It’s difficult to say anything for sure about Antarctica because the weather is so variable. Bumper snow one year, not so much the next. (Noise and uncertainty is large). But 800 years of ice cores spread across Antarctica shows the Surface Mass Balance (SMB) is more likely to have been increasing over the last century. (Which fits with what Zwally et al found in 2012 with ICESAT satellite data).
Note the correlation of the smoothed average of the SMB (orange line) with Total Solar Irradiance (green line).
H/t: HockeySchtick and Jaymez
A paper published today in The Cryosphere finds Antarctica has been gaining surface ice and snow accumulation over the past 150+ years, and finds acceleration in some areas noting, “a clear increase in accumulation of more than 10% has occurred in high Surface Mass Balance coastal regions and over the highest part of the East Antarctic ice divide since the 1960s.”
They used 67 firn/ice core records to reconstruct the last 800 years.
From this paper we can see:
- Over 800 years, Antarctic ice changes all the time, but current rates of change are not unusual. The surface mass balance (SMB) “changes over most of Antarctica are statistically negligible.” The “current SMB is not exceptionally high compared to the last 800 yr.”
- The times with highest accumulation (1370s and 1610s) match records of solar radiation.
- Since 1960 the ice and snow accumulation has increased by 10% in high SMB coastal regions and over the highest part of the East Antarctic divide.
Solar irradiance seems to matter to Antarctica
How curious:
Eight hundred years of stacked records of the SMB mimic the total solar irradiance during the 13th and 18th centuries. The link between those two variables is probably indirect and linked to a teleconnection in atmospheric circulation that forces complex feedback between the tropical Pacific and Antarctica via the generation and propagation of a large-scale atmospheric wave train.
As far as we can tell, the Antarctic Ice Sheet (AIS) is growing
The Surface Mass Balance appears to be growing at 2100Gt/year (though this is much higher than the ICESAT satellite estimates of Zwally which estimate a net gain of 49Gt/year.)
[UPDATE: ManicBeanCounter, pointed out that if 2100Gt was being shifted from the ocean to the land, it would reduce oceans by 5mm annually. An improbable figure! DumbScientist below helpfully points out that Zwally is using Total Mass Balance, which is different to Surface Mass Balance. The SMB figure involves “precipitation, evaporation and snowdrift physics” but not glacier run-off. Thanks to both readers.]
“The SMB of the grounded AIS is approximately 2100 Gt yr−1, with a large interannual variability. Those changes can be as large as 300 Gt yr−1 and represent approximately 6% of the 1989–2009 average (Van den Broeke et al., 2011).”
Climate models predict that snow and ice ought to accumulate over Antarctica and that this will help slow down sea-level rise. Maybe the models are right on this, but there’s no evidence in this data that the current accumulation is different to natural cycles.
The summer melt might be faster at the moment, but the accumulation rate is also seemingly at the higher end. If climate scientists want to blame increased CO2 emissions in the last 150 years for the increased ice mass (snow accumulation) and faster summer melt, then how do they explain all the other rises and falls over the last 800 years? Look at the graph below and ponder that all the bumps and falls were natural apparently but that last bump — we’re 90% sure it’s caused by coal power stations.
The full paper is here: The Cryosphere, 7, 303-319, 2013
REFERENCE
Frezzotti, M., Scarchilli, C., Becagli, S., Proposito, M., and Urbini S. (2013) A synthesis of the Antarctic surface mass balance during the last 800 yr The Cryosphere, 7, 303-319, doi:10.5194/tc-7-303-2013 Final Paper (PDF) Discussion Paper (TCD)
Zwally, H. Jay; Li, Jun; Robbins, John; Saba, Jack L.; Yi, Donghui; Brenner, Anita; Bromwich, David (2012) Mass Gains of the Antarctic Ice Sheet Exceed Losses Click to View PDF File [PDF Size: 256 KB] [ WUWT discussion]
Seee WUWT GRACE’s warts – new peer reviewed paper suggests errors and adjustments may be large
*”Balance” added to the title to clarify