New York Times: Without Climate Change, U.S. Heat Wave Called ‘Virtually Impossible‘

Scientists have said the conditions are the result of a climate that is “fundamentally different” from the time before fossil fuel use started rapidly warming the world.

Takeaways

• Heat and humidity as severe, prolonged and far-reaching as this week’s would have been “virtually impossible” in the Northeast and eastern Canada before humans began warming the planet, a team of scientists said on Friday.
• Emissions of carbon dioxide and other greenhouse gases from the burning of oil, gas and coal have trapped more of the sun’s heat at Earth’s surface, raising temperatures worldwide for more than a century. Summer hot spells are nothing new, but because of the excess heat around the planet caused by global warming, they can produce higher temperatures today than they once did.
• To estimate how much climate change increased the likelihood of this week’s sweltering conditions, the scientists analyzed records of a measurement of heat stress called “wet bulb globe temperature,” a figure that accounts for humidity, wind and direct sunlight. Given that the heat wave is still unfolding, the researchers combined weather observations and forecast data.