Tuesday, September 29, 2009

Tipping points and climate confusion

What is a “tipping point”?

Malcolm Gladwell wrote a best-selling book with that title. He says it is the point at which something takes off and becomes a runaway phenomenon whose growth is exponential. He gives examples of everything from Paul Revere’s famous ride, to the spread of STDs, to the popularity of Hush Puppies.

I suspect Harry Potter would fit that category. It started out as a book that was rejected by every publisher in the U.K. but one. Eventually, people began talking about it and news of it spread. That is how I first heard about it, a friend raved about it over lunch. By the time I got around to reading it, everybody was into it.

That brings us to the use of the expression tipping point in the climate change debate.

James Hansen, the leading Chicken Little in the global warm-mongering camp, uses the term quite often. He says it is the point at which climate changes cannot be controlled by man, that nature’s feedback mechanisms take off and become like a shark feeding frenzy.

Think about that statement for a minute. It implies that we can manage climate. Not that there is any historical precedent for such a conceit. In fact, it is probably the most monumentally foolish idea of the 21st century.

We can have an impact on the climate, for sure, but we cannot manage something we barely understand.

For about 800,000 years the CO2 level has been about 280 ppm, sometimes a little higher, sometimes a little lower, but that is the order of magnitude. In the past century it has climbed to around 380 ppm; hence the alarm. It is generally agreed amongst the Hansenites that most of the cause of this climb in CO2 is related to the release of carbon into the atmosphere by humans. The real debate is that not all scientists buy into the idea that CO2 is the main driver of climate change.

To add further confusion, there is now a contradiction around the concept of tipping point that needs clarification if one wants to persist in claiming CO2 as the key.

Hansen claims that the maximum CO2 level that would preserve the status quo is 350 ppm. He says that at 380+ ppm we have already past the tipping point, and points to high Arctic and glacier ice melting as proof. This means that even if we substantially reduce our carbon contribution it is too late, nature is now in a runaway mode to much higher global temperatures that will see all the ice melt and the oceans rise. He also claims that 450 ppm is probably the maximum safe level.

However, in a just released study, a team of scientists from the U.K. and the U.S. have determined that declining CO2 in the atmosphere led to ice forming over the continent of Antarctica about 34 million years ago, a continent that had previously experienced a tropical climate. On its face, that result would not seem to contradict anything James Hansen says; except when you start talking about tipping points.

The new CO2 study determined that 34 million years ago the CO2 level dipped to 760 ppm. This was considered the tipping point for ice formation.

So which is the real tipping point: 350+ ppm when ice melts or 760 ppm when ice forms?

And what about the claim that CO2 levels are unsafe after 450 ppm? All kinds of new life forms emerged on other continents in an atmosphere of 760+ ppm.

This is far from a “settled science”.

No comments: