Polar Ice for 2017

Sorry, I didn't see which article you were referencing. So I did a quick check of the usual sources:
https://climate.nasa.gov/vital-signs/land-ice/





Bob Wilson

 

Thanks! I needed the reference:

• surface height, 1992-01 and 2003-08 - reports more volume and using assumptions on density, calculate the mass.
• GRACE, 2002-2016 (current) - measures mass and reports a decrease

When I first read the surface height study, it sounded more like a promotion of the ICESat-2 mission. Regardless, earth observing satellite missions involve 'ground truth' surveys as part of the calibration. I suspect somewhere around 2019 we'll see the results of ICESat-2 with more details comparing ground truth versus airborne and ground metrics.

Now you've raised a good question about sea level change versus land ice loss. If the analysis of the earlier surface data is accurate, then something is growing the sea level much faster ... a nice puzzle. But it begs the question of did they also use the same technique to analyze Greenland?

If their technique and data applied to Greenland surface levels also shows an accumulation, well that would be interesting because Greenland has many more observations. That is an obvious hole in their report (i.e., the summary.) Getting the formal report would be a good first step and searching the 'usual suspects' to see if they did a Greenland analysis too.

LATE THOUGHT:
Sorry I didn't mention this before but I remember some recent reports of liquid water in the 'snow packs'. Since this is fairly recent, I wonder if it would change the earlier results?
Water is streaming across Antarctica: New survey finds liquid flow more widespread than thought

Bob Wilson

 

An interesting synopsis of the NorthEast passage shipping for 2016:
http://arctic-lio.com/docs/25_04_17_Helsinki.pdf





Bob Wilson

 

How to cite this article: Nicolas, J. P. et al. January 2016 extensive summer melt in West Antarctica favoured by strong El Niño. Nat. Commun. 8, 15799 doi: 10.1038/ncomms15799 (2017).

My source: https://www.nature.com/articles/ncomms15799

ABSTRACT

Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. The unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.​

This helps explain some of the loss of sea ice around Antarctica this year:

More to read in the article but an interesting start. Instructive for how the Greenhouse gas effects occur with water vapor:

The observed CLWP [cloud liquid water path rjw] (Fig. 3c) was frequently within 10–40 g m−2, that is, the range where the cloud radiative enhancement effect previously observed over Greenland15 occurs. In this range, the clouds are thick enough to enhance the downwelling longwave radiation (Fig. 4a) but thin enough to also allow shortwave radiation to reach the surface (Fig. 4b). The CLWP was within this range 30–40% of the time during 10–13 January, suggesting that this enhancement mechanism contributed to the melt event. This is further supported by the frequent and widespread occurrence of clouds with CLWP within 10–40 g m−2 simulated by ERA-Interim during the same period (Supplementary Fig. 3 and Supplementary Fig. 5). However, we also notice a significant frequency of CLWP > 40 g m−2 (Fig. 3c), under which shortwave flux is attenuated and longwave flux is similar to blackbody radiation at the cloud effective temperature. These optically thicker clouds represent a contrast to the Greenland cloud radiative enhancement effect in that they signify a more prominent role of thermal blanketing as a consequence of the warm air advection (Fig. 3a,b).​

One of their important points is weather is not deterministic to what we know about climate change:

These relationships are by no means simple. For example, not all major El Niño events are accompanied by widespread surface melt in West Antarctica (for example, 1997–98); not all prominent West Antarctic melt events coincide with strong El Niño events (for example, 2005); and the magnitude of West Antarctic melt does not scale with the intensity of El Niño events. Accordingly, it is not possible to establish with certainty whether the 2015–2016 El Niño caused (in a deterministic sense) the January 2016 melt event, a problem inherent to weather and climate phenomena24. It is not uncommon for the polar jet around Antarctica to exhibit large meanders, giving rise to warm marine air intrusions3, even in the absence of an El Niño event. Following a probabilistic approach, we seek rather to assess the likelihood of the January 2016 melt event occurring given the concurrent strong El Niño and positive SAM conditions. The statistically small number of El Niño events (especially of strong events such as 1982–83, 1997–98 and 2015–16) observed since 1979 does not permit robust statistical analysis. However, climate model simulations can alleviate this issue by generating larger samples of events.​

I hope @wxman gets a chance to review the paper. In particular, this clear description of how a climate model is used to run a series of Monte Carlo simulations to understand the probability of Antarctica melting events:

Results from model simulations

Based on the model SAM Index and series of warm and cold events, we generated a contingency table (Table 1) tallying the number of events per type (warm or cold) and phase of SAM (positive, negative or neutral) across all simulated major El Niño events. Out of 45 El Niños, warm events occur 32 times (71.1%) versus 13 times (28.9%) for cold events. This result is consistent with the known positive impact of the El Niño teleconnection pattern in the South Pacific on West Antarctic temperatures already mentioned6. Out of the 32 warm events, 15 (46.9%) occur during a negative SAM phase. Out of the 13 cold events, 8 (61.5%) occur during a positive SAM phase. The chi-square statistic is significant at P<0.01, meaning that the type of event is significantly dependent on the combined states of El Niño and SAM. Such dependence confirms findings from previous literature7,29,30.​

Bob Wilson

ps. I drive a Prius because I'm thrifty about burning gas. Yet hybrid skeptics claimed it is because I am making a 'green statement.' The problem is if someone falsely accuses me of something, I'm such an ornery cuss that I'll take a look. This posting is just my follow-up to lies about why I drive a Prius. ... the law of unintended consequences. Add to that @mojo claims about character and motivations, well it just adds fuel to the fire (Hosea 8:7 For they have sown the wind, and they shall reap the whirlwind: it hath no stalk: the bud shall yield no meal: if so be it yield, the strangers shall swallow it up.)