Possibly Irreversible Ice-Free Conditions in Arctic as CO2 Levels Climb
30.06.2010 - Atmosphere & Space, Water & Oceans, Land & Geology, Ice & Snow, Flora & Fauna, Arctic
A new international study led by the University of Colorado at Boulder to be published in the journal Geology indicates that the Arctic climate system could be more sensitive to greenhouse warming than previously thought, and that current levels of atmospheric CO2 could be high enough to cause significant, irreversible shifts in Arctic ecosystems. The researchers found that mean annual temperature on Ellesmere Island in the Canadian High Arctic during the Pliocene Epoch 2.6 to 5.3 million years ago was about 19°C warmer than today, while CO2 levels were only slightly higher than present.
The team used three independent methods of measuring the Pliocene temperatures on Ellesmere Island:
- Measurements of oxygen isotopes found in the cellulose of fossilzed trees and mosses to reveal temperatures and precipitation levels tied to ancient water
- An analysis of the distribution of lipids in soil bacteria, which can be used as a proxy for temperature
- An inventory of ancient Pliocene plant groups that overlap in range with contemporary vegetation
The team found that "CO2 levels of approximately 400 parts per million are sufficient to produce mean annual temperatures in the High Arctic of approximately 0°C", which makes it difficult to maintain permanent sea and glacial ice in the Arctic. The current levels of approximately 390 parts per million of CO2 could cause irreversible ice-free conditions in the Arctic.
