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.