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Svalbard is a near pristine Arctic environment, where long-range transport from mid-latitudes is an
important air pollution source. Thus, several previous studies investigated the background
nitrogen oxides (NO x ) and tropospheric ozone (O 3 ) springtime chemistry in the region. However,
there are also local anthropogenic emission sources on the archipelago such as coal power plants,
ships and snowmobiles, which may significantly alter in situ atmospheric composition.
Measurement results from three independent research projects were combined to identify the
effect of emissions from various local sources on the background concentration of NO x and O 3 in
Svalbard. The hourly meteorological and chemical data from the ground-based stations in
Adventdalen, Ny-Ålesund and Barentsburg were analysed along with daily radiosonde soundings
and weekly data from O 3 sondes. The data from the ERA5 reanalysis were used to evaluate the
prevailing synoptic conditions during the fieldwork. Although the correlation between the NO x
concentrations in the three settlements was low due to dominant influence of the local
atmospheric circulation, cases with common large-scale meteorological conditions increasing the
local pollutant concentration at all sites were identified. In colder and calmer days and days with
temperature inversions, the concentrations of NO x were higher. In contrast to NO x values, O 3
concentrations in Barentsburg and at the Zeppelin station in Ny-Ålesund correlated strongly, and
hence the prevailing synoptic situation and long-range transport of air masses were controlling
factors for them. The Lagrangian models HYSPLIT and FLEXPART have been used to investigate air
mass transport and transformations during the large scale O 3 depletion and enrichment events.
The factors affecting Arctic springtime photochemistry of O 3 have been investigated thoroughly
using Lagrangian and Eulerian numerical weather prediction model data and Metop GOME-2
satellite observations.
2021
Svalbard is a remote and scarcely populated Arctic archipelago and is considered to be mostly influenced by long-range-transported air pollution. However, there are also local emission sources such as coal and diesel power plants, snowmobiles and ships, but their influence on the background concentrations of trace gases has not been thoroughly assessed. This study is based on data of tropospheric ozone (O3) and nitrogen oxides (NOx) collected in three main Svalbard settlements in spring 2017. In addition to these ground-based observations and radiosonde and O3 sonde soundings, ERA5 reanalysis and BrO satellite data have been applied in order to distinguish the impact of local and synoptic-scale conditions on the NOx and O3 chemistry. The measurement campaign was divided into several sub-periods based on the prevailing large-scale weather regimes. The local wind direction at the stations depended on the large-scale conditions but was modified due to complex topography. The NOx concentration showed weak correlation for the different stations and depended strongly on the wind direction and atmospheric stability. Conversely, the O3 concentration was highly correlated among the different measurement sites and was controlled by the long-range atmospheric transport to Svalbard. Lagrangian backward trajectories have been used to examine the origin and path of the air masses during the campaign.
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2023
State of the Climate in 2021: 5. The Arctic
American Meteorological Society
2022
State of the Climate in 2024: The Arctic
The Arctic environment in 2024 continued on a trajectory that has put it in a state far different from that of the twentieth century. Ongoing accumulation of greenhouse gases in the atmosphere continues to quickly warm the Arctic, resulting in rapid changes in the cryosphere that are driving cascading impacts to climate, ecological, and societal systems.
Many weather- and climate-related impacts in the Arctic are the result of compounding change, such as increased riverbank erosion, which is proximately due to increased river discharge from higher seasonal precipitation, yet is also exacerbated by thawing permafrost. However, even individual storms occur within very different ocean and ice conditions than were typically present in the late twentieth century. As a result, the impacts, including high winds, excessive precipitation, and coastal inundation, may be quite different nowadays, as exemplified by the October 2024 storm in northwest Alaska that produced severe coastal flooding in several communities. To share some of these impacts with a wider audience, select extreme weather impacts around the greater Arctic have been highlighted through the inclusion of sidebars in recent State of the Climate Arctic chapters (e.g., Benestad et al. 2023; Thoman et al. 2024).
Average surface air temperatures for the Arctic overall (poleward of 60°N) for 2024 averaged 1.27°C above the 1991–2020 baseline average, the second-highest annual temperature since records began in 1900. For the 11th consecutive year, the Arctic annual temperature anomaly was larger than the global average anomaly. Seasonally, summer (July–September) 2024 ranked as the third-highest average temperature, and autumn (October–December) 2024 saw its highest average temperature on record. At the subseasonal scale, an intense August heatwave brought all-time record high temperatures to parts of the northwest North American Arctic. Closely but not completely tied to spring and summer air temperature trends, productivity of tundra and boreal forest vegetation has dramatically increased in recent decades. Overall “tundra greenness” was the fifth highest since 1982. However, local to regional “browning” (reduced vegetation productivity) shows that disturbance factors besides temperatures, such as wildfire, can be important.
Sea ice is one of the most iconic features of the Arctic environment and plays an important role in regulating global climate, regional ecosystems, and economic activities. Sea ice extent typically reaches the annual maximum in March, and in 2024 the maximum was near the 1991–2020 average overall, but somewhat below average in the Barents Sea and Gulf of St. Lawrence. The annual minimum sea ice extent occurs in September, and in 2024 the September monthly average was the sixth lowest in the 46-year satellite record. The Northern Sea Route along the north Russia coast opened later than the past 20 years’ average due to persistent ice in the southwest Chukchi Sea. The Northwest Passage’s southern route through northwest Canada opened again this year and, quite unusually, the deepwater northern route was also almost entirely ice free at the end of September.
Decreasing sea ice extent during the late spring and summer months exposes larger areas of ocean to direct warming during the time of year of high incoming solar radiation. Poleward of 65°N, open ocean surface temperatures typically peak in August. In 2024, late summer sea surface temperature anomalies showed significant regional variability, with the waters in the Barents and Kara Seas 2°C–4°C warmer than normal. In sharp regional contrast, Chukchi Sea sea surface temperatures were the lowest in more than 40 years, while just to the east, sea surface temperatures in the southern Beaufort Sea were significantly above the 1991–2020 average.
Like sea ice, permafrost (soils or other earth materials that have remained frozen for at least two years) is an important feature of Arctic environments that occurs widely on land and throughout some submarine continental shelf areas that were exposed land during the last Ice Age (about 15,000 years ago). Unlike many parts of the Arctic environmental system, permafrost temperatures and the summer surface thaw zone cannot be monitored from space-borne instruments and depend on in situ measurements. While long-term observations are not available over most of the Asian Arctic, observations elsewhere show multi-decade warming of deeper permafrost continuing across the Arctic, with some sites in North America and Svalbard having seen their highest temperatures on record in 2024. Overall, colder permafrost is warming more rapidly; areas where permafrost temperatures are close to freezing have slower rates of warming as ice changes phase to liquid water.
Precipitation monitoring in the Arctic has historically been limited due to the lack of in situ measurements over the Arctic Ocean, a sparse land station network, and significant problems with solid precipitation undercatch because of the inherent difficulties in capturing solid precipitation in strong wind environments. Recent advances in reanalyses that combine observations and computer simulations now allow for more robust regional-scale precipitation analysis and historical comparisons. In 2024, Arctic-wide annual precipitation was the third highest on record, and summer (July through September) precipitation was the highest since 1950. Rivers serve as regional integrators of precipitation. Arctic river discharge overall for both 2023 and 2024 was close to the 1991–2020 average, albeit with significant differences across basins. For example, in North America, Mackenzie River discharge was well below average in both years, but Yukon River discharge was above average in both years; most basins in Eurasia saw above-normal discharge in 2024 but below-average discharge in 2023.
In much of the Arctic, snow is the dominant form of precipitation for most of the year, and the presence or absence of snow cover is a critical factor in many climate and environmental processes. During the 2023/24 snow season, there were marked regional and continental scale differences in snow cover duration. The snow cover duration varied from the shortest to date in the twenty-first century over parts of Canada to at or near the longest in this century in parts of the Nordic and Asian Arctic.
Melt and discharge from the Greenland Ice Sheet play important roles in modulating North Atlantic weather and climate. In 2024, the total amount of ice decreased, as it has every year since the late 1990s, but the loss was 50%−80% less than the 2002 − 23 annual average. This was the result of an unusual but persistent weather pattern that inhibited the development and persistence of warm air masses over Greenland during the summer. Ongoing monitoring of the Greenland Ice Sheet, which holds enough water to raise global sea levels by more than seven meters if entirely melted, is critical for understanding drivers of melt and ice sheet dynamics.
The Arctic stratosphere experienced two major sudden warming events early in 2024 that resulted in enhanced ozone transport into the region from lower latitudes. As a result, surface ultraviolet radiation was reduced in parts of the Asian Arctic in spring and the central Arctic and North America in summer.
Special Notes: The 1991–2020 baseline is used in this chapter except where data availability requires use of a different baseline. This chapter includes a focus on Arctic river discharge (section 5h), which alternates yearly with a section on glaciers and ice caps outside of Greenland.
2025
State of the environment in the Norwegian, Finnish and Russian border area. The Finnish environment 6/2007
2007