Last updated on April 9, 2021
Saturday was the first day that CO2 measured in the atmosphere was above 420 ppm since measurements began in the 1950s. This moment in time has sapiens in a perilous position of our own making where CO2 in the atmosphere is almost 50% higher than it was since the industrial revolution. Just a wisp of CO2 in the atmosphere can cause unfathomable disruption to the climate.
Now, this is news, but you would never hear about it unless you follow atmospheric scientists.
For the first time in recorded history, the concentration of atmospheric carbon dioxide, or CO2, was measured at more than 420 parts per million atop the iconic Mauna Loa Observatory on the Big Island of Hawaii. It marks a disconcerting milestone in the human-induced warming of the planet, around the halfway point on our path toward doubling preindustrial CO2 levels.
Within five years atmospheric CO2 will pass 427 parts per million, which was the probable peak of the mid-Pliocene warming period 3.3m years ago, when temperatures were 3C to 4C hotter and sea levels were 20 metres higher than today.
— Paul Dawson (@PaulEDawson) April 4, 2021
When the station began collecting CO2 measurements in the late 1950s, atmospheric CO2 concentration sat at around 315 parts per million. On Saturday, the daily average was pegged at 421.21 parts per million — the first time in human history that number has been so high. Previously, it had never exceeded 420 parts per million.
— Christopher Cartwright (@chriscartw83) April 5, 2021
The anticipated doubling of atmospheric CO2, which is likely by the year 2060, has been connected to a predicted 3-degree or greater warming of the planet.
A study released last year found doubling CO2 levels will likely lead to a temperature rise between 4.1 and 8.1 degrees Fahrenheit (2.3 and 4.5 degrees Celsius), ruling out more modest warming scenarios.
At the midpoint toward doubling CO2 levels, the planet has already warmed more than 2 degrees (1 to 1.5 degrees Celsius). Last year rivaled the planet’s hottest year in modern records.
The World Meteorological Organization recently said there is at least a 1 in 5 chance of the global average temperature temporarily exceeding 2.4 degrees (1.5 Celsius) by 2024, which the Paris climate accord sets out to avoid.
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