How can scientists tie extreme heat waves to global warming? An expert explains. – SILive.com
STATEN ISLAND, N.Y. — Two decades ago, climate scientists hesitated to tie individual weather events to global warming. The data was too scarce and tying the two together proved an insurmountable challenge.
Dr. Noah Diffenbaugh, a professor and senior fellow at Stanford University, recalls common answers to the question of climate-change attribution ranging from, “That’s not really what we are equipped to do at this point” and “We can’t attribute any individual weather event to global warming,” to, “Climate is what you expect, weather is what you get.”
The refrains mirrored the reality of a field unable to inextricably link a world that was undoubtedly warming to an increase in deadly events like heat waves and torrential rainfall.
“That’s really changed in the last 15 years,” said Diffenbaugh.
A 2004 study that found human-induced climate change contributed to a heat wave in Europe the year prior broke open an area of research that has now resoundingly found global warming increases the risk of extreme weather events.
Among those shifts is a nearly fourfold increase of extreme events under 1.5 degrees Celsius of warming — a critical threshold scientists said must be avoided to limit the extent of permanent climactic damage — and a fivefold increase under 3 degrees Celsius of warming. The planet is currently 1.1 degrees Celsius warmer than it was around 150 years ago.
Recent National Oceanic and Atmospheric Administration (NOAA) climate averages for the United States that shows average temperatures across the country have been unmistakably rising in recent decades. The NOAA said the current normal shows that, “the influence of long-term global warming is obvious.”
“We now have very clear evidence that global warming is already influencing individual extreme events,” said Diffenbaugh, with extreme heat topping the list in terms of confidence. Experts have also said a warming atmosphere is more capable to unleash heavier storms throughout the year.
Diffenbaugh, who studies the climate system, said the growing observational record is among the tools that are helping scientists better understand how temperatures and precipitation levels are changing over time. Those numbers serve as the foundation of a climate analysis.
Those well-established methods are mirrored in other fields like engineering and the finance industry, noted Diffenbaugh, but a tricky element of climate science is the very nature of climate itself — it’s always shifting.
Scientists need to account for that change when observing previous records, and then they need to create a scenario called a “counterfactual” that shows the planet’s course without global warming.
One path to complete that goal is to use computerized climate models, which Diffenbaugh said have become far more detailed, powerful and accurate in recent years.
“We’re running very high resolution, global simulations,” said Diffenbaugh. “Computing has been a big advance over the last 20 years and the methods have really advanced.”
That, on top of additional decades of satellite data, has made breaking-down events like heat waves far more doable.
“If you have a record-setting heat wave, having 20 years of historical record versus 40 years of historical record in the satellite era, that’s very different,” said Diffenbaugh.
Heat waves, which kill more people than any other climate impact, threaten not only human life but also vital infrastructure. Staten Island institutions are already preparing for a reality with more days surpassing 95 degrees within the coming three decades.
A recent heat wave in Europe sent temperatures to record highs in Britain, while locally, Newark Liberty International Airport saw five consecutive days surpass 100 degrees last week — the longest streak since record keeping began.