Don’t ask officials what they think of global warming — ask if they want a warning

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The Washington Post 2021-04-23

“What is your opinion about global warming?” We ask this question of political candidates, Supreme Court nominees and ourselves. But there is something more fundamental we should ask first, because it changes the framing of the discussion. The more fundamental question is: “If the climate were changing and expected to produce problems like sea level rise, floods and droughts, would you want a warning?”As a professor of atmospheric sciences, I have researched weather and weather forecasting for 40 years. Forecasters issue warnings for hazardous weather because people answer yes to questions such as: “If you live in Key West and a hurricane might hit, would you want a warning?” Weather and climate are closely related, characterizing things like temperatures, winds and rainfall on an hour-by-hour (weather) or a season-by-season (climate) basis.Turning from weather to climate, the analogous question becomes: “If you live in Key West and climate change is expected to produce sea level rise, would you want a warning?”Weather forecasters weigh three concerns when deciding to issue a warning. They don’t want to miss an event; they don’t want to issue false alarms; and they need to issue the warning with enough lead time for the public to take action.The later forecasters wait to issue a warning, the easier it is both to detect a developing event and to avoid a false alarm — but having an earlier warning can save lives and protect property. That’s why increasing the lead time for warnings has been a priority in the weather forecasting community. From 2008 to 2019, the average lead time for high-wind warnings issued by the National Weather Service increased from 6 to 12 hours, while the rate at which forecasters missed real events or issued false alarms stayed essentially constant.As an illustration of potential responses to long-lead-time forecasts, evacuation orders for the Florida Keys were issued four days before devastating Hurricane Irma came ashore in 2017. Major changes in hurricane intensity can easily occur over four days and are very difficult to forecast, but the Hurricane Irma warnings needed to go out in time for people to evacuate along the sole escape route, U.S. Highway 1.We also need long-lead-time warnings about climate change because our extensive existing investments in cars, power plants and similar infrastructure cannot be changed to quickly reduce the emissions from burning fossil fuels such as coal, gas and oil. Meanwhile, most carbon dioxide (CO2) added to the atmosphere each year by new emissions remains there for hundreds to thousands of years. Each day of business as usual allows more emissions to accumulate.Can we rely on new technologies to solve the problem of climate change, as some might be hoping, eliminating the need for long-lead-time warnings? Geoengineering technologies proposed to remove CO2 from the atmosphere have not demonstrated practical viability to significantly reverse our current emissions. There is no guarantee they will ever develop into anything more useful than the futile geoengineering effort to weaken hurricanes.Project Stormfury was launched in the 1960s with great optimism. Stormfury appeared to score an initial success when a fleet of Navy aircraft seeded the eyewall of Hurricane Debbie, and the winds decreased. Yet subsequent studies showed the working hypothesis behind Stormfury was incorrect, and the changes observed in Debbie occur spontaneously in many hurricanes. Today, we still have no way to reduce the intensity of a hurricane barreling down upon our coastal cities and towns. Warnings remain our best tool to survive hurricanes — not weather modification.Since we can’t count on having practical tools to remove CO2, delaying efforts to reduce current emissions amounts to placing an irreversible bet against our scientific understanding that releasing more heat-trapping gases will cause more global warming. Even if some are not entirely convinced that human emissions are warming and disrupting the climate, it’s worth returning to the fundamental question: Do we want advanced warning about global warming and its impacts? As with hurricanes, our response to the warnings will be far more effective if we act before the storm is fully upon us.We know that global average temperatures are increasing. The past six years were the six hottest years in recorded history; two of the three hottest years were 2019 and 2020. The observational and theoretical evidence that this temperature rise will continue and is driven by the emission of CO2 and other greenhouse gases is very strong. Even if we can’t be 100 percent sure of the precise timing of global-warming impacts, the available information is well above the threshold for conscientious scientists to issue warnings.The question for those of us planning for the future is: Do we want any warning?Dale Durran is a professor and past chair of the Department of Atmospheric Sciences at the University of Washington and a fellow of the American Meteorological Society.