She defines "irreversible" as change that would remain for 1,000 years even if humans stopped adding carbon to the atmosphere immediately.
The findings were announced as President Obama ordered reviews that could lead to greater fuel efficiency and cleaner air, with the president also saying the Earth's future depends on cutting air pollution.
Said Solomon, "Climate change is slow, but it is unstoppable" - all the more reason to act quickly, so the long-term situation doesn't get even worse.
Alan Robock, of the Center for Environmental Prediction at Rutgers University, agreed with the report's assessment.
"It's not like air pollution where if we turn off a smokestack, in a few days the air is clear," said Robock, who was not part of Solomon's research team. "It means we have to try even harder to reduce emissions," he said in a telephone interview.
Solomon's report "is quite important, not alarmist, and very important for the current debates on climate policy," added Jonathan Overpeck, a climate researcher at the University of Arizona.
In her paper Solomon, a leader of the International Panel on Climate Change and one of the world's best known researchers on the subject, noted that temperatures around the globe have risen and changes in rainfall patterns have been observed in areas around the Mediterranean, southern Africa, and southwestern North America.
Warmer climate also is causing expansion of the ocean, and that is expected to increase with the melting of ice on Greenland and Antarctica, the researchers said.
