Scientists say recent Northeast heat wave would have been virtually impossible before industrial-era warming
A team of researchers found that the extreme heat and humidity experienced in the northeastern United States and eastern Canada this week would have been exceedingly unlikely in a pre-industrial climate, attributing the increased risk to human-driven greenhouse-gas emissions.
A group of scientists analyzing the current heat wave in the northeastern United States and eastern Canada reported that the five-day average of wet-bulb globe temperature – a metric that combines heat, humidity, wind and sunlight – had only about a 0.5 percent chance of occurring in any given year under today’s climate. The same conditions, they said, would have been effectively impossible in the cooler climate that existed before the Industrial Revolution.
The researchers, affiliated with the World Weather Attribution collaboration, used a combination of recent observations and forecast data to assess the event’s rarity. Their analysis, which has not yet undergone peer review, follows a similar study of a recent heat spell in Western Europe that also linked the intensity of the event to global warming.
"On America’s 250th birthday, our study gives a clear reality check," said Theodore Keeping, a climate scientist at Imperial College London who contributed to the analysis. "The climate the country has today is fundamentally different to the one it had when the founding fathers signed the Declaration of Independence."
The team attributes the heightened likelihood of such extreme heat to the accumulation of carbon dioxide and other greenhouse gases from the combustion of fossil fuels, which have trapped additional solar heat at the planet’s surface for more than a century.
