The Consequences of Climate Change - the 2007 UN Report on Global Warming

Environment

11.11.2008

by Philip Bahnse

Dossier index

Copenhagen 2009

Political will... or won´t
Carbon conscience
- Europe's satellite leads climate change study
Copenhagen atmosphere - the Euranet blog
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- Climate change in Spain: Desertification
- The Consequences of Climate Change - the 2007 UN Report on Global Warming
- Climate change in the Netherlands: Flood protection
- Climate change in Cyprus: Battling drought
- Climate change in Slovenia: Rising snow lines

Climate change is a fact and it is man-made. These were the conclusions reached by the Intergovernmental Panel on Climate Change (IPCC) in 2007. Today, almost twice as many greenhouse gases are pumped into the atmosphere as in 1970. The IPCC noted that these greenhouse gases are most likely the reason that the Earth is gradually heating up. The consequences are varied and dramatic.

"The goal is now to avoid warming of more than two degrees Celsius. If we go beyond two degrees, then the overall damage will be so large that no one will be able to contain it, "says Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research .

Wolfgang Lucht, professor of biosphere dynamics and one of Mr Schellnhuber’s colleagues, was a contributor to the IPCC report. Mr Lucht warns that entire ecosystems are threatened by climate change: "Simulations using the highly regarded British climate model from the Hadley Centre show that during the 21st century rainfall, especially in the Amazon region, could fall to such levels that the tropical rainforest as we know it will die out because of lack of water."

The Rio Tambopata in the Amazon is one of the regions with the highest density of species on our planet - but for how long?

Photo: pixelio.de /Rebel

Poor countries worst hit

There is no doubt that the incidence of the extreme weather events will increase. Large parts of Africa and the Mediterranean region will be affected by droughts, while other regions will have to struggle with heavy rain and floods. The already poor nations of the world have to bear the brunt of the damage caused by climate change.

For a long time the scientific community believed that the positive consequences of climate change would mitigate the environmental damage. The IPCC report considers this to be very unlikely. One reason is the unexpectedly sharp rise in sea levels. Earlier estimates predicted a rise of not more than one metre. This prediction is now obsolete. Hans Joachim Schellnhuber assumes that coastal areas all over the world will be flooded: "We must prepare ourselves for a sea level rise of one metre this century. This is connected to the accelerated melting of the Himalayan glaciers and the Greenland ice cap."

Killer soot particles

Rising sea levels are leading to flooding in many regions.

Photo: pixelio.de/Thomas Max Müller

It is not just greenhouse gases such as methane, CO2 or nitrous oxide that are causing global warming. According to recent research, air pollution significantly warms our atmosphere as well. The main culprits are soot particles, according to Hans Joachim Schellnhuber.

Twenty percent of the particles that settle on the Greenland ice sheet, making it greyer and thereby causing it to absorb more heat, originate from Chinese coal-fired power plants. "If the surface is no longer so white, it reflects sunlight to a lesser extent, gets warmer and melts even more quickly," says Schellnhuber. The same is true of the Himalayan glaciers. "That means that air pollution plays a massive role in accelerating the pace of climate change," he states.

Global warming is driven by greenhouse gases like CO2.

Photo: Verena N.

A mixed blessing

However, the soot particles are not all bad: While on one hand, they heat up the earth, on the other hand, they cool down the atmosphere. For when they are up in the sky, the particles reflect sunlight and thus have a cooling effect, the US climate scientist Veerabhadran Ramanathan of the University of California explains. He predicts that if all soot particles – known as aerosols - were removed from the air by the use of modern technology, the Earth would warm even more quickly than predicted by the IPCC.

"If you take all the data collected by the IPCC, I have come to the conclusion that we have already emitted so much greenhouse gas into the atmosphere that this will cause a rise in temperature of 2.5 degrees Celsius," says Mr Ramanathan. This is above the two-degree mark, which the European Commission designated as being the threshold for dangerous climate change.

"But I am not saying that we should keep these dirty aerosols in the atmosphere to protect us from the warming of the earth. My work indicates that the cleaning of the air of aerosols will increase the urgency to reduce emissions of greenhouse gases," he adds.