The state of the Arctic in July 2009 is bad and getting worse. In a continuation of the trend established during May 2009, Arctic areal sea ice extent continues to be characterized as being nearly as sparse as it was in what ended up being the modern-day record low of the 2007 season. The areal extent has been below 2008′s extent on a day-to-day comparison for all of July so far. In late July/early August 2008, the weather situation in the Arctic was such that very rapid melt caused a precipitous decline in areal extent. A similar, almost-as-rapid decline has taken place this July. As I will show below, the difference between my last post one month ago and this post is dramatic.
It is useful to keep in mind that there is a lack of multi-year ice in the Arctic, as I’ve detailed before. Why is this important? One- and two-year old ice is thinner than multi-year ice and is thus more susceptible to fully melting during the Arctic summer, especially in the face of less-than-optimal weather conditions for a week or two. One factor working against record low areal extent is the decreasing amount of solar radiation impacting the Arctic. The sun is sinking lower and lower in the Arctic sky every day and will continue to do so through the end of the calendar year. Lower solar incidence and cloudy conditions could prevent another record low areal extent from being set.
I will begin updating my last post by showing the ice areal extent picture (as detected by satellite) for July:
And here is the comparison picture from June:
Like I wrote above, the differences are dramatic. The Chuckchi Sea, Kara Sea, Laptev Sea, Baffin Bay and Hudson Bay have seen an incredible loss of sea ice in one month’s time.
Next, I will update my last post by showing the time series graph for July:
And the same graph from one month ago:
The areal extent in the beginning of June matched the extent recorded in 2007. The difference in early July was due to the unprecedented melting of sea ice in 2007. Despite the fact that 2009 hasn’t seen a similar melt rate (yet), the areal extent isn’t that far behind the 2007 value. At this point, however, the extent reached is nearly at the climatological minimum in the modern record-keeping era (1979-2007) – approximately 6.7 million sq. km. The 2007 minimum was ~4.28 million sq. km. and the 2008 minimum was ~4.67 million sq. km (same NSIDC report). Another way to look at July’s ice extent loss is the following: at the beginning of July, the areal extent was ~10 million sq. km.; on the 26th, the extent was ~7.5 million sq. km. So in just under one month’s time, ~2.5 million sq. km. of ice has melted. That’s pretty scary.
Finally, this graph shows that despite a slow increase in the amount of ice in the Southern Hemisphere the past few years, the total amount of global sea ice is once again way below normal – 1 million sq. km. and growing. Last year, the minimum global sea ice extent was ~-2.6 million sq. km below normal; the 2007 minimum global sea ice extent was ~-3 million sq. km. below normal.
I will end by pointing out a new forecast I recently ran across: September areal extent based on June ice extent data (July report). Nine different methods predict this year’s minimum extent in September will be between the 2008 and 2007 record lows, which seems pretty realistic to me considering the state of the Arctic today. Most estimates are between 4.4 to 5.2 million sq. km. for this year’s value, well below the 1979-2007 September climatological mean value.
Cross-posted at SquareState.