If the results of the study I’m discussing are robust, and not just true, many more climate change effects will become apparent sooner than many think. It has been known for a number of years that the West Antarctic Ice Sheet (WAIS) has, on net, lost ice mass since ~2005. This phenomenon has occurred concurrently with the Greenland ice sheet also losing mass over a similar time period. That mass loss has contributed to a, until now, relatively small amount of sea level rise.
A new study suggests that sea level rise scenarios may need serious revision quickly: the East Antarctic Ice Sheet (EAIS) has, according to NASA’s GRACE satellite data, also lost mass in the 2005-present time period. Why is this a potential big deal? Because east Antarctica contains enough water to raise sea levels by 50-60m (160-200 feet!) if they melted completely. In contrast, the water in the WAIS and Greenland amount to “only” 6-7m (~20 feet) each if they melted completely. So the EAIS contains an order of magnitude more water than the other two large ice sheets on Earth.
I want to be clear: neither myself nor the authors are postulating that the entire ice sheets will melt any time soon. The point I want to drive home is the EAIS contains a lot more water than either WAIS or Greenland, which have already been shown to contribute to some sea level rise already. Another point of this study is that contrary to recent thought, the EAIS isn’t gaining mass, it could be losing mass. Thus, on top of the mass loss from WAIS,
Antarctica may soon be contributing significantly more to global sea-level rise.
This should serve as shattering news for the public – but I didn’t hear anything in the corporate media (big surprise!) last week. Every time one of these studies comes out, it shows that the observed warming is more widespread and happening faster than previously predicted. The blog I link to below has “Satellite data stunner” in its lede – but I don’t think this news should be shocking to scientists or people who are closely following the science. In fact, I’m sure there are dozens of other climate effect signals just waiting for us to detect them. The shock should be that we place such a low priority on searching for them.
This mass loss is being caused by another factor that scientists have, until recently, underestimated – temperature change as a result of greenhouse gas emissions. There was a relatively large discrepancy between the expected temperature rise per year as a result of GHG emissions. Additionally, temperature changes over Antarctica in the past are now appear to be larger than previously thought: during the last period of high CO2 (125,000 years ago) temperatures were up to 10.8F(6C) higher than present day levels. This article is about another recent study, “Evidence for warmer interglacials in East Antarctic ice cores“, a result of the British Antarctic Survey.
The problem with climate models and forecasts isn’t that they are too pessimistic, it is that they don’t include enough, as the set of studies I’ve discussed here prove. Earlier this year, I stopped using the IPCC temperature and sea level rise estimates as likely scenarios and started using them instead as best-cast scenarios. That’s not a knock against the IPCC effort per se. I simply want to emphasize that the studies leading up to the IPCC 4AR were incomplete in scope and design. As experiments are set up leading up to the IPCC 5AR (to be written in ~2014), I sincerely hope some “extreme”-climate scenarios are modeled. They have to be so that policy-makers can gain a better understanding of how quickly climate change effects are already taking place and how necessary our actions are.
Aggressive action must be taken within the next couple of years if we are to avoid substantial or even catastrophic changes to the climate system. There will be no more time after that to do the necessary heavy lifting to make a difference in this century. The chances of shattering antiquated goals like 450ppm CO2 concentration, 2C warming and 1m sea level rise are rising and they’re rising faster each day we continue to operate under business-as-usual mindsets.
Cross-posted at SquareState.
h/t Climate Progress.