Higher Forecast Temperatures in June Bring Enhanced Risk to Arctic Sea Ice

May Arctic Warming Event Follow-up — Not So Bad as Predicted, But Worries Remain for Early June

Robertscribbler,

31 May, 2018

There are many reasons why we monitor Arctic sea ice melt during summer. First, sea ice is a key climate indicator. Second, we are in a period of time where ice-free Arctic conditions are becoming more possible as global temperatures keep rising. And third, falling levels of Arctic sea ice have knock-on effects for a number of climate systems that we all rely on.

(Will we see a warmer than normal early June for the Arctic Ocean? If we do, it could seriously impact the Arctic Ocean’s remaining and thinning sea ice.)

Last week, we pointed out that GFS models were predicting a very warm spike to around 3.5 C above average temperatures for the Arctic come late May. Thankfully, due to the model running a bit hot, such extreme readings did not emerge. However, temperatures over the Arctic Ocean remained about 0.85 C above average overall for the past 7 day period.

Consistent, though somewhat mild, warmer than normal temperatures for this time of year over the Arctic during 2018 are still somewhat worrisome. Recent very warm winter years have experienced ‘saving grace periods’ during May and June in which temperatures near the pole returned to near average or slightly below average.

(Above freezing or near freezing temperatures predicted for most of the Arctic Ocean on June 4, 2018 in the GFS model. Sea ice tends to start melting at around -2 C due to the salt content in surrounding ocean waters. During recent years, the Arctic sea ice has been far weaker and thinner than historic norms. Image source: Earth Nullschool.)

This is not the case for 2018 so far. Temperatures have tended to remain warmer than average for the Arctic Ocean and near the pole throughout May. 

Moreover, short range forecasts indicate that the critical time period of early June could see continued above average temperatures — providing a potential kick for sea ice losses come late season.

Overall, GFS model runs indicate that temperatures will remain in a range between 0.5 and 1.3 degrees Celsius above average for the Arctic over the next five days. These above normal temperatures pose increased risk for sea ice losses during the crucial June window. June weather tends to greatly influence late season sea ice totals. A warmer than normal June will produce higher numbers of melt ponds and greater impetus for melt to continue with force through July, August, and September. Cooler and often cloudier Junes have tended to protect late season sea ice from hitting new all time record lows.

(Weekly averages for the Arctic Ocean during early June are expected to range near 1 C warmer than normal — extending what has already been a warmer than normal May. Image source: Global and Regional Climate Anomalies.)

2018, so far, has seen a warmer than normal May for the Arctic Ocean. And so we see ice getting swept back behind traditional lines in the Chukchi Sea, in the Beaufort Sea, and in the region north of Svalbard. Peripheral areas like Baffin Bay, Hudson Bay, and the south Kara Sea have seen slower ice melt due to their co-location with trough zones. But it is Central Arctic melt that we should be more concerned about. So we’ll be closely monitoring this region as May runs into early June.