Carbon dioxide emissions could reach highest level for 56m years

LOS ANGELES: Emissions of carbon dioxide — the greenhouse gas most responsible for global warming — could soar to levels not seen in 56 million years by the middle of next century, scientists warned in a new study on Wednesday.

‘‘You and I won’t be here in 2159, but that’s only about four generations away,’’ said study author Philip Gingerich, a University of Michigan paleoclimate researcher.

He said humans were now pumping carbon dioxide into the atmosphere at a rate nine to 10 times higher than it was during a natural global warming event roughly 56 million years ago.

That era, known by scientists as the PaleoceneEocene Thermal Maximum (PETM), was Earth’s warmest period since the extinction of the dinosaurs 66 million years ago.

During that period, according to the study, the poles were icefree and the Arctic was home to palm trees and crocodiles.

That warmth caused a major extinction of organisms in the deep ocean that are a key link in the marine food web.

Scientists are not sure what caused that spike in carbon dioxide during that era, but we do know what is causing it now.

Burning fossil fuels such as coal, oil and gas releases greenhouse gases like carbon dioxide and methane into Earth’s atmosphere and oceans.

That extra carbon has caused temperatures to rise to levels over the past century and ahalf that cannot be explained by natural factors, scientists report.

The increase in gases such as carbon dioxide, methane and nitrous oxide is fuelling climate change and making ‘‘the planet more dangerous and inhospitable for future generations,’’ the World Meteorological Organisation has said.

Experts said to slow or stop carbon emissions and this unnatural warming of the planet, people, governments and businesses must reduce burning fossil fuels and shift to renewable, carbonfree energy.

‘‘It’s not just about 100 years from now; it’s going to take significant periods of time for that carbon dioxide to make its way back into the Earth’s crust,’’ Larisa DeSantis, a paleontologist at Vanderbilt University, said.

‘‘It’s not a shortterm event. We’re really committing ourselves to many thousands of years of a warmer world if we don’t take action quickly.’’

The study was published in Paleoceanography and Paleoclimatology, a journal of the American Geophysical Union. — TCA