As fires ravage Arizona and sweltering heat settles into many areas across the country, a new study published in the journal Climate Change today by Stanford scientists finds that large areas of the globe will warm up so quickly that even the coolest summers will be hotter than the hottest summers of the past 50 years.
The pre-summer heat wave moved into the Northeast today, triggering heat advisories and warnings in cities from New York to Washington.
It was nearly 100 degrees in New Jersey and Karl Sottung and his construction crew are paid to sweat it out, but this spring has been brutal.
"If you are going to get a heat spell where you are gonna have this 95- to 100-degree day, day in and day out, it definitely starts taking a toll on the men," he told ABC News today.
Several deaths have been reported and the National Weather Service warned that the heat wave would bring temperatures in the 90s and triple digits with high humidity to the East Coast and Southeast for several days.
"We're forecasting the high to be pretty close to the record" of 98 degrees set for Washington in 1999, Brandon Peloquin, a meteorologist with the National Weather Service, told the Associated Press. That compares with normal highs in the upper 70s to low 80s for this time of year.
Is this a sign of things to come?
"What's going on is we are experiencing the most extreme spring on record -- tornados and wildfires, too," Dr. Jeff Masters, co-founder of Weather Underground, told ABC News.
A study in this month's issue of the journal Climatic Change predicts that much of the Northern Hemisphere is likely to experience an irreversible rise in summer temperatures within the next 20 to 60 years. The culprit, Stanford University scientists claim, is rising atmospheric greenhouse gas concentrations.
"According to our projections, large areas of the globe are likely to warm up so quickly that by the middle of this century even the coolest summers will be hotter than the hottest summers of the past 50 years," said the study's lead author, Noah Diffenbaugh, an assistant professor of environmental Earth system science and a fellow at the Woods Institute for the Environment at Stanford, in a prepared statement.
"When scientists talk about global warming causing more heat waves, people often ask if that means that the hottest temperatures will become 'the new normal,'" Diffenbaugh said. "That got us thinking: At what point can we expect the coolest seasonal temperatures to always be hotter than the historically highest temperatures for that season?"
No need to wait long, the researchers said, because the heat is already here.
"We find that the most immediate increase in extreme seasonal heat occurs in the tropics, with up to 70 percent of seasons in the early 21st century (2010-2039) exceeding the late-20th century maximum," the authors wrote.
Wide swaths of North America, China and Mediterranean Europe are also likely to enter into a new heat regime by 2070, they said.