Heat is entering the Arctic ocean through currents on the west side of Spitsbergen at the highest rate in the 2000 years studied, while the Arctic sea ice extent is at a record low for the end of January.
Sea ice extent determined by the NSIDC.
The Atlantic water flowing into the Arctic west of Spitsbergen has warmed 3 1/2 degrees Fahrenheit over the past century.
And:
We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.
The Arctic ocean is warmed by the north Atlantic current which flows northward and splits int a current that flows northward through the Fram strait west of Spitsbergen, the main island in the Svalbard archipelago, and a current that flows northeastward along the coast of Norway.
The Fram Strait represents the unique deep water connection between the Arctic Ocean and the rest of the world ocean. Its bathymetry controls the exchange of water masses between the arctic basin and the north atlantic seas. The significant heat flux through water mass exchange and sea ice transport, i.e. transport of fresh water and sea ice southwards and transport of warm saline waters northwards, influences the thermohaline circulation at a global scale (Schmitz 1995, Gerdes & Schauer 1997).
Two main currents control the water mass exchange through Fram Strait. Arctic surface waters flow southward in the East Greenland Current along Fram Straits western border. Along the eastern margin Atlantic Waters flow northward in the West Spitsbergen Current. These major currents are seperated by a transition zone of denser upper-layer waters (Swift 1986). Results of recent modelling studies emphasise the importance of the Fram Strait for heat inflow to and freshwater export from the Arctic Ocean (Zhang & Zhang 2001, Meredith et al. 2001).
To determine how the amount of heat entering the Arctic through the Fram strait has changed over the past 2000 years, investigators studied microfossils in a sediment core. Tiny calcareous shelled marine organisms called foraminifera can act as tiny thermometers. The ratio of Calcium to Magnesium in the carbonate shells change as a function of temperature. The temperature of the water entering the Arctic over the past can be determined "by proxy" using the calcium to magnesium ratios. Moreover, different species of foraminifera are found in polar water and subpolar water. The distribution of foraminifera species is also temperature sensitive.
For both methods, the temperature mean of the Modern Period exceeds all individual values from the preceding 2000 years. These results reveal a rapid warming by ~2°C of uppermost AW in the FSB in the Arctic Gateway during the past ~120 years... Our reconstructed warming of ~2°C since the LIA matches the reported temperature increase of the Arctic Atlantic Water Layer (AAWL), obtained from observational data of the past ~120 years...
Fig. 3
Planktic foraminiferal data and temperature reconstructions of upper Atlantic Water in the eastern Fram Strait over the past ~2100 years from sediment core MSM5/5-712-1. Thin lines are raw data, bold lines are three-point running means. Black triangles on the age scale mark calibrated accelerator mass spectrometry 14C ages. (A) Fluxes of polar and subpolar planktic foraminifers (100- to 250-μm fraction). (B) Percentage of subpolar planktic foraminifers in the 100- to 250-μm fraction. (C) Summer temperatures at 50-m water depth (red) calculated by the SIMMAX Modern Analog Technique. Gray bars mark averages until 1835 CE and 1890 to 2007 CE. Blue line is the normalized Atlantic Water core temperature (AWCT) record (standard deviations) from the Arctic Ocean (1895 to 2002; 6-year averages) obtained from (21). (D) Summer temperatures (purple) calculated from Mg/Ca ratios in planktic foraminifers N. pachyderma (sinistral). Gray bars mark averages until 1835 CE and 1890 to 2007 CE. Blue line is the sea ice margin anomaly (11-year means, less ice is up) in the Barents Sea (BS) obtained from (5). Dashed lines mark less reliable data before 1850 CE. (E) Terrestrial Arctic [green, from (6)] and Northern Hemisphere [black, 25-year means, from (19)] temperature anomaly records with reference to the 980 to 1800 CE and 1961 to 1990 CE averages, respectively.
Since 1997 the properties of water in the west Spitsbergen current have been measured directly by the by the Nansen Environmental and Remote Sensing Center.
The water temperatures measured directly rose by about 1 degree Fahrenheit on average from 1997-2008. These temperatures are not identical to the temperatures calculated from foraminifera which reflect water temperatures during shell formation in warm season near surface waters.
Variability of the Atlantic Water temperature in Fram Strait in 1997-2008
During the last decade a significant warming was observed in the Atlantic Water inflowing through Fram Strait to the Arctic Ocean. The first warm episode spanned 1998 to 2000, manifesting the most strongly in the West Spitsbergen Current, the second warm period has continued since 2004 onward, with a peak in late 2006. Now (2008) we are observing a decline in the Atlantic Water temperature but it is still higher than the long-term average.
Today's sea surface temperatures are much above normal in the far north Atlantic and ice-free basins in the Arctic. These anomalously warm waters continue the trend of increasing heat flow into the Arctic ocean.
The flow of heat into the north Atlantic and Arctic has reduced sea ice extent to a record minimum for this date (as calculated by the NSIDC).
The strong La Nina of 2010-2011 has transported heat, stored in the equatorial Pacific ocean, poleward. Oceanic heat has flowed towards Antarctica as well as the Arctic. Antarctic sea ice levels are near the minimum extent measured for the date also.
A major factor that amplifies the small orbital variations called Milankovitch Cycles (Milankovitch cycles should be causing Northern Hemisphere cooling at present.) is the darkening of the earth's surface that happens when ice melts and the increasing of reflectivity when snow and ice accumulate. The process of amplification by darkening appears to have accelerated from near zero to a significant factor around 2004 - 2005. The darkened surface will warm faster, hastening the melting of remaining ice and snow.
1979 – 2008 time series of cryosphere radiative forcing (CrRF) anomalies, relative to 1979 – 2008 means, from land-based snow,sea ice, and the combination of both components.
The increasing heat flux into the Arctic ocean combined with the amplification caused by darkening will tend to speed up the decline of Arctic sea ice in all seasons. December 2010 had the lowest sea ice extent on record.