The Guardian Australia

Scientific models saved lives from Harvey and Irma. They can from climate change too

- Dana Nuccitelli

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 hurricanes by 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.

Time to start listening to climate models

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.

40 years of remarkably accurate climate models

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:

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 applesto-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?

Deniers have lied about climate models for two decades

In 1998, leading up to the critically important Kyoto Protocol internatio­nal climate negotiatio­ns, Patrick Michaels from the fossil fuelfunded 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):

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. According to Skeptical Science, the claim that climate models are unreliable is the 6th most popular climate denial myth. It’s one that contrarian scientists repeat at every opportunit­y in congressio­nal testimony to this day.

The reason is quite simple – if climate models are right, then if we don’t start cutting our consumptio­n of fossil fuels, we’re in big trouble. But the GOP has now effectivel­y become the Grand Oil Party – a subsidiary of the fossil fuel industry that does its bidding. They don’t want to curb our reliance on fossil fuels, so they attack the models, or like Rush Limbaugh, claim it’s all a hoax and then flee to California, leaving the duped followers behind to face the ugly consequenc­es of science denial.

We need to act on model warnings about climate change too

There are some exceptions. The bipartisan Climate Solutions Caucus, which now includes 28 House Republican­s, acknowledg­ed the impacts climate change is having on disasters like Harvey and Irma. We need more conservati­ves to accept reality and join their ranks.

Scientific models saved countless lives from Harvey and Irma because we listened and acted. They can also save countless lives from climate change if we listen and take action to slow global warming. Or we can listen to the conspiracy theorists, ignore the scientists and their models, and suffer the consequenc­es while the Rush Limbaughs of the world flee in their private jets to higher ground.

 ??  ?? Traffic on the northbound lanes of Florida’s Turnpike on Friday, Sept. 8, 2017, as motorists evacuated for the anticipate­d arrival of Hurricane Irma. Photograph: Stephen M. Dowell/AP
Traffic on the northbound lanes of Florida’s Turnpike on Friday, Sept. 8, 2017, as motorists evacuated for the anticipate­d arrival of Hurricane Irma. Photograph: Stephen M. Dowell/AP
 ??  ?? Wallace Broecker’s 1975 global warming prediction (blue) compared to observatio­nal data from Nasa (black). Illustrati­on: Dana Nuccitelli
Wallace Broecker’s 1975 global warming prediction (blue) compared to observatio­nal data from Nasa (black). Illustrati­on: Dana Nuccitelli

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