̽��ֱ�� of Cambridge - Robert Beyer

Relocating farmland could turn back clock twenty years on carbon emissions

jg533 — Thu, 10 Mar 2022 10:00:00 +0000

̽��ֱ��reimagined world map of agriculture includes large new farming areas for many major crops around the cornbelt in the mid-western USA, and below the Sahara desert. Huge areas of farmland in Europe and India would be restored to natural habitat.

̽��ֱ��redesign - assuming high-input, mechanised farming - would cut the carbon impact of global croplands by 71%, by allowing land to revert to its natural, forested state. This is the equivalent of capturing 20 years’ worth of our current net CO2 emissions. Trees capture carbon as they grow, and also enable more carbon to be captured by the soil than when crops are grown in it.

In this optimised scenario, the impact of crop production on the world’s biodiversity would be reduced by 87%. This would drastically reduce the extinction risk for many species, for which agriculture is a major threat. ̽��ֱ��researchers say that croplands would quickly revert back to their natural state, often recovering their original carbon stocks and biodiversity within a few decades.

̽��ֱ��redesign would eliminate the need for irrigation altogether, by growing crops in places where rainfall provides all the water they need to grow. Agriculture is currently responsible for around 70% of global freshwater use, and this causes drinking water shortages in many drier parts of the world.

̽��ֱ��researchers used global maps of the current growing areas of 25 major crops, including wheat, barley and soybean, which together account for over three quarters of croplands worldwide. They developed a mathematical model to look at all possible ways to distribute this cropland across the globe, while maintaining overall production levels for each crop. This allowed them to identify the option with the lowest environmental impact.

̽��ֱ��study is published today in the journal Nature Communications Earth & Environment.

“In many places, cropland has replaced natural habitat that contained a lot of carbon and biodiversity – and crops don’t even grow very well there. If we let these places regenerate, and moved production to better suited areas, we would see environmental benefits very quickly,” said Dr Robert Beyer, formerly a researcher in the ̽��ֱ�� of Cambridge’s Department of Zoology, and first author of the study. Beyer is now based at the Potsdam Institute for Climate Impact Research (PIK), Germany.

Previous studies have identified priority areas for ecological restoration, but this is the first to plot the relocation of agricultural land to maximise long-term environmental benefits without compromising food security.

While a complete global relocation of cropland is clearly not a scenario that could currently be put into practice, the scientists say their models highlight places were croplands are currently very unproductive, but have potential to be hotspots for biodiversity and carbon storage.

Taking a pared-back approach and only redistributing croplands within national borders, rather than globally, would still result in significant benefits: global carbon impact would be reduced by 59% and biodiversity impact would be 77% lower than at present.

A third, even more realistic option of only relocating the worst-offending 25% of croplands nationally would result in half of the benefits of optimally moving all croplands.

“It’s currently not realistic to implement this whole redesign. But even if we only relocated a fraction of the world’s cropland, focusing on the places that are least efficient for growing crops, the environmental benefits would be tremendous,” said Beyer.

̽��ֱ��study finds that the optimal distribution of croplands will change very little until the end of the century, irrespective of the specific ways in which the climate may change.

“Optimal cropping locations are no moving target. Areas where environmental footprints would be low, and crop yields high, for the current climate will largely remain optimal in the future,” said Professor Andrea Manica in the Department of Zoology at the ̽��ֱ�� of Cambridge, senior author of the paper.

̽��ֱ��researchers acknowledge that relocating cropland must be done in a way that is acceptable to the people it affects, both economically and socially. They cite examples of set-aside schemes that give farmers financial incentives to retire part of their land for environmental benefit. Financial incentives can also encourage people to farm in better suited locations.

̽��ֱ��model generated alternative global distribution maps depending on the way the land is farmed – ranging from advanced, fully mechanised production with high-yielding crop varieties and optimum fertiliser and pesticide application, through to traditional subsistence-based organic farming. Even redistribution of less intensive farming practices to optimal locations would substantially reduce their carbon and biodiversity impacts.

While other studies show that if we moved towards more plant-based diets we could significantly reduce the environmental impacts of agriculture, the researchers say that in reality diets aren’t changing quickly. Their model assumed that diets will not change, and focused on producing the same food as today but in an optimal way.

Many of the world's croplands are located in areas where they have a huge environmental footprint, having replaced carbon-rich and biodiversity-rich ecosystems, and are a significant drain on local water resources. These locations were chosen for historical reasons, such as their proximity to human settlements, but the researchers say it is now time to grow food in a more optimal way.

This research was funded by the European Research Council.

Reference

Beyer, RM et al: ‘Relocating croplands could drastically reduce the environmental impacts of global food production.’ Nature Communications Earth & Environment, March 2022. DOI: 10.1038/s43247-022-00360-6

Scientists have produced a map showing where the world’s major food crops should be grown to maximise yield and minimise environmental impact. This would capture large amounts of carbon, increase biodiversity, and cut agricultural use of freshwater to zero.

If we moved production to better suited areas, we would see environmental benefits very quickly

Robert Beyer

Wheat fields

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Climate change may have driven the emergence of SARS-CoV-2

jg533 — Fri, 05 Feb 2021 12:03:26 +0000

A new study published today in the journal Science of the Total Environment provides the first evidence of a mechanism by which climate change could have played a direct role in the emergence of SARS-CoV-2, the virus that caused the COVID-19 pandemic.

̽��ֱ��study has revealed large-scale changes in the type of vegetation in the southern Chinese province of Yunnan, and adjacent regions in Myanmar and Laos, over the last century. Climatic changes including increases in temperature, sunlight, and atmospheric carbon dioxide - which affect the growth of plants and trees - have changed natural habitats from tropical shrubland to tropical savannah and deciduous woodland. This created a suitable environment for many bat species that predominantly live in forests.

̽��ֱ��number of coronaviruses in an area is closely linked to the number of different bat species present. ̽��ֱ��study found that an additional 40 bat species have moved into the southern Chinese province of Yunnan in the past century, harbouring around 100 more types of bat-borne coronavirus. This ‘global hotspot’ is the region where genetic data suggests SARS-CoV-2 may have arisen.

“Climate change over the last century has made the habitat in the southern Chinese Yunnan province suitable for more bat species,” said Dr Robert Beyer, a researcher in the ̽��ֱ�� of Cambridge’s Department of Zoology and first author of the study, who has recently taken up a European research fellowship at the Potsdam Institute for Climate Impact Research, Germany.

He added: “Understanding how the global distribution of bat species has shifted as a result of climate change may be an important step in reconstructing the origin of the COVID-19 outbreak.”

To get their results, the researchers created a map of the world’s vegetation as it was a century ago, using records of temperature, precipitation, and cloud cover. Then they used information on the vegetation requirements of the world’s bat species to work out the global distribution of each species in the early 1900s. Comparing this to current distributions allowed them to see how bat ‘species richness’, the number of different species, has changed across the globe over the last century due to climate change.

“As climate change altered habitats, species left some areas and moved into others - taking their viruses with them. This not only altered the regions where viruses are present, but most likely allowed for new interactions between animals and viruses, causing more harmful viruses to be transmitted or evolve,” said Beyer.

̽��ֱ��world’s bat population carries around 3,000 different types of coronavirus, with each bat species harbouring an average of 2.7 coronaviruses - most without showing symptoms. An increase in the number of bat species in a particular region, driven by climate change, may increase the likelihood that a coronavirus harmful to humans is present, transmitted, or evolves there.

Most coronaviruses carried by bats cannot jump into humans. But several coronaviruses known to infect humans are very likely to have originated in bats, including three that can cause human fatalities: Middle East Respiratory Syndrome (MERS) CoV, and Severe Acute Respiratory Syndrome (SARS) CoV-1 and CoV-2.

̽��ֱ��region identified by the study as a hotspot for a climate-driven increase in bat species richness is also home to pangolins, which are suggested to have acted as intermediate hosts to SARS-CoV-2. ̽��ֱ��virus is likely to have jumped from bats to these animals, which were then sold at a wildlife market in Wuhan - where the initial human outbreak occurred.

̽��ֱ��researchers echo calls from previous studies that urge policy-makers to acknowledge the role of climate change in outbreaks of viral diseases, and to address climate change as part of COVID-19 economic recovery programmes.

“ ̽��ֱ��COVID-19 pandemic has caused tremendous social and economic damage. Governments must seize the opportunity to reduce health risks from infectious diseases by taking decisive action to mitigate climate change,” said Professor Andrea Manica in the ̽��ֱ�� of Cambridge’s Department of Zoology, who was involved in the study.

“ ̽��ֱ��fact that climate change can accelerate the transmission of wildlife pathogens to humans should be an urgent wake-up call to reduce global emissions,” added Professor Camilo Mora at the ̽��ֱ�� of Hawai‘i at Manoa, who initiated the project.

̽��ֱ��researchers emphasised the need to limit the expansion of urban areas, farmland, and hunting grounds into natural habitat to reduce contact between humans and disease-carrying animals.

̽��ֱ��study showed that over the last century, climate change has also driven increases in the number of bat species in regions around Central Africa, and scattered patches in Central and South America.

This research was supported by the European Research Council.

Reference
Beyer, R.M. et al: ‘Shifts in global bat diversity suggest a possible role of climate change in the emergence of SARS-CoV-1 and SARS-CoV-2.’ Science of the Total Environment, Feb 2021. DOI: 10.1016/j.scitotenv.2021.145413

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Hear from other ̽��ֱ�� of Cambridge researchers who are investigating how to reduce the risk of animal viruses jumping to humans.

Global greenhouse gas emissions over the last century have made southern China a hotspot for bat-borne coronaviruses, by driving growth of forest habitat favoured by bats.

Governments must seize the opportunity to reduce health risks from infectious diseases by taking decisive action to mitigate climate change.

Andrea Manica

Shi bai Xiao/ Greenpeace

Forest landscape in Yunnan Province, PRC

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Climate change and food demand could shrink species’ habitats by almost a quarter by 2100

jg533 — Fri, 06 Nov 2020 10:06:12 +0000

̽��ֱ��study, published today in the journal Nature Communications, analysed changes in the geographical range of 16,919 species from 1700 to the present day. ̽��ֱ��data were also used to predict future changes up to the year 2100 under 16 different climate and socio-economic scenarios.

A diverse abundance of species underpins essential ecosystem functions from pest regulation to carbon storage. Species’ vulnerability to extinction is strongly impacted by their geographical range size, and devising effective conservation strategies requires a better understanding of how ranges have changed in the past, and how they will change under alternative future scenarios.

“ ̽��ֱ��habitat size of almost all known birds, mammals and amphibians is shrinking, primarily because of land conversion by humans as we continue to expand our agricultural and urban areas,” said Dr Robert Beyer in the ̽��ֱ�� of Cambridge’s Department of Zoology, first author of the report.

Some species are more heavily impacted than others. A worrying 16% of species have lost over half their estimated natural historical range, a figure that could rise to 26% by the end of the century.

Species’ geographical ranges were found to have recently shrunk most significantly in tropical areas. Until around 50 years ago, most agricultural development was in Europe and North America. Since then, large areas of land have been converted for agriculture in the tropics: clearance of rainforest for oil palm plantations in South East Asia, and for pasture land in South America, for example.

As humans move their activities deeper into the tropics, the effect on species ranges is becoming disproportionately larger because of a greater species richness in these areas, and because the natural ranges of these species are smaller to begin with.

“ ̽��ֱ��tropics are biodiversity hotspots with lots of small-range species. If one hectare of tropical forest is converted to agricultural land, a lot more species lose larger proportions of their home than in places like Europe,” said Beyer.

̽��ֱ��results predict that climate change will have an increasing impact on species’ geographical ranges. Rising temperatures and changing rainfall patterns will alter habitats significantly, for example: other studies have predicted that without climate action, large parts of the Amazon may change from canopy rainforest to a savannah-like mix of woodland and open grassland in the next 100 years.

“Species in the Amazon have adapted to living in a tropical rainforest. If climate change causes this ecosystem to change, many of those species won’t be able to survive - or they will at least be pushed into smaller areas of remaining rainforest,” said Beyer.

He added: “We found that the higher the carbon emissions, the worse it gets for most species in terms of habitat loss.”

̽��ֱ��results provide quantitative support for policy measures aiming at limiting the global area of agricultural land – for example by sustainably intensifying food production, encouraging dietary shifts towards eating less meat, and stabilising population growth.

̽��ֱ��conversion of natural vegetation to agricultural and urban land, and the transformation of suitable habitat caused by climate change are major causes of the decline in range sizes, and two of the most important threats to global terrestrial biodiversity.

“Whether these past trends in habitat range losses will reverse, continue, or accelerate will depend on future global carbon emissions and societal choices in the coming years and decades,” Professor Andrea Manica in the ̽��ֱ�� of Cambridge’s Department of Zoology, who led the study.

He added: “While our study quantifies the drastic consequences for species’ ranges if global land use and climate change are left unchecked, they also demonstrate the tremendous potential of timely and concerted policy action for halting - and indeed partially reversing - previous trends in global range contractions. It all depends on what we do next.”

This research was supported by the European Research Council.

Reference
Beyer, R.M. & Manica, A.: ‘Historical and projected future range sizes of the world’s mammals, birds and amphibians.’ Nature Communications, Nov 2020. DOI: 10.1038/s41467-020-19455-9

Mammals, birds and amphibians worldwide have lost on average 18% of their natural habitat range as a result of changes in land use and climate change, a new study has found. In a worst-case scenario this loss could increase to 23% over the next 80 years.

We found that the higher the carbon emissions, the worse it gets for most species in terms of habitat loss.

Robert Beyer

Ulet Ifansasti/ Greenpeace

Baby orangutans in Central Kalimantan. Expansion of oil palm plantations is destroying their forest habitat.

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