New record of CO2 in the atmosphere

Levels of carbon dioxide in the atmosphere have just reached a new, 'depressing', record. The data, reported in the Scientific American magazine, come from the Mauna Loa Observatory of the National Oceanic and Atmospheric Administration (NOAA), which may soon be closed due to cuts to the US government budget.

The amount of carbon dioxide detected in the atmosphere reached a record high in April. CO2 levels averaged around 431 parts per million (ppm) during that month. Greenhouse gases, such as carbon dioxide, are measured as a proportion of the total amount in the atmosphere. Values are expressed as the number of molecules of a given gas per million total molecules, or ppm.

Climate scientist Zachary Labe of Climate Central, a non-profit organisation that researches climate change, says the new record is 'depressing', but not unexpected. "It is just another sign that carbon dioxide continues to increase in our atmosphere as our planet continues to warm," he says. "For many climatologists, this simply means 'here's another negative record again'."

Labe explains that the amount of CO2 in the atmosphere tends to peak in April each year, when decaying plants release greenhouse gases after winter. Some of this CO2 is reabsorbed by plants as they grow during the warmer months. But NOAA data show a worrying trend, with the average monthly amount of CO2 steadily increasing.

The Mauna Loa Observatory directly observes atmospheric CO2 and has been recording its levels for longer than any other US facility. Mauna Loa began monitoring the presence of this gas in the atmosphere in 1958. That year, in April, the CO2 level was below 320 ppm.