Pacific Northwest heatwave "virtually impossible" without climate change
Source: Ars Technica
As with other extreme weather events, the World Weather Attribution team has generated a rapid analysis of this heat wave in the context of climate change. The results were released Wednesday. The team coordinates scientists to perform a standard set of analyses—the method has been peer-reviewed, but this new paper obviously has not, yet.
That method includes a shotgun approach that starts with historical weather data. Focusing on a box between 45°N-52°N and 119°W-123°W that covers Portland, Seattle, Vancouver, and east to Washington's Tri Cities, the researchers examined annual maximum temperatures over time. The goal is to fit a mathematical relationship that tells you how unusual an event was—it can produce figures like 1-in-10 or 1-in-50 odds in any given year, for example. But with events this extreme, the statistics are often challenging, as this heat wave went far beyond anything in the instrumental record. As near as they could estimate, the researchers put this heat wave at a 1-in-1,000 probability—the kind of thing that ought to happen roughly once in a thousand years.
Comparing this to the world before human-caused climate change requires adding in model simulations. As usual, the team compared historical temperatures in the area to a large database of models, tossing the simulations that fit the historical trend poorly. Statistics from simulations of climate in the late 1800s can then be combined with the historical data to see how rare this event would have been in the past.
The analysis estimates the probability of this heat wave in the cooler climate of the late 1800s would be at least 1-in-150,000 if not rarer. It's an extreme event with climate change, but it's an almost unthinkable event without climate change—"virtually impossible," as the team puts it.
Read more: https://arstechnica.com/science/2021/07/pacific-northwest-heatwave-virtually-impossible-without-climate-change/
Submitted without comment.
= new reply since forum marked as read
