Something has gone wrong with the global weather pattern...

[Scott A. Kampas]

Special Online Collection: Climate Change -- Breaking the Ice

In the 24 March 2006 Science: A special report on what's happening to the world's ice sheets. Recent research papers in Science and elsewhere are pointing to a major acceleration in the loss of mass from the world's great ice sheets. That means that the sensitivity of these giant storehouses of water to climate warming may be far greater than expected -- with potentially dire sea level implications during the next several centuries. Science examines the state of this research, and its sobering implications, in an Editorial, a special News Focus, Perspective articles, and cutting-edge research papers in this week's issue -- as well as several segments in our 24 March podcast. We've also included links to selected review and research articles on the topic from previous issues of Science over the past several years.[/b]

Warnings rise over rising seas
23 March 2006; doi:10.1038/news060320-8

Fresh predictions about climate change prompt [email protected] to ask what we know about the future of our oceans.[/b]

Comment on "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment"
Science 24 March 2006: Vol. 311. no. 5768, p. 1713; DOI: 10.1126/science.1121522

Analyses of tropical cyclone records from the western North Pacific reveal that the recent increase in occurrence of intense typhoons reported by Webster et al. (Reports, 16 Sep. 2005, p. 1844) is not a trend. Rather, it is likely a part of the large interdecadal variations in the number of intense typhoons related to similar temporal fluctuations in the atmospheric environment.[/b]

Response to Comment on "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment"
Science 24 March 2006: Vol. 311. no. 5768, p. 1713; DOI: 10.1126/science.1121564

Although Chan makes several valid points, his analysis confuses relationships associated with the long-term variations with those associated with shorter term variability (interannual and decadal). We present an analysis that clarifies the observations from the western North Pacific.[/b]

Observed and Modeled Greenland Ice Sheet Snow Accumulation, 1958–2003, and Links with Regional Climate Forcing
Journal of Climate: Vol. 19, No. 3, pp. 344–358. doi: 10.1175/JCLI3615.1

ABSTRACT

Annual and monthly snow accumulation for the Greenland Ice Sheet was derived from ECMWF forecasts [mainly 40-yr ECMWR Re-Analysis (ERA-40)] and further meteorological modeling. Modeled accumulation was validated using 58 ice core accumulation datasets across the ice sheet and was found to be 95% of the observed accumulation on average, with a mean correlation of 0.53 between modeled and observed. Many of the ice core datasets are new and are presented here for the first time. Central and northern interior parts of the ice sheet were found to be 10%–30% too dry in ERA-40, in line with earlier ECMWF analysis, although too much (>50% locally) snow accumulation was modeled for interior southern parts of Greenland. Nevertheless, 47 of 58 sites show significant correlation in temporal variability of modeled with observed accumulation. The model also captures the absolute amount of snow accumulation at several sites, most notably Das1 and Das2 in southeast Greenland. Mean modeled accumulation over the ice sheet was 0.279 (standard deviation 0.034) m yr−1 for 1958–2003 with no significant trend for either the ice sheet or any of the core sites. Unusually high accumulation in southeast Greenland in 2002/03 leads the authors to study meteorological synoptic forcing patterns and comment on the prospect of enhanced climate variability leading to more such events as a result of global warming. There is good agreement between precipitation measured at coastal meteorological stations in southern Greenland and accumulation modeled for adjacent regions of the ice sheet. There is no significant persistent relation between the North Atlantic Oscillation index and whole or southern Greenland accumulation.[/b]

 

[Scott A. Kampas]

Significant Warming of the Antarctic Winter Troposphere
Science 31 March 2006: Vol. 311. no. 5769, pp. 1914 - 1917; DOI: 10.1126/science.1121652

We report an undocumented major warming of the Antarctic winter troposphere that is larger than any previously identified regional tropospheric warming on Earth. This result has come to light through an analysis of recently digitized and rigorously quality controlled Antarctic radiosonde observations. The data show that regional midtropospheric temperatures have increased at a statistically significant rate of 0.5° to 0.7°Celsius per decade over the past 30 years. Analysis of the time series of radiosonde temperatures indicates that the data are temporally homogeneous. The available data do not allow us to unambiguously assign a cause to the tropospheric warming at this stage.[/b]

Changes in Surface Water Supply Across Africa with Predicted Climate Change
Science 31 March 2006: Vol. 311. no. 5769, pp. 1917 - 1921; DOI: 10.1126/science.1119929

Across Africa, perennial drainage density as a function of mean annual rainfall defines three regimes separated by threshold values of precipitation. This nonlinear response of drainage to rainfall will most seriously affect regions in the intermediate, unstable regime. A 10% decrease in precipitation in regions on the upper regime boundary (1000 millimeters per year) would reduce drainage by 17%, whereas in regions receiving 500 millimeters per year, such a drop would cut 50% of surface drainage. By using predicted precipitation changes, we calculate that a decrease in perennial drainage will significantly affect present surface water access across 25% of Africa by the end of this century.[/b]

RealClimate.org also has several new articles.

 

[Scott A. Kampas]

Balloon Data Confirms Antarctic Warming Trend

Launching weather balloons has been a nearly daily habit at some Antarctic research facilities since 1957. Carrying radiosondes--instruments that measure atmospheric conditions such as temperature and wind speed--the balloons travel as high as 12 miles or more. A new analysis of the past 30 years of records from nine research stations, including Amundsen-Scott at the South Pole, reveals that the air above the entirety of Antarctica has warmed by as much as 0.70 degree Celsius per decade during the winter months.

John Turner of the British Antarctic Survey and his colleagues report in today's issue of Science that this warming trend is consistent across data from multiple stations run by multiple countries using multiple types of instruments. Previous studies had shown that Antarctica's surface temperatures had warmed by roughly 2.5 degrees C over the last half century, but this study provides the most complete look at atmospheric trends to date.[/b]

Sunshine on a Cloudy Day

Clouds sometime increase, rather than reduce, levels of ultraviolet radiation[/b]

Climate Change on the Flip Side

Global warming makes the headlines, but at least part of the world has been getting cooler over the last half-century, and migratory birds are noticing. Way down south, in eastern Antarctica, seabirds have begun arriving at their colonies and laying their eggs later on average than in the 1950s, potentially preventing new parents from finding enough food to keep their chicks alive and healthy.[/b]

Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity
Science 7 April 2006: Vol. 312. no. 5770, pp. 94 - 97; DOI: 10.1126/science.1123560

ABSTRACT
To better understand the change in global hurricane intensity since 1970, we examined the joint distribution of hurricane intensity with variables identified in the literature as contributing to the intensification of hurricanes. We used a methodology based on information theory, isolating the trend from the shorter-term natural modes of variability. The results show that the trend of increasing numbers of category 4 and 5 hurricanes for the period 1970–2004 is directly linked to the trend in sea-surface temperature; other aspects of the tropical environment, although they influence shorter-term variations in hurricane intensity, do not contribute substantially to the observed global trend.[/b]

Arctic water flow speeding up
Nature News; 6 April 2006; | doi:10.1038/news060403-9

One of Siberia's largest rivers is dumping about 10% more fresh water into the Arctic today than it was some 60 years ago, thanks to the complex effects of increased snowfall, melting permafrost and changing weather.

The result is in line with predictions of how climate change is expected to alter the Arctic water cycle, and is a worrying sign in terms of maintaining important ocean currents. The more fresh water that enters the northern seas, the less dense this water becomes and the less likely it is to sink. This sinking currently helps to drive a powerful Atlantic current that keeps the climate temperate and steady.

Freshening of the Arctic Ocean may already have begun to affect this so-called thermohaline circulation, but oceanographers and climate modellers are still puzzling about the magnitude and likely effects of the changes (see 'Climate change: A sea change').[/b]