merefaith: discipleship in the ruins of empire

Skeptics of anthropogenic global warming, the overwhelming consensus position of climate science, do not tend to publish original research. They simply cherry-pick data from published material, take it out of context, and make simplistic, conspiratorial arguments out of it. Detailed rebuttals of this charade have been made at Skeptical Science, Real Climate, and Climate Progress, among other places [Side note: I acknowledge Joe Romm at CP is unabashedly biased towards the Democratic Party. If that offends you, get over it, because that bias does not impact the science. If anything, it is the stubborn anti-science position of many Republicans that probably reinforces his partisanship. If it will make you feel better, visit Republicans for Environmental Protection to help prove that climate change isn't a progressivist conspiracy].

I could not think to reproduce the detailed arguments of climate scientists. Instead, I'd like to offer a fairly simple, graphically-rendered rebuttal of a simple, graphically-rendered skeptical argument.

Critics of the scientific consensus (which, by the way, is increasingly based on empirical evidence and not just "modeling") argue that current warming reflects natural variability and is not out of step with climatic history. In fact, they say, some periods were significantly warmer than today. The "Medieval Warm Period" of the 10th-14th centuries is a frequently-touted example. Note this graph provided by the denier site Watts Up With That:

In this graph, you can see the highest average temperature peak around 1000 AD. In context, the so-called "hockey stick" of the modern instrumental record for the last century is dwarfed in comparison. The world was warmer while Christendom and Islam were fighting the Crusades, and we managed to survive alright. Ergo, conspiracy.

Problem: the data set for this graph is not worldwide but reflects temperature variability only in Central Greenland. As everyone knows climate varies considerably by region and region-specific trends themselves are distinct from overall trends. The total accumulated data reveals that, during the Medieval Warming Period, the upward departure from average occurred only in specific areas, not worldwide. Much of the world actually experienced downward temperature trends. And where did the greatest increases in average temperature across the largest area occur? Who'd have thought it? Right around Greenland!

Meanwhile, the so-called Medieval Warming Period looks very, very mild when compared to a global picture of temperature pattern for the past decade set to the same color scheme...

All this correlates with a a tremendous increase in emissions of CO2, which is indisputably-proven to be a greenhouse gas.

What I cannot present in a graph is the evidence that climate change in the past has meant massive disruption of the Earth's ecosystem, including major extinction events. Climate change was likely a factor in the extinction of the Neanderthals, for example. Critics are right about one thing: life will go on and it will adapt. But that's a slow process not measured in human time scales. Nor is this adaptation easy, simple, and universal. Once-dominant forms of life may diminish or vanish as others rise. And successful adaptation for humans will not take place without great suffering along the way.