Severe heatwaves and flooding 'more likely' a warning of increasingly common severe heatwaves, flash floods and droughts was given by scientists yesterday (Hannah Devlin writes).  an Intergovernmental Panel report on Climate Change suggested that developing countries would be hit hardest by outcomes of climate change.  a report by the panel in 2007 was found to contain an exaggerated claim about how fast Himalayan glaciers were melting. But Rajendra Pachauri, the panel's chairman, said at a conference in Kampala that it was still credible and its findings would be a vital contribution to the UN Conference on Climate Change in Durban next month.  The two-year study is more confident about the prospect of heatwaves and downpours than the effect of climate change on hurricanes and tornados. "a small change can have a big impact on extremes," said Gerald Meehl, one of the report's reviewers.