PhillipS

Apologies if I'm splitting hairs, Bluewave, but August didn't see an increase in Arctic SIV, it saw a decrease in the anomaly. Arctic SIV continued to drop, albeit at a slower rate.

It's easy to just focus on the recent melt seasons but I got a jolt when I looked at the PIOMAS sea ice volume plot. The SIV is currently around 6.75K km3, just behind 2012 as ORH reported above, but the 1979-2001 average for this time of years is almost 17,000 km3, more 10,000 km3 greater than today - a loss I find sobering.

Dr Barry is welcome to come here to engage.

More open Arctic ocean -> increased evaporation -> increased water vapor -> increased precipitation. But GIS Surface Mass Balance is only half of the situation. It does not include dynamic GIS processes such as glacial calving, basal melting, or meltwater runoff. Look at the Total Mass Change data for the complete situation. As you can see, the GIS has lost around 3,600 km3 (3,600 Gtons) of ice since 2003.

Keeping in mind that SMB is only half of the mass balance equation, it looks like 2016 was the fifth worst melt season of the instrumental period, and the second greatest season for runoff. Just eyeballing the graph it looks like there is a long-term decline in snowfall but I don't know if that's due to less precipitation overall or more precip falling as rain. Here's the GRACE plot of total mass balance since 2003. I expect that 2016 will have a net mass loss of around 300 Gtons (300 km3).

Greenland saw a steep, but brief, resurgence of surface melting DMI shows the 2014 -2015 GIS melt season (which runs Sept through Aug) as being about 75 gigatons below the long term average, and about 250 gigatons above the record surface melt in 2011 - 2012. So it was a strong, but not exceptional GIS surface melt season. The overall net mass balance hasn't been announced yet - but with recent large calving events reported I would estimate a net mass loss for 2015 of between 300 and 400 gigatons.

Peter Sinclair has an interesting post up at ClimateCrocks on the effect of increased rainfall on the GIS. [link]

Thank you for the correction - the mistake in the estimated area was mine alone. I should of checked my numbers before I hit Post.

Here is a comment on the recent Jakobshavn glacier at Nevins. And a Washington Post article that includes quotes from Jason Box and Richard Alley And last, but certainly not least, is the NASA Earth Observatory post. There is a lot of uncertainty in the estimates of the size of the calving event, but this size of event will have a big impact on the net mass balance analysis for the 2015 melt season. Many estimates put it at around 125 12.5 km2 in area, so if the glacier is 1,000 meters thick at the calving site, that would mean a loss of roughly 125 12.5 Gtons of mass in four days. And the calving goes on all year, unlike the surface melt.

Since the SMB is only one component of the GIS net mass balance, and not even the biggest component, it's a bit early to declare it a bust. The DMI calculates the GIS melt season as Sept through August, and typically DMI posts a melt season summary late in the year that combines all factors. Here is the current accumulated SMB In my estimation, 2015 will be a net 275 - 325 km3 mass loss for the GIS, well below the record in 2012 of around 400 km3.

Don't attribute to boldness what can be better explained by confusion. I found the wording of the poll, particularly the second question, rather vague.

The GIS is also experiencing a large amount of mass loss through glacial calving. Here's a short video of one event in June where roughly 1 km3 (1 gigaton) calved off in a matter of minutes : http://climatecrocks.com/2015/07/02/watch-as-empire-state-size-chunk-breaks-off-greenland/

Latest from NSIDC on GIS surface melting: I believe it is safe to say that recent surface melting has made up for the slow start to the melt season. I wonder is some of the acceleration of the surface melting is due to the snow melting off and exposing the darker surface of the glacial ice. Here is the albedo change plot from DMI: The DarkSnow team, led by Dr Jason Box, is now in Greenland studying the processes that affect the albedo of glacial ice. If you haven't visited their website [link], it's worth a read

After a slow start the GIS surface melting is picking up its pace. From NSIDC: The melting is increased by the albedo change of the GIS surface. From the DMI:

DMI has begun updating their PolarPortal website to show 2015 surface conditions. Here is the daily and accumulated Surface Mass Balance (SMB) plots: I found it interesting that over the winter Greenland had a lot more surface accumulation than 2012 did, but currently 2015 is starting the melt season from about the same point as 2012. NSIDC is also showing the GIS as having a slow start to the melt season:

I think it's been a quiet thread simply because the GIS melt season is just getting started. So far it's been a mild melt season, at or a bit below the long-term average, for the Surface Mass Balance (SMB). From NSIDC Greenland Ice Sheet Today: And the Danish Meteorological Institute (DMI) hasn't started posting data for 2015 yet Of course, SMB is only part of the GIS mass dynamics. Mass loss through glacial melting and calving continues unabated. Here is one recent news article that describes how glacial breakup in 2014 revealed a mountain on the coast of Greenland to actually be an island. From the article: According to glacier researcher Mauri Pelto of Nichols College, the retreat of these two glaciers from 1999 to 2014 has led to several new islands, one of which emerged just last year. In a blog post for the American Geophysical Union, a society representing earth scientists worldwide, the Steenstrup Glacier has retreated by 6.21 miles, or 10 kilometers, during the past 60 years.

You're correct, SVT, the Greenland melt season is off to a very modest start.

I agree that paywalls are annoying. But if you go to Google Scholar, search for Box Greenland Part, you will find non-paywalled versions of all three papers.

Before you dismiss his findings you should read his papers to see whether you agree with his methodology - there are a number of proxies for glacial extent, such as terminal morraines and sediment cores. Also, annual layer thickness in ice cores can give an indication of snow accumulation - at least for recent decades where compression hasn't obscured the annual record.

Dr Jason Box is a leading researcher on the condition and dynamics of the Greenland Ice Sheet (GIS). He has two blogs on the GIS, www.meltfactor.org, and www.darksnowproject.org, which is focused on his crowd-sourced research project on the causes and consequences of the GIS albedo changes observed in recent years. Dr. Box had a recent post on Meltfactor that I thought might be of interest to the readers here. It deals with possible effects on the AMOC of the large volume of freshwater discharge from the GIS. An excerpt: My contribution was my work of 6 years, a 172 year Greenland mass balance reconstruction published in a 3 part series in the Journal of Climate (Box and others 2013; Box, 2013; Box and Colgan, 2013), enabling Greenland melting to be brought more into context of its ocean thermohaline perturbation. As an aside, the DarkSnow project is currently, April 2015, accepting donations for the 2015 research expedition. I've supported it for the past three years and feel that they are doing cutting-edge research and finding out some surprising things. It's worth checking out.

Here is the CH4 in-situ hourly average data at the Barrow AK observatory. There does appear to be a plume of CH4 in recent months. Looking at just the 2014 to present data makes it clearer. It looks like a series of CH4 events starting last Fall.

I think most readers on this forum have read the recent reports of large craters being found in Siberia, and the discussion of their origin. There was a post on the IFLScience website [link] that may be of interest. Here is an excerpt: An expedition from the Scientific Center of Arctic Studies found methane concentrations of 9.6% at the bottom of the crater – 50,000 times the atmospheric average. The possibility that methane released by melting permafrost produced the crater had been a favored hypothesis from its discovery in mid-July. Nevertheless, plenty of other theories were circulating, and scientists urged caution before leaping to conclusions. The extraordinary concentration of methane, on the other hand, seems unlikely to be a coincidence, particularly since methane is slightly lighter than air. The 2012 and 2013 summers on the Yamal peninsular, where the crater is, were around 5°C warmer than normal. Expedition leader Andrei Plekhanov told Nature that the high temperatures probably thawed the permafrost to the point where it collapsed, releasing the trapped methane. If my math is correct, 9.6% is 96,000 ppm, or 96,000,000 ppb (which is how atmospheric CH4 is usually measured). Current CH4 readings at Barrow are around 1880 ppb so the crater levels are alarmingly high. And given that CH4 is lighter than air, those levels aren't the result of CH4 pooling in the deep craters. I think that it would be interesting to monitor the levels on a periodic, say, weekly, basis to learn if the concentration is rising, falling , or stable.

There is a good column on the Shakova paper and global methane trends at RealClimate. The take-away, in my opinion, is that global methane concentrations aren't rising fast enough to be alarming at this time. The rate of methane increase is at least an order of magnitude smaller than what would be needed to significantly affect climate. Here is the conclusion from the column: Shakhova et al (2013) did not find or claim to have found a 50 Gt C reservoir of methane ready to erupt in a few years. That claim, which is the basis of the Whiteman et al (2013) $60 trillion Arctic methane bomb paper, remains as unsubstantiated as ever. The Siberian Arctic, and the Americans, each emit a few percent of global emissions. Significant, but not bombs, more like large firecrackers. So it appears that methane, including arctic methane, is something that we should be concerned about enough to study closely, but it is not alarming as several other AGW effects such as droughts, extreme weather, rising sea levels and ocean acidification.

There is a new report from Dr Shakova about increased arctic methane releases - that the rate of methane release from subsea permafrost has accelerated to 17 teragrams (17 megatons) per year. [Discovery article]. I'll try to track a link to the paper itself. Methane gas bubbles rising through Arctic Ocean water, seen by a remotely operated vehicle.

Blizzard should keep in mind, too that CO2 levels during the HTM never rose above about 280 ppm. As we approach 400 ppm (on our way to 500 ppm or greater) we are pushing the climate into conditions not seen for millions of years. [source] If one understands the GHE and the properties of CO2 and other GHGs it is hard to hope that some unknown 'braking effect' will appear and save us from the consequences of BAU.