Greenhouse gases are higher than ever in 3 million years

When it comes to our impact on the planet, we’ve been setting ever newer records. The trouble is they are the wrong sorts of records: the most polluted oceans, the worst loss of forest cover, the worst loss of biodiversity.

The latest record is a “highest”: the rates of carbon dioxide, methane and nitrous oxide (three of the worst greenhouse gases) are now the highest ever in the atmosphere over pre-Industrial Revolution levels, according to the World Meteorological Organization (WMO).

This is hardly news, however, to anyone who has been paying attention. Already last year levels of atmospheric CO2 were 405.5 parts per million on average, which well over twice higher than before the Industrial Revolution.

In other words, within a couple of hundred years we have pumped more CO2 into Earth’s atmosphere than was there before. The last time the planet had this much concentration of CO2 in its atmosphere was between 3 million and 5 million years ago when average temperatures were 2 to 3 Celsius warmer and sea levels were 10 to 20 meters higher.

The increase in the levels of methane, which accounts for almost a fifth of global warming, has been higher still. It is 3.5 times higher than what it was a mere few hundred years ago. The main sources of methane emission have been large-scale animal husbandry, especially of cattle, and agricultural practices such as rice growing.

And now that all these gases have been pumped by us into the atmosphere in vast amounts, they are bound to stay there. “Every fraction of a degree of global warming matters, and so does every part per million of greenhouse gases,” WMO deputy secretary general Elena Manaenkova said in a statement. “CO2 remains in the atmosphere for hundreds of years and in the oceans for even longer. There is currently no magic wand to remove all the excess CO2 from the atmosphere.”

And it isn’t as if we are now suddenly mending our ways and ceasing to pump yet more CO2 and methane into the atmosphere. We’ll carry on doing so, thereby setting ever newer unwelcome records.

“I am very concerned that all three gases most responsible for climate change are rising upwards unabated,” laments Corinne Le Quéré, a professor of Climate Change Science and Policy at the University of East Anglia in England. “It seems the urgency and extent of the actions needed to address climate change have not sunk in.”