The Zeppelin Observatory, Svalbard. At 474m (1600ft) above sea level, the Zeppelin Observatory is located in an undisturbed arctic environment near Ny-Ålesund in Svalbard. Photo: Birgitta Noone

Reports of record high values from Mauna Loa Observatory in Hawaii made international headlines four weeks ago. Exceeding 400 parts per million (ppm) at Mauna Loa was significant because scientists have been monitoring CO2 emissions there since 1958, longer than any other observatory in the world.

“Levels of 400 ppm and the steady increase we observe every year means that it is unlikely global warming will stay below the 2°C target that governments around the world have pledged not to exceed,” says Hans- Christen Hansson, Professor at ITM, and one of the scientists involved in monitoring CO2 levels in Svalbard.

Already in 2012, the monthly average levels for CO2 in March recorded at Zeppelin Observatory exceeded 400 ppm for the first time since measurements began 25 years ago. Parallel readings at monitoring stations in Alaska and northern Canada showed similar concentrations.

More worryingly, this year's readings for January 2013 showed that monthly average CO2 levels rose above 400ppm again and these levels persisted well into late May, five months in all. Scientists at the Norwegian Institute for Air Research (NILU) who have been monitoring CO2 levels at Zeppelin Observatory since 2011 reported the same trend.

“Soon we will observe not only monthly or seasonal averages but yearly averages of 400 ppm and above. We are undoubtedly moving in this direction,” says Hans-Christen Hansson.

CO2 drives climate change

Carbon dioxide is by far the main driver of climate change seeing that it is emitted in higher amounts than any other greenhouse gas and has a long residence life in the atmosphere. “We can be sure that the very first CO2 molecules humans emitted right at the start of the industrial age are still around today,” says Hans-Christen Hansson.

Carbon dioxide is also the greenhouse gas with the most pronounced “radiative forcing” effect - an effect on the balance between incoming solar radiation and outgoing infrared radiation. The combustion of fossil fuels is the largest source of CO2emissions followed by decay (or combustion) of biotic material on land. According to the World Meteorological Organization yearly global CO2 levels have increased from 280 ppm at the advent of the Industrial Revolution in the 18th century when the burning of fossil fuels began to soar, to 390 ppm in 2011.

The yearly average for 2012 recorded at Zeppelin Observatory was 392.5 ppm. While the targets for 2008-2012 set by the Kyoto Protocol were to stabilise and reduce CO2emissions by 2012, measurements at Zeppelin Observatory, among other places, show that CO2 levels continued to increase by 2.2 ppm on average per year during the last decade.

“The curve is upward with no signs of levelling off as readings from both last year and the last five months have shown. If we continue to emit CO2 at this rate, and there are no significant changes in the uptake of CO2 by oceans and plants, the world could reach 450 ppm in only a few decades,” says Hans-Christen Hansson.

The last time CO2 levels at Zeppelin Observatory were that high, humans were not around. In fact, the last time CO2 levels are thought to have been this high was more than 2.5 million years ago, during the Pliocene era, when the Arctic boasted forests, global temperature averaged about 3°C warmer whilst sea levels were 5 meters (16ft) higher. What's worse, there is no known geologic period during the last 800,000 years, in which rates of increase have been so sharp. “We are concerned that thespeed of the increase is too high for plants, animals and humans to adapt,” says Hans-Christen Hansson.

The milestone comes as the IPCC Fifth Assessment Report will be launched in September in Stockholm. ITM scientists hope that their findings will spark the climate debate anew, not least in relation to new challenges humanity will face in the future due to extreme weather and rising sea levels.

Text: Stella Papadopoulou