Seth Borenstein, The Associated Press Published Friday, June 3, 2022 2:47 PM EDT Last Updated on Friday, June 3, 2022 2:47 PM EDT
The amount of carbon dioxide trapped by heat in the atmosphere has exceeded a key milestone, more than 50% more than in pre-industrial times, and is at levels not seen for millions of years. years ago, when the Earth was a greenhouse flooded by the ocean. planet, federal scientists announced Friday.
The National Oceanic and Atmospheric Administration said its long-running monitoring station in Mauna Loa, Hawaii, had an average of 421 parts per million carbon dioxide during the month of May, which is when the gas Crucial greenhouse effect reaches its annual maximum. Before the industrial revolution in the late 19th century, carbon dioxide levels were 280 parts per million, according to scientists, so humans have significantly changed the atmosphere. Some activists and scientists want a level of 350 parts per million. Industrial emissions of carbon dioxide come from the combustion of coal, oil and gas.
Gas levels continue to rise, when they should go down, scientists say. This year’s carbon dioxide level is almost 1.9 ppm higher than a year ago, a slightly larger jump than between May 2020 and May 2021.
“The world is trying to reduce emissions, and you don’t see it. In other words, if you’re measuring the atmosphere, you’re not seeing anything happening right now in terms of change, “said NOAA climate scientist Pieter Tans, who monitors global greenhouse gas emissions. for the agency.
External scientists said the figures show a serious problem with climate change.
“Seeing these incremental but persistent increases in CO2 year after year is very similar to seeing a train barrel on the road to you in slow motion. It’s terrifying,” said Andrea Dutton, a climate scientist at the University of Wisconsin-Madison. . “If we stay on the track with a plan to get out of the way at the last minute, we can die of a heat stroke on the tracks before we get there.”
University of Illinois climate scientist Donald Wuebbles said that without cuts in carbon pollution, “we will see more and more harmful levels of climate change, more heat waves, more floods, more droughts, more storms and more of the highest sea “.
The slowdown in the pandemic slightly reduced global carbon emissions in 2020, but they recovered last year. Both changes were small compared to the amount of carbon dioxide pumped into the atmosphere each year, especially considering that carbon dioxide remains in the atmosphere for hundreds of thousands of years, Tans said.
The world puts about 10 billion metric tons of carbon in the air every year, much of it being dragged by the oceans and plants. That’s why May is the peak of global carbon dioxide emissions. Plants in the northern hemisphere begin to suck more carbon dioxide in the summer as they grow.
NOAA said carbon dioxide levels are now roughly the same as they were between 4.1 and 4.5 million years ago in the Pliocene era, when temperatures were 7 degrees (3.9 degrees Celsius). warmer and sea level were 5 to 25 meters (16 to 82 feet) higher than now. . South Florida, for example, was completely underwater. These are conditions that human civilization has never known.
The reason it was much warmer and the seas were higher millions of years ago at the same level of carbon dioxide as it is now is that in the past the natural rise in carbon dioxide levels was much more gradual. With carbon stuck in the air for hundreds of years, temperatures warmed up for longer periods of time and stayed there. Tans and other scientists said that the ice sheets of Antarctica and Greenland melted over time, greatly raising sea levels and making the Earth darker and reflecting less heat from the planet.
Scientists at the Scripps Institution of Oceanography calculated the levels slightly differently based on time and average, and placed the May average at 420.8 ppm, slightly lower than the NOAA figure.