The next climate conference is to start in Doha, Quatar this Monday – but already before it is started, participating parties are not really optimistic about a practical outcome.
This is especially striking when set into relation with the urgence of the world’s situation: First opinions come up claiming [german languange link] that it is not realistic anymore to limit global warming to plus two degree Celsius when compared to predindustrial level.

In this context, the World Bank released a new report last week. Written by the Potsdam Institute of climate change, they again outline what is to happen with the worlds (eco)systems in a +2 degree-world – and forecast what is to happen in a +4-degree world.

Put in simple matters: Consequences of additional four degrees won’t just be an extension of what is felt at two degrees. Naively one could guess that as temperature doubles from two to four degrees, effects “double” as well. But that is not the case. They amplify even more intense.

To give you an impression of what to expect in a +4 degree world, we have summarized the most important facts.

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With the world expecting to celebrate world records at the London Olympics from today, the weather in recent weeks has delivered many high scores we should be less happy with:  Record breaking high temperatures in the USA, droughts in Canada or deadly floods in Russia are just the most prominent examples.

Now there’s more. This summer, ice in arctic regions has been melting more extensively than ever seen before.

NASA scientists reported that in mid-July a whopping 97 percent of Greenland’s ice surface was melting. While the amount of surface melting can change extensively and in a matter of days (depending on the temperature of the air above), it’s never been observed to cover that large an area in more than 30 years of satellite observations.

Is this just a freak event or global warming in action? Scientists are careful not to draw a direct link between extreme weather events and climate change. For good reason: Some phenomena may not have been observed before, but scientists are not surprised to see them regardless of a global warming. Cores drilled out the Greenland ice sheets can help recover the temperature history for the place and indicate that extreme melting  regularly occured every 150 years or so. This summer’s thawing episode is “right on time”, says one NASA glaciologist.

But the accumulation of extreme weather events is something you would plausibly expect under conditions of global warming, says Global Ideas climate expert Anders Levermann of the Potsdam Institute of Climate Impact Research. Even then, “we can’t say what the further impacts will be,” he cautions. In the case of Greenland “we don’t know what a period of extreme melting actually means except that in this moment more water is being lost and the water level is rising.”

Taking a long hard look at individual regions, however, can help establish more direct links between regional trends and global warming. At least 70 percent of the reduction of Arctic sea ice over the last 30 years may be man made suggests a study by a British-Japanese team of scientists. Here’s how the lead author puts it: