Summer 2023 was quite an eventful summer in and around the Arctic, with record warmth at both weather and climate timescales, record wildfire in northern Canada and heavy precipitation in some areas.
Temperatures around the Arctic for summer 2023 as a whole (Fig.1) were generally above the 1991-2020 average in most land areas except for eastern Baffin Island, Canada and small portions Chukotka (Russian far northeast) and southwest Alaska. A large portion of northwest Canada had the warmest summer of record. A prominent feature of Fig. 1 is that over most high Arctic ocean areas the summer 2023 temperatures were within 0.5° C of average. This is not an artifact of the reanalysis: temperatures over the ice pack in the high Arctic rarely deviate far from average in summer because the heat goes into melting ice and snow instead of raising the air temperature. It takes energy to change the phase of water from solid to liquid even though there is no change in temperature and is known as the latent heat of fusion.
Figure 2 plots the time series of Arctic-wide summer temperatures since 1940. For the Arctic as a whole (land and ocean poleward of 60°N), the average temperature this summer was the second highest on record: 2016 was very slightly warmer.
The trend in Arctic summer temperatures has been remarkably steady in recent years. Four of the past five summers have been warmer than any summer was prior to 2016 and 18 of the 20 warmest summers since 2000 in ERA5 reanalysis.
Precipitation
Precipitation (rain plus the liquid equivalent of snow or other frozen precipitation) often varies dramatically over relatively short distances, even when aggregated over months. The most conspicuous departures from average of summer 2023 precipitation, shown in Fig. 3, are the large comparatively large areas in Scandinavia, Greenland and Alaska with well above normal precipitation. For Greenland, helped along by a very snowy June over much of the ice sheet, this was the highest summer total precipitation in the ERA5 reanalysis, at 142 percent of 1991-2020 average.
Parts of the northwest Canada and eastern Siberia were unusually dry during the summer and this contributed to the extensive wildfire in these regions. This was especially in Northwest Territories, Canada, where 2023 has burned over 3.7 million hectares and is now the largest area burned since 1980 and forcing evacuations in a number of communities, including Yellowknife.
Greenland
For summer 2023 the average daily melt area on the Greenland ice sheet was the second highest on record, behind only 2012. For additional details of daily melt of the ice sheet see my post from late August here. There is of course year-to-year variability, but as the smoothed average shown in Fig. 4 shows, the multi-year average daily melt area has been fairly steady for about 15 years.
Figure 5 plots the daily surface mass balance for the 2022-23 snow year, which by convention for Greenland runs from September 1 to August 31. Above normal snow through most of June is evident with mass gain continuing more than two weeks after the average date when more melt is occurring than being replaced by new snow.