by Seth Borenstein | The Associated Press
The amount of carbon dioxide trapping heat in the atmosphere has passed a significant milestone – more than 50% compared to pre-industrial times – and is not at levels that were observed from millions of years ago when Earth was a Hothouse was an ocean-submerged planet. Federal scientists announced Friday.
The National Oceanic and Atmospheric Administration said its long-term monitoring station in Mauna Loa, Hawaii, averaged 421 parts per million of carbon dioxide in the month of May, which is when the critical greenhouse gas reaches its annual high. Is. Before the Industrial Revolution in the late 19th century, carbon dioxide levels were 280 parts per million, scientists said, so humans have changed the atmosphere significantly. Some activists and scientists want a level of 350 parts per million. Industrial carbon dioxide emissions result from the burning of coal, oil and gas.
Scientists say gas levels continue to rise when they need to fall. Carbon dioxide levels this year are about 1.9 ppm higher than a year ago, slightly larger than those from May 2020 to 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 right now in terms of change,” said NOAA climate scientists Peter Tans, who tracks global greenhouse gas emissions for the agency.
Outside scientists said the numbers reflect a serious climate change problem.
“Humanity needs to make more serious efforts and see a rapid reduction in greenhouse gas emissions, otherwise the effects of climate change will only continue to worsen,” said Jonathan Overpeck, dean of the environment at the University of Michigan.
“We will see more damaging levels of climate change, more heat waves, more floods, more droughts, more major storms and higher sea levels,” climate scientist Donald Vuebles of the University of Illinois said without cutting carbon pollution.
The recession from the pandemic did cut global carbon emissions slightly in 2020, but they made a comeback last year. Tans said both changes were small compared to how much carbon dioxide is pumped into the atmosphere each year, especially given that carbon dioxide remains in the atmosphere for hundreds to a thousand years.
The world puts about 10 billion metric tons of carbon into the air each year, much of it pulled up by the oceans and plants. So May is the peak for global carbon dioxide emissions. Plants in the Northern Hemisphere tend to absorb more carbon dioxide as they grow in summer.
NOAA said carbon dioxide levels were now about 4.1 to 4.5 million years ago in the Pliocene epoch, when temperatures were 7 degrees (3.9 degrees Celsius) warmer and sea levels were 16 to 82 feet (5 to 25 meters) higher than now. ) was excessive. , For example, South Florida was completely under water. These are conditions that human civilization has never known.
The reason it was much warmer and the oceans were higher at the same carbon dioxide levels millions of years ago is because the natural rise in carbon dioxide levels in the past was more gradual. Due to the carbon sticking in the air for hundreds of years, the temperature warmed up and remained there for long periods of time. Tan and Overpeck said the Antarctic and Greenland ice sheets melted over time, causing a tremendous rise in sea level and making Earth deeper and reflecting less heat from the planet.
Scientists at the Scripps Institution of Oceanography calculated the levels slightly differently based on time and averages, and put the May average at 420.8 ppm, slightly lower than NOAA’s figure.