This post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense.
On January 13, Nature Geoscience published an article that reports large increases in ice loss from West Antarctica over the past 10 years. It's a sobering result that's in line with earlier, independent studies.
But then why do some people say that Antarctic ice is growing?
There are three regions of Antarctic ice: the East Antarctic Ice Sheet (EAIS), the West Antarctic Ice Sheet (WAIS), and the Antarctic Peninsula. Most studies indicate that the EAIS is unchanged or growing slightly, while the WAIS and the Peninsula are losing ice.
Measurements of the entire ice sheet from 1993 to 2003 have ranged from 50 gigatons (Gt) growth per year to 200 Gt loss per year, according to the IPCC Fourth Assessment Report (IPCC AR4). But overall, the trend is towards loss of ice. Even with the higher uncertainty for Antarctica compared to Greenland, the AR4 concludes that "losses from… Antarctica have very likely contributed to sea level rise".
So why do some people imply the opposite?
The Inhofe report quotes Duncan Wingham as saying: "72% of the ice sheet covering the entire land mass of Antarctica is growing." It's hard to know for sure, but if Wingham was referring to the EAIS, he’s correct that some older studies inferred increased snow accumulation there. What's easy to miss is that Wingham said parts of the Antarctic ice sheet are growing rather than shrinking.
More than that, the most recent studies have found no evidence of increased
snow accumulation on the EAIS overall.
And then there is the question of model projections versus observations. The IPCC AR4 says:
Current global model studies project that the Antarctic Ice Sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.
This means the models made two predictions: more snow and little melt. But the IPCC also points out that recent observations don't match the model projections. Antarctic ice is, in fact, shrinking. The ice sheet models were wrong on both counts.