Sunday, September 6, 2015

What is happening to Antarctic ice shelves and why should we care?

Front of Ross Ice Shelf
Front of Ross Ice Shelf from research icebreaker Palmer.
Photo © Bruce Luyendyk

Antarctic ice shelves are thinning. What are ice shelves and are they important in any way? These massive floating sheets of ice border over a third of the Antarctic coast. 

Ice shelves are not frozen ocean. That is sea ice. In the simplest notion they are floating glaciers and part of the cryosphere cycle in Antarctica and Greenland. The largest Antarctic ice shelf is the Ross Ice Shelf, about the size of Texas (or France) and formed by the merging of glaciers flowing off the Antarctic continent. This shelf for example, is hundreds of meters thick (up to two thousand feet or more) and floats over sea floor hundreds of meters deeper.

This spring Science magazine published a research study on the state of the Antarctic ice shelves1.

Tuesday, February 17, 2015

Two Degrees Global Warming, Geoengineering, West Antarctic Ice Sheet collapse!

A break in the clouds on October 29, 2014, allowed scientists
the opportunity to fly over Pine Island Glacier—one of Antarctica’s
most rapidly changing areas. The flight was part of NASA’s

Operation IceBridge, a mission that makes annual surveys
 of Greenland and Antarctica with instrumented research aircraft.
Photo Michael Studinger

Is Earth headed towards warming of two degrees Celsius this century? If yes, can it be reversed? Should it be? How would it be done? 

Two recent publications offer some startling insights. The first by hockey-stick author Michael Mann estimates when the Earth can be expected to reach a level of 2°C warming (3.5°F) of the atmosphere. The answer it seems is very soon. Mann assumes business as usual in carbon emissions, which are increasing in amount every year, and the effect of the carbon dioxide (CO2) already in the atmosphere. These numbers are easy to come by, but he has to come up with a climate sensitivity model to translate the increase of CO2 in the atmosphere into warming. He determines that an equilibrium climate sensitivity about midway between estimates of the IPCC best-fit recent climate data. From this he projects forward and estimates the year Earth’s atmosphere reaches 2°C warming is 2036, twenty-one years from now. This is much sooner than estimates by the IPCC.