Report: Extreme heat days by 2050 will not spare Berkshires Scientists' group paints an uncomfortable picture for region, US if climate change issues not addressed

Posted Wednesday, July 17, 2019 7:06 pm

Heat advisory information The National Weather Service uses its heat index, a combination of temperature and humidity, to issue advisories to avoid strenuous outdoor activities or prolonged exposure outdoors. An official heat wave is three or more days in a row with high temperatures of 90 or above. Heat advisory: Issued when the heat index value is expected to reach 105 to 109 degrees, or less during a multiday heat wave. A temperature of 90 and humidity of 70 percent produces a heat index of 105. Excessive heat watch: Issued when there is a potential for the heat index to reach or exceed 110 degrees within the next 24 to 48 hours. A temperature of 92 with 68 percent humidity triggers a heat index of 110. Excessive heat warning: Issued when the heat index value is expected to reach or exceed 110 degrees within the next 12 to 24 hours, or for lower values during a multiday heat wave. A temperature of 94 with 60 percent humidity equals a heat index of 110. Source: National Weather Service On the web For an interactive map charting the impact of climate change: ucsusa.maps.arcgis.com/apps/MapSeries/index.html?appid=e4e9082a1ec343c794d27f3e12dd006d For an interactive tool to explore climate change in any town or county: ucsusa.org/global-warming/global-warming-impacts/extreme-heat-interactive-tool?location=berkshire-county--ma&heat=above-90

A cautionary climate-change study predicts that without coordinated global efforts to reduce heat-trapping fossil fuel emissions, extreme heat and humidity will envelop Berkshire County and the nation by the year 2050.

The only likely Northeast refuge from more extreme, lower-elevation heat is likely to be high peaks in the Adirondacks of upstate New York, the Green Mountains of Vermont and the Whites of New Hampshire by 2070, if there's no significant action to tackle climate change, according to the Union of Concerned Scientists.

Coastal areas like the Cape, the Islands and downeast Maine also will escape the worst impact, according to the report's interactive map.

"Our results show that failing to reduce heat-trapping emissions will lead to a pretty staggering growth in heat across the U.S.," said environmental scientist Erika Spanger-Siegfried, co-author of the UCS study.

Based in Cambridge, she has been an associate scientist at the U.S. Center of the Stockholm Environment Institute, and earlier worked with the Harvard Center for Health and the Global Environment, and the Massachusetts Department of Public Health's environmental laboratories.

"In places like the Berkshires, we won't see the kind of relentless, dangerous heat the Sun Belt will see by midcentury," Spanger-Siegfried told The Eagle in a phone interview.

"But the increases we do see will transform the experience of living in the Berkshires because of a heat index above 90 for more than 3 weeks per year, compared to the recent historical average of two days," she said. "That's meaningful change for how people spend their time and the activities they can safely do."

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Released Tuesday, the UCS report, "Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days," includes county-by-county national forecasts using the National Weather Service's heat index, which combines the effects of high temperatures and humidity.

For example, a 90-degree day with 70 percent humidity — quite possible locally during the coming weekend heat in Western Massachusetts — produces a heat index of 100. A high of 86 degrees with 60 percent humidity yields a heat index exceeding 90.

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In Berkshire County, the total number of above-90 heat index days would increase to 23 per year starting in 2036, and to 50 beginning in 2070, without significant action to combat climate change, the report found.

The higher-elevation Berkshires will be better off than lower-lying places like Springfield, with 46 days of above 90 by midcentury, and 40 days in Boston. The coolest spots will be Cape Cod and the Islands, thanks to reliable ocean breezes, Spanger-Siegfried pointed out, with 17 days of a 90-plus heat index.

Not too late

"It's important to note that while we were pretty shocked by the steep increase in extreme heat days for much of the country," Spanger-Siegfried said, "we were also surprised by how much difference emission choices make by midcentury. Even though we're going to see unavoidable increases in extreme heat, we do have agency and we can avoid unrecognizably hot futures."

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And it's not too late, she stressed — "although the time to avoid changes altogether has passed, the time to limit or contain them is right now."

The Union of Concerned Scientists is a nonprofit that advocates for science-based climate change policy. Spanger-Siegfried has served on the Massachusetts Climate Change Adaptation Advisory Committee.

The report's analysis shows "a hotter future that's hard to imagine today. Nearly everywhere, people will experience more days of dangerous heat, even in the next few decades."

By the end of the century, without reduced global emissions, parts of Florida and Texas would experience the equivalent of at least five months per year, on average, when the heat index tops 100, with most of these days above 105.

On some days, "conditions would be so extreme that they exceed the upper limit of the National Weather Service heat-index scale and a heat index would be incalculable," the report warns. Such "off-the-charts" conditions "could pose unprecedented health risks."

Clarence Fanto can be reached at cfanto@yahoo.com, on Twitter @BE_cfanto or at 413-637-2551.