Global Warming: Which Future Do You Choose?

How urgent is global warming? This urgent, according to NASA scientist physicist and climatologist James E. Hansen:

Global warming isn’t a prediction. It is happening. That is why I was so troubled to read a recent interview with President Obama in Rolling Stone in which he said that Canada would exploit the oil in its vast tar sands reserves “regardless of what we do.”

If Canada proceeds, and we do nothing, it will be game over for the climate.

Canada’s tar sands, deposits of sand saturated with bitumen, contain twice the amount of carbon dioxide emitted by global oil use in our entire history. If we were to fully exploit this new oil source, and continue to burn our conventional oil, gas and coal supplies, concentrations of carbon dioxide in the atmosphere eventually would reach levels higher than in the Pliocene era, more than 2.5 million years ago, when sea level was at least 50 feet higher than it is now. That level of heat-trapping gases would assure that the disintegration of the ice sheets would accelerate out of control. Sea levels would rise and destroy coastal cities. Global temperatures would become intolerable. Twenty to 50 percent of the planet’s species would be driven to extinction. Civilization would be at risk.

Given that scenario, the statement "civilization would be at risk" seems an understatement. A better way to put it might be, "Civilization will be struggling to maintain itself -- if we're really, really lucky."

In the nearer term, things don't look any better. "Over the next several decades, the Western United States and the semi-arid region from North Dakota to Texas will develop semi-permanent drought, with rain, when it does come, occurring in extreme events with heavy flooding," Hansen writes. "Economic losses would be incalculable. More and more of the Midwest would be a dust bowl. California’s Central Valley could no longer be irrigated. Food prices would rise to unprecedented levels."

Hansen isn't pulling this out of his butt, as much as some would like to believe. His warning is based on a peer-reviewed statistical study showing that global warming is affecting weather -- not will affect the weather, is affecting the weather. We're seeing a process that's happening now.


Hansen’s reasoning has to do with math. Statisticians employ standard deviation to measure variability; it’s the calculation pollsters use to determine margin of error, and it’s especially valuable when looking at the weather. Perfect distribution of standard deviation is graphed as the familiar bell curve; about two-thirds of the time, data points fall in the middle of the bell — or within one standard deviation of the mean.


In the paper, which Time.com confirmed has been peer-reviewed, the authors show that extreme outliers of more than three standard deviations above the mean temperature covered between six and thirteen percent of the globe during the years 2003 to 2008. If they were normally distributed and similar to the climactic record, that should have been just a 0.1-to-0.2 percent frequency of an extreme heat event. (That’s about exactly as often as a perfect bell curve predicts they would occur.) Hansen dubs this difference a “three-sigma anomaly,” for the Greek-letter symbol for standard deviation. And in the world of statistics, these anomalies represent a stunning 10-fold increase in extreme weather events.

In other words, it's statistically impossible for this to be part of the "normal variation" that deniers claim it to be. To go back to the bell curve, think of throwing dice. "Imagine dice with two sides red (for hot), two sides blue (for cold) and two sides white (average temperatures)," Time explains. "If you roll the dice, you’re equally likely to get any result. With continued emissions of greenhouse gas, however, the authors predicted that by the early 21st century, four of the sides would be red."

"The climate dice are loaded now, just as we said back in the 1980s that they would be," Hansen told Time. "People should be able to recognize the change, especially the increasingly extreme events. Don’t be surprised if there are more examples this summer."

I know this whole climate change thing is scary, but it's long past time for people to put on their big kid pants and deal with it.


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