make a positive difference, as reducing deforestation and methane emissions and adopting policies to reach net zero by 2050 will help to limit ocean warming. However, more can and should be done. 

Summary
  • Oceans absorb atmospheric heat, the amount of which has increased due to high greenhouse gas emissions. The greatest warming occurs in the southern hemisphere and the upper 75m.
  • Ocean warming has a variety of impacts including deoxygenation, habitat loss, range shifting, coral bleaching and changes to breeding patterns. These various impacts can all have negative effects on marine biodiversity and human livelihoods.  
  • As the main driver for marine warming is increased greenhouse gas emissions, the main solution is cutting these emissions. Other solutions include protecting and restoring marine habitats, reducing pressures from other threats such as overfishing and increasing the accuracy and use of scientific research. 
Useful resources:

Duffy, J. E., et al. 2016. Biodiversity enhances reef fish biomass and resistance to climate change. PNAS 113(22): 6230-6235

Honeycutt, J. L. et al., 2019. Warmer waters masculinize wild populations of a fish with temperature-dependent sex determination. Scientific Reports 9(1): 6527

Poloczanska, E. S., et al. 2016. Responses of Marine Organisms to Climate Change across Oceans. Frontiers in Marine Science 3(62): 1-21

Slesinger, E., Jensen, O. P., and Saba, G., 2021. Spawning phenology of a rapidly shifting marine fish species throughout its range. ICES Journal of Marine Science 78(3): 1010-1022

Synthesis Report: Climate Change 2014 of the IPCC Fifth Assessment Report, Page 11 

Our previous blog, a round-up of COP26, covering the major outcomes of the event and how they might affect our efforts to combat climate change.

Impact of Climate Changes on Marine Environments
Paperback | October 2016

This book discusses the modifications in marine ecosystems related to global climate changes, including shifts in temperature, circulation, stratification, nutrient input, oxygen concentration and ocean acidification, all of which have significant biological effects.

 

Rewilding the Sea: How to Save Our Oceans
Hardback | June 2022

Charles Clover chronicles how determined individuals are proving that the crisis in our oceans can be reversed, with benefits for both local communities and entire ecosystems. Essential and revelatory, Rewilding the Sea propels us to rethink our relationship with nature and reveals that saving our oceans is easier than we think.

 

Ocean Ecology: Marine Life in the Age of Humans
Hardback | November 2021

This authoritative and accessible textbook advances a framework based on interactions among four major features of marine ecosystems – geomorphology, the abiotic environment, biodiversity, and biogeochemistry – and shows how life is a driver of environmental conditions and dynamics.

 

The Ocean and Cryosphere in a Changing Climate: Special Report of the Intergovernmental Panel on Climate Change
Paperback | May 2022

This special report is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks.

 

Climate and the Oceans
Paperback | October 2011

This offers a short, self-contained introduction to this subject, beginning by briefly describing the world’s climate system and ocean circulation and going on to explain the important ways that the oceans influence climate. Topics covered include the oceans’ effects on the seasons, heat transport between equator and pole, climate variability, and global warming.

 

The Great Ocean Conveyor: Discovering the Trigger for Abrupt Climate Change
Hardback | February 2010

Wally Broecker is one of the world’s leading authorities on abrupt global climate change. In The Great Ocean Conveyor, he introduces readers to the science of abrupt climate change while providing a vivid, firsthand account of the field’s history and development. This book opens a tantalizing window into how Earth science is practised.

James Lovelock Obituary

James Lovelock 1919–2022

We have recently received the sad news of the passing of James Lovelock, an environmentalist, chemist, futurist and the creator of the Gaia hypothesis.

Born in 1919, he attended the University of Manchester at age 21 and graduated with a PhD from the London School of Hygiene and Tropical Medicine in 1948, becoming an independent scientist in 1961. He had since been awarded honorary degrees from several institutions, including the University of Exeter, Stockholm University and the University of Colorado Boulder. His career was varied, from travelling aboard the research vessel RRS Shackleton to working on developing scientific instruments for NASA, and even performing cryopreservation experiments. 

Lovelock was the first person to detect Chlorofluorocarbons (CFCs) in the atmosphere after developing an electron capture detector in the late 1960s. CFCs are nontoxic chemicals used in the manufacturing of products such as aerosol sprays, and are used as solvents and refrigerants. Their role in the depletion of the ozone layer led to their inclusion in the Montreal Protocol, which worked to phase out several substances to protect the ozone layer. During his time aboard the RRS Shackleton, Lovelock measured the concentration of CFC-11 from the northern hemisphere to the Antarctic. These experiments provided the first useful data on the widespread presence of CFCs in the atmosphere, though the damage these cause was not discovered until the 1970s, by Sherwood Rowland and Mario Molina. 

James Lovelock was also known for his Gaia hypothesis. This hypothesis, first created in the 1960s, proposed that the complex interacting system of the Earth’s biotic and abiotic parts could be considered as a single organism. Drawing from research by Alfred C. Redfield and G. Evelyn Hutchinson, Lovelock formulated that living organisms interact with the non-living environment to form a synergistic and self-regulating complex system, by co-evolving with their environment. He suggested that the whole system, including the biosphere, atmosphere, hydrosphere and pedosphere, seeks an environment optimal for life. This evolution is facilitated through a cybernetic feedback system that is unconsciously operated by the biota, leading to a final ‘state’ of full homeostasis. 

While the Gaia hypothesis is generally accepted by many in the environmentalist community, there has been some criticism, particularly from the scientific community. Lovelock later made revisions to the hypothesis to clarify that there was no conscious purpose within this self-regulating system and to bring the hypothesis into alignment with ideas from other fields, such as systems ecology. This had reduced criticism, but there still remains scepticism from the scientific community.

Lovelock wrote more than 200 scientific papers as well as a number of books on a variety of topics within chemistry, environmentalism, geophysiology, climate change and more. Lovelock’s work has been recognised a number of times, receiving awards such as the Tswett Medal in 1975, the Dr A. H. Heineken Prize for Environmental Sciences in 1990 and the Royal Geographical Society Discovery Lifetime Award in 2001. He was also appointed a member of the Commander of the Order of the Britsh Empire for services to the study of Science and the Atmosphere in 1990 and a member of the Order of the Companions of Honour for services to Global Environmental Science in 2003. In 2006, he was awarded the Wollaston Medal, an achievement also received by Charles Darwin.

Bruno Comby, CC BY-SA 1.0, via Wikimedia Commons

James Lovelock: 26th July 1919–26th July 2022

This Week in Biodiversity News – 20th July 2022

Policy

The European Parliament has voted to ban ‘fly shooting’ fishing in a part of the Channel. This technique, also known as demersal seigning, involves towing weighted ropes along the seabed at either end of a net, which then encircles and captures entire shoals of fish. Fly shooter vessels catch up to 11 times more fish than inshore fishing vessels and have a devastating effect on the marine ecosystem, biodiversity and local fishers. This decision is seen as a victory for small-scale fishers but it will also help reduce the damage caused to the seabed and marine ecosystems in the Channel. 

A strategy designed to halt biodiversity loss across North Dublin by 2030 will not be achieved in full due to a lack of funding. Fingal County Council has completed the public consultation on its draft Biodiversity Action Plan 2022-2023, but has stated it would cost €4 million annually to implement and therefore two-thirds of the programme will not be achieved by the EU 2030 deadline. The funding gap is stated to be due to other competing priorities, such as housing, roads, sports and community facilities.  

Climate change

Experts are stating that the UK is no longer a cold country and must adapt to extreme heat to prevent thousands of deaths. A specific heat risk strategy must be drawn up by the government, as well as updating housing stock and ensuring that new builds can cool down in hot weather. Scientists are urging governments to work quickly to phase out fossil fuels and reach net zero emissions, as climate change is driving heatwaves, making them hotter, last longer and become more frequent. This comes after warnings that the UK, and countries across the world, could see heatwaves for the rest of summer.

Plastics

UK households recycle only 12% of single-use plastics, disposing of nearly 100 billion pieces of plastic packaging a year. A new survey by Greenpeace is one of the largest voluntary research projects on the scale of plastic waste and it asked households to count their plastic waste for one week in May. Almost 250,000 people from around 100,000 households took part and showed that the largest proportion of plastic waste was from food and drink packaging at 83%. The most common item was fruit and vegetable packaging. On average, each household threw away 66 pieces of plastic packaging in one week.

Pollution

The Environment Agency (EA) is calling for water company bosses to be jailed for serious pollution. Shocking levels of pollution occurred in the last year, with 62 serious incidents of pollution in 2021. The EA has stated that chief executives and board members of companies responsible for the most serious incidents should be jailed and that courts should impose much higher fines. Only three water companies received the highest rating of four stars for their pollution performance. The rating takes into account the number and severity of pollution incidents, as well as self-reporting and the use and disposal methods of sewage sludge. Two companies, Southern Water and South West Water, were given the lowest rating of one star.

Conservation

3D printed reefs are being used to restore marine biodiversity. WWF Denmark and Ørsted have been testing how structures made of 70% sand and 30% pozzolanic cement (a combination of volcanic ash and portland cement) could be used to create new habitats for fish and other wildlife in the Kattegat strait between Denmark and Sweden. Twelve of these structures have been deployed between the wind turbines at Anholt Offshore Wind Farm, and it is hoped that they will help reverse the decline of cod stock in the Kattegat. 

Bison have been released into the wild in the UK. Wild bison are ecosystem engineers and can help to restore biodiversity in woodlands through their natural behaviours, such as felling trees by rubbing against them and grazing. This is hoped to provide a nature-based solution to tackling the climate and biodiversity crisis. The releases are part of a five-year project led by Kent Wildlife Trust and the Wildwood Trust. The next steps include introducing Exmoor ponies, Iron Age pigs and Longhorn cattle. 

Contraceptives are being given to grey squirrels in an attempt to control their population and allow red squirrel populations to improve. Grey squirrels are a non-native species first introduced from North America in the 19th century. They cause significant damage to UK woodlands as they strip the bark from trees, and they tend to target younger trees that are typically between 10-50 years old, either killing them or maiming them and leaving them vulnerable to pests and diseases. Culling has not been found to be a sufficient control measure, therefore it is thought that using contraceptives, which have longer-lasting effects, may be more effective.

Young Maori divers are hunting invasive crown-of-thorns starfish to save coral reefs. The species, also known as taramea, feed on coral reefs and, when there are too many individuals, can destroy reef habitats. Korero O Te `Orau, a local environmental organisation, has been training young Maori people in scuba diving to remove taramea from the reef and bury them inland. The recent outbreak of this species around the island of Rarotonga in the Cook Islands could jeopardize the survival of the surrounding coral reef if not tackled properly. More than 3,700 taramea have been collected so far.  

Research 

Great white sharks might change their colour when hunting prey. Researchers conducted experiments off of South Africa using a specially designed colour board with white, grey and black panels. Each shark was photographed as it jumped out of the water at the panels, with the experiment being repeated throughout the day. One particular shark appeared to be both dark grey and a much lighter grey at different times. The results were verified using computer software to correct for variables such as weather, light levels and camera settings. While the research has not yet been validated and published in a scientific journal, experts are still excited about the results.

This Week in Biodiversity News – 6th July 2022

Climate change

The US Supreme Court has limited the Environmental Protection Agency’s (EPA) ability to curb power plant emissions, impacting America’s attempts to fight climate change. The Supreme Court ruled that the Clean Air Act does not give the EPA broad authority to regulate greenhouse gas emissions from power plants. The Biden administration plans to combat climate change by cutting the nation’s greenhouse gas emissions in half by the end of the decade and aiming for an emissions-free power sector by 2035. Now, the decision to curb power plant emissions must be taken by Congress itself, or “an agency acting pursuant to a clear delegation from that representative body.”

In other climate news, both Spain and Portugal are suffering the driest climate for at least 1,200 years, according to new research. Azores highs, high-pressure systems off the coast that blocks wet weather fronts in winter, have dramatically increased since 1980, pushing wet weather northwards. This is having severe implications for both food production and tourism. This change has been conclusively linked to increased anthropogenic emissions.

Scientists have warned Members of the European Parliament (MEPs) against watering down EU deforestation laws. Last week, a draft regulation was rewritten to define ‘forest degradation’ as the replacement of primary forests by plantations or other wooded land. As primary forests account for only 3.1m hectares of 159m hectares of overall forest, this definition would severely limit the law’s reach to only 2% of the total forest area.  A letter from more than 50 scientists has stated that any exclusion of forest degradation from the law would undermine the EU’s desire for Europe to “become the first climate-neutral continent by 2050.”

Conservation

Bird flu has been confirmed at the UK’s only breeding colony of roseate terns in Northumberland. This “new virulent” form of bird flu is having a devastating impact on a number of wild bird species, with hundreds of seabirds found dead on Coquet Island. There are now calls for the government to develop and implement a national response plan for bird flu in wild birds, including clarity for collecting dead birds and a long-term plan for future threats. This disease is affecting all four species of tern on the island, as well as eider ducks, black-headed gulls and large gulls. The island is also home to nesting puffins but, so far, no puffin deaths have been recorded.

A £4.1m scheme has been revealed to improve wildlife habitats and alleviate flooding alongside roads in Stafford. The Stafford Brooks Project will target 25 locations near local rivers and streams to address the environmental impact of roads. Space will be created for wildflowers, trees and wildlife in areas where habitats have been impacted by activities from previous road building. New wetlands and reed beds are also being designed to help filter polluted run-off from roads, which can significantly impact river health.

A 3-metre-high weir in Cumbria is being demolished as part of a national push to allow fish and invertebrates to move more freely along the UK’s rivers. The River Kent is an internationally important site of special scientific interest as its home to species such as white-clawed crayfish and freshwater pearl mussels. The removal of Bowston weir will help to renaturalise part of the River Kent by improving biodiversity, restoring migration routes and reducing flooding risks for local residents.

The greater glider is now considered endangered due to population declines caused by logging, bushfires and global heating. This cat-sized marsupial has slipped from vulnerable to endangered on the federal government of Australia’s list of threatened species. There are calls from experts and conservationists to back this move with urgent action to preserve habitats and reduce greenhouse gas emissions.

Research

Researchers are satellite-tracking whale sharks to explore the factors influencing their behaviour in the coastal waters of the Panamanian Pacific, including migratory and feeding behaviours. Rhincodon typus is vulnerable to population declines due to their slow maturation and they face a number of threats from humans, including entanglement in fishing nets and boat strikes. This study has shown that whale sharks spend more than 77% of their time in areas without any protection, indicating that conservation measures should go beyond the creation of local marine protected areas. 

A new study, part-funded by The Mammal Society, has revealed the presence of plastic consumption in small mammals. More than 261 faecal samples were analysed to assess the exposure of seven terrestrial UK mammals to plastics. Four species, the European hedgehog, wood mouse, field vole and brown rat all had plastic polymers detected within their faecal samples. This ingestion was shown to occur across species of differing dietary habits and locations, confirming that plastic consumption is a widespread issue.

New Discoveries

A new giant water lily species has just been discovered, despite being in the archives of the Royal Botanic Gardens, Kew, for 177 years. Now holding the record as the world’s largest water lily, with its leaves growing more than 3m wide, the Victoria boliviana grows in a single water basin in part of the Amazon river system in Bolivia. It was long suspected to be different from the two other known giant species, V. amazonica and V. cruziana, but it was only when Kew grew all three side-by-side under exactly the same conditions that they could clearly see V. boliviana was totally different.

Policy

Singapore strengthened a law on Monday 4th July to stamp out wildlife trafficking, with stiffer penalties for those found guilty. The changes to the Endangered Species (Import and Export) Act include tripling the maximum jail term for individuals from two to six years and increasing the maximum fine from $50,000 (~£29,550) per species to $100,000 (~£59,100) per specimen. Companies involved in the trafficking of endangered species will also face higher fines and prison sentences, according to the Senior Minister of State for National Development, Tan Kiat How.

Climate Challenges: 6. Agricultural Intensification

In the lead up to the 26th UN Climate Change Conference of the Parties (COP26) in November of last year, as well as the months that have followed, we have been writing a series of articles looking at some of the toughest global climate crisis challenges that we are currently facing. This post looks at the intensification of agricultural practices and how this can both be exacerbated by and contribute to climate change.

Farmer applying pre-emergence sprays. Chafer Machinery via Flickr
What is agricultural intensification?

Our global population is increasing year on year and is predicted to hit 10 billion by 2057. Agricultural production has to keep pace with the resource demands of this growing population. There are two main ways this can occur: an increase in the amount of land used for agricultural purposes or an increase in the yield from land already used through improvements or increased use of resources such as technology, fertilisers, labour, pesticides or scientific plant knowledge.

What are the impacts of land-use change?

Habitat destruction is considered one of the main causes of animal extinctions worldwide, and much of this destruction is due to clearing land for agriculture. Intensively managed agricultural land is far less valuable for the environment than natural habitats such as wetlands and forests. Intensively managed farmlands support less diverse and abundant species, sequester less carbon dioxide and suffer from increased water loss and soil erosion. Therefore, the increase in agricultural areas can contribute to climate change and worsen our ability to mitigate its effects.

Agricultural expansion and land clearing are pushed right up to Bwindi Impenetrable National Park boundaries in Uganda. USAID Biodiversity and Forestry via Flickr
What is the impact of increasing yields?

Intensification of agricultural management practices to increase yield includes an increase in the use of chemicals such as fertilisers, herbicides and pesticides, all of which can negatively impact wildlife, soil and nearby water quality. The artificial introduction of nutrients can be detrimental to the environment, particularly if it reaches waterways through run-off, as it can lead to algae blooms that can deplete aquatic oxygen levels.

Herbicides and pesticides have a direct impact on both target and non-target species, potentially disrupting populations and affecting whole ecosystems. Species can also be impacted through trophic poisoning, as the impacts of these chemicals can be heightened through biomagnification, where toxins build up in the food chain in greater and greater concentrations at each trophic level. This often results in the loss of top consumers which can destabilise ecosystems.

Another way to increase yield is by utilising as much of the existing agricultural land as possible. This, however, reduces the areas of non-crop species, such as trees and hedgerows. These areas represent essential diversity in plant species, helping to support a wide variety of fauna by providing food, shelter and breeding areas. Losing these areas reduces the variety and abundance of species that agricultural land can support. Additionally, crops are often grown in monocultures, a field composed of just a single crop species rather than multiple species, further reducing biodiversity. This increases the susceptibility of fields to disease and pest damage, furthering the need for additional chemical intervention.

Monoculture by Paul Barker Hemings via Flickr
Climate change and agricultural intensification

Agriculture is one of the major sources of greenhouse gases that contribute to climate change. Methane and nitrous oxide, produced from livestock and as an indirect product of fertilisers, are particularly problematic. Increasing production or land area can increase the amount of greenhouse gases released into the atmosphere while reducing the amount of carbon that the land can sequester, enhancing the impact on climate change.

Climate change affects agriculture in return. Changes in precipitation patterns impact crop yields and reduce yield reliability. Higher temperatures, particularly heat waves, can lead to high yield losses, livestock death or sickness, a reduction in workable hours, increases in water supply needs and even damage to equipment. More frequent and higher intensity extreme weather, such as storms, can also impact in a similar way. Therefore, agriculture may not be able to keep up with food demands and would need to further increase its production. This could continue to drive climate change and exacerbate the impacts on agriculture in a cycle of detrimental effects.

What are the other options?

One solution is reducing food loss (by food suppliers) and waste (by retailers, food service providers and consumers). It is thought that, globally, around one-third of all food produced for human consumption is lost or wasted every year. This amounts to about 1.3 billion tonnes of food per year. When this is buried in landfills, it is broken down by microorganisms using anaerobic digestion, producing greenhouse gases (specifically methane and carbon dioxide), which are released into the atmosphere. Some countries, however, have begun to set up food recycling centres to capture these gases to be used as a renewable source of biofuel.

Food waste recycling plant in America. James Loesch via Flickr

By reducing the amount of food wasted, there would be less need to increase agricultural intensification to keep up with the growing population. This can be achieved through several routes, including changing the strict cosmetic standards of many retailers, providing better clarity on food expiration dates and bringing consumers’ attention to how much food they waste each year. For example, through a campaign called ‘Love Food, Hate Waste’, the UK had a 21% reduction in avoidable household waste between 2007 and 2012.

Sustainable farming practices are needed to ensure that global agriculture does not continue to seriously contribute to climate change. Through research into sustainable practices and better techniques, agriculture may be better able to provide enough food for the global population without compromising our environment. By reducing livestock numbers, increasing the efficiency of fertiliser application and better management for manure, the EU reduced agricultural emissions by 24% between 1990 and 2012. Additionally, the UK government is changing how they subsidise farmers. The Sustainable Farming Incentive, piloted by Defra, will reward acts that improve environmental outcomes and reduce carbon emissions. This should hopefully help to increase the sustainability of our agriculture, reducing its impact on climate change.

Another potential solution is regenerative farming, a practice that aims to reverse the impacts of and contribution to climate change by rebuilding soil organic matter and restoring degraded soil biodiversity. This results in an increase in carbon drawdown and an improvement in the water cycle. These farming practices include low- or no-till techniques, increasing plant diversity, introducing cover crops and crop rotations and minimizing physical disturbance. It also includes growing trees and shrubs around crops, using perennial crops that do not need to be replanted annually and creating borders of pollinator habitats. It is hoped that, by restoring the health of soils, farms will be able to increase their yield without negatively impacting the environment, reducing the need for agricultural intensification.

Tilling is used to aerate the soil, prepare seedbeds, suppress weeds, level soil, incorporate fertilisers and turn over cover crops. however, tilling contributes to soil erosion, surface runoff and carbon emissions. Image by United Soybean Board via Flickr

There is a concern, however, that the reduced tilling may lead farmers to rely more heavily on herbicides to remove unwanted plants. There may also be an increased use of fertilisers, to meet the need for nitrogen to convert carbon into microbial organic matter to allow it to remain sequestered in the soil. Questions have also been raised about whether regenerative farming can sequester additional soil carbon effectively, without decreasing yield or requiring more land for farming. For example if cover crops or additional trees and shrubs are added to farmlands without decreasing yield, then carbon sequestration will increase. However, if yield decreases and habitats such as a forest have to be cleared to replace lost production, then carbon sequestration will either remain the same or decrease.

COP26

There were several pledges and agendas launched at COP26 last year, including the Glasgow Leaders’ Declaration on Forests and Land Use, which intends to halt and reverse forest loss by 2030, reducing agricultural expansion into forest areas; and the Agriculture Innovation Mission for Climate (AIM4C), which looks to fund scientific breakthroughs, public and private applied research, and the development, demonstration and deployment of tactical, actionable and innovative products services and knowledge to producers. AIM4C has been criticised, however, for being over-reliant on technological solutions rather than sustainable farming methods. Other announcements including the climate emissions pledges and the Global Methane Pledge will also impact agriculture and its contribution to climate change, as countries look to introduce new regulations and policies to reduce emissions from farms.

The Koronivia Joint Work on Agriculture (KJWA) was also discussed at COP26. Originally established at COP23 in 2017, KJWA aims to bring discussions of agriculture into the UNFCCC and address agricultural issues through the lens of climate change. This process was set to end at cop26, but due to many areas of disagreement, the roadmap of how the Koronivia process will be going forward was included in the debate at the next meeting of the UN climate process, the Bonn Climate Change Conference, in June 2022.

Summary
  • Agriculture must keep up with the resource demands of an increasing global population. This is mainly achieved through increasing agricultural land or increasing yield. Both have negative environmental impacts and can contribute to climate change.
  • Climate change can also negatively impact agriculture, through changing precipitation patterns and extreme weather causing loss of crops and damage to equipment. This, then, requires more agricultural intensification to make up for losses, further contributing to climate change.
  • Solutions include more sustainable agricultural practices and reducing food waste. This reduces the impacts of agriculture on climate change while also reducing the need for more agricultural intensification. Other practices such as regenerative farming may help to improve soil health and carbon sequestration but there are criticisms about its effectiveness.
  • Several pledges launched at COP26 will impact agriculture and its contribution to climate change, including the Glasgow Leaders’ Declaration on Forests and Land Use, the Global Methane Pledge and the Agriculture Innovation Mission for Climate.
Useful resources:

The Food and Agriculture Organization of the United Nations’ (FAO) 2013 report: food wastage footprint: impacts on natural resources, illustrating how food is wasted or lost through various stages of the supply chain, highlighting the significant environmental costs.

The 2021 policy paper for the Sustainable Farming Incentive, piloted by the Department for Environment, Food & Rural Affairs (Defra).

This 2015 article by the European Environment Agency on agriculture and climate change.

A 2019 document outlining the National Farming Union of England and Wales’ (NFU) plans for achieving net zero, outlining the current impacts of agriculture and their goals for increasing sustainability.

This 2018 report by IEA bioenergy on anaerobic digestion of food waste for a circular economy, containing food waste data, information on anaerobic digestion systems, and case studies from 11 different countries.

This 2021 article on the key outcomes from COP26 for food, forests, land use and nature by CarbonBrief.

 

Sixty Harvests Left: How to Reach a Nature-Friendly Future

Taking its title from a chilling warning made by the United Nations that the world’s soils could be gone within a lifetime, Sixty Harvests Left demonstrates why food and future harvests matter more than ever and shows us how we can restore our planet for a nature-friendly future.

 

 

Farming and Birds

Ian Newton discusses the changes that have occurred in British agriculture over the past seventy years, and the effects they have had on bird populations. He explains how different farming procedures have affected birds and other wildlife, and how an understanding of the processes involved could help in future conservation.

 

 

Soil Health and Intensification of Agroecosystems

This book examines the climate, environmental, and human effects on agroecosystems and how the existing paradigms must be revised in order to establish sustainable production.

 

 

 

Agricultural Development and Sustainable Intensification

This multidisciplinary book presents state-of-the-art reviews of current SI approaches to promote major food crops, challenges and advances made in technology, and the institutional and policy measures necessary to overcome the constraints faced by smallholder farmers.

 

 

Sustainable Intensification of Agriculture: Greening the World’s Food Economy

This book provides the first widely accessible overview of the concept of sustainable intensification as an innovative approach to agriculture and as a key element in the transition to a green economy.

 

 

Farming with the Environment: Thirty Years of Allerton Project Research

This book examines over 30 years’ worth of research from the Allerton Project, a research and demonstration farm in the UK. Designed to provide guidance, feedback and recommendations to farmers, practitioners and policymakers, the Allerton Project is an exceptionally well-documented case study of lowland agricultural land management which has the purpose of meeting multiple objectives.

Book Review: Abundance: Nature in Recovery by Karen Lloyd

Abundance: Nature in Recovery is a collection of essays by award-winning author, Karen Lloyd. Examining abundance and losses in the natural world, Lloyd laments the lack of sight humanity has for the holes we have created. Looking first at artists such as Mary Newcomb, Carry Akroyd, and Daniel Beltrá, the book begins with the struggles of those trying to draw attention to the damaging impacts of human encroachment on the natural world. While many are beginning to understand the harm we are causing, the momentum of our modern society hasn’t allowed us to stop. By recounting a moment when a willow warbler flies into her house, Lloyd compares the fight of individual people against the systems we operate under with the panicked movements of the bird battering against the glass. We, like the bird, have no perception of how to remove ourselves from ‘the world of window frames and glass’ that we inhabit.

Willow warbler by Ron Knight via Flickr

Abundance aims to give a voice to the species and habitats that are often disregarded in the political sphere. Travelling to places such as the Veluwe Forest in Switzerland, the Strathspey woodland in Scotland and the Hungarian Steppe, Lloyd tells the stories of people on the front line of conservation fighting to halt biodiversity loss. The volume of negative environmental news can often be overwhelming, and the author shares her own experience of this feeling in the opening essay. This book is a welcome break, reminding us that conservation success is possible and is taking place right now across Europe.   

Beaver felled tree by Corey Burger via Flickr

Through the exploration of local attitudes to conservation efforts, Lloyd touches on current themes such as rewilding and the return of wolves to the UK. Shifting baselines, where the current generation believes what they are seeing in nature around them is the norm and are unaware of the decline over previous generations, are impacting people’s perspective on the return of previously extinct species. Despite some extinctions being relatively recent, such as the beaver, the general public is unused to living with them. Therefore, they fear the impact these species may have on their daily lives. Worries of damage to livelihood and homes have been exacerbated by misconceptions and scapegoating. Lloyd recounts the concerns people have for the threatened wild salmon should beavers be allowed to remain, despite beavers being obligate herbivores, as well as the attempt to blame beavers for a flash flooding event in Alyth, Scotland. But if we are to allow the natural world to recover from the damage we have inflicted upon it, Lloyd believes that nature needs to be placed centre-stage in everything we do.

Wild salmon by Bureau of Land Management via Flickr

Abundance is an engaging and accessible book, presenting personal accounts of seeing firsthand the impacts of anthropomorphic destruction, riveting natural history stories and shocking data. From the conflict between the need for clean energy sources and the impacts of wind farms on birds to the impact of flood protection on beavers and kingfishers, Lloyd discusses our struggle to find effective solutions to tackle our biodiversity crisis. The engaging and entertaining nature of this book only increases as you read. Comparable to a travel book, each essay is a new adventure in wildlife-rich places. From eighty fragments on the pelican to tales from viewing platforms in the Lake District and the adventure of the 2020 lockdowns, the variety will hold your attention until the very end.


Abundance: Nature in Recovery
By: Karen Lloyd
Hardback | September 2021

 

 

 

 

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