‘This is not about ducks and daisies, but the very basis of life’
By Summit Voice
FRISCO — As many as 500 million people could face water shortages in the coming decades, as a warming climate affects global water supplies.
“We managed to quantify a number of crucial impacts of climate change on the global land area,” said Dieter Gerten, of the Potsdam Institute for Climate Impact Research.
Mean global warming of 2 degrees Celsius, the target set by the international community, is projected to expose an additional 8 percent of humankind to new or increased water scarcity. If global temperatures increase by 3.5 degrees Celsius, shortages would affect 11 percent of the world population.
“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 said. “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.
Another study shows how the planet’s green areas are likely to affected.
“The area at risk of ecosystem transformation is expected to double between global warming of about 3 and 4 degrees,” said 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.
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,” said 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,” said Wolfgang Lucht, one of the authors and co-chair of PIK’s Research Domain of Earth System Analysis. “This is not about ducks and daisies, but the very basis of life.”
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,” said Hans Joachim Schellnhuber, one of the co-authors and director of PIK.
The impacts might be 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.