A new study has warned that global temperatures will reach levels not seen in 50 million years if greenhouse emissions aren’t dramatically reduced.
The study by US and German experts analysed tiny fossils in cores drilled from the seabed to reconstruct the Earth’s climatic history back to the time of the dinosaurs.
Experts broke down the Earth’s climate from the last 66 million years into four categories: hothouse, warmhouse, coolhouse and icehouse. Each category is characterised by particular greenhouse gas concentrations and the extent of the ice to be found stored at the Earth’s poles.
It’s said that Earth has been in a state of ‘icehouse’ for the past three million years but human’s current actions are pushing the climate into a ‘warmhouse’ or ‘hothouse’ state.
‘Warmhouse’ conditions were last seen 34 million years ago and now there are concerns we will reach it again by the end of the century. During the previous ‘warmhouse’ state, there were no polar ice caps and global temperatures were 9 – 14 degrees Celsius higher than they are today.
The Intergovernmental Panel on Climate Change projections for 2300 in the “business-as-usual” [emissions] scenario will potentially bring global temperature to a level the planet has not seen in 50 million years.
In their study, Professor Zachos and colleagues created a ‘climate reference curve’ dubbed CENOGRID, which maps out global temperature changes in the past, at present and includes various predictions for the future based on emissions levels.
Using CENOGRID, Zachos and co. found that the Earth’s climate variability occurs as a result of changes in the Earth’s orbit around the sun.
He explained, ‘We’ve known for a long time that the glacial-interglacial cycles are paced by changes in Earth’s orbit, which alter the amount of solar energy reaching Earth’s surface, and astronomers have been computing these orbital variations back in time.’
The new findings, published in Science on Thursday, September 10, are the result of decades of work from a large number of researchers from across the world.
As we reconstructed past climates, we could see long-term coarse changes quite well. We also knew there should be finer-scale rhythmic variability due to orbital variations, but for a long time it was considered impossible to recover that signal.
Now that we have succeeded in capturing the natural climate variability, we can see that the projected anthropogenic warming will be much greater than that.
Adding to concerns, Zachos said that the Earth’s climate can become ‘unstable’ when nearing to a climate transition period.
Niamh Shackleton is a pint sized person and journalist at UNILAD. After studying Multimedia Journalism at the University of Salford, she did a year at Caters News Agency as a features writer in Birmingham before deciding that Manchester is (arguably) one of the best places in the world, and therefore moved back up north. She’s also UNILAD’s unofficial crazy animal lady.
An astronomically dated record of Earth’s climate and its predictability over the last 66 million years
Climate change, Climate variability and change, James Zachos
World news – GB – Global Temperatures To Reach Level Not Seen In 50 Million Years, Study Warns