Antarctica cooling controversy
Encyclopedia
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
. Observations unambiguously show the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
to be warming. Trends elsewhere on the continent show both warming and cooling but are smaller and dependent on season, methodology, and timespan over which the trend is computed. Climate models predict that temperature trends due to global warming will be much smaller in Antarctica than in the Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
, mainly because heat uptake by the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
acts to moderate the radiative forcing by greenhouse gases. The depletion of stratospheric ozone
Ozone depletion
Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere , and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon...
also has had a cooling effect, since ozone acts as a greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
.
There is no similar controversy within the scientific community, as the small observed changes in Antarctica are consistent with the small changes predicted by climate models. Novelist Michael Crichton
Michael Crichton
John Michael Crichton , best known as Michael Crichton, was an American best-selling author, producer, director, and screenwriter, best known for his work in the science fiction, medical fiction, and thriller genres. His books have sold over 200 million copies worldwide, and many have been adapted...
asserted that the Antarctic data contradict global warming. The author of the paper whose work inspired Crichton's remarks has said that Crichton "misused" his results.
Observations of trends
Antarctica has few long-term records. There are less than twenty permanent stations in all and only two in the interior. More recently AWSAWS
AWS or aws can refer to:Business* Alien Workshop, a skateboard company* Austria Wirtschaftsservice Gesellschaft , an Austrian bank* AWS Shopper, Automobilwerk Walter Schätzle, German manufacturer of a microcarMusic...
s supplement this, but their records are relatively brief. Hence calculation of a trend for the entire continent is difficult. Satellite observations
Satellite temperature measurements
The temperature of the atmosphere at various altitudes as well as sea and land surface temperatures can be inferred from satellite measurements. Weather satellites do not measure temperature directly but measure radiances in various wavelength bands...
only exist since 1981 and provide surface temperature measurements only in cloud-free conditions.
The 2007 IPCC Fourth Assessment Report states that Observational studies have presented evidence of pronounced warming over the Antarctic Peninsula, but little change over the rest of the continent during the last half of the 20th century. Chapman and Walsh note that "Trends calculated for the 1958–2002 period suggest modest warming over much of the 60°–90°S domain. All seasons show warming, with winter trends being the largest at +0.172 °C per decade while summer warming rates are only +0.045 °C per decade. The 45-yr temperature trend for the annual means is +0.082 °C per decade corresponding to a +0.371 °C temperature change over the 1958–2002 period of record. Trends computed using these analyses show considerable sensitivity to start and end dates, with trends calculated using start dates prior to 1965 showing overall warming, while those using start dates from 1966 to 1982 show net cooling over the region."
Several scientific sources have reported that there is a cooling trend observed in the interior of the continent for the last two decades of the 20th century, while the Antarctic Peninsula shows a warming trend.
Doran et al. (2002) find that "Although previous reports suggest slight recent continental warming our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn. The McMurdo Dry Valleys
McMurdo Dry Valleys
The McMurdo Dry Valleys are a row of snow-free valleys in Antarctica located within Victoria Land west of McMurdo Sound. The region is one of the world's most extreme deserts, and includes many interesting features including Lake Vida and the Onyx River, Antarctica's longest river.-Climate:The Dry...
have cooled by 0.7 °C per decade between 1986 and 2000, with similar pronounced seasonal trends... Continental Antarctic cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change".
There has been a public dispute regarding the apparent contradiction in the observed behavior of Antarctica, as opposed to the global rise in temperatures measured elsewhere in the world. This became part of the debate in the global warming controversy
Global warming controversy
Global warming controversy refers to a variety of disputes, significantly more pronounced in the popular media than in the scientific literature, regarding the nature, causes, and consequences of global warming...
, particularly between advocacy groups of both sides in the public arena, including politicians, as well as the popular media. In contrast to the popular press, there is no evidence of a corresponding controversy in the scientific community.
Origin of the controversy
Some public commentators have argued that this possible cooling trend observed in the interior of the Antarctica shows the lack of reliability of the models used for global warming predictions and even of climate theory in general. These arguments are made despite the fact that the small and variable observed trends are broadly consistent with the small magnitude of model-predicted temperature trends for Antarctica. The argument was popularized in Michael CrichtonMichael Crichton
John Michael Crichton , best known as Michael Crichton, was an American best-selling author, producer, director, and screenwriter, best known for his work in the science fiction, medical fiction, and thriller genres. His books have sold over 200 million copies worldwide, and many have been adapted...
's 2004 fiction novel State of Fear
State of Fear
State of Fear is a 2004 techno-thriller novel by Michael Crichton concerning eco-terrorists who attempt mass murder to support their views. The novel had an initial print run of 1.5 million copies and reached the #1 bestseller position at Amazon.com and #2 on the New York Times Best Seller list for...
. This novel has a docudrama
Docudrama
In film, television programming and staged theatre, docudrama is a documentary-style genre that features dramatized re-enactments of actual historical events. As a neologism, the term is often confused with docufiction....
plot based upon the idea that there is a deliberately alarmist conspiracy behind global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
activism. The author advocates skepticism in this matter.
As presented in page 193 of "State of Fear
State of Fear
State of Fear is a 2004 techno-thriller novel by Michael Crichton concerning eco-terrorists who attempt mass murder to support their views. The novel had an initial print run of 1.5 million copies and reached the #1 bestseller position at Amazon.com and #2 on the New York Times Best Seller list for...
": "The data show that one relatively small area called the Antarctic Peninsula is melting and calving
Ice calving
Ice calving, also known as glacier calving or iceberg calving, is a form of ice ablation or ice disruption. It is the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf, or crevasse...
huge icebergs. That's what gets reported year after year. But the continent as a whole is getting colder, and the ice is getting thicker". Crichton's footnote source is Doran et al., 2002.
The leading author of the research paper, Peter Doran
Peter Doran
Peter Doran, Ph.D. is Professor of Earth and Environmental Sciences at the University of Illinois at Chicago.Doran specializes in polar regions, especially Antarctic climate and ecosystems. Doran was the lead author of a research paper about Antarctic temperatures that was published in the journal...
, published a statement in the New York Times stating that "... our results have been misused as “evidence” against global warming by Michael Crichton in his novel “State of Fear”... Our study did find that 58 percent of Antarctica cooled from 1966 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the ozone hole over that continent. These models, conspicuously missing from the warming-skeptic literature, suggest that as the ozone hole heals — thanks to worldwide bans on ozone-destroying chemicals — all of Antarctica is likely to warm with the rest of the planet. An inconvenient truth?" He also emphasized the need for more stations in the Antarctic continent in order to obtain more robust results.
Scientific sources and interpretations
According to a NASA press release:- "Across most of the continent and the surrounding Southern Ocean, temperatures climbed... The temperature increases were greater and more widespread in West Antarctica than in East Antarctica, where some areas showed little change or even a cooling trend. This variability in temperature patterns across Antarctica complicates the work of scientists who are trying to understand the relative influence of natural cycles and human-caused climate change in Antarctica."
As a complement to NASA's findings, the British Antarctic Survey
British Antarctic Survey
The British Antarctic Survey is the United Kingdom's national Antarctic operation and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council and has over 400 staff. It operates five research stations, two ships and five aircraft in and around Antarctica....
, which has undertaken the majority of Britain's scientific research in the area, has the following positions:
- Ice makes polar climate sensitive by introducing a strong positive feedbackPositive feedbackPositive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that responds to a perturbation in a way that reduces its effect is...
loop. - Melting of continental Antarctic ice could contribute to global sea level rise.
- Climate modelClimate modelClimate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the climate system to projections of future climate...
s predict more snowfall than ice melting during the next 50 years, but models are not good enough for them to be confident about the prediction. - Antarctica seems to be both warming around the edges and cooling at the center at the same time. Thus it is not possible to say whether it is warming or cooling overall.
- There is no evidence for a decline in overall Antarctic sea ice extent.
- The central and southern parts of the west coast of the Antarctic Peninsula have warmed by nearly 3 °C. The cause is not known.
- Changes have occurred in the upper atmosphere over Antarctica.
Research by Thompson and Solomon (2002) and by Shindell and Schmidt (2004) provide explanations for the observed cooling trend.