Aug 30, 2013
Is fighting climate change bad news for biodiversity?
If we want to feed the world and save the planet then our farms are going to have to work much harder for us. But what impact will this super-efficient agricultural system have on biodiversity? A new study shows that some of the best ways of tackling climate change have drastic consequences for biodiversity.
By 2050 our planet is going to have to support and feed an estimated 9.3 billion people. Today there are 7 billion of us living on planet Earth, 1 billion of whom do not have enough to eat. Providing everyone with an adequate diet is going to be one of the greatest challenges over the coming decades.
Eating less meat and squeezing more produce out of the land are ways in which we can mitigate climate change and tackle the food crisis simultaneously. In order to investigate the impact that these changes might have on biodiversity, Tom Powell and Tim Lenton, both from the UK’s University of Exeter, modelled four different scenarios that we might follow: high-meat diet and low agricultural efficiency; high-meat diet and high agricultural efficiency; low-meat diet and low agricultural efficiency; and low-meat diet and high agricultural efficiency. They studied the impact that each of these scenarios had on land use change, climate change and biodiversity.
As expected, the high-meat, low-efficiency scenario led to the worst outcome. “In this scenario we found that by 2050 much of the temperate and tropical forests will have been converted to pasture or fodder crops, leaving little but desert and boreal forest, which to us spells a clear ecological disaster,” said Powell. The model findings, published in Environmental Research Letters (ERL), showed that biodiversity would drop by around 20% for both farmland and natural biomes. Meanwhile, the low-meat, low-efficiency scenario was little better. “In this case the prevalence of low-intensity grazing means that the relatively slight reduction in per capita consumption of animal products doesn't have a huge impact,” Powell said. And in both cases carbon-dioxide and global temperatures would continue to soar.
For the high-efficiency scenarios the model assumed considerable changes in farming practices would be put in place, including intensive livestock rearing systems, more fodder crops, higher grazing intensities and recycling of agricultural and food waste. Any land freed up by this increased agricultural efficiency was then assumed to be available to grow bioenergy crops, thereby helping to mitigate climate change. In both of the high-efficiency scenarios Powell and Lenton saw an overall contraction of the land required to support farming for food by 2050, and an easing of global temperature rise, which at first glance seems like good news. However, super-efficient fields and the rise of bioenergy crops are bad news for biodiversity.
“When we intensify farming, especially in the cases in which we replace pasture with high-yielding biomass crops, we are extracting a greater proportion of the available ecological energy from the habitat, leaving very little for any other organisms,” Powell told environmentalresearchweb. “If we are removing upwards of 60 or 70% of the biomass, and especially removing much of the residue (straw etc.) from the fields, what is left is not far removed from a desert from the perspective of other organisms.” And all of this is before the impact of pesticides and fertilizers has been considered, which would likely crush biodiversity further.
The low-meat, high-efficiency scenario had the most positive outcome in terms of tackling climate change, because significant areas of land are freed up for bioenergy crops. But the conversion of pasture to bioenergy crops meant it was still a disaster for ecosystems, resulting in a near 40% drop in biodiversity on farmland, their results showed.
Either way the model suggests the outlook is not good for biodiversity. If we fail to tackle global warming then climate change will take its toll but if we tackle climate change then our super-efficient farms will wipe out wildlife. That said, it isn’t all doom and gloom. There are less destructive ways of improving agricultural efficiency, such as biochar production, minimizing food wastage, recycling manure and sewage, and hi-tech fertilizer-application systems (with precise timing and delivery, for example). “I think what is really important is that we focus on the fact that farming is not only about increasing yields year on year, but is also about managing a swathe of ecological processes,” said Powell.
- Scenarios for future biodiversity loss due to multiple drivers reveal conflict between mitigating climate change and preserving biodiversity Thomas W R Powell and Timothy M Lenton 2013 Environ. Res. Lett. 8 025024
- ERL Focus on Biodiversity, Human Health and Well-Being
- Tom Powell, Department of Geography, University of Exeter
- Tim Lenton, Chair in Climate Change/Earth Systems Science, University of Exeter
- Biodiversity and global health – hubris, humility and the unknown
- Revealed: the keys to reducing the impact of agriculture on climate change
- Pesticides significantly reduce biodiversity in aquatic environments
- Small-scale farming could boost tropical biodiversity
- Preserving biodiversity can be compatible with intensive agriculture
About the author
Kate Ravilious is a contributing editor for environmentalresearchweb.