The amount of carbon dioxide in the atmosphere has risen to a record high – again.

For the past nine years the UN World Metereological Organisation has produced an annual greenhouse gas bulletin, with each year notching up a record high for average annual levels, and figures published on Wednesday show 2012 was no exception.

This isn't particularly surprising – in September the UN's climate science panel, the IPCC, told us that atmospheric CO2 concentrations were at levels "unprecedented in at least the last 800,000 years." In May this year, CO2 levels briefly passed the symbolic milestone of 400 parts per million (ppm), considerably higher than the average for 2012 of 393.1ppm. As we reported at the time:

...the last time so much greenhouse gas was in the air was several million years ago, when the Arctic was ice-free, savannah spread across the Sahara desert and sea level was up to 40 metres higher than today.

As the WMO points out, the amount of CO2 in the atmosphere is only half of the picture. Much of the CO2 we're responsible for is being absorbed by the oceans, which Prof Piers Forster, a climate scientists at the University of Leeds, says will catch up with us eventually:

This shows that greenhouse gases are heating the climate more and more every year. For the last decade or so the oceans have kindly been sucking up this extra heat, meaning that surface temperatures have only increased slowly. Don’t expect this state of affairs to continue though, the extra heat will eventually come out and bite us, so expect strong surface warming over the coming decades.

The rate of increase appears to be accelerating, too. 2012 was already above average for the last decade, but 2013's rate of increase looks almost certain to be higher still.

Unfortunately, the man-made carbon emissions driving these records show no sign of stopping, even though the rate of growth in emissions slowed last year. As a United Nations Environment Programme report showed on Tuesday, annual worldwide emissions from power plants, cars and other human activities are currently several billion tonnes too high to keep temperatures rises below 2C, the 'safe' level governments have agreed to limit rises to.

Expect all this and more to be on the minds of the world's environment ministers as they meet in Warsaw next week for the latest round of UN talks. As the WMO's secretary-general Michel Jarraud noted in a statement accompany today's figures: “Time is not on our side."