Monday, May 9, 2011

Mann's "hockey stick graph" and McIntyre et al. examined ;-)

Perhaps the most enduring argument AGW “skeptics” use against the scientific consensus regarding manmade global warming is attacking the “Mann hockey stick graph.”

What’s a hockey stick got to do with understanding global warming? Well, it goes back to the 1980s and 90s. With the flood of new atmospheric and Earth Observation data scientists began to search for ways of discovering past climate changes in order to put the new information into historical perspective.

Scientists realized there were many natural “proxies” that recorded climate conditions as they grew. Trees, glaciers, all kinds of geologic depositions on land, under lakes and oceans. They reasoned that it should be possible to learn how to tease out climate information from such proxies.

Michael Mann and a team of pioneering researchers focused on tree-ring proxy studies. In 1998 they released a graph reflecting the tree-ring data they had been working on for years. In 1999 their graph was extended back to cover a thousand years. It didn’t actually look like a hockey stick, it was a bunch of waves with a radical uptick at the end.

The “hockey stick” happens by drawing an average-line through the main body of past small and medium fluctuations before getting to the recent steep increase. Basically, the shape underscored the profound influence our energy consuming society is having. Thus it became a despised target for all who wanted to deny responsibility and duty.

Then Republicans, such as Senator Inhofe, really got carried away proclaiming the science was actually doctored. The PR goes that scientists wanted to unduly alarm the public about the seriousness of us injecting over a couple billion tons of greenhouse gases into our thin atmosphere month after month.

They claimed it was part of a conspiracy to hobble growth of our consumer/industrial/military/oil complex. Some even claimed: scientists wanted to promote a one world government. Sounds a bit silly, but so long as the Republican mass media machine focuses on such distractions it leaves no time for considering the real issues facing all of us.

Into this PR effort stepped a Canadian mining engineer, investment promoter, statistician Stephen McIntyre, who went over the team’s work with a fine toothed comb. McIntyre did find some minor flaws in how Mann et al. processed their calculations.

One would think no problem, a further refinement, considering that McIntyre’s work altered the look of the graph by way less than 1%. This was science after all, one of its cornerstones is finding and correcting mistakes made in the collection and processing of information. Although it should be noted, even this tiny correction is in dispute.

Yet the denier echo-chamber, and McIntyre himself, presented his tiny adjustment as somehow overturning the whole field of climatology ~ stuff that’s pure political propaganda far removed from real facts.

Such denialism ignores that since 2000 dozens of independent teams worldwide have been studying many different proxies and without exception the basic “hockey stick shape” emerges from the data. That shape is telling us that our world is on a trajectory of warming not seen since deep geologic time. And we are the ones forcing it.

A key part of the hockey stick myth is that it’s hiding a Medieval Warm Period and the Little Ice Age. But, it doesn’t, they are reflected in the graph. More importantly, those events were regional and driven by a combination of factors scientists have come to understand: vulcanism; solar activity; ocean current oscillations among others.

We should be clear that these factors are playing a role in today’s situation. Volcanoes have been adding their cooling aerosols; our sun is at a historic minimum, and ocean oscillations continue to exert their regional influence.

What’s so different about today’s situation is that previous to industrialization, CO2 levels hovered around 280 (±15) ppm for over four hundred thousand years, giving our biosphere the stability to develop into this cornucopia the age of discovery learned to exploit so well.

But with industrialization atmospheric CO2 broke free from the historic trend and started going uphill, driven by our society’s increasing consumption of coal, oil, gasoline and other carbon based energy sources. Currently, our atmosphere has surpassed 390 ppm, a level unexperienced on Earth in over ten million years.

Today all but the most committed quacks agree that CO2 is indeed a potent greenhouse gas and a significant regulator of our planet’s temperature. While there isn’t, and can never be, absolute agreement on the exact amount of warming, those arguments are over fine details!

We should find no comfort in that uncertainty, since Earth observations are showing our planet changing much faster than scientific forecasts predicted. Yes, this is cause for alarm.

While Republican’s have turned this into a parlor game of who can best manipulate the political debate ~ the harsh real down to earth consequences are already being felt across the planet and they promise only to get worse as Republican statesmen and business leaders with their media machine continue their contemptuous political game of manufacturing willful ignor-ance.

When are we the people going to demand of our business leaders, politicians, media and we ourselves to stop allowing faith-based pipe-dreams to trump real down to Earth realities?

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