Climate gases in Svalbard

Last updated 7 April 2025

The most important greenhouse gases emitted by human activity are carbon dioxide (CO₂), methane (CH₄), a combined group of gases called halocarbons, and nitrous oxide (N₂O). These are gases that contribute to an increase in temperature and where the concentration in the atmosphere is affected by human activities such as deforestation and fossil combustion.

Status and trend

Carbon dioxide (CO₂)

The annual mean CO₂ concentration at Zeppelin in 2023 was 421.5 ppm, representing an increase of 1.0 ppm from the previous year and marking the highest value measured at the site to date. Since NILU began measurements in 2012, the trend shows a steady rise in CO₂ with no indication of slowing. Variability is most pronounced in winter and spring, consistent with long-term patterns at this Arctic location.

Methane (CH₄)

The annual mean methane concentration at Zeppelin in 2023 was 2007.6 ppb, an increase of 8.0 ppb from the previous year, and the highest value recorded at the site. The time series continues to show a clear upward trend, with accelerating growth in recent years. Seasonal variation is visible but less pronounced than at other measurement sites closer to major sources.

Nitrous oxide (N₂O)

The annual mean N₂O concentration at Zeppelin in 2023 was 337.0 ppb, an increase of 1.18 ppb from the previous year and the highest recorded value at the site. Long-term measurements since 2010 show a steady upward trend, despite occasional data gaps. The 2023 result is based on NOAA flask samples due to technical issues with the in-situ instrument.

Causal factors

Carbon dioxide (CO₂)

Carbon dioxide is the most important man-made greenhouse gas, both globally and in Norway, accounting for over 80% of total national greenhouse gas emissions. The main source is the burning of fossil fuels, but land use changes, such as deforestation, land clearance, and soil degradation, also contribute. While these processes release CO₂, land areas can also act as sinks—for example through reforestation or improved land management. In the Arctic, the Zeppelin Observatory records a steady rise in CO₂ concentrations, reflecting the global imbalance between anthropogenic emissions and natural sinks. Most emissions come from fossil fuel use and cement production, which, though small compared to natural fluxes, are enough to drive atmospheric levels higher.

Methane (CH₄)

Methane sources include boreal and tropical wetlands, rice paddies, ruminant animals, waste, biomass burning, termites, and fossil fuel extraction and use. Methane is also the main component of natural gas, and leaks from pipelines and installations are a known anthropogenic source. Globally, around 60% of emissions are man-made. Isotope measurements suggest that much of the recent increase is linked to wetlands, where climate-driven changes have boosted methanogenic microbial activity. This creates a feedback loop, as warming leads to more emissions, which in turn intensify climate change. Emissions from tropical wetlands appear to be a major contributor, while Arctic sources like thawing permafrost remain a potential concern. The rise in methane since 2005 may also reflect increased leakage from fossil fuel infrastructure.

Nitrous oxide (N₂O)

Nitrous oxide is a greenhouse gas with both natural and man-made sources. These include oceans, tropical forests, biomass burning, cultivated soils, use of synthetic fertilizers, and various industrial processes. Emissions from agricultural soils are especially important, but estimates carry considerable uncertainty—particularly for soil, combustion, and marine sources. Frozen peat in Arctic tundra has been identified as a potential source, though recent studies, including those led by NILU, point to tropical and sub-tropical regions as the dominant contributors. While anthropogenic emissions account for about 45% of the global total, natural processes also play a significant role in driving observed increases.

Consequences

An increase in greenhouse gases in the atmosphere is directly related to climate change and increasing temperatures globally. The rise in temperature in the Arctic is greater than the rise in the global mean, which is consistent with current climate models.

Carbon dioxide (CO₂)

Carbon dioxide is the most significant anthropogenic greenhouse gas. Since 1750, its radiative forcing has increased to 2.16 W/m², up from 1.82 W/m² reported in the previous IPCC assessment. This rise is attributed to the continuous increase in atmospheric CO₂ concentrations in recent years.

Methane (CH₄)

Methane is the second most important greenhouse gas resulting from human activities. Its radiative forcing was 0.54 W/m² in 2019, an increase from 0.48 W/m² in 2011. When accounting for indirect effects, such as its influence on ozone and stratospheric water vapor, methane’s total radiative forcing is higher. The atmospheric lifetime of methane is approximately 12 years.

Nitrous oxide (N₂O)

Nitrous oxide is a potent greenhouse gas with a radiative forcing of 0.21 W/m² as of 2019, up from 0.17 W/m² in 2011. It accounts for about 6% of the total radiative forcing since 1750. Additionally, N₂O is a major source of ozone-depleting nitric oxide (NO) and nitrogen dioxide (NO₂) in the stratosphere, thereby affecting the stratospheric ozone layer.

About the monitoring

The atmospheric monitoring programme “Monitoring of greenhouse gases and aerosols at the Zeppelin Observatory, Svalbard, and Birkenes Observatory, Aust-Agder, Norway” focuses on the level of greenhouse gases and aerosols properties relevant for the interaction of aerosols and radiation in the Norwegian background air and in the Arctic. The main objectives are to quantify the levels of greenhouse gases including ozone depleting substances, describe the relevant optical and physical properties of aerosols, and document the development over time.

Measurements of greenhouse gases and aerosol properties provide key data for studies and evaluations of climate change, and are also vital for assessing strategies for emission reductions and evaluating whether measures are effective. The Norwegian monitoring stations are located in areas where the influence of local sources is minimal, with the result that the stations are representative of a wider region and can demonstrate long-term changes in the composition of the atmosphere.