From the European Space Agency (ESA):
Satellite observes rapid ice shelf disintegration in Antarctic
5 April 2012
As ESA’s Envisat satellite marks ten years in orbit, it continues to observe the rapid retreat of one of Antarctica’s ice shelves due to climate warming.
One of the satellite’s first observations following its launch on 1 March 2002 was of break-up of a main section of the Larsen B ice shelf in Antarctica – when 3200 sq km of ice disintegrated within a few days due to mechanical instabilities of the ice masses triggered by climate warming.
Now, with ten years of observations using its Advanced Synthetic Aperture Radar (ASAR), Envisat has mapped an additional loss in Larsen B’s area of 1790 sq km over the past decade.
The Larsen Ice Shelf is a series of three shelves – A (the smallest), B and C (the largest) – that extend from north to south along the eastern side of the Antarctic Peninsula.
Larsen A disintegrated in January 1995. Larsen C so far has been stable in area, but satellite observations have shown thinning and an increasing duration of melt events in summer.
“Ice shelves are sensitive to atmospheric warming and to changes in ocean currents and temperatures,” said Prof. Helmut Rott from the University of Innsbruck.
“The northern Antarctic Peninsula has been subject to atmospheric warming of about 2.5°C over the last 50 years – a much stronger warming trend than on global average, causing retreat and disintegration of ice shelves.”
Larsen B decreased in area from 11512 sq km in early January 1995 to 6664 sq km in February 2002 due to several calving events. The disintegration in March 2002 left behind only 3463 sq km. Today, Envisat shows that only 1670 sq km remain.
Envisat has already doubled its planned lifetime, but is scheduled to continue observations of Earth’s ice caps, land, oceans and atmosphere for at least another two years.
This ensures the continuity of crucial Earth-observation data until the next generation of satellites – the Sentinels – begin operations in 2013.
Credits: ESA
“Long-term systematic observations are of particular importance for understanding and modelling cryospheric processes in order to advance the predictive capabilities on the response of snow and ice to climate change,” said Prof. Rott.
“Climate models are predicting drastic warming for high latitudes. The Envisat observations of the Larsen Ice Shelf confirm the vulnerability of ice shelves to climatic warming and demonstrate the importance of ice shelves for the stability of glaciers upstream.
“These observations are very relevant for estimating the future behaviour of the much larger ice masses of West Antarctica if warming spreads further south.”
Radars on Earth observation satellites, such as Envisat’s ASAR, are particularly useful for monitoring polar regions because they can acquire images through clouds and darkness.
The Sentinel missions – being developed as part of Europe’s Global Monitoring for Environment and Security (GMES) programme – will continue the legacy of radar observations.
Henry says
My point was that the paper you (they) are quoting is apparently only based on the reported results from one station – which is completely rediculous.
It is the station closest to the Larsen icesheets under discussion, and it appears to the one that the frequently quoted ‘2.5C Peninsula warming’ comes from. It is also the longest continously operated station on the Peninsula.
Henry@Philip
The method they use to calculate mean temps. is incorrect. They measure the max. and min. together and then divide by 2. At best this a a reasonable estimate of the mean. But it is not the mean. Weather and temps. can change significantly in an hour. Also the human influence of recording every 6 hours. So there is no actual recorder. Too many possibilities for error…..
I could accept that by some fluke, minima are going up there as also noted at 4 of my 19 SH weather stations. But at the same time they report that maxima have stayed the same. That has not happened in any of my 19 SH weather stations. The average I found of maxima going up is 0.44 degrees per decade. I donot use any data before 1973 until the advent of continuous recorders.So, maxima may have indeed increased there by 0,5 degrees C per decade (seeing that the place is near to the ozone hole). And that it what has caused the warming.
The only conclusion I can reach from all that is that they must have messed up badly or they deliberately misrepresented the data to make it look like man’s carbon footprint is responsible for the warming.
Henry,
This is an article I wrote based on comparisons of min max temperatures with temps recorded at fixed times.
http://bishophill.squarespace.com/blog/2011/11/4/australian-temperatures.html
It concludes that mean temperatures calculated from min/max temperatures have a spurious warming signal caused by rising minimum temperatures that is about half of the total warming since around 1960.
The cause is almost certainly reduced cloud cover (in part due to reduced aerosol seeded clouds) and reduced aerosol scattering of solar irradiance.
If you did not find increasing min temps in the more recent continuous temp measurements that is consistent with my conclusion that increasing min temps since 1960 are primarily due to reduced developed world anthropogenic aerosols from the 1960s to the 1990s. An effect that stopped and may have reversed in the 1990s.
Hi Philip
It looks like your findings broadly correspond with my own,namely
“In overall summary, it is clear that increased solar insolation, caused by a combination of decreased clouds ”
The only important factor that you forgot to mention imho is that of the ozone layer. You have to understand that the sun’s UV makes ozone and ozone cuts ca. 20% of sunlight. So paradoxically, less UV from the sun makes less ozone which allows more sunlight in. In addition it has been proven that chlorine/fluor/bromine destroys ozone. (CFC’s). I understand that from 1980 the ozone layer has been growing again but it is not back to pre 1970 levels, I think…..
For minima, in the SH, the only two stations ducking the negative trend of -0.01 degree C per annum are those of Sao Paulo and Brasilia with 0.022 and 0.026 gegrees C per annum respectively. I suspect that UHI and more vegetation is the cause for that (like we saw in Las Vegas). Auckland was +0.015 degrees C per annum but Christchurch is -0.001. That is your NZ puzzle.
The way I understand “mean” is that it is the average of all measurements during the day. Nowadays with recorders, you can measure every second of the day or more and print a mean and a max. and a min. at the end of the day.
I am going to spend some time cutting my tables in periods – I first have to sit and figure out which periods would be giving us interesting information.
Australia’s ABC Takes it hook, line and STINKER.
http://www.abc.net.au/news/2012-04-08/climate-change-expert-on-diminishing-ice-shelf/3938322
Australia’s ABC takes it Hook , Line and Stinker!
http://www.abc.net.au/news/2012-04-08/climate-change-expert-on-diminishing-ice-shelf/3938322
Henry,
Ozone is a bit of a climate wildcard. I understand in general terms the role of ozone, but ozone is just as politicized as CO2, and the Montreal Protocol just as fraudulent as the Kyoto Protocol.
IMO published papers on the role of ozone in the climate can be relied upon just as much as papers on the role of CO2 in the climate – not much.
Philip says:
Ozone is a bit of a climate wildcard.
Henry@Philip
True. But it is a factor. You have to try to understand from the references I give here: http://www.letterdash.com/HenryP/the-greenhouse-effect-and-the-principle-of-re-radiation-11-Aug-2011
why I think the ozone is an important factor, many times greater than the CO2. If you look at the CO2 14-16 it is overlapped by water vapor and oxygen ozone. At 0-1 um ozone blocks ca. 15-20% of incoming light (of high energy) on its own. So less ozone means less blocking.
Whether the less ozone is due to natural depletion or whether depletion is helped by man, it could be a contributary factor for global warming (as witnessed by the increase in maxima)