The impacts of hurricanes Harvey and Irma were blunted because we saw them coming. Weather models accurately predicted the hurricane paths and anticipated their extreme intensities days in advance. This allowed millions of Floridians to evacuate the state, sparing countless lives.
Some contrarians have tried to downplay the rising costs of landfalling hurricanesby claiming they’re only more expensive because there are now more people living along the coasts with more expensive stuff vulnerable to hurricane damages. However, those arguments fail to account for our ability to predict hurricane tracks earlier and more accurately by using better and better scientific models. We’re able to prepare for hurricanes much better today than in the past because we have more warning.
Although they focus on much different timescales and resolutions, climate and weather models are based on the same core physics. Scientists have a solid understanding of the Earth’s oceans and atmosphere, and that understanding is improving all the time.
Millions of people watched the evolution of the model forecasts for hurricanes Harvey and Irma, and made important decisions based on those forecasts. People trusted the models, and their trust proved to be well placed, as the model predictions were accurate.
And climate models have an even better track record.
As I documented in my book Climatology versus Pseudoscience, since their inception in the 1970s, climate models have been remarkably accurate at predicting global warming. In a 1975 paper in Science, renowned climate scientist Wallace Broecker was one of the first to use early simple climate models to predict future global warming. Based on scientists’ understanding of the climate at the time, Broecker was only able to include the effects of human carbon emissions and ‘natural cycles’ (whose effects he overestimated) in his model, but the prediction was nevertheless remarkably accurate:
Wallace Broecker’s 1975 global warming prediction (blue) compared to observational data from Nasa (black). Illustration: Dana Nuccitelli
Renowned Nasa climate scientist James Hansen made even better global warming predictions in 1981 and 1988, and the IPCC improved further yet in 1990, 1995, 2001, and 2007. On the other hand, the few climate contrarians that have had the courage to make their own predictions (without using climate models) have fared remarkably poorly.
Meanwhile recent research has shown that climate models have been even more accurate than we thought, when we compare apples-to-apples.
And of course what those climate models tell us is extremely alarming. If we stay on our current path, we’re headed for 3–4°C global warming by 2100, which research indicates would lead to severe consequences like 40–70% of global species being at risk of extinction, millions more people being hit by coastal flooding, increased mortality from intensified heat waves, droughts, and floods, and so on.
This raises an obvious question – if people trust weather models, and climate models with their even stronger track record predict we’re on such a dangerous path, why aren’t people loudly demanding climate action?
In 1998, leading up to the critically important Kyoto Protocol international climate negotiations, Patrick Michaels from the fossil fuel-funded Cato Institute ‘think tank’ testified before Congress. Not surprisingly, considering his heavy reliance on fossil fuel funding, Michaels made the case that the US should not sign on to the Kyoto agreement (and succeeded - although the Clinton administration signed the treaty along with 150 countries, the US Senate refused to ratify it).
In his testimony, Michaels essentially committed perjury in a reprehensibly dishonest effort to discredit Hansen’s 1988 global warming predictions. Hansen’s study had projected temperature changes under three different possible scenarios, which he called A, B, and C. In his testimony, Michaels deleted all but Scenario A with the highest greenhouse gas emissions, which was also the scenario that was least representative of real-world conditions. Worst of all, Michaels didn’t mention that he had deleted Hansen’s other scenarios, simply claiming (falsely):
[Hansen’s] model predicted that global temperature between 1988 and 1997 would rise by 0.45°C (Figure 1). Figure 2 compares this to the observed temperature changes from three independent sources. Ground-based temperatures from the IPCC show a rise of 0.11°C, or more than four times less than Hansen predicted.
You can see Michaels’ figure here – it even labeled Scenario A, but at no point did Michaels mention Hansen’s other scenarios. His claim that Hansen’s model predicted 0.45°C warming between 1988 and 1997 was flatly false – that was the model estimate under a scenario of much higher greenhouse gas emissions. Hansen subsequently asked, “Is this treading close to scientific fraud?” (yes, and to perjury).
That was the start of a now nearly 20-year effort by climate deniers to discredit climate models.
Posted by dana1981 on Monday, 18 September, 2017
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