Scientists from the Intergovernmenal Panel on Climate Change (IPCC) now say that it is "very likely" that global warming is chiefly driven by the build-up of carbon dioxide and other greenhouse gases caused by human activity, and that dangerous levels of warming and sea rises are on the way.
The IPCC estimates that if the concentration of carbon dioxide reaches twice the pre-industrial level of 280 parts per million, temperatures could rise between 3.2 to 7.1 degrees (Fahrenheit) — with a more than one in ten chance of far greater warming. Sea levels could rise between 18 and 58 centimetres. Heat waves and droughts will become more intense and longer-lived. Though the new IPCC's latest assessment does not go into the social impacts of climate change, past studies indicate that the changes predicted will have a profound effect on humanity.