Climate scientist Benjamin Santer thought the dead rat left on his doorstep by the cursing driver of a yellow Hummer was bad, but several years later, the threats and attacks have gone beyond such childish pranks. Santer and other scientists say they fear for their own safety and that of their families more than ever since the hacked e-mail controversy of 2009 riled global warming skeptics, reports the St. Paul Pioneer Press.

Santer, who was involved in the so-called 'Climategate' scandal in which over 1,000 emails between climate scientists in America and the U.K. were stolen and publicly posted by hackers, is just one of many scientists who report email attacks, including some suggesting that they should be lynched and explicitly threatening harm to their children.

But despite such attacks – which have prompted Santer to hire bodyguards to accompany him to some conferences – scientists are speaking out on what they say is irrefutable evidence that climate change is already harming the planet.

255 members of the National Academy of Sciences, including 11 Nobel laureates, wrote a letter to Science Magazine in May reiterating their conclusions (PDF).

“We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular,” the letter began.

“All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything.”

“When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem so potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.”