September 26, 2007, 8:42 PM CT

North America's northernmost lake affected by global warming

Analyses conducted by scientists from Universit Lavals Center for Northern Studies reveal that the continents northernmost lake is affected by climate change. In an article would be reported in the September 28 edition of Geophysical Research Letters, the international research team led by Universit Laval researchers Warwick Vincent and Reinhard Pienitz reports that aquatic life in Ward Hunt Lake, a body of water located on a small island north of Ellesmere Island in the Canadian Arctic, has undergone major transformations within the last two centuries. The speed and range of these transformationsunprecedented in the lakes last 8,000 yearssuggest that climate change correlation to human activity could be at the source of this phenomenon.

The scientists conclusions are based on the analysis of a sediment core extracted in the center of Ward Hunt Lake in August 2003. This 18 centimeter long sediment core containing algae pigments and diatom remnants was used by the scientists as a biological archive in order to determine the diversity and abundance of aquatic life-forms in the lake over the last 8,450 years.

Analysis of the deepest layers of sediment revealed a very small number of algae as well as only minor variations in concentration. However, the top two centimeters of the core, which correspond to the last 200 years, showed abrupt changes in the lakes algae population: during that period, chlorophyll a concentration, a pigment found in every species in the lake, increased by a factor of 500. A type of diatom typical of very cold environments also made its first appearance during the same period. The absence of diatoms and the low pigment concentration below the top 2.5 centimeters of the core suggest that the lake waccording tomanently frozen in the past, explains lead author and Center for Northern Studies researcher Dermot Antoniades......... Posted by: Tyler      Read more         Source

September 26, 2007, 7:50 PM CT

Arctic heat wave stuns climate change researchers

Unprecedented warm temperatures in the High Arctic this past summer were so extreme that scientists with a Queen's University-led climate change project have begun revising their forecasts.

"Everything has changed dramatically in the watershed we observed," reports Geography professor Scott Lamoureux, the leader of an International Polar Year project announced yesterday in Nunavut by Indian and Northern Affairs Minister Chuck Strahl. "It's something we'd envisioned for the future - but to see it happening now is quite remarkable."

One of 44 Canadian research initiatives to receive a total of $100 million (IPY) research funding from the federal government, Dr. Lamoureux's new four-year project on remote Melville Island in the northwest Arctic brings together researchers and educators from three Canadian universities and the territory of Nunavut. They are studying how the amount of water will vary as climate changes, and how that affects the water quality and ecosystem sustainability of plants and animals that depend on it.

The information will be key to improving models for predicting future climate change in the High Arctic, which is critical to the everyday living conditions of people living there, particularly through the lakes and rivers where they obtain their drinking water......... Posted by: Tyler      Read more         Source

September 25, 2007, 8:57 PM CT

Greenland snow melting hit record high

A new NASA-supported study reports that 2007 marked an overall rise in the melting trend over the entire Greenland ice sheet and, remarkably, melting in high-altitude areas was greater than ever at 150 percent more than average. In fact, the amount of snow that has melted this year over Greenland could cover the surface size of the U.S. more than twice.

Marco Tedesco, a research scientist at the Joint Center for Earth Systems Technology, cooperatively managed by NASA's Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland at Baltimore County, used satellite data to compare average snow melting from 1988-2006 with what has taken place this summer. He observed that in high altitude areas over 1.2 miles above sea level, the melting index -- an indicator of where melting is occurring and for how long - was significantly higher than average. Melting over those areas occurred 25-30 days longer this year than the observed average in the prior 19 years.

"When snow melts at those high altitudes and then refreezes, it can absorb up to four times more energy than fresh, unthawed snow," said Tedesco. "This can affect Earth's energy budget by changing how much radiation from the sun is absorbed by the Earth versus that reflected back into the atmosphere. Refrozen snow can also alter the snow density, thickness and snow-water content." Tedesco's findings were published Sept. 25 in the American Geophysical Union's Eos newspaper......... Posted by: Tyler      Read more         Source

September 23, 2007, 11:47 AM CT

Greeks get space-based help

Cleanup and rebuilding teams responding to the devastation across Greece caused by this summer's deadly fires are getting help from space. A series of crisis map products based on satellite acquisitions of affected areas are being provided to aid damage assessment efforts following the activation of the International Charter on Space and Major Disasters.

More than 60 people were killed and thousands left homeless in the worst forest fires to hit Greece in decades. As per data from ESA's ERS-2 and Envisat satellites, which continuously survey fires burning across the Earth's surface with onboard sensors, Greece experienced more wildfire activity this August than other European countries experienced over the last decade.

In an effort to aid authorities responding to disasters such as this, ESA and other national space agencies established the International Charter on Space and Major Disasters in 2000 to provide rush access to a broad range of satellite data.

The Charter, activated by the Department of Emergency Planning and Response of the Greek Civil Protection Agency, processed this request and recruited the German Aerospace Centre (DLR) and the Strasbourg-based rapid mapping specialist company (SERTIT) to produce the maps using satellite images provided by the space agencies......... Posted by: Tyler      Read more         Source

September 21, 2007, 6:42 AM CT

Studying Volatile Earthquake Zone

Today, the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) gets underway, with the Japanese drilling vessel Chikyu departing from Shingu Port with researchers aboard, all ready to log, drill, sample, and install monitoring instrumentation in one of the most active earthquake zones on Earth. The vessel's launch starts the first of a series of scientific drilling expeditions that will retrieve geological samples and provide scientific data from the Nankai Trough fault zone for the first time. Situated off Japan's southwest coast, the Nankai Trough has reliably generated large-scale earthquakes and tsunamis for millions of years, including historic earthquakes in 1944 and 1946, which measured 8.1 and 8.3, respectively, on the Richter scale. The NanTroSEIZE expeditions are supported by the Integrated Ocean Drilling Program, a marine research initiative jointly funded by Japan, the United States, a consortium of European countries, the People's Republic of China, and South Korea.

NanTroSEIZE researchers are prepared to drill deeply into the Earth to observe earthquake mechanisms in a well-known subduction zone. The process of subduction occurs when tectonic plates collide and one plate slides beneath another. Geological samples will be collected from the subduction zone, so that IODP researchers can analyze them and study the frictional properties of the rock. Later, sensors are to be installed deep beneath the sea floor- in the seismogenic fault zone-to monitor development of earthquakes at close range. These sensors and data collected from cored samples are expected to yield new insights into naturally occurring processes responsible for earthquakes. IODP researchers anticipate that the new data also will help them understand water motion and how water affects subduction zones......... Posted by: Tyler      Read more         Source

September 21, 2007, 5:27 AM CT

Arctic sea ice minimum shatters all-time record low

Researchers from the University of Colorado at Boulder's National Snow and Ice Data Center said today that the extent of Arctic sea ice appears to have reached its minimum for 2007 on Sept. 16, shattering all prior lows since satellite record-keeping began nearly 30 years ago.

The Arctic sea ice extent on Sept. 16 stood at 1.59 million square miles, or 4.13 million square kilometers, as calculated using a five-day running average, as per the team. In comparison to the long-term minimum average from 1979 to 2000, the new minimum extent was lower by about 1 million square miles -- an area about the size of Alaska and Texas combined, or 10 United Kingdoms, they reported.

The minimum also breaks the prior minimum set on Sept. 20 and Sept. 21 of 2005 by about 460,000 square miles, an area roughly the size of Texas and California combined, or five United Kingdoms, they found. The sea ice extent is the total area of all Arctic regions where ice covers at least 15 percent of the ocean surface.

Researchers blame the declining Arctic sea ice on rising concentrations of greenhouse gases that have elevated temperatures from 2 degrees F to 7 degrees F across the arctic and strong natural variability in Arctic sea ice, said the researchers.

The CU-Boulder research group said determining the annual minimum sea ice is difficult until the melt season has decisively ended. But the team has recorded five days of little change, and even slight gains in Arctic sea ice extent this September, so reaching a lower minimum for 2007 seems unlikely, they reported......... Posted by: Tyler      Read more         Source

September 18, 2007, 5:33 AM CT

Satellites witness lowest Arctic ice coverage in history

The area covered by sea ice in the Arctic has shrunk to its lowest level this week since satellite measurements began nearly 30 years ago, opening up the Northwest Passage - a long-sought short cut between Europe and Asia that has been historically impassable.

In the mosaic image above, created from nearly 200 images acquired in early September 2007 by the Advanced Synthetic Aperture Radar (ASAR) instrument aboard ESA's Envisat satellite, the dark gray colour represents the ice-free areas while green represents areas with sea ice.

Leif Toudal Pedersen from the Danish National Space Centre said: "We have seen the ice-covered area drop to just around 3 million sq km which is about 1 million sq km less than the prior minima of 2005 and 2006. There has been a reduction of the ice cover over the last 10 years of about 100 000 sq km per year on average, so a drop of 1 million sq km in just one year is extreme.

"The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected and that we urgently need to understand better the processes involved."

Arctic sea ice naturally extends its surface coverage each northern winter and recedes each northern summer, but the rate of overall loss since 1978 when satellite records began has accelerated......... Posted by: Tyler      Read more         Source

September 12, 2007, 8:29 PM CT

Role Of Climate In Neanderthal Extinction

THE mystery of what killed the Neanderthals has moved a step closer to resolution after an international study led by the University of Leeds has ruled out one of the competing theories catastrophic climate change as the most likely cause.

The bones of more than 400 Neanderthals have been found since the first discoveries were made in the early 19th century. The finds suggest the Neanderthals, named after the Neander Valley near Dsseldorf, where they were first recognized as an extinct kind of archaic humans, inhabited Europe and parts of western Asia for more than 100,000 years.

The causes of their extinction have puzzled researchers for years with some believing it was due to competition with modern humans, while others blamed deteriorating climatic conditions. But a new study published recently in Nature has shown that the Neanderthal extinction did not coincide with any of the extreme climate events that punctuated the last glacial period.

The research was led by Professor Chronis Tzedakis, a palaeoecologist at the University of Leeds, who explained: Until now, there have been three limitations to understanding the role of climate in the Neanderthal extinction: uncertainty over the exact timing of their disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record......... Posted by: William      Read more         Source

September 10, 2007, 9:19 PM CT

Icy calculations on global warming

University of Utah mathematicians have arrived at a new understanding of how salt-saturated ocean water flows through sea ice a discovery that promises to improve forecasts of how global warming will affect polar icepacks.

In the current issue of the journal Geophysical Research Letters, math Professor Ken Golden and his colleagues show that brine moving up or down through floating sea ice follows universal transport properties.

It means that almost the exact same formulas describing how water flows through sedimentary rocks in the Earth's crust apply to brine flow in sea ice, even though the microstructural details of the rocks are quite different from sea ice, says Golden, who currently is on an Australian research ship in Antarctica.

The study suggests similar porous materials including ice on other worlds, such as Jupiters icy ocean-covered moon Europa should follow the same rules, he adds.

Golden has made several trips to Antarctica and the Arctic for his studies.

The American Geophysical Union, which publishes the journal carrying Goldens study, says sea ice is important because it is both an indicator and regulator of climate change; its thinning and retreat show the effects of climate warming, and its presence greatly reduces solar heating of the polar oceans......... Posted by: Tyler      Read more         Source

September 6, 2007, 9:35 PM CT

Pinpointing Turbulence in Clouds

A new turbulence detection system now being tested is alerting pilots to patches of rough air as they fly through clouds. The system, designed by the National Center for Atmospheric Research (NCAR) and tested by United Airlines on commercial flights, is designed to better protect passengers from injuries caused by turbulence while reducing flight delays and lowering aviation costs.

The new system uses a mathematical method developed by NCAR scientists, known as the NEXRAD Turbulence Detection Algorithm, or NTDA, to analyze data obtained from the National Weather Service's network of Next-Generation (NEXRAD) Doppler radars. The resulting real-time snapshot of turbulence can be transmitted to pilots in the cockpit and made available to airline meteorologists and dispatchers via a Web-based display.

The research is funded by the Federal Aviation Administration (FAA) in partnership with the National Science Foundation, NCAR's primary sponsor.

"Pinpointing turbulence in clouds and thunderstorms is a major scientific challenge," says NCAR scientist John Williams. "Our goal is to use these radar measurements to create a three-dimensional mosaic showing turbulence across the country that can help pilots avoid hazardous areas, or at least give them enough warning to turn on the 'fasten seat belt' sign"......... Posted by: Tyler      Read more         Source