All posts tagged albedo

You Know There’s Something Wrong When Vast Expanses of Greenland Look Like A Blackened Volcanic Crater

Lowest albedo on record for Greenland.

That’s what data provided by NASA and processed by polar scientist Jason Box are showing for August of 2014.

But it doesn’t take a polar scientist to tell you something is dreadfully wrong with this:

(Swaths of Greenland’s Ice Sheet look more like a volcanic crater than mountains of frozen water. Video source: Dark Snow.)

The above video, provided by the Dark Snow Project and featured on Peter Sinclair’s fantastic Climate Crocks blog, shows a vast swath of the Greenland Ice Sheet from helicopter. Miles and miles of previously pristine ice now show a blackening similar in color to volcanic basalt. A color vastly uncharacteristic of Greenland and more suited to melting and salted snow in an urban parking lot.

Melt is a primary driver of such widespread blackening of the Greenland Ice Sheet. Compaction and removal of snow through melting of the surface layer uncovers dirt, dust and soot left over through the years and millennia, depositing it in a dense layer just beneath the newly melted and washed away snow.

Snow and ice darkening is also compounded by vastly expanding Arctic wildfires. And this year featured the most severe outbreak of wildfires on record for the Northwest Territory of Canada together with extreme and explosive fires throughout Arctic Siberia.The dark soot ejected in immense plumes from these fires is borne aloft by the winds, eventually falling together with rain and snow over the Greenland Ice Sheet.

Lastly, manmade sources of black and brown carbon are also implicated in the great ice sheet’s blackening. And, during recent years, with the explosion of dark particulate sources in developing countries and through global slash and burn agriculture, more and more dark particulate from human activities is finding its way to the great ice sheet.

The net effected is Greenland ice sheet albedo dropping like a rock.

(Falling like a rock. Greenland Ice Sheet albedo hits record low for August of 2014. Data source: NASA MOD10A1. Data Processed by: Dr. Jason Box.)

Albedo is a measure of reflectivity. The less reflective an ice sheet is, the more vulnerable it is to melting through direct heating by solar radiation. The ice sheet surface absorbs more energy from the sun’s rays as reflectivity falls and this process, in turn, further hastens a melt that is already being amplified by human-caused atmospheric and ocean heating.

But charts and graphs do little justice to this ongoing tragedy. In looking at vast stretches of ice, now colored an ominous grey-black, blanketing Greenland, it becomes all-too-easy to realize that we are likely witnessing the start of the Great Ice Sheet’s demise.

Links:

by robertscribbler on October 1, 2014 • Permalink

Posted in Climate Change

Tagged albedo, amplifying feedbacks, Black Ice, greenland, Greenland ice sheet, Hothouse, hothouse warming, Human Hothouse, human warming, ice sheet collapse, Ice sheet darkening, Loss of Reflectivity, polar amplification, Reflectivity

Posted by robertscribbler on October 1, 2014

https://robertscribbler.wordpress.com/2014/10/01/you-know-theres-something-wrong-when-vast-expanses-of-greenland-look-like-a-blackened-volcanic-crater/

Smokey Greenland Sees Another Summer of Substantial Melt

(Smoke from Record Northwest Territory Wildfires on August 1, 2014 crossing Baffin Bay and the West Coast of Greenland. Image source: LANCE-MODIS.)

According to our best understanding of paleoclimate, at current greenhouse gas levels of 402 parts per million CO2 and 481 parts per million CO2e, the Greenland Ice Sheet eventually melts out entirely. It’s a level of atmospheric heat forcing we’ve already set in place, a level that keeps rising at a rate of about 2.2 parts per million CO2 and 3 parts per million CO2e each and every year due to our ongoing and reckless carbon emissions. And it’s a level that is already starting to receive substantial additions from destabilizing permafrost carbon together with likely increasing releases from sea bed methane stores.

In this, rather stark, geological, climatological and physical context, we ask the question — is it possible for us to stop a wholesale collapse of Greenland’s ice? And we wonder, how long can the ice sheet last as human greenhouse gas forcings together with ongoing releases from some of Earth’s largest carbon stores continue to rise?

(Extensive melt ponds, Dark Snow on West Face of Greenland Ice Sheet near the Jakobshavn Glacier on July 30, 2014. Extensive darkening of the ice sheet surface, especially near the ice sheet edge, is resulting in more solar energy being absorbed by the ice sheet. Recent studies have shown that edge melt results in rapid destabilization and speeds glacier flows due to the fact that edge ice traditionally acts like a wall holding the more central and denser ice pack back. Notably, the Jakobshavn is currently Greenland’s fastest glacier. Image source: LANCE-MODIS.)

For ultimately, our ability or inability to rapidly mitigate and then draw down extreme levels of atmospheric greenhouse gasses will provide an answer these key questions. And whether we realize it or not, we are already in a race against a growing Earth Systems response that may eventually overwhelm our efforts, if we continue to delay for too long.

But there’s a lot of inertia in the ice. It represents aeons and aeons of ancient cold locked in great, mountain-high blocks. And its eventual release, which is likely to continue to ramp higher and higher this century, is bound to result in a temporary and weather-wrecking outrush of that cold causing dramatic swings in temperature and climate states to be the rule of the day for Greenland as time moves forward.

(Large melt ponds, extensive surface water over Zachariae Glacier in Northeast Greenland on July 25 of 2014. For reference, the larger melt ponds in this image range from 1 to 4 kilometers at their widest points. The Zachariae Glacier sits atop a deep, below sea level channel that runs all the way to a massive below sea level basin at the center of the Greenland Ice Sheet. This Glacier is now one of more than 13 massive ice blocks that are moving at ever increasing velocity toward the ocean. Image source: LANCE-MODIS)

So we should not expect any melt to follow a neat or smooth trend, but to instead include large variations along an incline toward greater losses. In short, we’ve likely locked in centuries of great instability and variability during which the great ice sheets are softened up and eventually wither away.

Another Year of Strong Greenland Melt

In the context of the past two decades, the 2014 summer melt has trended well above the 30 year average in both melt extent and surface mass losses. Though somewhat behind melt during 2012, 2014 may rank in the top 10 melt years with continued strong melt in various regions and an overall substantial loss of ice mass.

Surface melt extent appears to be overall above 2013 values, ranging well above the 1981-2010 average, but significantly below extents seen during the record 2012 melt:

(Last three years of surface melt extent with the most current melt graph for the 2014 melt season at the top and the preceeding years 2013 and 2012 following chronologically. Dotted blue line indicates 1981-2010 average. Top three surface melt years in the record are 2012, 2010 and 2007, respectively. Image source: NSIDC.)

Overall, 2014 showed four melt spikes above 35% melt coverage with three spikes nearing the 40% melt extent coverage mark. By contrast, 2013 only showed two such melt spikes, though the later spike was slightly more intense than those seen during 2014. 2012’s 150 year melt, on the other hand, showed melt extents ranging above 40 percent from mid June to early August with two spikes above 60% and one spike above 80%.

Losses of mass at the surface also showed above average melt trends, but with net melt still below both 2013 and 2012:

(Greenland surface mass balance trend for 2014 [blue line] compared to mean for 1990 to 2011 [gray line] and record melt year of 2012 [red line]. Image source: DMI.)

2012 was a strong record year and, on average, we’d expect to see the record jump back to lower levels after such a severe event. However, there’s little to indicate that either 2013 or 2014 have bucked the trend of ongoing and increasing surface melt over Greenland. To the contrary, that trend is now well established with yearly surface mass losses now taking place during all but one of the last 13 years. And there is every indication that 2014 will be a continuation of this trend.

Basal, Interior Melt Not Taken Into Account in the Surface Measure

While surface measures are a good measure of melt on the top of the ice sheet, it doesn’t give much of an idea of what’s happening below the first few feet. There, during recent years, sub surface melt lakes have been forming even as warming ocean waters have eaten away at the ice sheet’s base. And since more than 90% of human-caused warming ends up in the world’s oceans even as many of Greenland’s glaciers plunge hundreds of feet into these warming waters, one might expect an additional significant melt to be coming from the ocean-contacting ice faces.

We can see an indication of the severe combined impact of basal, interior and surface melt in the GRACE mass measurements of the Greenland Ice Sheet since 2002. A record that finds a precipitous and increasing rate of decline:

(Greenland cumulative mass loss through mid 2013. Data provided by the GRACE satellite gravity sensor. Image source: NOAA.)

It is this ongoing overall mass loss that tells the ice sheet’s full tale. One that now includes an ever-increasing number of destabilized glaciers speeding more and more rapidly seaward.

Links:

Nature: Human Warming Now Pushing Entire Greenland Ice Sheet Into the Ocean

Dark Snow

The Arctic Methane Monster Exhales

Large Methane Plumes Discovered on Laptev Continental Slope Boundary

53 Comments

by robertscribbler on August 1, 2014 • Permalink

Posted in Climate Change

Tagged albedo, albedo loss, climate change, dark snow, global warming, greenland, Greenland ice sheet, greenland ice sheet melt, greenland melt, human warming, ice mass, ice mass balance, Ice sheet darkening, melt ponds, smoke, surface melt, surface melt extent, wildfires

Posted by robertscribbler on August 1, 2014

https://robertscribbler.wordpress.com/2014/08/01/smokey-greenland-sees-another-summer-of-substantial-melt/

NSIDC: Greenland Experiencing “Extraordinarily High Melting.”

Back in July, Greenland experienced a very rare period of warm weather that resulted in melting over all of Greenland’s ice cap. That said, for this summer, this single period of extremely warm weather was just the capstone of what has been an extraordinary melt season.

The National Snow and Ice Data Center (NSIDC) recently released a report including statements on Greenland’s record high elevation melt, noting that such events tend to occur with 150 year frequency (according to ice cores, the last such event happened in 1889). But the NSIDC was quick to note that lower elevation melting was perhaps even more extraordinary:

“Perhaps more important, however, is the extraordinary high melting occurring this year around the lower elevations in Greenland. Figure 6 (above) shows that the first few months of melt exceeded past higher-than-average melt seasons.”

Taking a look at the figure, it is pretty clear that Greenland melt through late July has far exceeded even the record 2010 and 2011 melt seasons. NSIDC went on to report that this year’s melt resulted in flooding for a number of rivers in Greenland and this, in turn, resulted in instances of structural damage.

Putting this event in context, it is important to note that increased volumes of melt from Greenland also increase the rate of sea level rise. Furthermore, increased rates of melt in Greenland result in large iceberg calving events that directly impact world shipping and maritime industries. One such calving event in July resulted in an iceberg larger than Manhattan breaking off from the ice sheet.

Finally, the unprecedented melt in Greenland did not occur in a vacuum. This summer has also brought record sea ice melt as well as a record early snow melt to the Northern Hemisphere. This series of events punctuates an ongoing trend that is years ahead of climate scientist’s expectations for impacts to global warming. In short, these kinds of events were predicted, but for one, two, or three decades on — not now. In particular, the discrepancy for sea ice melt and model predictions has been among the most glaring of these earlier than expected melt events. This issue is one we will explore more deeply in another post.

For now, I’ll leave you with this record of albedo loss for Greenland so far this year:

(NOTE: Albedo measures an ice sheet’s reflectivity. The less reflective an ice sheet becomes, the more heat it absorbs and the faster it tends to melt.)