Pliocene Epoch Arctic Air Temperatures Probably Were 11 to 16 Degrees Celsius Higher than Today — A View of Our Not too Distant Weather Future?

© 2011 Peter Free

 

11 April 2011

 

 

Looking ahead for implications regarding climate change

 

Scientists are combing geologic history for clues about what to expect, as the atmosphere’s levels of greenhouse gases continue to rise.

 

The Pliocene Epoch (2.6 to 5 million years ago) reportedly experienced carbon dioxide levels in the range from 365 to 415 parts per million.  The lower end of that range overlaps with where we are today.  The higher end marks what we can anticipate.

 

Researchers used two proxy markers (delta oxygen 18 and carbonate clumped isotope thermometry) to estimate growing season temperatures on the Arctic’s Ellesmere Island, during the Pliocene.  These proxies indicate that Ellesmere temperatures were 11 to 16 degrees Celsius (20 to 29 degrees Fahrenheit) higher than today.

 

Overall, global Pliocene temperatures were 2 to 3 degrees Celsius warmer than today.

 

 

Citation

 

Adam Z. Csanka, Aradhna K. Tripati, William P. Patterson, Robert A. Eagle, Natalia Rybczynski, Ashley P. Ballantyne, and John M. Eiler, Estimates of Arctic land surface temperatures during the early Pliocene from two novel proxies, Earth and Planetary Science Letters 304 (3-4): 291-299 (15 April 2011)

 

 

“So what?”

 

The study implies that:

 

Ice sheets and sea ice in polar regions reflect incoming solar radiation to cool the Earth — a phenomenon that makes the poles incredibly sensitive to variations in climate, [author Aradhna Tripati] said.

 

An increase in Arctic temperatures would not only cause the ice sheets to melt but would also result in the exposed land and ocean absorbing significantly more incoming solar energy and further heating the planet.

 

Without a permanent ice cap in the Arctic, global temperatures in the early Pliocene were 2 to 5 degrees Fahrenheit higher than the current global average.

 

This suggests that the carbon dioxide threshold for maintaining year-round Arctic ice may be well below modern levels, Tripati said.

 

© 2011 Stuart Wolpert, Ancient fossils hold clues for predicting future climate change, scientists report, UCLA Institute of the Environment and Sustainability (08 April 2011) (paragraph split)

 

 

The change in temperature gradient between tropics and poles will have an impact

 

Global heat flows will change, probably radically.  What that means for specific regions is hard to predict.  One can guess that for some, the change will not be welcome.

 

 

Nobody is going to care much about these findings, of course, until agriculture fails to keep up

 

For most people, climate change is either (a) something so slightly incremental as to be justifiably overlooked or (b) an imagined and inflated evil, with which we can pretend-scare ourselves in Hollywood fashion.  Neither perspective motivates action toward controlling human contributions to greenhouse gases.

 

The planet’s atmosphere has probably already passed the practicable point of no return, insofar as our ability to maintain the weather to which people are accustomed.

 

We are well into an experiment that may make human tenancy on the planet more challenging than it has been.