Extreme weather events such as heat waves and droughts but also longer cold periods will occur more frequently in the future, scientists warned at a conference in Paris. They want world leaders at the climate conference at the end of this year to agree to halve global CO2 emissions by 2050, writes Elke Bunge.
Weather stations in Paris recorded 40-degree-Celsius temperatures at the end of June, which is unusually hot for this time of year, but this could become the norm if we listen to climate scientists are telling us. 2,000 climate scientists, economists and politicians met in Paris last week in preparation for the upcoming UN climate change conference in December. And their findings are disturbing.
5 times as many heat waves
Scientists at the Potsdam Institute for Climate Impact Research (PIK) evaluated measurements from the last quarter of a century and found that there has been a fivefold increase in the number of heat waves recorded than would have been in a world without human-induced global warming.
“Such heat waves oftentimes lead to droughts and can result in crop losses, forest fires and increased mortality. This trend will continue if greenhouse gases continue unabated,” says Stefan Rahmstorf, an oceanographer and climate scientists who participated at the Paris conference on behalf of PIK.
The other prediction is one of torrential rain. Air masses become warmer not only over land but over bodies of water, too. The consequence is that warmer air can hold more water, which it then releases during short-term heavy rainfall over land.
“We can make a clear connection between global warming and the increase in extreme weather events, such as observed record rainfall,” says Dim Coumou, research director for extreme weather at PIK. Heavy rainfall in Europe increased by 12 per cent since 1980; in some southeast Asian countries that figure jumps to 56 per cent.
Now is the time for solutions
The climatologists, oceanographers, industry representatives and politicians gathered in Paris also dealt with extreme weather phenomenon. The four-day meeting at the UNESCO offices and the University Pierre et Marie Curie (UPMC) aims to develop additional templates for the UN climate conference that will take place in five months.
If carbon dioxide emissions continue unabated, the world can expect global temperatures to rise anywhere from 3.7 degrees Celsius to 4.5 degrees Celsius, say the scientists. “Then we are faced with an irreversible situation,” warns Hervé Le Teur, director of the Pierre-Simon Laplace climate research institute and co-organiser of the conference. “The debate about whether or not climate change exists is behind us. Ahead of us lies the task of seeking joint solutions for the future we want,” says the climatologist.
The targets reached by the Our Common Future under Climate Change conference are clearly and explicitly defined: the ongoing process of global warming and the changes experienced around the world can only be stopped if it we succeed in halving CO2 emissions by 2050. All other targets don’t deal with reality.
An appeal to politicians
The four-day meeting, which explored the latest scientific understanding of all dimensions of climate-change management, from sustainable economic models and social attitudes, to coastal protection projects and renewables, was succinctly summed up in one sentence by the secretary general of the conference Claire Weill:
“We, the researchers and economists who have gathered here, have written a joint appeal to all decision-makers, entrepreneurs, non-governmental organisation, educational institutes, politicians and globally involved scientists that we are calling for a binding climate agreement at COP21, which will take place in December in Paris.”