A top UN scientist has insisted humans are warming the planet, in a bid to lay the so-called “climategate” row to rest.Sceptics have seized on a scandal over hacked e-mails from a British University to claim researchers have exaggerated the threat of global warming. But, at the Copenhagen summit, the UN’s climate chief said there were rigorous checks on all research. “Given the wide-ranging nature of change that is likely to be taken in hand, some naturally find it inconvenient to accept its inevitability,” Dr Rajendra Pachauri, head of the UN’s Intergovernmental Panel on Climate Change, told delegates. “The recent incident of stealing the e-mails of scientists at the University of East Anglia shows that some would go to the extent of carrying out illegal acts.” With climate legislation stalled in Congress, the US Environmental Protection Agency has taken an historic step. Having ruled greenhouse gases endanger human health, it will be able to regulate emissions, bypassing Capitol Hill. “Today’s action is a step towards enduring, pragmatic solutions to the enormous challenge of climate change,” said Lisa Jackson, the EPA administrator. “It is a step towards innovation, investment and implementation of technologies that reduce harmful emissions.” The US is the number two emitter behind China. Due at the summit next week, President Barack Obama is to pledge his country will cut emissions by roughly 17 percent by 2020 from 2005 levels.