Have a question?

Ask MIT Climate

Straightforward answers to your questions about climate change.

Ask MIT Climate is here to answer your questions about how our planet is changing, how it will impact life on Earth and what we can do about it. Whether it's simple or sticky, about science or solutions, ask us! We work with MIT faculty and scientists to give you clear, no-nonsense answers grounded in the best scientific information. New answers posted every month.

Has there been climate change before?

The Earth’s climate and atmosphere have changed drastically over the last 4.5 billion years. Today’s global average temperature is around 59°F, but scientists estimate it has been as low as 10°F1 (during “snowball Earth” events) and as high as 95°F or above2 (so hot the Arctic North resembled today’s tropics). The atmosphere has changed too: Earth used to have very little oxygen, until the first cyanobacteria (or “blue-green algae”) showed up and started producing it. Today, oxygen is the second-most common element in the atmosphere.

What method of waste disposal is best for the climate?

Every day, the U.S. creates about 4.9 lbs of trash per person. In 2018, this amounted to 292 million tons of trash. But what sort of impact does all this trash have on greenhouse gas emissions? The situation isn’t good, says Jonathan Krones, Visiting Assistant Professor of Environmental Studies at Boston College. “There is no sustainable scenario in which we consume a lot of materials, particularly single-use materials,” Krones says, “and rely on disposal processes to manage the waste and mitigate its effect on human and environmental health.”

Should we be worried about Earth getting warmer if we cut coal power?

Wait a second—how could the Earth get warmer if we cut coal power? Coal plants, like all fossil fuel plants, emit carbon dioxide (CO2), which is a greenhouse gas that traps heat in our atmosphere. So cutting coal power should help stop global warming… right?

It will—but when we get into the details of how coal power changes temperatures, it gets a little more complicated. Coal power doesn’t just emit carbon dioxide. It also emits fine particles called aerosols. And aerosols’ effects on climate change are not as straightforward as CO2’s.