Extreme weather likely to worsen
Disaster tolls will grow, Stanford study forecasts
The extreme weather that brought record floods and ruinous wildfires to the United States in the past year is just a taste of what’s to come, new research out of Stanford University shows.
Owing to global warming, increasingly brutal spells of heat and drought as well as rain and snow are up to five times as likely to occur over large stretches of the planet in coming decades, according to a study published Wednesday,
The work was led by Earth system scientist Noah Diffenbaugh, who is at the fore of a growing cadre of researchers working to pinpoint the largely amorphous effects of climate change.
The study is among the first to quantify how much more probable devastating weather has become — and where it will strike. It offers not only a grim picture of what may lie ahead, but a chance for cities and nations to prepare for the climatic upheaval.
“These extremes are really where we get test-
ed,” Diffenbaugh said. “We’ve seen that in California in recent years, and we’ve seen that in the U.S. in recent years, particularly in this last year.”
In those 12 months, San Francisco saw a new temperature high of 106 degrees, San Jose experienced its worst flood in a century, and the most destructive firestorm in state history ripped through Northern California, killing 45 people. A mudslide in January in Santa Barbara County, the result of heavy rain following a wildfire, killed 21.
Nationwide, 16 climate events, including the California fires, inflicted at least $1 billion each in damage last year, making 2017 the costliest year for natural disasters in U.S. history, according to federal data.
Diffenbaugh’s research found that the toll in California and elsewhere should dramatically worsen as global temperatures continue to climb.
Even if warming is limited to 3.6 degrees above preindustrial levels — the amount prescribed in the Paris climate agreement from which the Trump administration has decided to withdraw — the probability of record-setting weather is likely to increase across 50 to 90 percent of North America, Europe and eastern Asia, according to the study.
Virtually all of the U.S. would face a greater likelihood of hitting new heat and rainfall highs at any given time if temperatures rise 1.8 to 3.6 degrees above preindustrial levels. The planet is closing in on this range now.
If the planet warms more than 3.6 degrees, the probabilities of extreme weather would shoot up exponentially, the study found. Up to 60 percent of North America, Europe and eastern Asia would be three times as likely to set new weather records. Some spots would be five times more likely.
Global warming affects the weather in a number of ways, some of which are better understood by researchers than others. While it’s intuitive that higher temperatures bring more intense hot spells, the process that sees heat-trapping gas emissions drive other weather patterns is more complex.
Scientists have shown that warmer air means more evaporation and greater surface drying, as well as more moisture in the atmosphere and bigger storms. Higher temperatures also melt ice caps and raise sea levels, resulting in more storm surges and flooding. One area of research is looking into how temperature changes can shift the jet stream and the trajectory of major weather systems.
Sewing all of these strands into a forecasting model remains extraordinarily difficult.
Diffenbaugh’s work comes on the heels of some of the first modeling he did last year to uncover the higher probabilities of extreme weather in the era of climate change. The new study uses up-to-date models to look at what’s likely to happen.
His models simulate the point and place in which increasing temperatures prompt weather extremes, represented by eight indexes that include hottest day, wettest day and longest dry spell.
Ben Preston, director of the nonprofit Rand Corp.’s Infrastructure Resilience and Environmental Policy Program, said gaining a better understanding of future climate is vital for governments so they can prepare.
New highways, bridges, sewage treatment plants and other infrastructure, Preston said, must be designed with weather extremes in mind. This approach hasn’t always been taken in the past and won’t necessarily be adopted across the United States going forward, even as the White House proposes a $200 billion infrastructure package. President Trump has called global warming a hoax.
“You have any number of cities, particularly on the West Coast and East Coast, that are actively planning for the future and actively planning for climate change, but you have other parts of the country that aren’t,” Preston said. “We’re still far away from keeping pace with the climate change that we’re experiencing, much less preparing for the climate change we’re likely to see down the road.”
The new study was published in the journal Science Advances and was co-authored by Deepti Singh and Justin Mankin, postdoctoral research scientists at Lamont Doherty Earth Observatory of Columbia University.