Wednesday, August 22, 2007

Climate Tipping Points Get Scarier

By Carlos Rymer:

The warmest year on record was 2005. Scientists today indicate that the world has warmed by about 0.6C above the pre-industrial average. Earlier this year, the IPCC painted dire consequences for the world as a result of man-made global warming, which included widespread water shortage and famine, more intense floods and droughts (afflicting agriculture), prolonged heat waves, sea level rise, millions of climate refuges, the extinction of up to 50% of all species, etc. Today, we can look at several recent studies that show that the IPCC report didn’t go far enough on documenting the seriousness of the problem. Let’s take a look.

Shortly after the IPCC technical report was released, the National Snow and Ice Data Center showed that Arctic sea ice was being lost faster than the IPCC projections. The IPCC concluded that, from 1953 to 2006, the average sea ice loss per decade was 2.5%. This was concluded using model simulations. The recent data, on the other hand, shows that the average was in fact about 7.8%, 30 years ahead of forecast. As a result, the Arctic could be ice-free during the summer by 2020, warming the planet much faster due to the vast open waters that will be absorbing heat (and melting Greenland, by the way). Check out the release here and here.

Also this year, Dr. James Hansen and a team of scientists at NASA’s Goddard Institute for Space Studies published a study showing that the Earth was at a “dangerous tipping point.” Hansen and his team pointed out that the CO2 limit of 450 ppm was likely dangerous due to the consequences we’ve seen with 0.6C of warming, and that the ceiling should probably be a lot lower. They warned that even moderate business-as-usual would lead to “global and regional disasters.” Hansen has also warned that sea level will undoubtedly rise by at least 1 meter this century, and suggested that the Greenland ice sheet is beginning to desintegrate (could raise sea level by 7 meters). See here and here for more.

Recently, the Brazilian government, alarmed by climate change effects, decided to reconsider climate policy. 2005 saw a major drought in the Amazon that killed crops and caused other major losses. 2006 and 2007 have also been drought years. Scientists at the Woods Hole Research Institute, together with Brazilian scientists, have shown that 3 years of continued drought leads the Amazon to a massive transformation, ending with much of it as a Savannah. If 2008 turns out to be like this year, we may begin to see trees die in the Amazon, a huge tipping point that would elevate carbon emissions.

Since 2005, the frozen Siberian peat bog has been partly melting during the summer (see here). This year, in particular, a vast area that had never melted in recent human history became liquid water. Scientists estimate that these peat bogs could release more than 70 billion tons of methane, a greenhouse gas 23 times more potent than carbon dioxide (by contrast, humans release about 25-30 billion tons of CO2 per year, so this would equal about 50 years of our current CO2 emissions!).

Another study, this time near Antarctica, showed that the Souther Ocean is almost at capacity for holding carbon dioxide. The vast ocean served us well by taking up to 1/3 of all the carbon dioxide we released every year. But now, it will hold no more, so more of what we emit will stay in the atmosphere. IPCC, check your emission projections next time!

On the emissions side, new research shows that global carbon emissions rose faster than the worst-case scenario used by the IPCC. The average in the last few years was 3.1%. This means that, if unchecked, we will likely see temperature rising above the worst-case scenario predicted by IPCC: 4.0C.

And just recently, The Guardian released an article about scientists warning about the proximity of tipping points in the climate system. It notes a new study showing that the Greenland ice sheet could disintegrate within 300 years (note that Hansen warns it could happen this century). It also notes other tipping points such as the loss of the Amazon rainforest, the disintegration of the West Antarctic ice sheet, and the shutdown of the world’s ocean circulation.

These things tell us two things: 1) All current projections are likely underestimates of what’s really happening and what’s to come, and 2) any further increase in the concentration of greenhouse gases in the atmosphere is very risky (i.e. we should be a lot more aggressive about our targets if our goal is to avoid tipping points). A more concerned administration/world would use this to declare war against greenhouse gases/global warming, making a complete transition to clean energy within 2 decades.

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