Air temperature and precipitation

Last updated 1 March 2023

Temperature and precipitation are key climatic factors that influence ecosystems and human activity. The monitoring period has seen an increase in both air temperature and precipitation. It is expected that the Arctic weather will keep warming significantly, and that precipitation levels will keep rising. These inferences are drawn from climate models simulating future changes in response to larger concentrations of greenhouse gases in the atmosphere.

Status and trend

The annual mean temperature shows quite similar trends at the various stations.

The longest temperature series is from Svalbard Airport. This series was recently prolonged backwards, from 1911 to 1898, based on old observations from hunters and scientific expeditions. The series shows periods of cooling early in the 20th century and in the 1960s, but warming from 1912 until the 1930s and from 1970 until now.

An analysis of this series gives a linear trend of 0.34°C per decade from 1899 to 2020. The trend is statistically reliable at the 1% level. This represents significantly faster warming than is indicated by the corresponding series from the Norwegian mainland, and about three times faster than the trend in the global mean temperature over the same period. All the seasonal temperatures at Svalbard Airport show a temperature increase statistically reliable at the 1% level. The trends shows the largest temperature increase in winter and spring, with 0.42°C per decade and 0.45°C per decade, respectively.

The 1930s and 1950s saw relatively mild periods. Since 2000, however, there have been several exceptionally warm years in Svalbard and on Jan Mayen. At all 5 stations, the 3 warmest years in the series have all occurred since 2000. This is not unique to the Norwegian part of the Arctic.

Unlike temperature, the precipitation series from Norwegian Arctic stations show fairly different individual trends. The main reason for this is that precipitation has a much greater spatial variation than temperature, and local variations are greater. Nevertheless, all stations except Jan Mayen show a positive trend in annual precipitation throughout the measurement period as a whole, even though the start date varies. Annual precipitation at Ny-Ålesund, Svalbard Airport, Hopen and Bjørnøya has increased by respectievly 7, 4, 6 and 3% per decade compared with the normal period 1991-2020. The trends are significant at the 5% level.

The Svalbard Airport series shows a statistically reliable increase in precipitation in all seasons. For the Bjørnøya and Hopen series, the same is true for the winter, spring and autumn precipitation. The Ny-Ålesund series shows a statistically reliable increase only for the autumn and winter precipitation. The linear trend in the annual precipitation was much lower (0.5% per decade) on Jan Mayen, and not statistically reliable. None of the season values show statistically reliable trends.

Causal factors

There is widespread consensus that the cause of the global rise in temperature is anthropogenic emissions of greenhouse gases. Climate models also predict bigger increases in temperature at the far north on the Earth, compared to the global average. The situation for precipitation is the same – the global changes in climate are expected to result in higher precipitation levels in the Arctic.

It is still impossible to determine exactly how much of the warming and rise in precipitation in Svalbard is due to natural variations in the climate, and how much is caused by increased anthropogenic emissions of greenhouse gases.

Studies show that:

• a large part of the warming in the Arctic during the first part of the 20th century was due to natural variation
• the temperature development in the 1960–2000 period was related to changes in atmospheric circulation, in the form of increased transport of warmer maritime air masses from the south-east
• the warming observed in recent years may be caused by air mass characteristics and sea ice extent.

Newer data show that several of the warm years since 2000 coincided with low sea ice concentration in the Arctic Ocean during summer, causing the ocean to absorb more heat, and resulting in higher surface temperatures during autumn. Percipitation in Svalbard may also be affected by this. As for the development in percipitation during the 20th century, it can be largegly explained by atmospheric circulation. One of the reasons for the increase in precipitation in recent decades may be that rain gauges are catching more precipitation. Higher winter temperatures cause more of the precipitation to fall as rain instead of snow, which reduces undercatch because a higher proportion of the precipitation falls into the rain gauge (due to the fact that raindrops are heavier than snowflakes and therefore do not blow laterally past the gauge as readily). This means that the increase in precipitation in recent decades will be somewhat less than is indicated by the measurement series.

Consequences

There are many potential consequences of higher temperatures and more precipitation, and virtually all other areas covered by MOSJ are in some way influenced by these two factors. To mention a few:

• the duration of the snow cover
• the cover of sea ice
• permafrost
• glaciers
• flora
• fauna
• introduced species
• spread of pollution
• cultural heritage remains

In addition, changes in the temperature and precipitation conditions may affect the risk of avalanches and landslides in the archipelago.

About the monitoring

Temperature and precipitation are key climate factors, with major effects on ecosystems and human activity.

Model calculations of how the climate will change in response to the rising concentration of greenhouse gases in the atmosphere predict significantly warmer weather and more precipitation in the Arctic.