Climate Change Predications Confirmed by Ancient Warming Event
Current climate change predictions have been confirmed by an ancient warming event that surpasses today's warming world, according to a new study.
Between 2.3 to 3.3 million years ago during the Pliocene Epoch, the Earth's temperature was around 2 degrees Celsius (35.6 degrees Fahrenheit) warmer than it is today, while atmospheric levels of carbon dioxide (CO2) were around 350-450 parts per million (ppm), similar to the levels reached in the past few years (400 ppm).
Evidence of this previous warm period came from an analysis of ancient plankton fossils drilled from the ocean floor.
By studying the relationship between CO2 levels and climate change during a warmer period in Earth's history, the scientists have been able to estimate how the climate will respond to rising CO2 levels - a parameter known as "climate sensitivity." The findings, published in the journal Nature, are in line with future predictions from the Intergovernmental Panel on Climate Change (IPCC), according to the international research team.
"Our estimates of climate sensitivity lie well within the range of 1.5 to 4.5 Celsius [34.7 F to 40.1 F] increase per CO2 doubling summarized in the latest IPCC report. This suggests that the research community has a sound understanding of what the climate will be like as we move toward a Pliocene-like warmer future caused by human greenhouse gas emissions," co-author Dr. Gavin Foster, from the University of Southampton, said in a press release.
Skeptics of man-made climate change (including even members of the US Senate) have long referred to the global warming "pause," or "hiatus" as evidence that humans are not to blame for the changing climate, and that climate models are inaccurate. But this new study shows that despite this pause, climate models are right on target. (Scroll to read on...)
As things continue to heat up on Earth (2014 was the warmest year on record), and it gets harder for scientists to blame these changes on natural processes alone, they will need to look back in the geological record to better predict how our planet will be affected. Past events like that during the Pliocene are examples of what's yet to come, allowing us to brace ourselves for the future.
In addition, the findings suggest that climate sensitivity was different in warmer times, like the Pliocene, than in colder times, like the glacial cycles of the last 800,000 years.
"We find that climate change in response to CO2 change in the warmer period was around half that of the colder period. We determine that this difference is driven by the growth and retreat of large continental ice sheets that are present in the cold ice-age climates; these ice sheets reflect a lot of sunlight and their growth consequently amplifies the impact of CO2 changes," said Eelco Rohling of The Australian National University, who was involved in the study.
"When we account for the influence of the ice sheets, we confirm that the Earth's climate changed with a similar sensitivity to overall forcing during both warmer and colder climates," added Richard Pancost from the University of Bristol Cabot Institute.
And that's bad news considering ice sheets in Greenland, West Antarctica and the Arctic are rapidly melting.With all of this freshwater being dumped into the oceans, global seas can rise by as much as 20 feet in the future.
The impact of increased CO2 levels can be felt just 10 years down the line, and if carbon emission release continues as its current rate, the Pliocene Epoch shows us just what the Earth may come to.
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