It has been 30 years since the specter of global warming began to loom before the world. It was 1988 when James Hansen, a scientist at NASA, first testified before Congress about the supposed link between the greenhouse effect and observed global warming. Al Gore was late to the party when he released his Oscar-winning movie, “An Inconvenient Truth,” in 2006. With three decades of predictions about warming to look back on, we can now assess the accuracy of those early claims about global warming.
I am old enough to remember the dire predictions of the late 1990s and early 2000s. There were predictions of coastal cities being flooded and drastic temperature increases that would destroy crops and cause millions to become climate refugees. Weather site Stormfax.com compiled a list of “Bad Things Attributed to Global Warming” that ranges from acne to zoonotic diseases.” A lot of severe problems were supposed to have happened by now.
Writing in the Wall Street Journal, Pat Michaels and Ryan Maue of the Cato Institute’s Center for the Study of Science note that back in 1988 James Hansen presented three possible scenarios. The first scenario was “business as usual,” which showed emissions accelerating at a rate typical of the 1970s and 1980s. Hansen estimated that the current trends would cause the earth to warm by 1° Celsius by 2018. Hansen called the second scenario “most plausible.” This assumed that emissions would increase at the 1988 rate through today, which would cause the earth to be 0.7° warmer. The final scenario was constant emissions after the year 2000. This scenario would warm the earth by a few tenths of a degree before 2000 and then temperatures would level off. Hansen considered this unlikely.
As it turned out, the third scenario was the one that became reality. For almost a decade now, writers in the Journal have reported on a global warming pause. In 2014, Matt Ridley described how the pause in increasing temperatures had continued “for 16, 19 or 26 years—depending on whether you choose the surface temperature record or one of two satellite records of the lower atmosphere.”
Michaels and Maue point out that several of Hansen’s other predictions missed the mark as well. There was no “greater than average warming in the southeast US and the Midwest” in the late 1980s and 1990s as Hansen predicted in his Senate testimony. In 2007, he predicted that melting ice would cause sea levels to rise by 23 feet over 100 years. Subsequent research proved this to be impossible. In 2016, Hansen forecast stronger hurricanes, but there is no evidence of relationship between storm strength and global temperature. Hurricane damage as a percentage of GDP has also not increased.
If forecasts by Hansen and organizations such as the UN and the IPCC have been off base, the wilder predictions of Al Gore and other alarmists have had worse results. In 2006, the former vice president predicted a tipping point where global warming would be irreversible within 10 years. The United Nations warned of tipping points three times in 1989, 2007 and 2015. Decades later there is still little evidence of catastrophic warming.
Gore and climate scientists also made alarming predictions of rising sea levels that range from a few inches to more than 20 feet. Climatologist Judith Curry points out, “Sea level has been overall rising since the last ice age, with some ups and downs. Sea level has been rising for the past 200 years…. Humans are not going to stop sea level rise on the time scale of a few centuries by ceasing emissions of CO2.”
Regardless of cause, sea levels that increase even a few feet could be catastrophic for very low areas. The problem is that cutting emissions won’t stop the rising seas if the end of the ice age is to blame.
What about the polar ice caps? In 2016, Peter Wadhams, a Cambridge University scientist and an expert on Arctic ice loss, told The Guardian, “Ice-free means the central basin of the Arctic will be ice-free and I think that that is going to happen in summer 2017 or 2018.” Wadham’s prediction was obviously incorrect.
The predictions of the experts have been off base for decades. Michaels and Maue say that the reason is that most scientific models do not include the effect of aerosols in countering the warming caused by greenhouse gases. “Several newer climate models account for this trend and routinely project about half the warming predicted by U.N. models, placing their numbers much closer to observed temperatures,” they write.
For whatever reason, the global warming forecasts have not been accurate for the past 30 years. The scientific method says that when a prediction based on a hypothesis is not correct, then it’s time to reevaluate the hypothesis. In this case, most scientific models have been observed to be inaccurate and fail to explain the pause in global warming.
While there has been a modest increase in world temperature, the alarmist predictions have failed. Scientists owe it to the public to tone down the apocalyptic rhetoric until they can develop models that accurately account for what is happening in the real world.