Two days ago a wrote a post about Swedish scientist Lennart Bengtsson denouncing alarmist climate science. The original source of that story was a letter that Bengtsson and 3 other climate scientists had published at Sweden’s daily newspaper Dagens Nyheter.
What follows is the letter that Bengtsson and the 3 other scientists had published January 21, 2013 by the Swedish major daily newspaper Dagens Nyheter in English (my emphasis):
Misinterpreted climate report threatens the credibility of scientists
The World Bank’s recent climate report was not saying that we necessarily face an extreme global temperature increase – but was about the potential consequences of such. It is one of several examples of how climate information can be misinterpreted and ultimately damage the credibility of researchers, writes leading climate scientists.
Recently, the World Bank published a report entitled ‘Turn down the heat: Why a 4° C warmer world must be avoided’.
The report received wide media exposure with its dramatic title, and in that it was the World Bank, which published it. The Bank had commissioned a German institute in Potsdam to write the report. It does not contain an analysis of the Earth’s climate, but primarily deals with the consequences of a supposed global temperature rise of 4°C. No detailed analysis was made of the probability of such a change. This was not clear in the Swedish debate.
As a warming of 4°C during this century is extremely worrying, it is important to try to assess how reasonable such a strong warming is. Individual model simulations have calculated global warming by 2100 of +6°C or more, but these have been deemed highly unlikely by the UN climate panel (IPCC 2007). The slow global warming, especially over the past 15 years, has reinforced this view.
Since the 1800s, the concentration of carbon dioxide along with other greenhouse gases have increased by about 75 per cent. Meanwhile, the earth’s average temperature has increased by about 0.8°C. Such a temperature increase is much smaller than the model calculations provide and only takes into account the increase in greenhouse gases as the cause. There may be compensatory cooling from aerosol particles, but systematic errors in the model calculations can not be excluded.
There is great uncertainty over how sensitive the climate system is to human influence and thus how high the carbon content must be to provide a warming of 4°C. Even with a high climate sensitivity a level of at least 1000 ppmv is probably required. This would require annual carbon emissions significantly higher than today.
An increase in temperature leads to an increase of the amount of water vapour in the atmosphere. This leads to a climate with more extreme precipitation with a tendency for increased precipitation at high latitudes and in the equatorial region and reduced rainfall in many parts of the areas just outside the tropics. One exposed area is the Mediterranean region. Given the dominant natural variations in the weather from year to year, it is not yet possible to reliably determine whether a systematic change in precipitation has occurred.
The increase in sea level is a result of ocean thermal expansion and mass contribution from melting of mountain glaciers and land ice. The increase based on recent satellite measurements amount to an average of about 3 mm/year (approximately 2 mm/year due to water mass addition, about half from mountain glaciers and the other half from land ice).
During the past 20 years, no acceleration of the increase of the sea level occurred. No apparent relationship between sea levels and global temperature changes during the 1900s appears to exist.
Extreme weather events create a great deal of attention because of the loss of life and extensive economic damage. With a generalized global warming, one can expect more extreme high temperatures, but also fewer extremely low temperatures, for which there are now indications.
Tropical storms are often attributed to global warming. Current examples include Hurricane Sandy that plagued parts of the U.S. East Coast in late October 2012 and the typhoon Bopha that hit the Philippines a month later.
The mass media conveyed in many cases the perception that these tropical hurricanes were a result of the greenhouse effect. But there are no indications of an increasing trend in the intensity or number of tropical hurricanes. The large increase in damage caused by severe storms in different parts of the world is caused mainly by people increasingly living and working in more exposed locations.
The most obvious consequences of climatic change during the last decades is the melting of mountain glaciers over most of the earth and of summer sea ice in the Arctic.
Although it is not entirely inconceivable that similar reductions may have occurred in previous centuries, it is likely that the reduction of summer sea ice in the Arctic is unique. Model calculations support the view that this is linked to an increasing greenhouse effect.
In summary, we believe that a temperature increase of as much as 4° C during this century is very unlikely. Nor is there any basis for claims that tropical hurricanes have become more extreme and more frequent.
We believe that the media, instead of blowing up the results of individual publications should give special attention to the specific international organization – IPCC – which by the international community has been charged with the continuous and comprehensive synthesis of a large body of research on the climate thus putting individual reports like the The World Bank’s in a larger perspective. The next IPCC assessment will be published in September 2013.
We want to use this article in no way to detract from the problem of global warming and its possible consequences. We only want to warn that misguided information may have the effect that the credibility of scientists can be questioned and that measures to deal with climate change may receive the wrong priorities. The Royal Swedish Academy of Sciences has in their analysis of energy issues assumed that reducing carbon emissions will have high priority in global politics and that very large investments over time are needed to replace fossil fuels with sustainable alternatives.
Society must also be prepared for climatic changes in order to protect the population against extreme weather events and systematic changes in climate, whether as a result of global warming or not.
Signed by the following four climatology scientists and members of the Royal Swedish Academy of Sciences: Lennart Bengtsson, Deliang Chen, Marie-José Gaillard, Henning Rodhe.
Translation by LRG Jan 22, 2013. Source of the letter: donnerunddoria.welt.de/zu-viel-alarmismus671 (Ulli Kulke’s blog at Die Welt)