Anders Levermann on geopolitics of climate change
Professor at Germany's Potsdam Institute for Climate Impact Research, Anders Levermann's interests range from monsoon in India to glacier melt in Antarctica. He has contributed to the fourth assessment report of the Intergovernmental Panel on Climate Change released last year. He talks to Mario D'Souza on the geopolitics of climate change
Climate change is for real
The indicators state the obvious. The global mean temperature is increasing, glaciers and sea ice in the Arctic are retreating and sea levels are rising.
Tipping point
Tipping point refers to a critical threshold, a point at which even a tiny change in a system can have large and long-term consequences. In case of climate, the change we see appears to occur at a slow and gradual pace on human time scales.But in some cases, human activities may induce an abrupt and irreversible change. Scientists have identified nine such elements that are sensitive or may tip in response to anthropogenic-induced climate changes. Of the nine, the Arctic sea-ice and Greenland Ice Sheet sub-systems have been identified as the two most sensitive tipping elements.
Not anthropogenic?
A molecule of carbon dioxide would be my counter argument to those who say climate change is not due to anthropogenic activities. We can calculate the molecule's absorption spectra (amount of radiation absorbed by the molecule), which gives the greenhouse effect (when an atmospheric gas molecule like carbon dioxide absorbs radiation, it traps a part of the radiation, which leads to warming, called the greenhouse effect). So we don't need any assumptions here.
More evidence
There is feedback in the climate system which is fundamental. The water vapour feedback, for instance. It says for every degree of warming you will get an additional 7 per cent of water vapour, which is a very strong greenhouse gas. So it's from such first principles that we know that carbon dioxide is going to increase the global temperature. Global warming is not climate behaviour over the past 100 years; it is something more fundamental