Phil Duffy, Senior Policy Analyst, Becky Fried, Policy Analyst, Office of Science and Technology Policy, Executive Office of the President
New data released last week by the National Oceanic and Atmospheric Administration (NOAA) showed that the 2011-2012 winter season was the fourth warmest ever recorded in the United States.
The data were published in NOAA's National Climatic Data Center State of the Climate report, which provides regularly updated climate and weather information for regions across the United States.
The data show that this past winter was generally both warmer than average and drier than average for the lower 48 States. The average temperature across these states for December through February was 36.8 degrees F, nearly 4 degrees higher than the long-term average for U.S. winters from 1901-2000. Precipitation was down 12 percent on average, and when it came to snow, the United States experienced its third smallest winter snow-cover footprint square miles of snow-cover, as measured by satellites since recording began 46 years ago.
Becky Fried, Policy Analyst,
Office of Science and Technology Policy, Executive Office of the President
USGC Scientists collecting melt water
samples from a glacier.
A new study by USGS scientists and university researchers reveals that a substantial amount of organic carbon on Alaskan glaciers comes from atmospheric deposition of fossil fuel emissions. Prior research suggested that the primary source was ancient soil, plants and other organic materials from forests and peat lands that were over run by glaciers thousands of years ago.
While ancient organic plant material is still a potential source of some glacial organic carbon, the new study indicates that human-createdâ€”or anthropogenicâ€”sources are major contributors.
The results, published in the journal Nature Geoscience, build upon previous USGS studies that found organic carbon in the Yukon River and determined that its source was glacial meltwater. With the new study, USGS scientists and their university partners traced organic carbon further â€œupstreamâ€ tounderst and how it arrives at glaciers in the first place. To do this, they analyzed the chemical composition of dissolved organic matter in glacial surface water, snow, and meltwater from coastal areas of Alaska and looked for specific compounds that are consistent with different sources.
Analysis revealed arelative absence of compounds associated with plants and the presence of several compounds in forms consistent with human-made origins, including combustion products that are found in anthropogenic fossil-fuel emissions, such as black carbon
While fossil fuels themselves are ancient, deriving from plants and organisms that lived millions of years ago, fossil fuelburning is a relatively modern practice. When fossil fuels are burned, carbon is emitted into the atmosphere, making it available for deposition on surfaces such as glaciers. The studyâ€™s findings suggest that a large portion of organic carbon found on glaciers comes from such atmospheric deposition as a result of human activity.
Glacial carbon deposits matter because they reduce the amount of sunlight reflected into the atmosphere and because their dark particles absorb heat from the sun, causing glaciers to melt faster and contribute to sea-level rise.
Glacial melt also transports compounds locked up in glaciers into rivers and streams, where they serveas a fundamental food source for microbes and other organisms at the bottom of the aquatic food web. The new studyâ€™s conclusion that most glacial carbon derives from human activity raises new questions about whetherand how this anthropogenically derived carbon may be influencing aquatic ecosystems.
To learn moreabout the USGS study on glacial carbon, please visit here.
Cross-posted from USGS, a member of the U.S. Global Change Research Program
This image, from April 2004, shows mortality of some adult Joshua trees resulting from years of hot-dry climate.
As the climate gets warmer, many forests are feeling the heat. Impacts range from increased forest fire hazards and tree mortality to detrimental beetle outbreaks and alterations to leaf abundance and bloom.
When forest cover or composition changes, there are impacts to the availability of wood products, clean water, recreational opportunities, and habitats for many plants and animals.
In recognition of World Forestry Day, letâ€™s take a glimpse at U.S. Geological Survey science to understand the fate of forests from climate change.
To sustain the health and production of Americaâ€™s forests, managers need sound science to guide their decisions. The USGS is involved in several initiatives across the nation and in other countries to provide science to understand climate change impacts to forests. Read moreâ€¦
Monday March 19, 2012Becky Fried, Policy Analyst,
Office of Science and Technology Policy, Executive Office of the PresidentA new NASA study shows that the average thickness of sea ice in the Arctic is on the decline. In fact, oldest and thickest Arctic sea ice is disappearing faster than younger, thinner ice that surrounds it creating an overall thinning effect and more areas of open, ice-free water during the summer months.
Older, thicker ice is the mainstay of the Arctic ice cover and historically would be the one most likely to survive the summer melt, said Joey Comiso, a senior scientist at NASA Goddard Space Flight Center and author of the study. â€œUnless a sustained cooling in the Arctic happens in the near future, the Arctic Ocean will soon have very little or no sea ice-cover in the summer.
Typically, old ice called multi-year sea ice when it lasts through at least two summersâ€”is thick enough to survive multiple summertime melt seasons. Newer ice, on the other hand, is thinner and can melt seasonally, just as quickly as it was formed. The rapid disappearance of older ice means areas of the Arctic Ocean are increasingly comprised of ice-free, open water during the summer season, which has implications for global climate as well as regional communities and ecosystems.
To measure ice cover, scientists use satellite sensors that detect microwaves emitted by the ice surface, then turn those signals into digital images. As it turns out, younger ice is saltier than older iceâ€”a difference that results in distinctive microwave emissions that allow satellite sensors to distinguish between old and young ice. Scientists use two primary measures to describe the amount of polar sea-ice cover: sea ice extent the size of the ice-covered region, including some ice-free gaps and sea ice area, which is the total area of the ice itself, not including gaps.
In 2008, the extent of multi-year Arctic sea ice hit a record minimum, reaching just 55 percent of its average extent since satellite measurements began in the late 1970s. So far, 2012 shows the second lowest multi-year ice extent ever.
In the new study, published recently in the Journal of Climate, Comiso used microwave data from NASA's Nimbus-7 satellite and the U.S. Department of Defense's Defense Meteorological Satellite Program to map multi-year ice area and extent in the Arctic over a 32-year period. Over three decades, the extent of multi-year sea ice decreased at a rate of 15.1 percent per decade, and the area of multi-year sea ice declined by 17.2 percent per decade. By contrast, the extent of perennial ice or ice that has survived at least one summer (compared to multi-year ice two) decreased at a rate of 12.2 percent per decade and its area declined at a rate of 13.5 percent per decade. In other words, the thickest and oldest ice is declining faster than the younger ice that surrounds it.
Many factors may be contributing to this phenomenon, including rising surface temperatures in the Arctic generally, which result in a shorter ice-forming season and, thus, less time for sea ice to build the thickness required to survive multiple summers.
Changes in extent or area of sea ice generally can have important impacts in the Arctic and beyond. Most importantly, by lowering the region's reflectivity and increasing the marine absorption of solar energy, loss of sea ice accelerates global warming. Moreover, sea-ice loss triggers a feedback mechanism whereby ice loss leads to more sunlight absorbed, more rapid warming, and, in turn, even more ice loss. This feedback mechanism is one reason why the Arctic has been warming approximately twice as fast as the planet as a whole.
At the same time, reduced ice cover has important implications for local communities, ecosystems, and industries that use and depend on Arctic waters. The 2004 Arctic Impacts Assessment, for example, described sea-ice loss as â€œlikely to have devastating consequences for polar bears, ice-dependent seals, and local people for whom these animals are a primary food source. The increased amount of open-water that results from sea-ice loss is also opening up new routes and access points for shipping and maritime industries. That presents new opportunities for regional economic activity, but also poses new regional vulnerabilities to the environmental impacts of those activities.
As old ice continues its rapid disappearing act, these impacts will be increasingly felt during the summer months, when more and more areas of water normally protected by multiyear ice cover open up completely.
NASA's January 2012 Blue
Marble Image of Earth's Western Hemisphere.
Friday March 16, 2012
NASA's most recently launched earth-observing satellite, Suomi NPP, is proving to pack both beauty and brains. Since its launch into space in October, Suomi NPP has taken some of the most stunning images of Earth ever generated and, at the same time, has begun to collect critical data about Earth's environment and atmosphere. The satellite, the product of a partnership between NASA, NOAA, and the Department of Defense, carries five instruments that collect a host of important information including sea surface temperatures, ozone levels, and measures of biological productivity on land and in oceans.
Suomi NPP received significant attention in late January and again in February for its latest Blue Marble images stunning, high definition composite images of Earth from space. January's Blue Marble, which shows Earthâ€™s western hemisphere, immediately went viral after its release. The photo-sharing site Flickr reported that the image received more than 3.1 million views as of February 1, making it one of the most viewed images in the site's history after just one week on the web. February's image shows Earth's eastern hemisphere and was created from data collected during six orbits of Earth.
Suomi NPP satellite under development.
But while the satellite is churning out eye-pleasing images, it's also busy collecting data that will help us better understand how Earth is changing. Among the five instruments aboard the satellite is the latest version of the Clouds and the Earth's Radiant Energy System (CERES) which measures Earth's energy budget, or balance of incoming and outgoing energy. Having accurate, timely measurements of minute changes in Earth's energy budget is crucial to increasing our understanding of long-term climate change, including the potential impacts of heat-trapping gasses on ocean and atmospheric temperatures and sea-level.
At the same time, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is monitoring cloud systems, which strongly influence Earth's energy budget by either reflecting incoming sunlight or blocking energy that would otherwise radiate into space. Scientists want to understand the effects of such cloud characteristics as thickness, altitude, and distribution on energy budgets and climate change.
As Suomi NPP continues its anticipated 5-year mission, meteorological and earth scientists around the world will gain new information to better understand how Earth is changing. We'll also be sure to see more beautiful pictures of our planet.