Direct satellite observation reveals that the Arctic planetary albedo, a measure of reflectiveness, decreased from 0.52 to 0.48 between 1979 and 2011, a change in albedo that corresponds to a climate forcing 25% as large as that due to changes in atmospheric carbon dioxide concentrations over the same time period, according to this study.
But looking at more recent CERES measured data showing what is light is reflected into space by the posited changing albedo, neither Arctic nor Antarctic seem to have changed much at all; less than a watt per decade everywhere. For recent CERES data the trend lines look dead flat at any reasonable scale. See the graph:
The graph is from Willis Eschenbach, who will have more on this in subsequent post.
I’ve said in the past that black carbon is likely playing a role in Albedo change in the Arctic, but I’ll have to admit it is puzzling why the signal isn’t stronger in Willis’ graph above.
Compare the period above from 2000-2013 to the graph they cite in the paper:
Note they claim a drop of clear sky albedo from about 36 to 33%, that may be true for their method, but the base CERES all sky reflected data suggests no trend at all. Tis a conundrum that may be due to the sea-ice method they chose:
The sea ice surface albedo is estimated using two steps. First, the clear-sky planetary albedo associated with 100% sea ice cover is computed from an ordinary least squares linear regression between albedo and sea ice cover for each month constrained to go through an ocean albedo of 0.175 (cf . ref. 25) at 0% sea ice cover. For this calculation, a region containing all ocean grid
cells between 80 and 90°N is used to reduce the extrapolation to 100% ice calculation and to focus on multiyear ice for comparison with the in situ observations. Next, surface albedo (ásfc) is calculated from this clear-sky planetary albedo (ács) based on a linear estimate, ásfc = (ács . a)/b, with empirically derived seasonally varying monthly parameter values of a and b adopted from a previous study (17).
The clear-sky albedo during 1979–1999 is computed from sea ice using a total least squares linear regression between 2000 and 2011 clear-sky albedos and sea ice. All-sky albedos during 1979–1999 are similarly computed from clear-sky albedos using a total least squares linear regression between the two albedos during 2000–2011. In both regressions, the quantities are
normalized by their uncertainties, and error bars are estimated based on the regression confidence intervals (details provided in Supporting Information).
Article #13-18201: “Observational determination of albedo decrease caused by vanishing Arctic sea ice,” by Kristina Pistone, Ian Eisenman, and Veerabhadran Ramanathan.
The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming.