It was the scientific culmination of a year during which the Intergovernmental Panel on Climate Change (IPCC) has held a steady series of press conferences. The international group of global warming experts presented its 2007 World Climate Report to the world in four stages.
The first three courses were served up in February, March and May: it was heavy fare that caused widespread stomach ache because the reports made absolutely clear how much of a danger climate change poses. Now, in the Spanish city of Valencia, came a fourth course in the form of the Synthesis Report. But anyone who thought the fourth course would round off the opulent menu with gusto was greatly disappointed.
If one reads the 23-page "Summary for Policymakers" line for line, then it is clear that this report is merely summarizing what has already appeared in the first three reports.
Quite a few climate researchers had been hoping that Part IV would go beyond that and comprehensively demonstrate what can be deduced from the knowledge about climate change (Part I), its consequences for the ecosystems and human society (Part II) and the possible measures to be taken against it (Part III). But above all the IPCC has failed to point out in the conclusion of its publication marathon that the 4th World Climate Report is likely to have been overtaken on many points. And that the problem is even more serious than the 3,000 page main report indicates.
The allegedly new climate bible is not even up to date. It dates back to the middle of 2006. The IPCC authors and experts looked at and assessed all the scientific literature in the field of climate research that had been published by that date. That had been the deadline from the beginning. But 15 months have passed since then.
And more recent reports, which were not mentioned in the Synthesis Report, mean that the picture the IPCC paints may in fact be too rosy:
- The global CO2 emissions from the burning of fossil fuels are increasing faster than ever. Since 2000 they are averaging a growth of more than 3 ppm (parts per million) a year. In previous decades the average was only 1.3 ppm. "Recent emissions seem to be near the high end of the fossil fuel use scenarios used by the Intergovernmental Panel on Climate Change (IPCC)," says Michael Raupach, the Australian physicist and leader of the Global Carbon Project.
- Around half of the anthropogenous CO2 emissions don't remain in the earth's atmosphere and are absorbed by the oceans and by plants. But these natural carbon reducers may have been overestimated. The forests of the mid-range and high northern latitudes probably absorb 40 percent less carbon dioxide than climate change calculations estimate, according to a multinational study recently published in Science magazine. Kevin Gurney, climate researcher at Purdue University in West Lafayette in the US, said it was wrong to assume that the biosphere will somehow come to the rescue. Trees can't absorb that much additional CO2, he said.
- Scientists are also taking a more cautious view of how much help the world's oceans can provide. Current measurements show that the North Sea's capacity to absorb CO2 is already declining. Belgian, Dutch, Canadian and US researchers referred to a "rapid decline in CO2 buffer capacity" in the Global Biogeochemical Cycles magazine. Other studies see a similar development in the entire North Atlantic.
- There is a steady decline in sea ice in the Artic Ocean each summer. At the beginning of October the National Snow and Ice Data Center (NSIDC) reported a new record low for 2007. The entire ice surface amounted to just 4.3 million square kilometers -- 23 percent down from 2005, the previous record season. The legendary Northwest Passage was found to be free of Arctic ice. The NSIDC researchers now expect the Arctic to be free of ice during the summer from 2030 onwards -- decades earlier than forecast in the climate projections referred to the new IPCC report which foresees ice-free Arctic summers in the latter part of the 21st century.
- The IPCC forecast for the further rise in ocean levels -- between 18 and 59 centimeters by 2099 depending on the level of CO2 emissions -- also looks too conservative now. A number of researchers say the figures need to be revised upwards because they fail to take an important aspect into account: The water flowing into the sea from melting glaciers will add to the rise in sea levels. The IPCC hasn't quantified that effect because it's unclear how strong it will be.
IPCC head Rajendra Pachauri recently said that even if the world community succeeds in reducing CO2 emissions from 2015 onwards, ocean levels will rise by between 0.40 to 1.40 meters over the long term, maybe not in the 21st century, but a bit later. That shouldn't calm climate fears though. The climate reacts extremely slowly and carbon emissions to date suffice to cause deep changes.
That too is an aspect the IPCC report only mentions briefly in its new global report: according to current studies a certain part of the anthropogenous greenhouse gases will remain in the earth's atmosphere for thousands of years -- and impact the climate for half an eternity.