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Greenhouse gas levels are constantly rising

Zeppelinobservatoriet i Ny Ålesund på Svalbard
Foto: Markus Fiebig

The most important greenhouse gases monitored by NILU – The Norwegian Institute for Air Research continued to rise in 2017. Levels have now reached new records both at Svalbard and in Aust-Agder in Norway. Both CO2, methane and nitrous oxide continue to increase in both Southern Norway and Svalbard, and there is no sign of reduction or flattening in this trend.

Previously, scientists has stated that the CO2 concentration in the atmosphere had to be below 400 ppm in order to achieve the international goal of not exceeding two degrees global warming.

– Significant reductions in both CO2 and methane are needed to reach the goal of only two, or preferably 1.5 degrees of heating, explains senior scientist Cathrine Lund Myhre from NILU.

– The 1.5-degree target is actually so ambitious that CO2 emissions must be down 45% compared to 2010 by 2030. Moreover, it does not stop there. We have to cope with net zero emissions of CO2 by 2050.

In order to monitor the changes in emissions, precise observations of greenhouse gas levels in air is essential. Lund Myhre leads the national monitoring program “Monitoring of greenhouse gases, ozone layer and atmospheric pollutants”. Results are published in the annual report “Monitoring of greenhouse gases and particles in Svalbard and Birkenes in 2017”. The report states that the two most important greenhouse gases, CO2 and methane, also set new records last year. This also applies globally, according to a new World Meteorological Organization (WMO) report that came today.

CO2 is still rising over Norwegian areas and the Arctic

NILU carries out the monitoring program on behalf of the Norwegian Environment Agency. At the Zeppelin Observatory at Svalbard, they measure 46 different greenhouse gases, in addition to CO2 and methane measurements made at the observatory at Birkenes in Aust-Agder.

In 2017, the annual average concentration of CO2 in the atmosphere was record high – 408.0 ppm (parts per million) at Zeppelin and 411.3 ppm at Birkenes. There are increases of 3.6 ppm (0.89%) and 1.5 ppm (0.37%) respectively from 2016.

Figure 1: The orange bars show the annual average concentrations of CO2 measured at the Zeppelin Observatory during the period 1989-2017. The green bars show annual average values from Birkenes. The latest global 2017 average published November 22, 2018 from the World Meteorological Organization (WMO) is shown in black (WMO, 2018).

– The increase of 3.6 ppm on Zeppelin from 2016 to 2017 is the second highest increase we have measured since the start in 1988, Lund Myhre says.

– When we compare with data from the WMO report, we see that the CO2 levels have increased more than the global average increase (an increase by 2.2 ppm from 2016 to 2017). This is partly because there are more people living in the northern hemisphere, with associated higher CO2 emissions from industry, traffic, combustion and other sources.

The methane levels in the north at a new record level

The concentrations of methane also reached new heights in 2017, with an annual mean value of 1939 ppb (parts per billion) at Zeppelin and 1945 ppb at Birkenes. Compared to the 2016 levels, this represents increases of 7 ppb (0.35%) and 3 ppb (0.18%) on Zeppelin and Birkenes respectively. For Zeppelin, this is comparable to the global increase, which was 7 ppb for the same period. The changes over the last few decades are large in relation to the development of the methane level in the period 1998-2005, as the changes were virtually zero on both Zeppelin and globally. Understanding the reason for this is a complicated and important research topic.

Figure 2: Development of annual average methane concentration in the atmosphere indicated in parts per billion (ppb). The orange bars show annual mean values measured at the Zeppelin observatory in the period 2001-2017, the green bars correspondingly measured at the Birkenes observatory in the period 2010-2017. The black bars show the global average published November 22, 2018 from the World Meteorological Organization (WMO, 2018).

As Figure 2 shows, the methane concentration in the atmosphere is much higher here in the north than the global average. About. 60% of methane emissions originate from manmade sources. The major difference between levels here in the north and global values, is that most methane emissions occur in the northern hemisphere. In addition, it takes some time before the methane mixes with the global atmosphere.

Natural methane sources include wetland areas, termites and ruminant gut gas. In addition, there are thawing permafrost and possible processes in the sea that lead to emissions of methane from reservoirs under the seabed. The new report from the UN Intergovernmental Panel on Climate Change on how to limit heating to 1.5 degrees, assumes that methane emissions are reduced by 35% compared to the 2010 level by 2050. To achieve this, it is crucial to know as much as possible about the methane sources and how they change over time. In particular, it is important to understand the balance between manmade sources and natural sources.

What Meta Sources Are Changing?

NILU has measured methane isotopes on Zeppelin since 2012, as part of various research projects funded by the Norwegian Research Council, but it is only now that these measurements are included in the monitoring program.

– The isotope signatures can tell us more about which sources the methane comes from, explains Lund Myhre.

– Methane from fossil sources such as oil and gas installations, or combustion of biomass, for example, has a different isotope signature than methane that comes from wetlands in the Arctic or lower latitudes.

In other words, isotope signatures are very useful as additional information when researchers want to find out more about the different sources of methane in the atmosphere, and why methane increases so much. However, in order to provide answers, they must be combined with monitoring of methane level and solid models.

At Zeppelin, the researchers see a clear reduction (more negative values) in the methane isotope δ13CCH4 after 2012, in parallel with the increase in methane levels.

This indicates that the bulk of the increase is not due to an increase in emissions from fossil sources. Instead, it is probably due to emissions from sources such as wetlands at both northern and southern latitudes, ruminants and changes in forest fires. Many of these sources are very vulnerable to climate change, such as changes in precipitation and temperature.

Monitoring is crucial for finding solutions

– The most likely is that it is a combination of human and natural sources that account for the increase in methane levels we have seen in recent years, Lund Myhre says.

– It can also be about changes in methane degradation in the atmosphere, so it is not easy.

By combining these unique datasets with models, scientists can in the long term provide much better and safer answers to what is happening, and thus the basis for what can be done.

The monitoring program provides a completely central database in the work of finding solutions to limit the temperature increase to 2 or preferably 1.5 degrees.