Le climat a toujours changé selon des cycles naturels, et les variations climatiques actuelles n’ont rien d’inhabituel.
As it happens, the project’s initial findings, published last month, show no evidence of an intensifying weather trend. « In the climate models, the extremes get more extreme as we move into a doubled CO2 world in 100 years, » atmospheric scientist Gilbert Compo, one of the researchers on the project, tells me from his office at the University of Colorado, Boulder. « So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871. »
In other words, researchers have yet to find evidence of more-extreme weather patterns over the period, contrary to what the models predict. « There’s no data-driven answer yet to the question of how human activity has affected extreme weather, » adds Roger Pielke Jr., another University of Colorado climate researcher.
Some climate alarmists claim that cyclones, such as Cyclone Yasi, are a result of man-made CO2 emissions.
We do know that carbon dioxide and other gases trap and re-radiate heat. We also know that humans have emitted ever-more of these gases since the Industrial Revolution. What we don’t know is exactly how sensitive the climate is to increases in these gases versus other possible factors—solar variability, oceanic currents, Pacific heating and cooling cycles, planets’ gravitational and magnetic oscillations, and so on.
Given the unknowns, it’s possible that even if we spend trillions of dollars, and forgo trillions more in future economic growth, to cut carbon emissions to pre-industrial levels, the climate will continue to change—as it always has.