The spectre of abrupt climate change, which could render massive infrastructure projects such as the Three Gorges Dam and the South-North Water Diversion Project useless, has prompted the central government to launch a national scientific study. Some mainland scientists are warning that annual temperatures could drop sharply in the next two decades, causing a drastic shift in rain distribution and hitting the agricultural sector hard. Like their peers around the world, the mainland's scientific community long regarded the possibility of abrupt climate change as minimal, and funding for research into its ramifications was non-existent. If you asked researchers at the National Climate Centre last year, they would happily quote the latest Intergovernmental Panel on Climate Change (IPCC) assessment that a sudden shift - such as the dramatic global freeze in the Hollywood blockbuster The Day After Tomorrow - would not happen in the foreseeable future. But today, with snowstorms raging across northern China, unprecedented drought in the south and the IPCC's credibility coming under serious attack, some mainstream scientists are not so sure any more. They admitted that they could not rule out the possibility that China, as well as the rest of the world, is caught up in the process of an abrupt climate change. In 2003, the Global Business Network, a US think tank, prepared a report for the US Department of Defence titled 'An Abrupt Climate Change Scenario and Its Implications for United States' National Security'. The report created a climate change scenario based on interviews with leading scientists, and historical data, which estimated that global warming would stop abruptly in 2010 and long cold winters would follow. 'Mega-droughts begin in key regions in southern China ... around 2010 and last throughout the full decade,' the report says. 'China, with its high need for food supply given its vast population, is hit hard by a decreased reliability of the monsoon rains ... longer, colder winters and hotter summers caused by decreased evaporative cooling because of reduced precipitation stress, already tight energy and water supplies. 'Widespread famine causes chaos and internal struggles as a cold and hungry China peers jealously across the Russian and western borders at energy resources.' The report was covered by some mainland newspapers at the time but was met with derision from scientists. The most important reason was that the authors, Peter Schwartz and Doug Randall, were futurists with no formal meteorological training. Their scenario was not based on sophisticated mathematical models but on face-to-face interviews, and their conclusions were regarded as far too extreme. Mainstream scientists firmly believed that global warming was irreversible and that climate change would be a slow and gradual process. But it now seems the futurists could have been right. Since September, areas of southwestern China such as Yunnan, Guizhou , Guangxi and Chongqing have been hit by the worst drought in more than a century. Xinhua says rainfall is down by as much as 90 per cent and water levels in major rivers are at their lowest in history. Nearly 20 million people are suffering from drinking water shortages. Meanwhile, enormous snowstorms, not seen in decades, have hit northern China. Some dams along the Yellow River, which have not flooded for many years, are reporting dangerous water levels. These happenings match almost perfectly with the 2003 report's prediction that China's normally wet south would see droughts and the normally dry north would experience floods. Now the question is, will it last for a decade? The Ministry of Science and Technology launched an emergency national science project last month to deal with the issue. Its top priority is to identify the mechanism behind abrupt climate change and find solutions. Scientists have been asked to 'study the time and space distribution of global and regional abrupt climate change, examine signals of abrupt changes and study their physical mechanism to come up with forecasting theories and methods', according to the ministry's explanation of the project. Scientists are also encouraged to 'estimate the risk of natural catastrophes caused by abrupt climate change, review the abrupt climate change incidents in the past 2,000 years and analyse the process of human adaptation to such incidents'. Luo Yong, deputy director of the China Meteorological Administration's National Climate Centre, said the emergency project indicated that leaders had become concerned about abrupt climate change. 'The drought in southwest China is no longer a weather phenomenon. It is a climate phenomenon, a rare and extreme climate phenomenon,' Luo said. 'It is unlikely to have been caused by human activities and carbon dioxide emissions. It is most likely caused by nature. 'Unfortunately, we have paid very little, if any, attention to the issue of abrupt climate change in the past. Therefore we cannot explain why it happens, how long it will last and when will it happen again. 'With the scientific knowledge, methods and equipment at present, we cannot rule out the possibility that China is in the course of an abrupt climate change process which will bring a rapid drop of temperatures and dramatic redistribution of precipitation in the north and south. 'But we can't count on the futurists' report either. I don't think their prediction really matches what's going on right now. Their forecast is about the entire south of China, but now only the southwest is hit. 'Personally I still believe the trend of global warming will continue, but a better understanding of abrupt climate change is necessary.' One of the most popular hypotheses about the cause of abrupt climate change is that global warming will increase the inflow of fresh water to the North Atlantic. Because fresh water is lighter, it would block the warm salty water at the bottom of the ocean from rising in winter, causing the Atlantic to get cold and subsequent cooling around the world. But Yang Xuexiang, a retired professor from Jilin University College of Geo-exploration Science and Technology, said some mainland scientists had a different theory. Yang said Professor Guo Zengjian, former director of the Lanzhou Seismic Research Institute, proposed in 2002 that rising sea levels caused by global warming would increase the pressure on tectonic plates and cause mega earthquakes. The earthquakes would change oceanic flows and cause abrupt climate change. 'Recent earthquakes in South America will lead to a significant drop of temperature, according to Guo's theory,' Yang said. 'If he's right, China will suffer dearly because in the past decade the decision-makers were building infrastructure projects under the assumption of gradual global warming. 'The Three Gorges Dam on the Yangtze River, for instance, will have no water. The Yellow River regions, whose irrigation systems were designed to fight drought rather than flood, will have to deal with the sudden arrival of huge floods. The ongoing South-North Water Diversion Project will be useless because water can only flow from south to north by design. 'The most urgent thing is to let people know the risk. If the propaganda machine avoids talking about abrupt climate change for fear of social panic, the people will suffer, get panicked and lose the trust in the government when it does happen.' But not all mainland scientists have accepted the idea of abrupt climate change. Professor Qin Dahe, former director of the China Meteorological Administration and a key author of the most recent IPCC assessment, brushed off the possibility of abrupt climate change. 'The droughts and snows are weather phenomenon. They have no impact on our assessment of long-term climate change,' he said. 'The world is getting warm and will continue to do so.'