No, Dorothy, it isn't the vagaries of galactic forces and nature causing the super-tornadoes and extreme weather, it turns out. Climate change is man-made, concludes a nonlinear physicist at McGill University, in a paper published in Climate Dynamics.
In a paper enticingly titled "Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming," Shaun Lovejoy can't prove a negative – that humans aren't ruining our planet. What he can do is demolish the claim that natural variability is the root cause of the warming world, not to mention extreme weather phenomena the world has been experiencing.
"This study will be a blow to any remaining climate-change deniers," Lovejoy said in a statement. "Their two most convincing arguments - that the warming is natural in origin, and that the computer models are wrong - are either directly contradicted by this analysis, or simply do not apply to it."
Lovejoy set out to test whether the causes of climate change are likely to be natural using statistics. Crucially, his calculations are based not on computer models, but on actual findings in the field – of surface air temperatures - going back to the 16th century, before industry started belching clouds of carbon dioxide into the air.
Computer models forecasting the future are based on historic data. Well and good. What Lovejoy did is look at the temperature data collected for the models, and ask if nature could have caused it.
Lovejoy calculated the probability of measured warming from natural variability, based on the probabilities of natural fluctuations on a centennial scale. His conclusion: The probability that Mother Nature caused the degree of global warming the planet has experienced since 1880 is less than 0.1%.
Or, he has a 99.9 percent degree of confidence that the fluctuation of 0.9 of one degree in average temperature since 1880 it isn't natural. Not clear on the math? The chance is less than 1 in 100, he argues.
Critics may snipe that Lovejoy simplified his calculation by using carbon dioxide emissions from the burning of fossil fuels to cover all human impact on the climate. The scientist explains that global economic activity is tightly correlated to greenhouse gas emissions and particulate pollution.
He can't say it's man causing the mayhem. But if it isn't Mother Nature behind the storm, we all know what remains.
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