Multiple metrics of climate change reveal unappreciated impacts on biodiversity

A new study has shed fresh light on how climate change will affect global biodiversity by exploring different measurements of climate change together.

Scientists use climate change metrics, such as changes in seasonality or the emergence of new climates, to predict how climate change will impact biodiversity levels. These climate change metrics are typically studied in isolation, so it is difficult to accurately predict how changes in climate might impact levels of biodiversity.

For the very first time, a study published today in the journal Science has compared climate change metrics together, instead of in isolation, on a global scale, to look at how biodiversity will be impacted.

This unique comparison reveals that when multiple dimensions of climate change are studied together, different regions emerge as threatened by different aspects of climate change.  For example, this new research predicts that tropical areas are set to experience novel climates, much hotter than today’s tropical climates, that are not currently experienced by species anywhere on Earth. Such climates are projected to affect up to 62 per cent of the world’s tropical areas.

Lead researcher Professor Miguel Araújo, from the Department of Life Sciences at Imperial College London, said: “Polar regions have gained substantial attention because they are experiencing a very high temperature increase. Polar climates will shrink by up to 66% in area, providing reduced habitat for arctic and subarctic species, but climate change is more than melting ice. Warming in the tropics will create entirely novel climatic conditions, owing to increased temperatures. Whether species will be able to adapt to them is an open question. By building an overall picture of the likely changes in climate and the ways in which these changes will affect biodiversity, as we have in our new research, we can get a much more rounded insight into how the world’s species are likely to be affected.”

The researchers argue that understanding this contrasting, but complimentary, information is crucial to understanding the threats and opportunities for biodiversity. They hope this will ultimately improve natural resource management and conservation efforts.

The results published expose the complexities of climate change effects on biodiversity and the challenges in predicting and preserving natural ecosystems in a changing Earth.

To examine how changes in temperature and precipitation could impact the biological diversity of the planet, the scientists reviewed the most commonly used climate change metrics used in biodiversity assessments and applied them to 21st century climate projections using 15 climate change models used by the IPCC (Intergovernmental Panel for Climate Change). The scientists also present a conceptual framework that describes the links between climate change metrics, and their resulting climate change patterns, and expected threats and opportunities for biodiversity.

The study is the first to provide a detailed global overview of the threats and opportunities for biodiversity arising from different measurements of climate change. Raquel Garcia, the first author and a researcher from the CSIC National Museum of Natural Sciences in Madrid and the University of Copenhagen, said: “Climate change can be measured in many more ways than is traditionally done in studies of climate change impacts on biodiversity. For example, we can measure whether extreme events will become more or less extreme, whether given climatic conditions will become more or less available, and how far climatic conditions will move from their current locations. When we compare this variety of measurements into the future, it becomes apparent that biodiversity will experience different climatic challenges in different regions. Extreme warming and drying events, for example, are projected to mainly affect the tropics, causing a severe threat for sensitive species. When we consider how far the current climatic conditions will move, the distance is greatest in some regions of cold and polar climates. Species in such regions will thus face greater difficulties in tracking the types of climates they have adapted to.”

The results of the study emphasise that there is not a ‘one size fits all’ way to address the impacts that climate change will have on levels of biodiversity. Professor Carsten Rahbek, co-author of the paper from the Department of Life Sciences at Imperial College London, said: “These results provide us with a much more nuanced picture of the implications of climate change for biodiversity. Although climate change is a global phenomenon, it is expressed in many different ways, varying from region to region and thus there is no single cure to apply to all areas.

“We need to consider the consequences according to the main regional effects. The good news is that the better we understand the implications of climate change, the better we can design management actions to preserve biodiversity and ecosystems,” concluded Professor Rahbek, who is also Director of the Center for Macroecology, Evolution and Climate at the University of Copenhagen.

Professor Araújo who also holds a joint appointment with the CSIC National Museum of Natural Sciences in Madrid and a temporary visiting appointment at the University of Copenhagen highlights why accurate predictions are crucial for responding to changes in biodiversity: “Scientists are still far from being able to accurately predict the impacts of global environmental changes on biodiversity and ecosystems worldwide. It is extremely difficult to predict the future effects of climate change on species and ecosystems because there are so many complex factors involved. This new research will help us to better understand the complexities of climate change and what climate change is likely to mean for biodiversity on our planet.”

The study is an outcome of an international collaboration involving the Grand Challenges in Ecosystems and Environment based at Imperial College London, the CSIC National Museum of Natural Sciences in Madrid, and the Universities of Copenhagen, Évora, and Helsinki.