With the mainland gripped by its coldest winter since 1951 and northern provinces blanketed by thick snowfall, Chinese scientists are again raising questions about the reliability of a global assessment that forms a pillar of climate change policy. The Fourth Assessment Report by the Intergovernmental Panel on Climate Change in 2007 predicted that global temperatures would increase consistently from 1900 to 2100, roughly in the shape of a hockey stick. Some mainland farmers have suffered severely as government officials use the intergovernmental body's findings as a guideline for long-term agricultural planning. Work on the Fifth Assessment Report is due to begin in six months and follows the failure by world leaders to reach a meaningful agreement at a UN summit on climate change in Copenhagen last month. Many developed countries blamed China for the talks' failure and public questioning of the IPCC assessment reflects growing doubt on the previously accepted effects of climate change on China itself. 'The IPCC's hockey stick gives the public the impression that the global temperature will only increase and never drop,' said Cheng Jicheng, a professor at the School of Earth and Space Sciences at Peking University. 'But the reality is very different. The 'hockey stick' flattens many cold periods like the recent blizzards. If citizens and government officials take the IPCC estimates seriously and rely on them to make decisions or policies, our country will be in turmoil.' Professor Cheng is the most outspoken of a group of scientists who oppose the IPCC's conclusions. They remain a minority, as the central government continues to endorse it and most researchers prefer to stay in line with government thinking. Cheng said at the heart of the problem were flawed general circulation models used in the assessment. 'The 'climate gate' incident [in which emails of climate change scientists were hacked] showed that some lead scientists in the IPCC manipulated data to fit the models. This is not a scientific approach, it is a Cultural Revolution approach,' he said. 'The models must undergo some fundamental changes if they can correctly describe what will happen in the future.' On its website, the IPCC said that the models were the most advanced tools available for simulating a response to the global climate system. '[Only general circulation models] have the potential to provide geographically and physically consistent estimates of regional climate change which are required in impact analysis,' the IPCC said. Professor Zhao Zongci, a researcher at the China Meteorological Administration and a key author appointed by Beijing to write the IPCC report, published a paper before her retirement last year admitting the models excluded factors that would actually cause global cooling. 'In all four assessment reports, when making predictions about the future, the IPCC considered only human reasons and ignored almost completely the natural factors,' Zhao wrote. The omitted factors included solar activity, the earth's magnetic field and volcanic eruptions. Zhao estimated that natural factors could lower temperatures in China by as much as 0.8 degrees from 2020 to 2030, while human activity could raise temperatures by 0.5 degrees. That means China could actually become colder in the near future. The paper also showed temperature fluctuations would be greater if natural factors were taken into account. Professor Chen Xing, a climate change expert at Nanjing University, said people should not include blizzards when trying to overturn the hockey stick forecast. 'The models are not meant to generate a weather forecast. They are a hypothesis and should not be used as evidence in decision making,' he said. However, local governments had already started to do precisely that, said Professor Sun Zhongfu, a senior researcher of the Chinese Academy of Agricultural Sciences. Sun said a growing portion of agricultural losses in recent years were caused by overconfidence in warming. 'Some provinces, such as Guangdong, Fujian, Guangxi and Yunnan, encouraged farmers to plant tropical fruits and flowers because they believed winters would only become warmer and shorter,' Sun said. 'But the temperature has dropped and wiped out most of the plants. The farmers suffered badly. Agricultural experts held a national meeting last year about these lessons. Our conclusion is that policy makers must equally access the risk of warming and cooling.' Cracked stick The report says global temperatures will rise in a hockey stick shape The Fourth Assessment Report says global temperatures will rise consistently from 1900 to: 2100
