Perhaps the most enduring argument global-warming skeptics use against the broad scientific consensus regarding manmade climate change is attacking something called 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. Following a flood of new atmospheric and Earth observation data, scientists began to search for ways of uncovering 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. They reasoned that it should be possible to learn how to tease out climate information from such proxies.
Michael Mann and a team of fellow researchers focused on tree-ring 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” appears when one draws 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 target of scorn for all who wanted to deny humans’ responsibility in climate change.
Republicans such as Sen. James Inhofe (R-Okla.) really got carried away proclaiming that the science was doctored in a broad scientific plot 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 the 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 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, and statistician named Stephen McIntyre, who went over the team’s work with a finetoothed comb. McIntyre did find some minor flaws in how Mann, et al., processed their calculations.
One might think this was no problem – a further refinement, considering that Mc- Intyre’s work altered the look of the graph by less than 1 percent. This was science after all; one of its cornerstones is finding and correcting mistakes. Although it should be noted, even this tiny correction is in dispute.
Yet the denier echo-chamber, and Mc- Intyre himself, presented this tiny adjustment as somehow overturning the whole field of climatology.
Such “denialism” ignores the fact 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 propelling the change.
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, and 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 before industrialization, CO2 levels hovered around 280 parts per million for over 400,000 years, giving our biosphere the stability to develop into this cornucopia that we have 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 not experienced on Earth in over 10 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 Republicans have turned this into a parlor game of who can best manipulate the political debate, the harsh, 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 cynical political game of manufacturing willful ignorance.
When are we the people going to demand of our business leaders, politicians, media and ourselves that we all stop allowing faithbased pipe dreams to trump realities?
Peter Miesler writes from near Durango, Colo. His essays, along with global-warming information, are posted at Citizenschallenge.blogspot.com.
