Greenhouse gas emissions must be reduced by half by 2050, the IPCC warns in its latest synthesis report. The document should be based on sober research – but it covers up central contradictions.
Under huge attention from the global media, the IPCC has published three comprehensive reports in the last 13 months, which set out the most recent climate science. Now the final report has been published.
In Copenhagen, the UN has published the IPCC Synthesis Report, which gathers the most important information of its last three climate reports. It does not contain any new knowledge. Coming to almost 120 pages, it is about as long as the summaries of the three previously published climate reports together, all titled “Summaries for Policymakers”.
Why do the three summaries have to be rewritten and compiled again?
The synthesis report is intended as a “roadmap” for policymakers , IPCC chairman Rajendra Pachauri said at the start of the deliberations on Monday in Copenhagen. The document should help delegates to come to an agreement on a global climate treaty at the UN climate negotiations. “We still have time to create a better, more sustainable world,” Pachauri said.
There remains only little time to prevent a warming of two degrees Celsius, Pachauri announced as the report was released. It would be necessary to reduce CO2 emissions by 40 to 70 percent by 2050. During the next three decades, climate change could be slowed at “acceptable cost”, the IPCC said.
According to IPCC calculations, global growth would not be “strongly affected” by the costs of reducing CO2 emissions. Even “ambitious” measures would only cost 0.06 per cent per annum of world consumption in the 21st century, while an annual growth of between 1.6 and three per cent is expected. However, should something not be done quickly, costs would rise sharply, the IPCC warned.
“The international community must now do everything possible to adopt an ambitious climate agreement, a further delay would be irresponsible,” said the German Environment Minister Barbara Hendricks (Social Democrats, SPD).
But while previous climate reports by and large showed the current state of science with all its contradictions, the new synthesis report omits significant scientific findings. This is particularly noticeable for predictions about the most complex environmental areas, such as grain production, energy usage or armed conflicts.
This distortion is particularly evident in the statements about the predicted extinction of species.
Crass statements appear in the 40-page executive summary of the report for policymakers. In two places, the extinction of species is discussed (pages 10 and 13). The notion there is exclusively of high risks; the considerable uncertainty of the forecasts and serious gaps in knowledge on the subject are not mentioned – are they not relevant for policymakers?
The new Synthesis Report says this about the prediction:
A global warming of four degrees or more since the beginning of industrialization (one degree has already been reached) implies a high to very high risk of significant biodiversity loss which would increase the rate of species extinction. The forecast modelling is given “high confidence.”
On the other hand, the experts in the respective chapter of the IPCC 5th Assessment Report states:
Climate models cannot represent various key processes of the evolution of species, which significantly affect the vulnerability of species to climate change. For example: The ability of adaptation of genetic and external features to new environmental conditions, the ability to spread to new habitats, the dynamics of populations, the effects of fragmentation of habitats, the interaction of communities, micro-refuges, the effect of rising CO2 concentrations on vegetation (pages 299/300).
The Synthesis Report relies on evidence from the past:
The current and predicted rate of climate change is much faster than natural climate change events during the past million years, which have already triggered significant species extinctions. Therefore, there is a strong basis for the assumption that climate change is a risk to living organisms (pages 14 and 25).
However, the thematic chapter of the IPCC 5th Assessment Report states:
Paleontological data from the past hundreds of thousands of years show very low extinction rates during major climatic fluctuations. This evidence may indicate that the predictions of very high extinction rates may be exaggerated. At the end of the Ice Age, there were climate changes of ten degrees Celsius within 50 year in major parts of the world, which is 20 times faster than in the 20th century – greater climate-induced extinctions are not documented. Perhaps because the climate variability mainly affected higher latitudes (pages 432ff).
The Synthesis Report says this regarding specific scenarios:
The expected extinction is caused by various climate phenomena such as warming, shrinking rivers, ocean acidification and oxygen depletion in waters. The cause of extinction is both the speed and the strength of global warming (page 26)
Some species with limited adaptive capacity, particularly in the Arctic and in coral reefs, are already threatened with a warming of two degrees compared to the current climate (page 29).
In technical chapter of the 5th Assessment Report, however, it says:
Studies since the last IPCC Report (2007) have challenged the ability of climate models to predict the future risk of species extinction. The results of the models vary widely and are difficult to check. The uncertainties could be larger than shown in models because essential factors are not taken into account (pages 295, 299, 300).
While the 2007 IPCC Report still predicted that a global warming of two to three degrees threatened to cause the extinction of 20 to 30 per cent of animal and plant species, the new climate report no longer makes any concrete predictions – the uncertainties are too large (pages 299/300). This does not mean there is no risk; it simply indicates a significant lack of knowledge.
The Synthesis Report says this about already extinct species:
Numerous species have already shifted their ranges and seasonal activities due to climate change. However: climate change could have played a role only in a few cases of species extinction (page 14).
The technical chapter of the 5th Assessment Report, however, states:
There is low confidence in the conclusions that some species could have already become extinct due to climate change, for example the disappearance of Central American amphibians (page 300).
However, just recently it was reported that a snail, which had supposedly died because of climate change, has resurfaced. The generally higher rate of extinction of species in recent decades has reasons other than climate change, as the experts make clear: agriculture, deforestation, hunting and fishing, for example (pages 295/300)..
The main climate risks:
The underlying state of climate science, which is summarized in the Synthesis Report, nevertheless remains worrying. The greatest climate risks, according to the IPCC, are:
* Unabated emissions of greenhouse gases would probably heat the climate by 0.3 to 4.8 degrees by the end of the century – depending on how much greenhouse gases are still emitted and how much water vapor, clouds and other factors affect the climate.
* More heat waves. In large cities, heat stress could become a problem.
* Sea levels could rise for centuries. By the end of this century, there was a risk of sea level rise by 26 to 82 centimeters, depending on how much greenhouse gases warm the world, the IPCC warns.
* Many glaciers, which serve as drinking water sources, could completely disappear. The sea ice in the Arctic could suffer substantial losses.
* The oceans could become acidic, organisms would struggle to form their shells.
* Climate zones may shift. In the subtropics and adjacent regions such as the Mediterranean, therefore, there could be more frequent droughts.
* In the tropics and in mid-latitudes, such as Germany, there would be more heavy rain – a problem especially for large cities with poor drainage and villages along rivers.
The IPCC scenarios on the following topics are subject to extreme uncertainty:
* Wars and refugees
* Nutrition and harvest
* Economic Development
Translation Philipp Mueller