From the British Antarctic Survey
New climate history adds to understanding of recent Antarctic Peninsula warming
Results published this week by a team of polar scientists from Britain, Australia and France adds a new dimension to our understanding of Antarctic Peninsula climate change and the likely causes of the break-up of its ice shelves.
The first comprehensive reconstruction of a 15,000 year climate history from an ice core collected from James Ross Island in the Antarctic Peninsula region is reported this week in the journal Nature. The scientists reveal that the rapid warming of this region over the last 100 -years has been unprecedented and came on top of a slower natural climate warming that began around 600 years ago. These centuries of continual warming meant that by the time the unusual recent warming began, the Antarctic Peninsula ice shelves were already poised for the dramatic break-ups observed from the 1990’s onwards.
The Antarctic Peninsula is one of the fastest warming places on Earth – average temperatures from meteorological stations near James Ross Island have risen by nearly 2°C in the past 50 years.
Lead author Dr Robert Mulvaney OBE, from British Antarctic Survey (BAS) says,
“This is a really interesting result. One of the key questions that scientists are attempting to answer is how much of the Earth’s recently observed warming is due to natural climate variation and how much can be attributed to human activity since the industrial revolution. The only way we can do this is by looking back through time when the Earth experienced ice ages and warm periods, and ice cores are a very good method for doing this.”
Dr Mulvaney continues,
“We know that something unusual is happening in the Antarctic Peninsula. To find out more we mounted a scientific expedition to collect an ice core from James Ross Island – on the northernmost tip of the Peninsula. Within the 364m long core are layers of snow that fell every year for the last 50,000 years. Sophisticated chemical analysis – at BAS and the NERC Isotope Geosciences Laboratory (part of British Geological Survey) – was used to re-create a temperature record over this period.
“For this study we looked in detail at the last 15,000 years – from the time when the Earth emerged from the last ice age and entered into the current warm period. What we see in the ice core temperature record is that the Antarctic Peninsula warmed by about 6°C as it emerged from the last ice age. By 11,000 years ago the temperature had risen to about 1.3°C warmer than today’s average and other research indicates that the Antarctic Peninsula ice sheet was shrinking at this time and some of the surrounding ice shelves retreated. The local climate then cooled in two stages, reaching a minimum about 600 years ago. The ice shelves on the northern Antarctic Peninsula expanded during this cooling. Approximately 600 years ago the local temperature started to warm again, followed by a more rapid warming in the last 50-100 years that coincides with present-day disintegration of ice shelves and glacier retreat.”
Co-Author Dr Nerilie Abram formerly from British Antarctic Survey and now with the Research School of Earth Sciences, at The Australian National University says,
“The centuries of ongoing warming have meant that marginal ice shelves on the northern Peninsula were poised for the succession of collapses that we have witnessed over the last two decades. And if this rapid warming that we are now seeing continues, we can expect that ice shelves further south along the Peninsula that have been stable for thousands of years will also become vulnerable.”
Olivier Alemany, from the French Laboratoire de Glaciologie et Géophysique de l’Environnement was part of the expedition. He says,
“The international polar science community has collected and analysed ice cores from Antarctica and Greenland as part of an effort to reconstruct the Earth’s past climate and atmosphere. Our team wanted to understand how the recent warming and the loss of ice shelves compared to the longer term climate trends in the region.”
This research makes a significant contribution to the understanding of the role that Antarctica’s ice sheets play in influencing future climate and sea-level rise. It was funded by NERC (Natural Environment Research Council).
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Regarding that rapid warming of 2C in the last 50 years, just remember that most weather stations in the Antarctic are near humanity, and humanity requires warmth to survive. For example:
The Antarctic peninsula is the most populated place in Antarctica.
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I believe it’s referring to the rate of warming.
Well done, ScousePete, getting them to change it. Maybe you could ask them why they changed it to “very unusual” when the paper said just “unusual”. Anyone would think they want to make it sound bad, instead of reporting science properly.
By 11,000 years ago the temperature had risen to about 1.3°C warmer
These ice core temperatures are so exact to tenths of a degree C. Yet NASA goes back and adjusts temperatures taken by professional meteorological observers in the 1940’s by more than 0.3°C. Amazing accuracy these ice cores. I don’t suppose anyone has validated the temperature proxies? — ahh thought not. Wouldn’t want to see any declines after all.
About thermal radiation, its heat transfer is proportional to the fourth root of the absolute temperature difference in addition to being subject to R^-2 and shielding. Convection MAY be efficient here but the mixing of turbulent cold air – lots of it – makes me wonder.
BBC news AGW agit-prop is in full swing curtsey of Bob Watson, appeared with lot of facial fur grown just in case hi got wrong his 2-4C degrees temperature rise.
Looking at the First Day Cover and comparing my recollections of other thermometer housings; they are on stands, I imagine to elevate the sensor above the boundary layer air. Here it *appears* that the thermometer may be within a reasonable boundary layer, that may be occasionally deeper (due to smooth up wind) and warmer for conduction/convection of the possibly warmer snow field.
Most of the “Antarctic Peninsula” stations that the 2dC increase refer to are in fact on King George Is in the So. Shetlands, out in the currents about 100km offshore from the actual Peninsula. John Ross Is is tucked in closer to the Peninsula on the E side, and so is more representative of the actual Peninsula.
If ice core sampling is so precise, surely then the ice core data from the last several years accumulation will provide excellent calibration for the thermometers in current use.
PRESS RELEASE,
The scientists reveal that the rapid warming of this region over the last 100 years has been VERY unusual and came on top of a slower natural climate warming that began around 600 years ago.
ABSTRACT,
The high rate of warming over the past century is unusual (but not unprecedented) in the context of natural climate variability over the past two millennia.
Not much difference is there.
Thanks Bob. It is useful to remember that the Antarctic Peninsula projects into the Drake Passage and that the latter has existed as a deep water passage allowing a powerful southern circumpolar current for only the last 34 – 30 Ma. The Drake Passage opening was clearly the trigger for the abrupt Eocene–Oligocene climate deterioration and the growth of extensive Antarctic ice sheets without any need whatsoever to invoke a mysterious reduction in atmospheric CO2. It is highly likely that prior to that event, driving forces for global climate homeostasis were far weaker (than they now are). This invalidates the currently fashionable attempts by the CAGW lobby to scare us with the earlier Paleocene-Eocene Thermal Maximum (PETM) at 56 Ma.
Back to the radiant heat theme and presumed surface emissivity from the camp structures impinging on the weather station, (which undoubtedly will be comfortably heated) an infrared image of the encampment would be most enlightening.
Depending on the time resolution of the proxies (ice cores here), it may actually be hard to say if the rate of temp. rise is unprecedented or not. I’m pretty sure we have not had good thermometer coverage in this region for hundreds of years.
Certainly the maximum temp.’s in the last 15,000 years have been 1.3 to 6 degrees higher!
If they wanted to insure that there is no effect of radiant heat on the temp. probe it really should be at least 20 yards from the houses and upwind if there is a prevailing wind direction. And if many of the other temp. probes are in the island chain, they are obviously influenced strongly by ocean current temperatures which is something that Antarctic researchers freely admit but sometimes do not go out of their way to emphasize.
I would like to see their data. Some of their findings tend to confirm what I have observed in analyzing isotope depletion data from ice cores. slides 44 to 51 at http://www.kidswincom.net/climate.pdf. I do not agree that the warming rate in the last 100 years is unprecedented and I doubt that the word is even used in their paper.
Reading the exerts from this article made me wonder about what has happened with the Andrill project results- This 60 million dollar project drilled down from the Ross Ice Shelf to material dating to the start of the present glacial periods, which showed that the Ross Ice Shelf had collapsed 25 or 26 times. Then drilling went beyond to materials predating the glaciation to the end period of the prior glaciation period. The latest from Google was that the University of Nebraska was just now shipping out a 2 billion dollar drill for the new Andrill project which will start next year. NSF is providing another billion to cover the first two years of the project.
http://www.dailynebraskan.com/mobile/news/unl-built-andrill-voyages-to-antarctica-1.2751637#.UDYbBCJcS1s
From Ian W on August 23, 2012 at 5:09 am:
I’ve started to try to understand the Time of Observation (TOBs) adjustments made by NOAA-NCDC to the USHCN numbers, been comparing the “raw” and “TOBs-only adjusted” monthly records. If NASA-GISS is only adjusting around 0.3°C, they’re on the low end for finagling. And that’s just looking at TOBs.
If I ever understand that adjustment, then I’ll consider looking at the others. I wouldn’t be surprised if there was a “Hg purity” adjustment snuck in somewhere, which will be argued as needed since mercury way back then was less pure, causing it to expand more, thus it’s justified to cool the past another 0.1°F or so.
The paper doesn’t present any evidence for recent warming.
I looked into the Antarctic Peninsula warming claim, and found it results from a single British station. All the warming was in the minimum temperature in a place where the minimum temperature never gets above zero.
Thus, the claimed Antarctic Peninsula (atmospheric) warming can not be the cause of the increased iceshelf melt.
The cause is increased insolation from decreased clouds, resulting from decreased anthropogenic aerosols.
As it is for the Arctic.
Non-paywalled version available here.
It was warmer way back then. But that doesn’t matter a damn.
Now that they’ve “corrected” the press release, I wonder if they will re-issue the corrected one or just record the fact that they corrected it? Kind of like correcting an email after you’ve already sent it out to hundreds of people…
According to HH Lamb,
he greatest extent of ice on the Antarctic Ocean may have been as late as around 1900.
While this is not specific to the Peninsula, it does not support the idea of gradual warming for 600 years.
http://notalotofpeopleknowthat.wordpress.com/2012/06/24/hh-lambclimate-present-past-futurevol-2in-reviewpart-i/
The Sun is “OFF”. The Flux is under 100 units [the lowest values during a Sunspot minimum is about 70 units]. During a Sunspot peak [“NOW”], the Flux should have values of 250 to 300 units. Get ready for a cold summer and a horrific winter next year [unless the Sun avoids its natural 350 year min/max cycle.
Mann’s Hockey Stick is correct except for one detail: It should be upside down!
As for the Antarctic peninsula, hasn’t anyone seen the increase in ice over the last years?
Antarctic are near humanity, and humanity requires warmth to survive.
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And all you have to do is check the average wind velocity to see if this has a plausible influence on the temperature record. High winds means no.
Mulvaney et al. confirm that the earth has been cooling since the Holocene Climatic Optimum.
The duration of recent interglacials has been approximately half a precession cycle or 11,000 years.
Kukla, G. J., Matthews, R. K. & Mitchell, J. M. The end of the present interglacial. Quat. Res. 2, 261269 (1972).
Determining the natural length of the current interglacial. Tzedakis et al. (2012) predict that the next glacial period would start in 1500 years “if atmospheric CO2 concentrations did not exceed 240.5 ppmv.”
Do we know how well CO2 predicts climate – or lags climate?
Glaciation is far more dangerous than a few degrees of warming.
We can use all the CO2 we can get to fend off the onslought of the next glacial period!
Another staging by BAS in Nature. Appaling!
BTW the largest iceberg ever mappped came from the Filchner Shelf in… 1956.
“One of the key questions that scientists are attempting to answer is how much of the Earth’s recently observed warming is due to natural climate variation and how much can be attributed to human activity since the industrial revolution.”
The climate is a non-linear system with so many variables they have not all been counted yet. There is ‘sensitivity to initial conditions’ (the mathematical definition of ‘chaos’) in all aspects: temperature, pressure, motion, moisture, cloud formation, albedo, etc. To deconvolute the observed variations into “natural” and “anthropogenic” is a mathematical impossibility.
“The only way we can do this is by looking back through time when the Earth experienced ice ages and warm periods, and ice cores are a very good method for doing this.”
Climatologists may THINK this can be done, but they are only deluding themselves. Any student of mathematics would know better.
Parsing out the ‘man-made’ climate change is as impossible as turning a chianti into a chablis by subtracting out the “red”.