The first comprehensive study of glaciers around the coast of the Antarctic Peninsula reveals the real impact of recent climate change.

Results from the study by researchers at British Antarctic Survey (BAS) and U.S. Geological Survey (USGS) published this week in the journal Science, show that over the last 50 years 87% of 244 glaciers studied have retreated, and that average retreat rates have accelerated.

BAS and USGS analysed more than 2000 aerial photographs dating from 1940, and over 100 satellite images from the 1960s onwards, to calculate the position of glacier fronts along the coast of the Antarctic Peninsula. These historical records reveal previously unknown patterns of change.

Lead author, Alison Cook said,

“Fifty years ago, most of the glaciers we looked at were slowly growing in length but since then this pattern has reversed. In the last 5 years the majority were actually shrinking rapidly. The retreat began at the northern, warmer tip of the Antarctic Peninsula and, broadly speaking, moved southwards as atmospheric temperatures rose. This region has shown dramatic and localised warming - around 2C in the last 50 years - but this is not the only factor causing the changes. It’s a complex picture.”

“On average the glaciers we studied retreated by 50 m per year in the last five years, faster than at any other time in the last fifty years. However 32 glaciers go against the trend and are showing minor advance. Had we not studied such a large number of glaciers we may have missed the overall pattern. It’s the change from advance to retreat that suggests warming is the key cause, but these glaciers clearly show a more complex response than neighbouring ice shelves.”

BAS Glaciologist, Dr David Vaughan is a co-author of the paper. He said,

“These glacier retreat patterns combined with dramatic ice shelf break-ups leave us in no doubt that the Antarctic Peninsula ice sheet is extremely sensitive to recent warming. What we still need to determine is whether or not the warming in this area has its roots in human-influenced global warming. Either way, continuing retreat of glaciers in this area is important because it could allow more ice to drain from further inland and contribute to sea level rise. The current effect may be small in global terms, but this research takes us a step closer to understanding the cause and predicting the future.”

Original press release: Antarctic Peninsula Glaciers in Widespread Retreat (BAS)

Ten years and 52 289 orbits on from its launch, the Earth Observation mission of ESA’s ERS-2 satellite continues with all instruments functioning well. A growing global network of ground stations is receiving data from the veteran spacecraft.

A solid decade of ERS-2 observations has helped cement a worldwide community of more than 3000 users. Demand for ERS-2 data is ever increasing, spurred on by the fact that the spacecraft keeps on updating its data archives as it orbits the Earth at more than seven kilometres a second.

When the Asian tsunami struck in December 2004, satellites provided rapid damage mapping. The continued availability of ERS-2 enabled the only change assessment via radar, complementing optical satellite views because radar can see through tropical clouds.

A new January 2005 ERS-2 high-resolution radar image of the Nicobar Islands north of Sumatra, near the epicentre of the tsunami, was combined with an archived image acquired in 1992 by sister spacecraft ERS-1.

The resulting multi-temporal composite highlights the stricken state of the islands’ west coast. The composite was only possible due to the wide coverage of the 15-year combined ERS archive.

ERS-2 is also regularly utilised for disaster mapping during activations of the International Charter on Space and Major Disasters, which provides space-derived information to emergency responders.

The continuing availability of new ERS-2 images along with its archive is proving very useful for a technique called SAR Interferometry or InSAR. Growing in popularity, InSAR involves mathematically combining different radar images of the same spot to create digital elevation models (DEMs) and also revealing otherwise undetectable changes occurring between image acquisitions.

In effect InSAR works like a sophisticated version of ’spot the difference’, identifying millimetre-scale ground movement to reveal urban subsidence, landslides or seismic motion � even the rhythmic ‘breathing’ of active volcanoes as they periodically inflate and deflate.

“The fixed geometry of the ERS-2 SAR provides a very consistent and reliable product, one which is proving to be highly beneficial for many interferometric applications and operations requiring frequent repeat data sets,” says Professor Fabio Rocca of Politecnico di Milano. “The long time series of images means that new ERS-2 acqusitions are especially valuable for the analysis and monitoring of stable targets in urban areas.”

ERS-based InSAR is increasingly being employed in this way for urban risk assessment. Some 200 European and Mediterranean towns are being surveyed as part of the initial activities for Global Monitoring for Environment and Security (GMES), a joint ESA and European Union initiative to create an independent global monitoring capability in support of European policy goals.

Near-real time results for weather forecasting and ozone monitoring

ERS-2 also carries a C-band scatterometer measuring ocean wind fields; the only instrument of its type currently in orbit, capable of making observations in the very heaviest of weather, even peering into the centre of hurricanes and typhoons.

Processed by the Royal Dutch Meterological Institute (KMNI), these unique data are assimilated operationally by users including the European Centre for Medium-Range Weather Forecasts, improving the quality of weather forecasting and short term ‘nowcasting’.

Another ERS-2 sensor working in near-real time is its Global Ozone Mapping Experiment (GOME), delivering atmospheric global coverage of ozone, other trace gases, supporting operational services such as Tropospheric Emission Monitoring Internet Service (TEMIS), providing daily ozone, ultraviolet and air pollution monitoring.

“The GOME instrument on ERS-2 has given us more than we ever dreamed of,” explains Professor Paul Crutzen of the Max Planck Institute in Germany, winner of the 1995 Nobel Prize for his work on ozone. “GOME has been a pioneer instrument. Such instruments are of great value for international negotiations on air quality and climate.”

ERS-2’s fall and rise

ERS-2 was launched on 21 April 1995, ensuring continuity of data from ERS-1, the first European Remote Sensing programme mission.

Back in 2001 the spacecraft was struck a blow as the last of its pointing gyroscopes failed. However all instruments were still functioning perfectly, so ESA engineers worked with industry to develop a new ‘gyro-less’ working mode to resume data delivery.

Then in June 2003 the onboard Low Bit Rate data recorder failed, used to store non-radar image data when out of touch with ESA ground stations. However, recognising the value of this data, international ground stations responded by working voluntarily to collect and distribute ERS-2 results in near-real time.

This week NASA’s McMurdo Ground Station in Antarctica is set to begin acquiring ERS-2 data for the first time. The work is being carried out on a voluntary basis, displaying NASA’s commitment to international cooperation.

The addition of McMurdo means that ERS-2 data are now being received across all seven continents. A new Beijing ground station is anticipated to come online by the end of this month.

Working with other spacecraft

Making up its other sensors, ERS-2’s Radar Altimeter (RA) measures land, ocean and ice altimetry, while its Along Track Scanning Radiometer (ATSR) works like a space-based thermometer, taking the temperature of cloud tops as well as the sea surface - the best means of assessing the long-term extent of global warming - as well as surface land changes.

Since 2002, ESA’s ten-instrument Envisat environmental satellite has also been monitoring sea surface temperature and atmospheric ozone as well as altimetry and radar observations.

However the stable and well-characterised nature of ERS-2 measurements make them extremely useful for synergistic cross-checking with Envisat for the time being, and for planned future missions such as CryoSat and MetOp.

“Simultaneous operation of ERS-2 and Envisat provides excellent and important opportunities to cross-calibrate and cross-validate the data from the two sensors,” states Professor David Llewellyn-Jones of the University of Leicester, Principal Investigator of ERS-2’s ATSR and the equivalent Envisat instrument.

“The difference in ERS-2 and Envisat overpass times of 30 minutes is providing opportunities for investigating diurnal variations in land surface temperature. This is important in the context of soil moisture, an important parameter for predicting vegetation development.”

ERS-2’s future

The spacecraft has been a key link in a chain of European and international missions to provide long-term observation of key environmental variables. The mission’s well-defined products and services are playing an important role in initial services of GMES, and this is expected to continue until the new generation of operational Sentinel spacecraft are deployed.

Excellence of spacecraft and instrument engineering has led to a long service so far, and with its data still in high demand there may be yet more achievements to come.

Original press release: A Decade After Launch, ERS-2’s Mission Continues (ESA)

Taking place in Vienna from 24 to 29 April 2005, the European Geosciences Union General Assembly will bring together over 8 000 scientists from the fields of Earth and Planetary sciences. ESA will present recent space-based findings and results concerning the Earth, Mars, Titan and the Moon as well as its future missions.

The European Geosciences Union (EGU) General Assembly is an annual event bringing together geoscientists from all over the world into one meeting covering all disciplines of the Earth and Planetary Sciences: geomorphology, geochemistry, geophysics, geobiology and hazards research alike. During the week, over 3 000 papers will be presented, with nearly 7 000 poster sessions.

The unique view afforded from space has become integral to the geosciences. For example, satellite imagery enables long-term objective monitoring of climate change effects, measuring precise shifts in land cover, ice field extent, sea surface height and even the composition of the atmosphere.

In the shorter-term, satellites yielded rapid mapping of the December 2004 Sumatran tsunami, swiftly bringing home the full scope of the disaster. And ESA and the European Union’s Global Monitoring for Environment and Security (GMES) initiative aims at combining satellite and in-situ information for enhanced natural hazard awareness and management.

ESA’s planetary missions have transformed our understanding of the worlds beyond Earth. Results from the historic Huygens landing on Titan are providing fresh insights into the distant methane-rich moon of Saturn, while Mars Express continues to deliver spectacular images of the Martian surface and new information on the planet’s atmosphere and climate. At the same time, Smart-1 is commencing the first detailed survey of the Earth’s Moon since the Apollo programme.

The Agency’s forthcoming missions Venus Express and Bepi-Colombo will visit Venus and Mercury, the two worlds closest to the Sun, while Rosetta continues its ten-year voyage to rendezvous with Comet 67 P/Churyumov-Gerasimenko.

ESA personnel are presenting a number of papers during the event, on subjects including Mars, space-based monitoring of the tsunami disaster and also worldwide river and lake levels, preparations for CryoSat data exploitation and details of current performance of the ERS-2 and Envisat Radar Altimeters.

Conference visitors can also meet ESA personnel on the exhibition stand in Hall Y, stand number 24. The exhibit will focus on Earth Observation results, applications and future missions such as CryoSat. Presentations of the ESA Planetary Science Archive will be made twice-daily from 12.00 to 13.00 and from 17:00 to 18:00. This is a new online tool for the distribution of scientific data from ESA’s planetary missions and includes Mars Express data. Huygens, Rosetta and Smart-1 data will be available over the coming months.

Evening Townhall Speeches are a daily feature of the EGU General Assembly. On Wednesday 27 April ESA Science Director David Southwood will give a keynote speech on ‘Cosmic Visions: The Long Term European Space Science Programme’ together with Marcello Coradini, ESA Solar Systems Mission Coordinator.

Original press release: ESA at the European Geosciences Union General Assembly (ESA)

Scientist Joanie Kleypas of the National Center for Atmospheric Research (NCAR) will join with colleagues from other institutions in a press briefing on Wednesday, April 20, during the Workshop on the Impact of Carbon Dioxide on Marine Life in St. Petersburg, Florida.

Kleypas is a marine ecologist/geologist specializing in the interactions between marine ecosystems and climate.

The Workshop on the Impacts of Increasing Atmospheric CO2 on Coral Reefs and Other Marine Calcifiers is hosted by the USGS Florida Integrated Science Center for Coastal and Watershed Studies, in cooperation with scientists from NOAA and NCAR. It brings together international experts who will compare research on the impact of increasing CO2 on skeletal formation of coral reef organisms and other marine life, and propose courses of action to deal with the impacts of rising CO2. They will examine the technology needed to monitor the CO2 system in sea water and explore the best methods for measuring the impact on many important marine organisms, including coral reefs. The workshop runs from April 18-20.

Original press release: Workshop on the Impact of Carbon Dioxide on Marine Life (NCAR)

AUSTIN, Texas - Desert blooms - plants that flourish in arid areas after rains - might reduce water accumulation in soil should the climate shift toward wetter conditions, according to a study conducted by a team led by University of Texas at Austin hydrogeologists.

By the same token, such vegetation keeps water from reaching the water table deep below the surface in such areas.

“Monitoring soil-water response to extreme El Ninos in Nevada indicates that vegetation response will dampen the impact of increased precipitation and result in no net downward water movement to aquifers,” said Bridget Scanlon, a senior research scientist at the Bureau of Economic Geology at the university.

The paper was published this week in the online edition of the Proceedings of the National Academy of Sciences.

Vegetation has, in fact, been drying out the soil in desert basins throughout the southwestern United States since the last glacial period, 10,000 to 15,000 years ago. Satellite data indicate that these vegetation responses to increased precipitation occur in deserts globally.

Because plants can maintain dry conditions, minimizing leaching of wastes into underlying aquifers, important implications exist for radioactive and hazardous waste disposal, the study’s results show.

The study provides important insights into links between climate, ecology and hydrology that are critical for water resources and waste disposal.

The hydrogeologists studied eight years (1994-2002) of soil-water storage data in vegetated and nonvegetated lysimeters in the Mojave Desert (Nevada) that are operated by the U.S. Department of Energy. Lysimeters, similar to the scales that weigh semis on the highway, are buried beneath the desert to precisely measure changes in the amounts of water in the soil.

The eight years included two El Nino weather patterns, which bring wetter and colder than normal weather during winter, each followed by a La Nina pattern, which brings drier and warmer weather during winter.

Even during the El Nino winter of 1997-1998, the largest of the 20th century, with rainfall as high as 2.5 times normal, the vegetation soaked it all up and did it quickly.

“Within two months, vegetation productivity increased tremendously and used up all the excess water,” Scanlon said.

When the plants soak up water, they leave the water’s chloride behind. By measuring chloride in soil water, therefore, the team also determined that this pattern of soil water movement has been ongoing for millennia.

“So vegetation has been able to maintain very dry conditions in these soils and create upward water movement,” Scanlon said.

Study results should apply to deserts globally, as indicated by satellite data, which show large vegetation responses to wet El Nino periods in Australia, South America and Africa.

Original press release: University of Texas at Austin Study Indicates
Thirsty Plants Peep Deserts� Subsurface Dry (University of Texas)

Maps of Antarctica need to be amended. The long-awaited collision between the vast B-15A iceberg and the landfast Drygalski ice tongue has taken place. This Envisat radar image shows the ice tongue - large and permanent enough to feature in Antarctic atlases - has come off worst.

An image acquired by Envisat on 15 April 2005 shows that a five-kilometre-long section at the seaward end of Drygalski has broken off following a collision with the drifting B-15A. The iceberg itself appears so far unaffected. With more than half the iceberg still to clear the floating pier of ice, Drygalski may undergo more damage in coming days.

It is an old philosophical paradox: what happens when an irresistible force meets an immovable object? For the past few months, ESA’s Envisat satellite has been watching an answer play out in ice, as the B-15A iceberg converged on the Drygalski ice tongue.

The sheer scale of B-15A is best appreciated from space. The bottle-shaped Antarctic iceberg is around 115 kilometres long, with an area exceeding 2500 square kilometres, making it about as large as the entire country of Luxembourg.

From January the iceberg has been drifting towards, then past, the 70-kilometre-long Drygalski ice tongue in McMurdo Sound on the Ross Sea. In the last month prevailing currents have been slowly edging B-15A along past the northern edge of Drygalski.

Envisat’s Advanced Synthetic Aperture Radar (ASAR) instrument has been monitoring events since the start of the year, gathering the highest frequency weather-independent satellite dataset of this area ever.

Ice in opposition

B-15A is the largest remaining section of the even larger B-15 iceberg that calved from the Ross Ice Shelf in March 2000. Equivalent in size to Jamaica, B-15 had an initial area of 11 655 square kilometres but subsequently broke up into smaller pieces.

Since then, the largest piece - B-15A - has found its way to McMurdo Sound, where its presence has blocked ocean currents and led to a build-up of sea ice. With the Antarctic summer now at an end and in-situ observations therefore limited, the ASAR instrument aboard Envisat becomes even more useful for monitoring changes in polar ice and tracking icebergs.

Its radar signals pass freely through the thickest polar storm clouds or local darkness. And because ASAR is sensitive to surface texture as well as physical and chemical properties, the sensor is extremely sensitive to different types of ice - for example clearly delineating the older rougher surface of the Drygalski ice tongue and iceberg B15A from the surrounding sea ice pack.

The Drygalski ice tongue is located at the opposite end of McMurdo Sound from the US and New Zealand bases. The long narrow tongue stretches out to sea as an extension of the land-based David Glacier, which flows through coastal mountains of Victoria Land.

Twin-mode ASAR Antarctic observations

Envisat’s ASAR instrument monitors Antarctica in two different modes: Global Monitoring Mode (GMM) provides 400-kilometre swath one-kilometre resolution images, enabling rapid mosaicking of the whole of Antarctica to monitor changes in sea ice extent, ice shelves and iceberg movement.

Wide Swath Mode (WSM) possesses the same swath but with 150-metre resolution for a detailed view of areas of particular interest.

ASAR GMM images are routinely provided to a variety of users including the US National Oceanic and Atmospheric Administration (NOAA) National Ice Centre, responsible for tracking icebergs worldwide.

ASAR imagery is also being used operationally to track icebergs in the Arctic by the Northern View and ICEMON consortia, which provide ice monitoring services as part of the Global Monitoring for Environment and Security (GMES) initiative, jointly backed by ESA and the European Union.

This year also sees the launch of CryoSat, a dedicated ice-watching mission designed to precisely map changes in the thickness of polar ice sheets and floating sea ice.

CryoSat, in connection with regular Envisat ASAR GMM mosaics and SAR interferometry - a technique used to combine radar images to measure tiny centimetre-scale shifts between acquisitions - should answer the question of whether the kind of ice-shelf calving that gave rise to B-15 and its descendants are a consequence of ice sheet dynamics or other factors.

Together they will provide insight into whether such iceberg calving occurrences are becoming more common, as well as improving our understanding of the relationship between the Earth’s ice cover and the global climate.

Original press release: B-15A Collides with Antarctic Ice Tongue (ESA)