The latest findings by a group of prominent scientists say our planet has not seen its surface warm up so much, in such a short period, during the past 66 million years and the impact will come much quicker and with much worse consequences than previously thought.
According to a study published in 2006 in the online journal Science, the last sudden rise of CO2 in the Earth’s atmosphere happened 55 million years ago and lasted for about 170,000 years. The global temperature then increased about five degrees Celsius, causing profound changes in the planet’s ecology, including mass extinctions.
In a new 52-page report, published Tuesday in the scientific journal Atmospheric Chemistry and Physics, 19 scientists say we are releasing CO2 in the atmosphere much faster than 55 million years ago, and that even two degrees Celsius rise of the average temperature will have catastrophic effects on the planet’s climate.
Authors warn of collapsing ice sheets, violent mega storms and giant waves.
The leader of the study, former NASA scientist James Hansen, says we may already have passed the point of no return and future generations will bear the dire consequences.
When Hansen issued the first warning last summer, some journalists and fellow scientists criticized it as lacking enough evidence. But he has since been joined, in a peer review, by many other prominent scientists who revised the paper and made it less dramatic. But serious concerns remain.
Combining evidence about ancient climate changes, modern observations and results of computer modeling, the authors conclude that rapid melting of Greenland and Antarctica ice will cause not only a rise in sea levels, but also many other climate changes.
Specifically, they point to a phenomenon called ‘stratification,’ which means formation of cold water pools on the ocean’s surface, caused by melting of the ice sheets. The warm water trapped below will continue to melt the bottom of the ice sheets, contributing to rapid sea level rise. Evidence of stratification has already been observed off the Greenland’s southern coast.
According to the study, the changes will lead to a growing temperature differential between northern and equatorial regions, that in turn will cause intense cyclones and storms with gigantic waves.
The findings cited in the study are supported with other research, such as that done by the U.S. National Oceanic and Atmospheric Administration.
Some reviewers have been praising the report as a “masterwork of scholarly synthesis”, while others say it is still not certain that it will “match what will happen in the real world.”
However, as one of the reviewers, Penn State glaciologist Richard Alley, said, "the paper reminds us that large and rapid changes [of the climate] are possible. We just don’t know how much and how likely."