Carbon Dioxide levels are the highest in human history

The amount of planet-warming carbon dioxide in the atmosphere broke a record in May, continuing its relentless escalation, scientists said Friday. It is now 50% higher than the pre-industrial average, before humans began burning oil, gas and coal on a large scale in the late 19th century.

There is more carbon dioxide in the atmosphere now than at any time in at least 4 million years, National Oceanic and Atmospheric Administration officials say.

Concentrations of the gas reached nearly 421 parts per million in May, the highest level of the year, as power plants, vehicles, farms and other sources around the world continued to pump large amounts of carbon dioxide into the atmosphere. . Total emissions 36.3 billion tons in 2021the highest level in history.

As carbon dioxide levels increase, the planet will continue to warm, with impacts such as increased floods, more extreme heat, droughts and wildfires that millions worldwide are experiencing. experience. The average global temperature is currently about 1.1 degrees Celsius, or 2 degrees Fahrenheit, higher than it was in pre-industrial times.

The rising carbon dioxide levels are evidence that countries have made little progress toward the Paris target set in 2015 to limit warming to 1.5 degrees Celsius. That’s the threshold exceeded. over which scientists say the potential for catastrophic effects of climate change increases dramatically.

They are “a stark reminder that we need to take urgent and serious steps to become a more climate-ready nation,” Rick Spinrad, NOAA administrator, said in a statement. .

Pieter Tans, senior scientist with NOAA’s Global Monitoring Laboratory, said that although carbon dioxide levels fell a bit around 2020 during the economic downturn caused by the coronavirus pandemic, they were not. have any effect on long-term trends, Pieter Tans, a senior scientist with NOAA’s Global Monitoring Laboratory, said in an interview.

The rate of increase in carbon dioxide levels “continues to happen,” he said. “And it continues to happen at the same rate as it has over the past decade.”

Levels of carbon dioxide vary throughout the year, increasing as plants die and decay in the fall and winter, and decrease in spring and summer when growing plants absorb this gas through photosynthesis. fit. The peak is reached in May every year, just before the acceleration of plant growth in the Northern Hemisphere. (The North has a greater influence than the Southern Hemisphere because there is more land surface and vegetation than in the North.)

Dr Tans and others at the lab calculated this year’s peak concentration to be 420.99 parts per million, based on data from a NOAA weather station atop the Mauna Loa volcano in Hawaii. Observations began there in the late 1950s by scientist Charles David Keeling of the Scripps Institution of Oceanography, and the long-term record became known as the Keeling Curve.

Scripps scientists still make observations at Mauna Loa under a program run by Dr. Keeling’s son, Ralph Keeling. Using that independent data, similar to that of NOAA, they calculated a concentration at 420.78.

Both numbers are about 2 parts per million higher than last year’s record. This peak is 140 parts per million higher than the average concentration in pre-industrial days, which is about 280 parts per million. Since that time, humans have pumped about 1.6 trillion tons of carbon dioxide into the atmosphere.

To reach the Paris Agreement target of 1.5 degrees Celsius, emissions must reach “net zero” by 2050, meaning drastic cuts, with remaining emissions balanced by carbon sequestration. ocean dioxide and vegetation. If the world approaches that goal, the rate of increase in carbon dioxide levels will slow and the Keeling Curve will flatten.

If emissions are eliminated entirely, the Keeling Curve will begin to decline, as oceans and vegetation continue to absorb existing carbon dioxide from the air, said Dr Tans. The decline in atmospheric concentrations will continue for hundreds of years, though more slowly, he said.

At some point, equilibrium will be reached, he said, but carbon dioxide concentrations in both the atmosphere and ocean will be well above pre-industrial levels and will remain so for thousands of years.

Over such a long period of time, sea levels could rise dramatically as the polar ice melts, and other changes could take place, such as the conversion of arctic tundra into forests.

“It’s that long tail that’s really unsettling to me,” said Dr Tans. “That has the potential to really change the climate.”