Scientists criticize the UN Climate Report

It looked that the Climate Council of the UN, the Intergovernmental Panel on Climate Change, IPCC, had done it again! When at the end of September, in Stockholm, at the occasion of a pompous press conference, the panel of government representatives and scientists published a 36 page abstract of its 2200 page situation report, its message about threatening changes in the environment reigned over the world’s front-pages; many of its findings do indeed give reason to worry: for instance, its warnings about a sharp rise in the level of the oceans, about frequent heat-waves, the melting of glaciers and increasing acidification of the world ocean.

Three days later, the full 2200 page climate report was published on the Internet, this time without the benefice of a press-conference – and the resonance was weak. Yet, since then, criticism of the climate council has been growing: reputed researchers are independently questioning some dubious discrepancies between the report and its abstract intended for the politicians.

Criticism #1: "It's too optimistic"

One faction believes that the abstract of the report is painting too optimistic a picture. For instance, on the subject of the rising sea levels, the abstract suppresses evidence of studies which project an increase twice as high as the one reported by the IPCC in the abstract, warns Michael Mann of Penn State University in the USA.

So-called semi-empirical models, engineering statistical past correlations between air temperature and water levels have fueled fears that within a century the oceans could rise by two meters – rendering all coastal protection plans obsolete. But the IPCC scientists saw no physical basis for such dramatic predictions: beyond statistics, there are no insights provided by geology which could make one expect a correspondingly rapid melting of the great ice shields.

Then there are the estimations about the thawing of the permafrost which, according to Kevin Schaefer of the University of Colorado in Boulder, USA, are altogether too cautious. Granted that, up until now, the thawing of the permanently frozen grounds in Siberia, Alaska and Canada is getting along at a moderate pace. In the abstract of its report, the IPCC is announcing a receding of the surfaces of the permafrost from 27 to 81 per cent in this century.

But the greatest danger lies in the fact that the thawing releases methane gases which warm up the air as greenhouse gases. The additional heat effect is not captured in the simulations of the IPCC, Schäfer warns, therefore the prognostications are too timid. But the IPCC has only moderate trust in the predictions about the permafrost. It says that the data about the concerned regions is rare.

Criticism #2: "A pretense of having acquired additional knowledge"

Other researchers in turn charge that the climate council is leaving considerable uncertainties in its scenarii unmentioned. Relying on six years’ additional data, the IPCC states that its conviction that man-made emissions are responsible for the greatest part of climate warming since 1950 has increased from 90 to 95%. This estimation has met with the immediate approval of all the governments in the IPCC-plenum, reports Martin Claussen of the Max-Planck-Institute of Meteorology, who was a member of the German delegation in Stockholm. "That’s really remarkable,” he says.

Yet, this politically significant value is not directly upheld by scientific calculations, it was arrived at by means of an opinion poll conducted among a certain number of IPCC researchers, who remain unnamed. Despite the fact that it lacks a statistical basis, “these figures have been employed very accurately,” stresses Michael Oppenheimer of Princeton University in interview with the PBS channel. He was responsible for one chapter in the IPCC-Report and was formerly employed by the Environmental Defense Fund.

Other scientists cast doubt on such accuracy: how can the scientific world be more assured now about the extent of the human share in the responsibility for global warming, when in the past 15 years natural factors have surprisingly brought the warming of the air to a stop, asks climate researcher Judith Curry from the Georgia Institute of Technology, who heads theClimate Forecast Applications Network.

Yet, while the UN climate report admits that the influence of ocean currents, sun and clouds of volcanic ash on the climate has been greater in recent years than had been surmised, the IPCC is more convinced than even before that it is mainly man-made emissions which have changed the climate since 1950 .

Yet, while the UN climate report admits that the influence of ocean currents, sun and clouds of volcanic ash on the climate has been greater in recent years than had been surmised, the IPCC is more convinced than even before that it is mainly man-made emissions which have changed the climate since 1950 .

Criticism #3: "Uncertainties have been hidden."

The IPCC practices „engaged public relations for its own sake,“ says environment scientist Roger Pielke Jr from the University of Colorado in Boulder, USA. On the one hand, the climate council maintains that the data from six additional years have considerably improved the quality of its assessments from one report to the next. On the other hand, a 15-year pause in the warming was apparently not sufficient to be considered of scientific significance.

In the abstract of the IPCC report the word “pause,” or “hiatus” doesn’t even occur. Following the advice of Germany and of a few other countries, merely a “slowing down in the temperature increase” during what was moreover “the warmest decade” since the beginning of measurements was mentioned.

In the full report, the “pause” carries more weight than the abstract of the IPCC report would make one believe. The problem of the 15 year hiatus is openly addressed: "It is specifically mentioned there that only 3 out of 114 climate simulations were able to render the trend of the past 15 years and that the reason for these differences between models and observations remains unclear,” according to climatologist Eduardo Zorita from the Helmholtz-Zentrum for Coastal Research. "This point should have been more clearly exposed in the abstract, for it stresses he fact that important deficits in climate modelling are still not understood. "

Criticism #4: "Good PR, but it is sustainable?"

"I would not give too much importance to the discrepancies between the modelized and the observed temperatures of recent years, especially considering that the oceans are bringing a beginning of an answer,“ declares consiliatorily the renowned polar researcher Heinrich Miller of the Alfred-Wegener-Institut (AWI). Recent studies show that the oceans might have absorbed more heat than was expected; normally they take up nine tenth of the energy to begin with. Still, proof for the additional heat cushion raises difficulties: for it is especially at greater depths that the oceans are supposed to have warmed up – but there are few measurements available from there.

This new situation has moved the climate counsel to address the significance of oceans more prominently. While in the same time displaying differently the evolution of the temperature of the air: while in its earlier reports the IPCC had always put up-front a rising air temperature curve, the graph in the new IPCC abstract, displaying a curve having buckled in the meanwhile, was completed with a ladder graphic, the steps of which are showing that the average air temperature has gotten warmer decade after decade. “That was good PR,” according to climate sociologist Reiner Grundmann of the University of Nottingham, "but is it really sustainable?"

criticism #5: "Failure to deliver un-warnings"

Lack of sustainability is, in Grundman’s eyes, one of the problems of the IPCC report: scenarii from earlier reports were not compared, he criticizes. Warnings from the last report about an increase in extreme events like hurricanes, tornados and storms have meanwhile been rated as being “of little reliability“ – and are no longer mentioned in the new abstract of the report.

"I lift my hat to the IPCC, that they corrected themselves on this,” admits Roger Pielke. "But then", he adds, "why didn’t scientists jump to correct, when President Obama warned recently about hurricanes increasing in numbers?” In consideration of the scant research results, Pieke thinks that the present constant alarm over an increase in river floodings, droughts, hurricanes and tornados is tantamount to “zombie-science.”


That the UN climate counsel may have a problem with the presentation of its results had been adumbrated already at the occasion of the presentation of the abstract. At the press conference in Stockholm, a reporter had dared to put a heretical question to the scientists on the podium, as to why computer simulations had not foreseen the pause in the temperature increase in the past 15 years. Michel Jarraud, the head of the World Meteorological Organization WMO, chided the reporter: “This is not the way the question should be put.”

Maybe the meteorologist lacked training - critical questioning doesn’t really belong to the tradition of press conferences on climate science.

Axel Bojanowski
(Translated from the German by Anne-Marie de Grazia)
Originally published in Der Spiegel

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