A new study says the earth is on track to becoming the hottest it has been at any time in the past 11,000 years, a period spanning the history of human civilisation
Based on fossil samples and other data collected from 73 sites around the world, scientists have been able to reconstruct the history of the planet's temperature from the end of the last Ice Age ago to the present.
They have determined that the past 10 years have been hotter than 80% of the past 11,300 years, AFP reports.
But virtually all the climate models evaluated by the Intergovernmental Panel on Climate Change predict that the Earth's atmosphere will be hotter in the coming decades than at any time since the end of the Ice Age, no matter what greenhouse gas emission scenario is used, the study published in Science found.
The data shows temperatures cooled by 0.8 degrees Celsius over the past 5000 years, but have been rising again in the past 100 years, particularly in the northern hemisphere where land masses and population centres are larger.
The climate models project that average global temperatures will rise by 1.1 to 6.3 degrees Celsius by the end of the century, depending on the level of carbon dioxide emissions resulting from human activities, the researchers said.
The earth's position with respect to the sun is the main natural factor affecting temperatures during that time, the scientists said.
Other studies have concluded that human activities - not natural causes - have been responsible for the warming experienced over the past 50 years.