CR
Cryospheric Sciences

Cryospheric Sciences

Image of the Week — Greenland ice sheet and clouds

Image of the Week — Greenland ice sheet and clouds

A new study combining satellite observations and model simulations shows that clouds increase meltwater runoff in Greenland by one-third compared to a cloud-free scenario.

Precipitation effects not considered, clouds above the Greenland ice sheet reduce its Surface Mass Balance (SMB) [red in figure] compared to clear-sky conditions [blue in figure]. Because clouds trap the outgoing radiation from the ice-sheet surface, they locally warm the atmosphere below, which reduces Greenland’s meltwater refreezing at night. Hence, clouds increase runoff from the ice sheet by 56 billion tons of water each year.

Reference/further reading:

  • Van Tricht, K., S. Lhermitte, J. T. M. Lenaerts, I. V. Gorodetskaya, T. S. L’Ecuyer, B. Noël, M. R. van den Broeke, D. D. Turner, and N. P. M. van Lipzig. 2016. “Clouds Enhance Greenland Ice Sheet Meltwater Runoff.” Nature Communications 7 (January). Nature Publishing Group: 10266. doi:10.1038/ncomms10266.
  • Article in the Washington Post about the paper.
  • You can follow Kristof Van Tricht the study’s lead author on twitter @kristofvt.

Image of the Week — Happy New Year

Image of the Week — Happy New Year

December 2014, 11:50 p.m., the sun licks the horizon on Derwael ice rise; It’s time to go back to the tent …

The shot was taken during the 2014 IceCon Field campaign in East Antarctica (read Brice’s blog post  telllling about his first journey to Antarctica).

Here, you can also read about the 2016 field season of the IceCon project, which started just a few days ago.

Image of the Week — Greetings from Antarctica

Image of the Week — Greetings from Antarctica

Christmas greetings from people at Rothera Research Station, Adelaide Island, Antarctica.

Rothera, which is the British Antarctic Survey’s largest base in Antarctica, is a centre for marine biology and gateway for getting scientists into their deep field camps.

Christmas Day is a regular working day for the staff of around 90. However the chefs will be getting everyone into the festive spirit with a traditional turkey dinner with all the trimmings

Image of the Week — AGU Fall Meeting 2015

Image of the Week — AGU Fall Meeting 2015

The American Geophysical Union (AGU) Fall Meeting, which takes place every December in  San Francisco is ending today.

With more than 24 000 attendees, 14 000 poster presentations and 7 000 talks, the AGU meeting is the largest conference on geophysical sciences in the World.

The cryosphere is one the topics covered by the meeting and we hope that this year edition was a fruitful for every participant.

Busy poster session on the Cryosphere. (Credit: Konstantinos Petrakopoulos)

Busy poster session on the Cryosphere. (Credit: Konstantinos Petrakopoulos)

 

Image of the Week: Ice Sheets in the Climate

Image of the Week: Ice Sheets in the Climate

Ice sheets play a central role in the climate system. They store significant amounts of fresh water and are the conveyor belts for transporting snow that accumulates on land back into the oceans. The figure above shows a few of the ice-climate interactions. In the figure below (click on the figure for full resolution) we see the complete picture of the processes taking place between ice sheets, solid earth and the climate system. These interactions have an internal variability but also affect the coupled ice sheet–climate response to external forcings on time scales of months to millions of years. The inlay figure represents a typical height profile of atmospheric temperature and moisture in the troposphere.

If the current warming of the climate continues, the ice sheets will respond at a yet unknown rate, with unknown consequences for the rest of the climate system. Decisions reached at COP21 in Paris this week  may impact the future of our ice sheets and halt the current trend.

FigBox5.2-1_interaction_ice_sheet_rest

The interaction of ice sheets with the climate system. Credit: Figure 1 in Box 5.2, IPCC AR5.

Image of the Week: Atmospheric CO2 from ice cores

Image of the Week: Atmospheric CO2 from ice cores

The measurements of atmospheric CO2 levels at Manu Loa, Hawaii read 401.01ppm on the 7th of December this year. To understand the significance of this number, you just need to look at the figure above from the 4th IPCC report. It shows the changes in CO2 concentrations during the past 800,000 years based on ice core measurements. Values have fluctuated between 190ppm and 280ppm. In other words, both the level of present-day atmospheric CO2 and the rapidity of the increase is unprecedented.

The figure also shows the projections from the IPCC AR4 report for different emission scenarios. Which scenario will turn out to be the most likely might be determined at COP21 in Paris right now.

Read more:

Measurements at Manu Loa, Hawaii

Image of the Week: Changes in Snow Cover

Image of the Week: Changes in Snow Cover

Who is dreaming of a white spring?

In daily life we might be more interested in the chances of a white Christmas, but the amount of snow-covered ground in the spring is a very good indicator of climate change. The figure above shows the projected change in snow cover extent in the Northern hemisphere in March-April according to different future scenarios (i.e. Representative Concentration Pathways or RCPs of the IPCC). All the scenarios predict a decrease in spring snow, and the reduction goes up to 30% by 2100, for the most pessimistic scenario.

Below is shown the changes in snow cover in historical times for the Northern hemisphere, the grey line is the change in snow cover in the spring. The red crosses are based on satellite data and show the snow cover in June. Undoubtedly, we are heading for a warmer climate but it would also seem that springtime skiing holidays could become a thing of the past.

The COP21 meeting will determine what steps will be taken in the future and which scenario path we will follow. Regardless of whether you worry about the future of our planet or the future of your skiing holiday – you should take an interest.

March–April NH snow cover extent (SCE, circles) over the period of available data, filtered with a 13-term smoother and with shading indicating the 95% confidence interval; and June SCE (red crosses, from satellite data alone), also filtered with a 13-term smoother. The width of the smoothed 95% confidence interval is influ- enced by the interannual variability in SCE. Updated from Brown and Robinson (2011). For both time series the anomalies are calculated relative to the 1971–2000 mean.

March–April NH snow cover extent (circles) over the period of available data, filtered with a 13-term smoother and with shading indicating the 95% confidence interval; and June (red crosses, from satellite data alone), also filtered with a 13-term smoother. The width of the smoothed 95% confidence interval is influenced by the interannual variability in SCE. For both time series the anomalies are calculated relative to the 1971–2000 mean.

 

The figures in this blog post are taken from the IPCC report (Fig. TS-18 and Fig. 4.19 respectively). You can read more here:

Vaughan, D.G., J.C. Comiso, I. Allison, J. Carrasco, G. Kaser, R. Kwok, P. Mote, T. Murray, F. Paul, J. Ren, E. Rignot, O. Solomina, K. Steffen and T. Zhang, 2013: Observations: Cryosphere. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Image of the Week — Future Decline of sea-ice extent in the Arctic (from IPCC)

Image of the Week — Future Decline of sea-ice extent in the Arctic (from IPCC)

The Arctic sea-ice extent has declined in the past 20 years and its future is uncertain. In the end, greenhouse gas emissions will determine the impact on the sea-ice from man-made climate change through radiative forcing (i.e. Representative Concentration Pathways or RCPs). The COP21 can determine the path we will follow and which course we will take to reduce emissions.

Reduction in sea-ice cover ranges from 43% (RCP 2.6) to 94% (RCP 8.5) in the period 2081-2100 compared to 1986-2005.

Why is sea important?

Decrease in sea-ice extent would:
– decrease the albedo of the Arctic ocean, therefore more heat would be absorbed by the ocean which would enhance the warming in this region.
– affect the global oceanic circulation as sea-ice formation influences the density of ice masses, which drives oceanic circulation.
– completely alter the ecosystem in the Arctic.

 

Further Reading

Stocker, T F, D Qin, G.-K. Plattner, L V Alexander, S K Allen, N L Bindoff, F.-M. Bréon, et al. 2013. “Technical Summary.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by T F Stocker, D Qin, G.-K. Plattner, M Tignor, S K Allen, J Boschung, A Nauels, Y Xia, V Bex, and P M Midgley, 33–115. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. doi:10.1017/CBO9781107415324.005.

Read about sea ice and its importance on the NSIDC website

 

Previous blog posts featuring sea-ice science:

Do beers go stale in the Arctic?

Cruising for mud sediments from the ocean floor

Camping on the Svalbard coast

Image of the Week: Under the sea

Image of the Week — Ice Sheets and Sea Level Rise (from IPCC)

Image of the Week — Ice Sheets and Sea Level Rise (from IPCC)

Context

On the eve of the COP21, it is of paramount importance to recall how strongly the cryosphere is affected by Climate Change. Today, we present the impact of melting ice on sea level rise, as it is presented in the latest assessment report of the Intergovernmental Panel on Climate Change.

Quick facts

-Since 1992, the Glaciers, Greenland and Antarctic Ice Sheets have risen the sea level by 14, 8 and 6 mm, respectively.
-The Greenland and Antarctic ice losses have accelerated for the last 2 decades.
In Greenland ice-loss rates increased from 34 Gt/yr* (between 1992-2001) to 215 Gt/yr (between 2002-2011), which was caused by more widespread surface melt + run-off and enhanced discharge of outlet glaciers.
While in Antarctica, ice-loss rates “only” rose from  30 Gt/yr (between 1992-2001) to 147 Gt/yr (between 2002-2011), this loss mostly occurred in West Antarctica (Amundsen Sea Sector and Antarctic Peninsula) and  was driven by  the acceleration of outlet glaciers.

 

*An ice loss of 100 Gt/yr is approximately 0.28 mm/yr of sea level equivalent

Further Reading [Read More]

Image of the Week: Under the Sea

Image of the Week: Under the Sea

Always wondered how it looks like under the sea ice?
Getting an answer is simpler than you might think: Just go out to the front of McMurdo ice shelf in Antarctica and drill a tube into the sea ice. Then let people climb down and take pictures of the ice from below.
More information:
– Photo taken by Marcus Arnold, Gateway Antarctica, University of Canterbury during his November 2015, Antarctic Expedition.
– More photos of their expedition on https://instagram.com/the_ross_ice_shelf_programme/