Even if global warming is limited to 2 degrees above pre-industrial levels, 500 million people could be subject to increased water scarcity – while this number would grow by a further 50 percent if greenhouse-gas emissions are not cut soon.
At 5 degrees global warming almost all ice-free land might be affected by ecosystem change. This is shown by complementary studies now published by scientists of the Potsdam Institute for Climate Impact Research (PIK).
“We managed to quantify a number of crucial impacts of climate change on the global land area,” says Dieter Gerten, lead-author of one of the studies. Mean global warming of 2 degrees, the target set by the international community, is projected to expose an additional 8 percent of humankind to new or increased water scarcity. 3.5 degrees – likely to occur if national emissions reductions remain at currently pledged levels – would affect 11 percent of the world population. 5 degrees could raise this even further to 13 percent.
“If population growth continues, by the end of our century under a business-as-usual scenario these figures would equate to well over one billion lives touched,” Gerten points out. “And this is on top of the more than one billion people already living in water-scarce regions today.” Parts of Asia and North Africa, the Mediterranean and the Middle East are particularly vulnerable.
For the green cover of our planet, even greater changes are in store. “The area at risk of ecosystem transformation is expected to double between global warming of about 3 and 4 degrees,” says Lila Warszawski, lead author of another study that systematically compared different impact models – and the associated uncertainties – in order to gain a fuller picture of the possible consequences of climate change for natural ecosystems. This is part of the international Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP).
A warming of 5 degrees, likely to happen in the next century if climate change goes on unabated, would put nearly all terrestrial natural ecosystems at risk of severe change. “So despite the uncertainties, the findings clearly demonstrate that there is a large difference in the risk of global ecosystem change under a scenario of no climate change mitigation compared to one of ambitious mitigation,” says Sebastian Ostberg, lead author of the third study.
The regions at risk under unabated global warming include the grasslands of Eastern India, shrublands of the Tibetan Plateau, the forests of Northern Canada, the savannas of Ethiopia and Somalia, and the Amazonian rainforest. Many of these are regions of rich and unique biodiversity.
The combined changes to both water availability and ecosystems turn out to be nonlinear. “Our findings support the assertion that we are fundamentally destabilizing our natural systems – we are leaving the world as we know it,” says Wolfgang Lucht, one of the authors and co-chair of PIK’s Research Domain of Earth System Analysis.
The studies use a novel methodological approach, introducing new measures of risk based on changes of vegetation structure and flows and stores of carbon and water. To this end, biosphere simulation models were used to compare hundreds of climate change scenarios and highlight which regions may first face critical impacts of climate change.
“The increase in water scarcity that we found will impact on the livelihoods of a huge number of people, with the global poor being the most vulnerable,” says Hans Joachim Schellnhuber, one of the co-authors and director of PIK. This might get buffered to some extent through adaptation measures such as expanding of irrigated cropland. However, such an expansion would further increase the pressure on Earth’s ecosystems and water resources. “Now this is not a question of ducks and daisies, but of our unique natural heritage, the very basis of life. Therefore, greenhouse-gas emissions have to be reduced substantially, and soon.”
Article: Gerten, D., Lucht, W., Ostberg, S., Heinke, J., Kowarsch, M., Kreft, H., Kundzewicz, Z.W., Rastgooy, J., Warren, R., Schellnhuber, H.J. (2013): Asynchronous exposure to global warming: freshwater resources and terrestrial ecosystems. Environmental Research Letters, 8 [doi:10.1088/1748-9326/8/3/034032]
Article: Ostberg, S., Lucht, W., Schaphoff, S., Gerten, D. (2013): Critical impacts of global warming on land ecosystems. Earth System Dynamics, 4, 541-565, [doi:10.5194/esdd-4-541-2013]
Article: Warszawski, L., Friend, A., Ostberg, S., Frieler, K., Lucht, W., Schaphoff, S., Beerling, D., Cadule, P., Ciais, P., Clark, D.B., Kahana, R., Ito, A., Keribin, R., Kleidon, A., Lomas, M., Nishina, K., Pavlick, R., Rademacher, T.T., Piontek, F., Schewe, J., Serdeczny, O., Buechner, M., Schellnhuber, H.J. (2013): A multi-model analysis of risk of ecosystem shifts under climate change. In: Environmental Research Letters (accepted)
For further information please contact:
PIK press office
Phone: +49 331 288 25 07
(Link to the article by Gerten et al)
(Link to the article by Ostberg et al once it is published on Tuesday afternoon)
Jonas Viering | Source: PIK Pressestelle
Further information: www.pik-potsdam.de
More articles from Earth Sciences:
No Undo for Climate Change: Potential Pitfalls of Geoengineering
05.12.2013 | Max-Planck-Institut für Biogeochemie
NASA Sees Rainfall Quickly Fade in Dying Depression 33W
05.12.2013 | NASA's Goddard Space Flight Center
The Light: Global study gets underway with online user survey
Light has a fundamental impact on our sense of well-being and performance. In cooperation with Zumtobel, a supplier of lighting solutions, Fraunhofer IAO has launched a global user survey of lighting quality in offices. The objective is to identify the best lighting conditions for a variety of spaces and lighting ...
Quantum entanglement, a perplexing phenomenon of quantum mechanics that Albert Einstein once referred to as “spooky action at a distance,” could be even spookier than Einstein perceived.
Physicists at the University of Washington and Stony Brook University in New York believe the phenomenon might be intrinsically linked with wormholes, hypothetical features of space-time that in popular science fiction can provide a much-faster-than-light shortcut from one part of the universe to another.
But here’s the catch: One couldn’t actually ...
A star is formed when a large cloud of gas and dust condenses and eventually becomes so dense that it collapses into a ball of gas, where the pressure heats the matter, creating a glowing gas ball – a star is born.
New research from the Niels Bohr Institute, among others, shows that a young, newly formed star in the Milky Way had such an explosive growth, that it was initially about 100 times brighter than it is now. The results are published in the scientific journal, Astrophysical Journal Letters.
The young ...
EPFL scientists have shown how to achieve a dramatic increase in the capacity of optical fibers; Their simple, innovative solution reduces the amount of space required between the pulses of light that transport data
Optical fibers carry data in the form of pulses of light over distances of thousands of miles at amazing speeds. They are one of the glories of modern telecommunications technology.
However, their capacity is limited, because the pulses of light need to be lined up one after the other in ...
NASA's Hurricane and Severe Storms Sentinel airborne mission known as HS3 wrapped up for the 2013 Atlantic Ocean hurricane season at the end of September, and had several highlights. HS3 will return to NASA’s Wallops Flight Facility in Wallops Island, Va., for the 2014 Atlantic hurricane season.
During the 2013 mission, two unmanned Global Hawks flew from Wallops for the first time. The mission highlights included studying the Saharan Air Layer, following the genesis of a tropical storm, finding a unique hybrid core or center circulation in a redeveloped storm, obtaining measurements on the strongest side of ...
05.12.2013 | Health and Medicine
05.12.2013 | Ecology, The Environment and Conservation
05.12.2013 | Information Technology
05.12.2013 | Event News
04.12.2013 | Event News
12.11.2013 | Event News