Scientists at the National Oceanic and Atmospheric Administration (NOAA) have just released their most recent iteration of the Arctic Report Card and it suggests that there are some interesting changes in the Arctic ecosystem that have become even more pronounced over the past year even though air temperatures were not unusually high this year compared to those of the past decade.
First, NOAA scientists note that record low snow extent occurred in the month of June and record low sea ice extent occurred in September. The areal extent of snow cover over the Northern Hemisphere for the month of June has decreased by 17.6 percent per decade. It is the fifth year in a row that Eurasia has experienced record low snow cover and the third time in five years that North America has set a new record low. Here is a map showing the difference in the average snow extent with the browner colours showing snow losses up to 40 percent below average:
The extent of sea ice reached a new record low of 1.3 million square miles on September 16th, 18 percent smaller than the previous record and 49 percent below the average from 1979 to 2000. The period between March and September 2012 showed the largest decline in sea ice extent between maximum and minimum coverage since satellite record-keeping began; a total loss of 11.83 million square kilometres was observed. During the month of August, the Arctic sea ice lost an average of nearly 92,000 square kilometres of ice per day, the fastest losses on record for the month of August. On top of a loss of areal extent, the ice found in the Arctic is getting thinner and younger. Here is a satellite photo showing the declining areal coverage of Arctic sea ice:
Second, NOAA reports that there was widespread melting for the longest period recorded on the Greenland ice sheet. For the first time since record-keeping began, a nearly ice sheet-wide melt was recorded in July as shown on this map where the extent of the mid-July melting is shown in blue:
Melting covered 97 percent of the ice sheet with melting in some locations lasting 2 months. The surface of the Greenland ice sheet also became darker in colour as the snow cover melted. This darkening results in changes to albedo, the amount of the sun's light energy that is absorbed by various surfaces. As the colour of the ice surface darkens, more of the sun's energy is absorbed by the ice causing it to melt more quickly as shown on this diagram:
This process becomes self-reinforcing; as the ice melt increases, the colour of the surface darkens and becomes less reflective causing additional melting and so on.
Third, the tundra is getting greener with more above-ground vegetation growth. The plant biomass in some areas has increased by as much as 26 percent over the last three decades as the growing season in the Eurasian part of the Arctic has increased by roughly 30 days between the years 2000 and 2010. Changes in biology are also present in the Arctic Ocean where massive blooms of phytoplankton are occurring below the surface of sea ice. This is having an impact on the diets, physiology and survival rates of many species in the Arctic.
Slightly off topic, the World Meteorological Organization (WMO) recently released its Provisional Statement on the State of the Global Climate in 2012. The WMO notes that the last 11 years were among the top warmest years on record with the 2012 global land and ocean temperature estimated to be 0.45 degrees Celcius above the 1961 to 1990 average. This is the ninth warmest period since records began in 1980. WMO notes that Greenland had above average temperatures for most of 2012, recording its all-time highest May maximum temperature of 24.8 degrees Celcius on May 29th. In sharp contrast, during late-January to mid-February, eastern Russia experienced minimum temperatures ranging between -45 to -50 degrees Celcius with northern Europe and central Russia experiencing temperatures below -40 degrees Celcius. Several cities in Russia set new record minimum temperatures during the first half of February.
The WMO also notes that the global averaged mole fractions of carbon dioxide, methane and nitrous oxide reached new highs in 2011. Carbon dioxide levels reached 390.9 ppm, a 2.0 ppm rise from the previous year. Methane levels reached 18.13 ppb due to increased human-sourced emissions a rise of 5 ppb on a year-over-year basis. The average global nitrous oxide level reached 324.2 ppb, a rise of 1.0 ppb over the previous year. Just in case you were curious, here is a graph showing the global fossil fuel carbon emission levels since the world's economy became industrialized:
While many naysayers dismiss what certainly appears to be a growing mountain of evidence that the world's climate is changing, at some point, evidence like that presented in this posting will provide incontrovertible proof that "the times they are a'changin'" and that there is no going back.