Bioenergy cropland expansion could be as bad for biodiversity as climate change

European Business & Biodiversity Campaign - News

Bioenergy cropland expansion could be as bad for biodiversity as climate change

Nature is one of the beneficiaries of climate protection measures, among which bioenergy has long been touted as a potential savior. However, to reach the 1.5 degree goal, bioenergy crops will have to be cultivated on a large scale. New models show that this will lead to the destruction of more habitats of vertebrate species than would benefit from lessened climate change effects.

© Christian Hof
The study by researchers from the Senckenberg Biodiversity and Climate Research Centre, the Technical University Munich and the Durham University is published this week in "PNAS." The presumed advantages of such climate protection measures would thus be of no benefit to biodiversity.

To prevent global temperatures from rising by more than 1.5 degrees compared to the pre-industrial era, the amount of carbon released into the atmosphere worldwide must be lowered significantly. Reduced climate change effects also benefit nature, since climate change is among the major threats to species and ecosystems. One of the strategies currently in use is the production of energy using renewable resources such as corn, rape, oil palms, etc., instead of fossil resources.

However – from a biodiversity perspective – this might amount to replacing one evil with another. "In order to limit climate change in this way, we would need to cultivate bioenergy crops on approximately 4.3 per cent of the global land area by 2100 – which corresponds to almost one-and-a-half times the area of all EU countries combined. This would severely affect the biodiversity currently found in these regions. The reduction of the negative effects of climate change achieved by the maximum use of bioenergy is not enough to offset this loss of biodiversity," explains Dr. Christian Hof, who conducted the study at the German Senckenberg Biodiversity and Climate Research Centre and who currently works as a researcher at the Technical University in Munich.

For some time now, bioenergy has been a controversial topic among scientists, and to date it had usually been the subject of studies on individual threats and at small geographical scales. Hof and his team were the first to examine how amphibians, birds, and mammals may become be affected by climate and land use changes from now until 2100 on a global scale. As part of their study, they compared two scenarios: One scenario with maximum use of bioenergy, which corresponds to a warming by approx. 1.5 degree and another with minimum bioenergy use and a rise in temperatures by approx. 3 degrees by the year 2100, compared to the pre-industrial era.

The results are surprising. "Regardless whether the temperature will rise by 1.5 or 3 degrees until 2100, around 36 % of all vertebrate species’ habitats are severely threatened, either by climate change or by the new land use practices involving the cultivation of bioenergy crops. The effects on biodiversity are very similar. The main difference is who ultimately is responsible," says the study’s co-author Dr. Alke Voskamp of the German Senckenberg Biodiversity and Climate Research Centre.

In addition, there are areas where vertebrate species will have to compete with bioenergy plantations for space with and where at the same time they will also have to cope with the rising temperatures. "The reduced temperature increase of only 1.5 degrees that we can achieve through maximum use of bioenergy may actually expose larger areas to this double stressor. Under this 1.5 degree scenario a larger percentage of vertebrates’ habitats will be affected by climate change, land use, or both." explains Voskamp.

Moreover, mitigating climate change through the use of bioenergy crops will likely affect a larger number of vertebrate species with small ranges than would be affected by a temperature increase of 3 degrees. Such vertebrates – primarily amphibians – are mainly found in the tropics and neotropics. And it is these areas that will see the greatest increase in bioenergy plantations.

For Hof and his team, the study is making a definite point: "Climate change continues to be one of the biggest threats to biodiversity and must be limited to a temperature increase of no more than 1.5 degrees, if possible. However, as shown by our study, bioenergy and the accompanying massive expansion of cropland are the wrong approach to this problem. Instead, we need to work harder on developing ways to save energy."

The study is part of the BioScen1point5 project in the program "Support for an expanded and improved scientific basis for the IPCC special report regarding a global temperature increase by 1.5 °C (SR1.5)," sponsored by the German Federal Ministry of Education and Research.

Source: Pressemitteilung Senckenberg Forschungsinstitut und Naturmuseen, 07.12.2018
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