If greenhouse emissions continue their steady escalation, temperatures across most of the earth will rise to levels with no recorded precedent by the middle of this century, researchers said Wednesday. …

Scientists from the University of Hawaii at Manoa calculated that by 2047, plus or minus five years, the average temperatures in each year will be hotter across most parts of the planet than they had been at those locations in any year between 1860 and 2005. …

“Go back in your life to think about the hottest, most traumatic event you have experienced,” Dr. Mora said in an interview. “What we’re saying is that very soon, that event is going to become the norm.”

The research comes with caveats. It is based on climate models, huge computer programs that attempt to reproduce the physics of the climate system and forecast the future response to greenhouse gases. Though they are the best tools available, these models contain acknowledged problems, and no one is sure how accurate they will prove to be at peering many decades ahead.