Environmentalist and former US Vice President Al Gore, in a Silicon Valley speech urging businesses to push clean technology, said the United Nations report on climate change released last Friday makes it a near certainty that global warming is real and needs to be addressed immediately.
"The degree of certainty, which was already very high, is now as close to certain as scientists are ever willing to say something is certain," Gore said.
The International Panel on Climate Change's fourth report on the subject since 1990 says human activity, including the burning of fossil fuels, is the primary cause of global warming.
Gore implored his audience of 1,500, many of them executives and employees of technology companies in Silicon Valley, to use their collective knowledge and resources to promote green technology that causes less pollution and can reverse the effects of climate change.
"The world faces an unprecedented challenge, and Silicon Valley can make an unprecedented contribution to meeting that challenge," Gore told them. "You can chart a course and change the future of civilisation."
Technology companies recently have been focusing more on green technology, such as designing computer processors that generate less heat, building systems that better manage electricity use in data centres, improving manufacturing processes and recycling old computers. Gore urged them to do more.