Rising surface temperatures due to climate change could have grave consequences for human life. An international group of scientists has pinpointed 41 specific places around the globe where abrupt temperature changes could trigger natural disasters affecting ocean currents, sea ice, snow cover, tundra permafrost and terrestrial biosphere. The scientists cite environmental neglect and over-exploitation of the Earth's resources as the main contributing factors.
These "global warming tipping points" include regions that host critical elements of Earth's planetary system, such as the Amazon forest and the Tibetan plateau. While none of the areas implicated in the study are located near any major cities, the potential impact to the planet could still be grave, as they could cause a domino effect that would intensify the risk of climate change and have dramatic impacts on ecosystems and biodiversity, which in turn could affect human civilization.
Published online earlier this month in the Proceedings of the National Academy of Sciences (PNAS), the study is the "first systematic screening of the massive climate model ensemble" that was presented in reports for the 5thIntergovernmental Panel of Climate Change (IPCC), the United Nations body that supports the ongoing efforts to establish an international treaty on climate change. The research team included meteorologists, oceanographers, climatologists, ecologists, and environmental scientists from the United Kingdom, the Netherlands, Germany and France.
The researchers report evidence of "forced regional abrupt changes in the ocean, sea ice, snow cover, permafrost and terrestrial biosphere that arise after a certain global temperature increase." Even more worrisome is the fact that their research casts some doubt on the generally accepted goal of keeping the increase of global surface temperature to a maximum of 2° Celsius, as they found that 18 of the potential disaster events occur at global warming levels below the 2° "safe limit" threshold.
These abrupt ecosystemic shifts, which are caused by an increasing global mean temperature change, suggest the "potential for a gradual trend of destabilization of the climate."
Study co-author Victor Brovkin noted that these abrupt climactic events might lead to natural disasters. “Interestingly, abrupt events could come out as a cascade of different phenomena,” added Brovkin, a meteorologist at the Max Planck Institute for Meteorology in Hamburg, Germany. “For example, a collapse of permafrost in Arctic is followed by a rapid increase in forest area there. This kind of domino effect should have implications not only for natural systems, but also for society.”
We are already witnessing such impacts in the form of droughts, wildfires,more frequent and intense storms and other forms of extreme weather.
Specific examples of "climate tipping" include sudden movements of sea ice and changes in ocean circulation, which is Earth's "conveyor belt" that maintains a stable climate. In addition, the scientists detected evidence of sudden alterations in vegetation and marine productivity, which could impact regional and even global food security. With demand for food on target to increase 60 percent by 2050, when the human population is expected to reach 9.6 billion, it is critical to assess the impact of climate change on agricultural production. U.N. Secretary-General Ban Ki-Moon has called for "climate-smart" agriculture to maintain global food security through a rapidly changing climate.
Sybren Drijfhout, the study's lead author, said that the study "illustrates the high uncertainty in predicting tipping points." Drijfhout, a professor at the National Oceanography Center at the University of Southampton in the United Kingdom, added, "More precisely, our results show that the different state-of-the-art models agree that abrupt changes are likely, but that predicting when and where they will occur remains very difficult. Also, our results show that no safe limit exists and that many abrupt shifts already occur for global warming levels much lower than two degrees."
“The majority of the detected abrupt shifts are distant from the major population centres of the planet, but their occurrence could have implications over large distances.” says Martin Claussen, director of the Max Planck Institute for Meteorology and one of the co-authors. “Our work is only a starting point. Now we need to look deeper into mechanisms of tipping points and design an approach to diagnose them during the next round of climate model simulations for IPCC.”