Currently in Boston — May 20th, 2022

Significant heat and humidity this weekend

The weather, currently.

Rainfall was barely measurable in greater Boston earlier today and unfortunately that means you'll have to continue to water. The heat you've heard about is still on the docket. It looks as though temperatures will be well into the 70s tomorrow, with plenty of sunshine—generally a nice early summer kind of day. The heat arrives on Saturday with temperatures in the lower to perhaps middle 90s. The first part of the morning will be very comfortable but by the mid to late afternoon you'll definitely notice the change. Heat and humidity peak on Sunday. Temperatures could reach the upper 90s and if Boston hits 97°F that would tie the all-time warmest reading ever recorded in May.

—Dave Epstein

What you need to know, currently.

As a heatwave sweeps across the nation, Denver is set to see some significant snowfall this weekend, with temperatures dropping from the 90s to the low 30s. Snow in late-May is unusual, but not alarming — nothing compared to 1816, which is known as the Year Without a Summer.

In April of 1815, Mount Tambora — a volcano in present-day Indonesia, that had been dormant for 200 years — erupted, sending a plume of ash the size of Australia into the sky and causing a volcanic winter. The ground froze in July and August, snow fell in June, crops and livestock died off — causing widespread famine. According to the New England Historical Society, farmers, who had already shorn their sheep for the summer, tried to tie their wool back onto them, to no avail.

Allegedly, the founder of the Old Farmer’s Almanac, Robert Thomas, had mistakenly printed copies predicting a cold, snowy July that year. Upon discovering his mistake, he had the copies destroyed — only to be vindicated by the volcanic winter.

The basic principles behind volcanic winters are what have inspired researchers to look into certain kinds of geoengineering—namely shooting aerosols into the atmosphere, that would block the sun and effectively mimic the effects of a volcanic eruption.

The risks to geoengineering are manifold, however. Although it may succeed in cooling the climate temporarily, geoengineering is not an argument against reducing emissions and could very well end up worsening the situation.

Alan Robock, a climatologist at Rutgers University outlined some of the risks in a 2016 paper, including ocean acidification, widespread drought and famine, and rapid warming if stopped (once you stop shooting aerosols into the atmosphere, the planet warms faster than if you’d done nothing at all.)

“So far geoengineering research concludes that there is no safe Plan B,” Robock writes. “And provides enhanced support for mitigation and adaptation.”

—Rebecca McCarthy