Around 300 scientists from different parts of the world have reconstructed Earth's temperature history back to the end of the last Ice Age. They have said that the planet today is warmer than it has been during 70 to 80 per cent of the time over the last 11, 300 years. And all this, according to them, is happening because of global warming.
The Intergovernmental Panel on Climate Change (IPCC) evaluated the projections of global temperature for the year 2100, with the help of climate models. It shows that the temperature will exceed the warmest temperatures during that 11,300-year period known as the Holocene, under all plausible greenhouse gas emission scenarios.
The Lead author, Shaun Marcott from Oregon State University's College of Earth, Ocean, and Atmospheric Sciences, said: “We already knew that on a global scale, Earth is warmer today than it was over much of the past 2,000 years.” Researchers say that from the past 5,000 years the earth has cooled about -17 degree Celsius on an average. But until last 100 years, it warmed again and is showing the maximum effect in northern hemisphere, reported Indian Express.
Peter Clark, an OSU paleoclimatologist and co-author on the Science article, said: “When you combine the data from sites all around the world, you can average out those regional anomalies and get a clear sense of the Earth's global temperature history.” The climate model used by the scientists projects that global temperature will rise another -16.7 to -11.3 degrees Celsius by the end of this century, and this largely depends on the ratio of carbon emissions.
Clark added: “What is most troubling is that this warming will be significantly greater than at any time during the past 11,300 years.” One of the factors that affects the global temperature is gradual change in the distribution of solar insulation associated with Earth's position relative to the Sun. The research team included Jeremy Shakun of Harvard University. And the primary things used for the research were fossils from ocean sediment cores and terrestrial archives to reconstruct the temperature history.
