About half of the Earth’s surface has been converted to agricultural use, leading to three of the world’s most pressing environmental issues. The largest contributor to greenhouse gas emissions is agriculture, which consumes approximately 70% of global freshwater. This is also the largest driver of habitat destruction, which is threatening terrestrial biodiversity.
A group of international scientists now proposes that croplands be relocated to more productive locations around the globe. This would allow ecosystems in these areas to recover and reduce carbon and biodiversity footprints. The new croplands would be located in areas that receive all the water they need, thus eliminating the need to irrigate.
Today, the journal publishes details about their reimagined world maps for agriculture. Nature Communications Earth & Environment. Experts propose large new farming areas to support major crops in the Cornbelt region in the mid-western US and south of Sahara desert. Large areas of existing farmland in Europe, India, and elsewhere would be allowed to return to their natural habitat.
In many places, cropland has replaced natural habitat that contained a lot of carbon and biodiversity – and crops dont even grow very well there. These places could be regenerated and production moved to more suitable areas. This would bring about environmental benefits quickly, said Dr. Robert Beyer, the study’s first author. He was previously a researcher at the Department of Zoology. University of Cambridge.
Global maps of the current crops of 25 major crops were used to determine the impact of climate change. These crops include wheat, soybean and barley. Together, they account for 77 per cent of croplands in the world. The researchers compared the carbon stock in each crop to the carbon bound up in soil and natural vegetation. They also estimated the difference in local biodiversity between natural vegetation and croplands.
These methods enabled researchers to predict the potential carbon and biodiversity impacts of crop production in places that aren’t currently cultivated. The researchers developed a mathematical model to consider all possible distributions of the cropland, while maintaining the overall production levels for each crop. They calculated potential yields for three farming scenarios. These included traditional, subsistence-based organic farming systems, advanced, fully-mechanized production with high yielding crop varieties, and optimal fertilizer and pesticide applications.
The models predict that the proposed redistribution would reduce the carbon impact of crop farming by 71 percent if the original croplands are allowed to return to their natural forested state. This is equivalent to capturing 20 year’s worth of current net CO2.2 emissions. Trees can capture carbon as they grow and allow more carbon to be absorbed by the soil than when crops have been grown in it.
This optimized scenario would reduce crop production’s impact on biodiversity by 87 percent. This would dramatically reduce the extinction risk of many species to which agriculture poses a threat. Researchers believe that croplands will quickly return to their natural state, often recovering their original carbon stock and biodiversity within a few years.
It is currently not possible to move croplands to new, more productive locations on a global basis. Their maps and models show areas where croplands are not productive, but could be hotspots of biodiversity and carbon storage.
Even less extreme changes would lead to significant benefits, such as a reduction in global carbon emissions by 59 per cent and a decrease in biodiversity impact of 77 percent.
A third, more realistic option that would only relocate 25 percent of the most infected croplands in the country would bring half the benefits of moving all crops.
This complete redesign is not feasible at the moment. Beyer stated that even if only a fraction of the cropland in the world were relocated, the environmental benefits would still be significant, especially if they concentrated on the most efficient places for growing crops.
Their study shows that the optimal distribution for croplands will not change until the end of this century, regardless of the specific effects of climate change.
The ideal locations for cropping are not a moving target. Professor Andrea Manica, senior author of the study, stated that areas with low environmental footprints and high crop yields will be largely maintained optimal in the future.
Although other studies have shown that a shift to more plant-based diets could significantly reduce the environmental impact of agriculture, the researchers claim that diets aren’t changing rapidly. Their model assumes that diets won’t change and focuses on producing food in the same way as today, but in a more efficient manner.
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 areas were chosen historically for their proximity to human settlements. But, researchers now believe it is time to cultivate food in a more optimal way.
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By Alison Bosman, Earth.comStaff Writer