New Studies Back IPCC -- and Then Some

This May 30, 2012 image provided by Ian Joughin shows an iceberg in or just outside the Ilulissat fjord, that likely calved f
This May 30, 2012 image provided by Ian Joughin shows an iceberg in or just outside the Ilulissat fjord, that likely calved from Jakobshavn Isbrae, the fastest glacier in west Greenland. Polar ice sheets are now melting three times faster than in the 1990s, but so far that's added just less than half an inch to already rising global sea levels, a new giant scientific study says. While the amount of sea level rise isn't as bad as some earlier worst case scenarios, the acceleration of the melting, especially in Greenland, has ice scientists worried. (AP Photo/Ian Joughin)

Some exciting new studies related to climate change came out this past week, and I figured I'd bring them to attention. Why are they exciting? Because their findings are related to the much-maligned uncertainty of climate projections and the Intergovernmental Panel on Climate Change (IPCC).

The first study analyzed the five available global land and ocean temperature series and sea level rise for the past few decades and compared them with the projections in the third and fourth assessment reports of the IPCC. They found that, while current warming trends of 0.16°C per decade is close to the IPCC's projections, sea level is rising 60 percent faster than it was predicted by the IPCC. This is extremely significant, especially in light of the fact that many scientists (including myself) have commented on how the IPCC estimates are actually not alarmist; on the contrary, they tend to be too conservative.

The second study found that the fingerprint of current atmospheric temperature changes mainly reflects human influences on climate. This is significant because it is the first study to actually show that the current pattern of temperatures (cooling in the stratosphere and warming in the troposphere) is only consistent with an increase of human-produced CO2, not with natural fluctuations like the ones that happened in the past. This result agrees with the statement in the fourth IPCC assessment that the current warming is very likely due to human activities. Pretty neat.

The third study narrowed estimates for past climate sensitivity, after identifying the main reason why there was such a wide range of values: mainly the study found that researchers were using different definitions! After correcting for different definitions, the authors found that the "likely range of climate sensitivity consistently has been of the order of 2.2°C to 4.8°C per doubling of CO2, which closely agrees with the IPCC estimates." Pretty neat too.

Why am I writing all this? Because it seems to me that we are at a crucial time, where awareness of climate change is increasing and studies are coming out to support the IPCC, to reduce uncertainty, and to show that the forecasts of future climate are actually panning out. Hopefully, with studies like these and a wider awareness, we'll have more chance of getting much needed action to deal with climate change efficiently.