Yesterday I witnessed a fine example of what scientists call a "tipping-point." This is a point in a process of change where the change becomes radical and difficult to reverse. My daughter and I took a six mile hike around Bass Lake, just north of Ely (pronounce it eelee) Minnesota. The trail winds around the Lake and crosses the run off between Bass and Low Lakes. On the north side of Bass Lake we walked across a soft, sandy plane overgrown with pine trees. It was in fact the old lake bed. Bass lake used to be much higher than Low Lake (hence the name), separate from the latter by a natural dam. Loggers opened up a sluice in the dam to facilitate the movement of, well, logs. Eventually, the dam collapsed causing a tremendous release of water from the higher lake, and a new place for pine trees to do their business. The dam's collapse was a tipping point.
Its reasonable to worry about a tipping point with regard to global warming, but that doesn't mean we can assume that one is coming. Gen-you-wine climate expert Al Gore has his new movie out to scare us about rising tides drowning all coastal cities. But a major part of that argument has just been cut out from under him.
The Intergovernmental Panel on Climate Change, which is the authority that all the global warming folks cite, has now revised its projections from warming in this century. From Mathew Warren in the Australian:
THE world's top climate scientists have cut their worst-case forecast for global warming over the next 100 years.
A draft report by the Intergovernmental Panel on Climate Change, obtained exclusively by The Weekend Australian, offers a more certain projection of climate change than the body's forecasts five years ago.
For the first time, scientists are confident enough to project a 3C rise on the average global daily temperature by the end of this century if no action is taken to cut greenhouse gas emissions.
The Draft Fourth Assessment Report says the temperature increase could be contained to 2C by 2100 if greenhouse gas emissions are held at current levels.
In 2001, the scientists predicted temperature rises of between 1.4C and 5.8C on current levels by 2100, but better science has led them to adjust this to a narrower band of between 2C and 4.5C.
The new projections put paid to some of the more alarmist scenarios raised by previous modelling, which have suggested that sea levels could rise by almost 1m over the same period.
The report projects a rise in sea levels by century's end of between 14cm and 43cm, with further rises expected in following centuries caused by melting polar ice.
Now, a 43cm rise in sea level is not nothing. It just isn't the water world that Al Gore needs to make his point. Anyone who has been following the IPCC's progress will know that the upper bound of global warming projections has been constantly revised downward. Global warming is a cause for concern. We should monitor it and try to make projections, which is what the IPCC is obviously doing. But in fact the world is going to get warmer even if we all moved to Mars, and if we stay here and keep on as we have been going, the results will probably be mixed.
Global economic development is the only hope for bringing such problems under control. I am cautiously optimistic.
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