Archive for the ‘British Antactic Survey’ Category

Antarctic cooling? Or WHY "The Antarctic Ain’t Cooperating" [Updated]

March 3rd, 2008 4 comments

[Significant update at bottom] 

I’ve decided to put up this little post in connection with Walter Block’s recent post,, in order to avoid having my comment stuck in a spam filter (I’ve found that comments with too many links get caught).

I see I missed providing a cite to a recent article by Andew Revkin at the NYT on what scientists think of some of this winter’s screwy weather (the topice of Block’s post):  

Skeptics on Human Climate Impact Seize on Cold Spell,  March 2, 2008:

Here’s a little information that shows the progress of understanding of climate change affecting the Southern Hemisphere and Antarctic:

The IPCC’s 2001 report says: “For the change in annual mean surface air temperature in the various cases, the model experiments show the familiar pattern documented in the SAR with a maximum warming in the high latitudes of the Northern Hemisphere and a minimum in the Southern Ocean (due to ocean heat uptake).”

Ozone Hole Is Now Seen as a Cause for Antarctic Cooling, May 3, 2002:

Science 3 May 2002:

“Despite an overall global warming trend, temperatures over large parts in the interior of Antarctica have exhibited a small but distinct cooling trend during the past several decades. Thompson and Solomon (p. 895; see the news story by Kerr) present evidence that high-latitude Southern Hemisphere circulation changes during the past few decades reflect a systematic trend in regional atmospheric circulation. Trends in tropospheric circulation trends can be traced to the recent cooling of the lower stratosphere caused by photochemical ozone losses.”

Study Shows Potential for Antarctic Climate Change, Oct. 6, 2004:

“Since the late 1960s, the SAM [Southern Annular Mode] has more and more favored its positive phase, leading to stronger westerly winds. These stronger westerly winds act as a kind of wall that isolates cold Antarctic air from warmer air in the lower latitudes, which leads to cooler temperatures.

“Greenhouse gases and ozone depletion both lower temperatures in the high latitude stratosphere. The cooling strengthens the stratospheric whirling of westerly winds, which in turn influences the westerly winds in the lower atmosphere. According to the study, greenhouse gases and ozone have contributed roughly equally in promoting a strong-wind, positive SAM phase in the troposphere, the lowest part of the atmosphere.”

Antarctic cooling, global warming? 3 December 2004:

King penguin faces extinction due to climate change, 11/02/2008:

Antarctica is Cold? Yeah, We Knew That, 12 February 2008:


In comments below, Geoffrey Plauche points to a post entitled “The Antarctic Ain’t Cooperating” at the “World Climate Report” – the website run by former climate scientist, now policy critic Pat Michaels, as “criticizing … the alarmist hype coming from some scientists, some politicians and others (like Gore), and particularly the media”.  While a review of the post certainly shows criticism of the press (not scientists) for incomplete disclosure and discussion of data about Antarctica (a criticism that is not in itself unfair), a little further digging reveals that it is Pat Michaels who is being deceptive – for self-acknowledged political and business reasons – by failing to refer to or provide additional background information that show that there is plenty of evidence indicating that while Antarctica may be warming more slowly than elsewhere (which was not unexpected), there are ample signs of warming and other changes consistent with GHG forcings.

Pat Michaels describes the “World Climate Report” as “concise, hard-hitting and scientifically correct” and “exhaustively researched, impeccably referenced, and always timely”.   It is intended as a “response to the global change reports which gain attention in the literature and popular press” that “points out the weaknesses and outright fallacies in the science that is being touted as “proof” of disastrous warming” and is “the perfect antidote against those who argue for proposed changes to the Rio Climate Treaty, such as the Kyoto Protocol, which are aimed at limiting carbon emissions from the United States”.  Michaels trumpets World Climate Report as the “definitive and unimpeachable source for what Nature now calls the “mainstream skeptic” point of view, which is that climate change is a largely overblown issue ….”

But who produces the World Climate Report?  Pat Michaels’ personal and self-described “advocacy science consulting firm”, New Hope Environmental Services.  And who hires Pat Michaels?  Well, firms that have a direct financial stake in trying to hang onto their present ability to emit GHGs free of charge into the global atmopsheric commons, of course, even though Pat does his best for his clients’ sake to keep it under his hat.;  It is not surprising that particularly heavy users of the global commons (clearly electric utilities and coal producers in Pat’s case) would like to continue to operate under the same sweet terms that they have up until now, but other users of the global commons of course have the right to their own preferences as well.  But why the secrecy?  Why aren’t the electric utilities and coal producers who support Pat, instead of funding one-sided arguments about science, willing to be straightforward about their preferences so all commons users can discuss how to manage the atmospheric commons?  I suspect that it has something to do with the small problem called “rent-seeking” whenever governments are in the middle of a problem – viz., these fossil fuel interests are trying to influence government in order to get (manintain!) favorable treatment, as opposed to trying to come to terms with others.  Thus the desire to mask their behavior and muddy the science – to influence public opinion and government – rather than forthrightness. 

In other words, Pat Michaels is in the business of selling climate policy positions.  This is clearly manifested in posts like “The Antarctic Ain’t Cooperating”, which while “scientifically correct” is much less than scientifically complete, and misleadingly so.  This shows that his motivation isn’t really so much to clarify as it is to muddle – in order to advance his own policy preferences and/or those of his clients.  While Pat is fully entitled to his own preferences, he is not entitled to his own facts.  If Pat wants to really advance our understanding of climate developments, he should be providing a rounder picture, rather than feeding factoids to those who are happy to pretend (or continue to fool themselves) that there is no scientific case for ongoing climate change (and a significant human role in it).

But as “skewed but technically accurate” science is what Pat’s clients want, it’s hard to fault him for doing his best to be responsive to them.  But it nevertheless behooves us to be aware, when Pat speaks, who has actually paid for his voice, and why, so we might better know how to weigh his words.

Allow me to expand on the information I’ve already provided above by quoting relevant parts of two recent publications that provide a fuller picture of develoments in Antarctica:

1.    The British Antarctic Survey released in December 2007 a statement about climate change in Antarctica entitled “Climate Change – Our View”:  Among others, the BAS statement concludes (with some rephrasing):

  • The Southern Ocean is a significant sink for both heat and carbon dioxide, acting as a buffer against human-induced climate change.

  • Since the commencement of continuous observations of Antarctic climate in1957-58, surface temperatures have remained fairly stable over much of Antarctica, although individual station records show a high level of year-to-year variability, which could mask any underlying long term-trend.

  • By contrast, large and statistically-significant warming trends are seen at stations in the Antarctic Peninsula. Over the past 50 years, the west coast of the Peninsula has been one of the most rapidly-warming parts of the planet. Here, annual mean temperatures have risen by nearly 3°C, with the largest warming occurring in the winter season. This is approximately 10 times the mean rate of global warming, as reported by the IPCC. The east coast of the Peninsula has warmed more slowly and here the largest warming has taken place in summer and autumn.

  • Significant warming has also been observed in the Southern Ocean. Upper ocean temperatures to the west of the Antarctic Peninsula have increased by over 1°C since 1955. Within the circumpolar Southern Ocean, it is now well-established that the waters of the Antarctic Circumpolar Current (ACC) are warming more rapidly than the global ocean as a whole. A comparison of temperature measurements from the 1990s with data from earlier decades shows a large-scale warming of around 0.2°C in the ACC waters at around 700-1100 m depth.

  • Analysis of weather balloon data collected over the past 30 years has shown that the Antarctic atmosphere has warmed below 8 km and cooled above this height. This pattern of warming in the troposphere and cooling in the stratosphere is seen globally and is the expected signature of increases in greenhouse gases, such as carbon dioxide. However, the 30-year warming at 5 km over the Antarctic during winter (0.75°C) is over three times the average rate of warming at this level for the globe as a whole.

  • Subtle but important changes have occurred in the atmospheric circulation around Antarctica. Since the early 1960s, atmospheric pressure has dropped over Antarctica and risen in the mid-latitudes of the Southern Hemisphere, a pattern of variability known as the Southern Hemisphere Annular Mode (SAM). These changes have resulted in a strengthening of the westerly winds that blow over the Southern Ocean around Antarctica. Stronger westerlies will impact on ocean currents, upwelling and mixing, but the consequences of such changes have yet to be fully understood.

  • Recent climate change has driven significant changes in the physical and living environment of the Antarctic. Environmental change is most apparent in the Antarctic Peninsula, where climate change has been largest. Adélie penguins, a species well adapted to sea ice conditions, have declined in numbers and been replaced by open-water species such as chinstrap penguins. Melting of perennial snow and ice covers has resulted in increased colonisation by plants. A long-term decline in the abundance of Antarctic krill in the SW Atlantic sector of the southern ocean may be associated with reduced sea ice cover.

  • Large changes have occurred in the ice cover of the Peninsula. Many glaciers have retreated and around 10 ice shelves that formerly fringed the Peninsula have been observed to retreat in recent years and some have collapsed completely. Furthermore, 87% of glaciers along the west coast of the AP have retreated in the last 50 years, and in the last 12 years most have accelerated. The Antarctic Peninsula is contributing to sea-level rise, at about the same rate as Alaska Glaciers.

  • Analysis of global measurements of atmospheric CO2 indicates that the Southern Ocean carbon sink has weakened significantly since 1981. This reduction in the capacity of the ocean to absorb CO2 has been attributed to increased upwelling of carbon-rich waters associated with strengthening of the westerly winds. Although future changes in the ability of the Southern Ocean to sequester CO2 are not completely known, this will be a key factor that helps shape global climate.

  • Most of the IPCC model experiments do simulate the observed strengthening of the circumpolar westerly winds, suggesting that this phenomenon is a robust response to changed climate forcing.

  • Further experiments have indicated that changes in anthropogenic forcings, particularly stratospheric ozone depletion and increases in greenhouse gases, have made the largest contribution to the strengthening of the westerlies. Recent climate observations show that changes in the strength of the westerlies strongly influence temperature variations on the east coast of the Antarctic Peninsula.

  • Taken together, these two results suggest that a significant fraction of the recent observed changes in climate in this part of the Antarctic can be attributed to human activity with a reasonable degree of certainty. Further support for this view comes from analysis of marine sediment records which enable us to examine how the extent of Antarctic Peninsula ice shelves has varied over time. While some of the smaller ice shelves in this region have periodically grown and decayed over the past 10000 years, the Larsen-B ice shelf appears to have been stable throughout this period until it collapsed suddenly in March 2002. This suggests that recent warm temperatures are exceptional within the context of the last 10000 years, making it unlikely that they can be explained by natural variability alone.

  • Many of the theories that seek to explain the circumpolar warming of the Antarctic Circumpolar Current also have the strengthening of the westerly winds as their root cause. Whilst there is not yet a clear consensus on which are the mechanisms that are most important, there is increasing evidence that a significant part of this change is ultimately driven by human activities.


2.  In May 2007, ENVIRONMENTAL RESEARCH LETTERS published “Scientific reticence and sea level rise” by James Hansen of the NASA Goddard Institute,, which discusses in part recent developments in the Antarctic:

  • Positive feedback from the loss of buttressing ice shelves is relevant to some Greenland ice streams, but the West Antarctic ice sheet, which rests on bedrock well below sea level, will be affected much more. The loss of ice shelves provides exit routes with reduced resistance for ice from further inland, as suggested by Mercer and earlier by Hughes.

  • Warming ocean waters are now thinning some West Antarctic ice shelves by several meters per year.

  • The Antarctic peninsula recently provided a laboratory to study feedback interactions, albeit for ice volumes less than those in the major ice sheets. Combined actions of surface melt and ice shelf thinning from below led to the sudden collapse of the Larsen B ice shelf, which was followed by the acceleration of glacial tributaries far inland. 

  • The summer warming and melt that preceded the ice shelf collapse was no more than the global warming expected this century under BAU scenarios, and only a fraction of expected West Antarctic warming with realistic polar amplification of global warming.

  • Modeling studies yield increased ocean heat uptake around West Antarctica and Greenland due to increasing
    human-made greenhouse gases.  Observations show a warming ocean around West Antarctica, ice shelves thinning several meters per year, and increased iceberg discharge

  • As the discharge of ice increases from a disintegrating ice sheet, as occurs with all deglaciations, regional cooling by the icebergs is significant, providing a substantial but temporary negative feedback. However, this cooling effect is limited on a global scale as shown by comparison with the planetary energy imbalance, which is now sufficient to melt ice equivalent to about one meter of sea level per decade.  Yet the planetary energy imbalance should not be thought of as a limit on the rate of ice melt, as increasing iceberg discharge yields both positive and negative feedbacks on planetary energy imbalance via ocean surface cooling and resulting changes of sea ice and cloud cover. 

  • Global warming should also increase snowfall accumulation rates in ice sheet interiors because of the higher moisture content of the warming atmosphere. Despite high variability on interannual and decadal timescales, and limited Antarctic warming to date, observations tend to support this expectation for both Greenland and Antarctica.  Indeed, some models have ice sheets growing overall with global warming, but those models do not include realistic processes of ice sheet disintegration.  Extensive paleoclimate data confirm the common sense expectation that the net effect is for ice sheets to shrink as the world warms. 

  • The most compelling data for the net change of ice sheets is provided by the gravity satellite mission GRACE, which shows that both Greenland and Antarctica are losing mass at substantial rates.  The most recent analyses of the satellite data confirm that Greenland and Antarctica are each losing mass at a rate of about 150 cubic kilometers per year, with the Antarctic mass loss primarily in West Antarctica. These rates of mass loss
    are at least a doubling of rates of several years earlier
    , and only a decade earlier these ice sheets were much closer to mass balance. 

  • Warming [in Antarctica] has been limited in recent decades, at least in part due to the effects of ozone depletion.  The fact that West Antarctica is losing mass at a significant rate suggests that the thinning ice shelves are already beginning to have an effect on ice discharge rates.  

  • Warming of the ocean surface around Antarctica is small compared with the rest of world, consistent with climate model simulations, but that limited warming is expected to increase.  The detection of recent, increasing summer surface melt on West Antarctica raises the danger that feedbacks among these processes could lead to nonlinear growth of ice discharge from Antarctica.