MEXICO: It is true that there has been a warming hiatus and that the surface of the earth has warmed up much less rapidly since the turn of the millennium than all the relevant climate models had predicted.
However, the gap between the calculated and measured warming is not due to systematic errors of the models, as the sceptics had suspected, but because there are always random fluctuations in the Earth’s climate. Recently, Jochem Marotzke, Director at the Max Planck Institute for Meteorology in Hamburg, and Piers M. Forster, a professor at the University of Leeds in the UK, have impressively demonstrated this by means of a comprehensive statistical analysis. They also clearly showed that the models do not generally overestimate man-made climate change. Global warming is therefore highly likely to reach critical proportions by the end of the century – if the global community does not finally get to grips with the problem.
Climate is subject to chance and chaos – which makes life difficult for climate researchers. No wonder that these two unpredictable climate factors lie at the root of a mystery that has baffled scientists since the start of the 21st century. Since then, the temperature of the Earth’s surface has increased by only around 0.06 degrees Celsius – much less than had been predicted by all 114 model simulations considered in the climate report by the IPCC. Jochem Marotzke and Piers M. Forster have now explained the warming pause in terms of random fluctuations arising from chaotic processes in the climate system. Even more importantly for the two researchers and their colleagues around the world: they did not find any conceptual errors in the models. Most notably, the models do not generally react too sensitively to increases in atmospheric carbon dioxide.
The claim that climate models systematically overestimate global warming caused by rising greenhouse gas concentrations is wrong,” says Jochem Marotzke. Climate sceptics often make precisely this claim, citing the warming pause as evidence. Yet they cannot deny that nine of the ten warmest years since systematic climate observations began have occurred in the new millennium and that global warming has slowed at a very high level. The sceptics also ignore the fact that ocean temperatures continue to rise as rapidly as many models have predicted.
