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-An international team coordinated by the Catalan Water Research Institute (ICRA) shows how the temperature and ice in the lakes have changed in the last forty years, and establishes that only climate change can explain it.
– It is estimated that, at the end of the 21st century, the average warming of the lakes may increase up to 4.0 °C and the duration of the ice layer will be 46 days less.
– The relevance of this study is that for the first time we can rule out that these observed changes are caused by the natural variability of the climate system”, explains Rafael Marcé, ICRA researcher and coordinator of the international network that has made this work possible
The international research, led by the BCLIMATE research group of the Vrije Universiteit Brussel (VUB), shows an average increase of 0.5ºC in the average surface water temperature of the lakes in the last 40 years, and a reduction in the covered period of 10-day ice , as the ice layer forms later and melts earlier. These global changes in temperature and ice cover are not due to natural climate variability and can only be explained by greenhouse gas emissions since the Industrial Revolution. “These physical properties are fundamental to lake ecosystems,” says Luke Grant , VUB researcher and lead author of the study. “Many species are already noticing these changes, and as impacts continue to increase in the future, we risk serious damage to ecosystems, including water quality and populations of native fish species.”
The results of the research, which has been published in Nature Geoscience, also predict future development under different warming scenarios. By the end of the 21st century , in a low-emissions scenario, average lake warming is estimated to stabilize at 1.5°C above pre-industrial levels and ice sheet duration will be 14 days shorter . In a high-emissions world, these changes could lead to an increase of 4.0°C and 46 fewer days of ice .
“The fact that the lakes are warming is something that has been clear to us for a decade or more. The relevance of this study is that for the first time we can rule out that these observed changes are caused by the natural variability of the climate system” , explains Rafael Marcé , researcher at the Catalan Water Research Institute (ICRA) and coordinator of the international network that has made this work possible. To achieve this, the team used a Global Climate Change Impacts Simulation Network (ISIMIP) to run millions of computer simulations, which simulated the temperature and ice in 17,000 of the planet’s lakes under historical climate conditions and future “Comparison of historical simulations with lake data over the past 40 years is conclusive: lakes are warming and ice less and less, and this cannot be explained in any other way than by including induced climate change by man in the simulations,” explains Rafael Marcé.
Projections of temperatures and lake ice cover indicate increasing trends for the future in all models. For every 1°C increase in global air temperature, lakes are estimated to warm 0.9°C and lose 9.7 days of ice cover. In addition, the analysis reveals significant differences in the impact on the lakes at the end of the century, depending on the measures taken by humans to combat climate change. “Our results underline the great importance of the Paris Agreement in protecting the health of lakes around the world,” explains Wim Thiery, VUB climate expert and coordinator of the study. “If we manage to drastically reduce our emissions in the coming decades, we can still avoid the worst consequences for lakes around the world.”
Publication :
Grant, L., I. Vanderkelen, L. Gudmundsson, Z. Tan, M. Perroud, V. Stepanenko, A. Debolskiy, B. Droppers, A. Janssen, IR Woolway, M. Choulga, G. Balsamo, G. Kirillin, J. Schewe, F. Zhao, I. Vega del Valle, M. Golub, D. Pierson, R. Marcé , S. Seneviratne, and W. Thiery. 2021. Attribution of global lake systems change to anthropogenic forcing. Nature Geoscience, https://www.nature.com/articles/s41561-021-00833-x .
