28 March-1 April 2011

ITEMS OF INTEREST

• Reconstructing past climates --
  Scientists from many disciplines have developed a variety of methods that use proxy indicators such as tree rings, ice cores and ocean cores to reconstruct past climates, some extending back thousands of years. For more details on paleoclimatology, or the study of past climates, and available data sets, please read this week's Supplemental Information…In Greater Depth.

CURRENT CLIMATE MONITORING

• Monitoring ice loss from polar ice caps from space --
  An image made last November by the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite shows the Astrolabe Glacier streaming out from the interior of Antarctica to dump ice into the sea. A graph of the temporal variations in the polar ice mass shows a net decline in ice mass since 1992. [NASA Earth Observatory]
• Record Arctic ozone loss linked to cold vortex --
Atmospheric scientists from the National Center of Atmospheric Research and their colleagues have found decreases in stratospheric ozone over the Arctic by between 25 and 38 percent during the last several weeks. They believe that the development of this "Arctic ozone hole" could be linked with the exceptionally cold pool of stratospheric air associated with an unusually strong circulation regime that appears as a vortex. Increases in certain atmospheric greenhouse gases along with decreased stratospheric ozone appear to have resulted in this winter's cold vortex. [NCAR/UCAR]
• Measurements indicate continuing loss in winter Arctic sea ice --
A study conducted by the National Snow and Ice Data Center at the University of Colorado-Boulder indicates the annual maximum Arctic sea ice extent in winter continues to dwindle. In their analysis of satellite data, they found that the 2011 Arctic sea ice extent maximum in early March 2011 at the beginning of the melt season appears to be tied with 2006 for the lowest ever during the period of satellite surveillance that began in 1979. [University of Colorado News Center]
• Significant increase seen in freshwater content of Arctic Ocean --
Researchers at Germany's Alfred Wegener Institute have found that the freshwater content of the upper Arctic Ocean has increased by approximately 20 percent since the 1990s. This increased freshwater content near the surface not only controls the flow of heat from ocean to atmosphere or to sea ice, but affects global oceanic circulation. The researchers came to their conclusions based upon their analysis of over 5000 measured salt concentration profiles. [Alfred Wegener Institute for Polar and Marine Research]
• New imaging tool on International Space Station monitors Earth's coastal regions --
A prototype scanner called the Hyperspectral Imager for the Coastal Ocean (HICO) has been operating onboard the International Space Station for 16 months, collecting environmental data on the Earth's coastal regions. The data and images obtained from HICO are being made available through an online clearinghouse operated by Oregon State University to scientists to help monitor the role that human impacts and climate change have upon the world's coastal regions. [Oregon State University]
• An All-Hazards Monitor --
This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [NOAAWatch]
• Global and US Hazards/Climate Extremes --
A review and analysis of the global impacts of various weather-related events, including drought, floods and storms during the current month. [NCDC]

CLIMATE FORCING

• Reducing atmospheric carbon dioxide could result in a wetter climate --
  Climate modeling simulations run by scientists at the Carnegie Institution for Science indicate that reductions in atmospheric carbon dioxide concentrations would lead to a wetter planetary climate with fewer droughts that would be associated with increased temperatures. They found that increased warm air through a large atmospheric column tends to inhibit convective precipitation. [Carnegie Institution for Science]
• Antarctic icebergs may play role in global carbon cycle and climate --
A National Science Foundation-funded project involving multi-disciplinary scientists from the Scripps Institution of Oceanography and their colleagues from other research institutions around the nation have discovered that a floating iceberg in the Weddell Sea can cool and dilute the seas for days following passage, resulting in a rise in chlorophyll levels that may ultimately increase carbon dioxide absorption in the Southern Ocean. [NSF]
• New analysis of a "lost" classic experiment yields clues to origins to life --
Scientists at NASA's Jet Propulsion Laboratory and Scripps Institution of Oceanography who recently re-examined the contents of the test tubes used by Stanley Miller in his classic experiments of the 1950s reported on the results of involving hydrogen sulfide gas. They found that this "lost" version of the experiment meant to simulate a prebiotic environment where hydrogen sulfide may have occurred in volcanic plumes created amino acids containing sulfur and represented the one that produced amino acids in the greatest diversity and highest abundance. Miller had not published these results as he was reluctant to work with hydrogen sulfide due to its rotten egg odor. [NASA GSFC]

CLIMATE AND THE BIOSPHERE

• Recent cold weather damages crops in western Mexico --
  A map showing the Normalized Difference Vegetation Index (NDVI) across the Mexican State of Sinaloa generated from data collected by NASA's Terra satellite shows the damage to the state's winter corn crop by the invasion of a cold air mass with subfreezing temperatures in February 2011. [NASA Earth Observatory]
• Future is uncertain for Joshua trees as climate changes --
Using climate forecast models, along with ecological data, an ecologist with the US Geological Survey and colleagues have found that projected increases in temperature due to a changing climate would likely eliminate Joshua trees from their current range across the Southwest within 60 to 90 years. [USGS Newsroom]
• "Think globally, but act locally" when studying biosphere responses to global climate change --
Biologists from the University of Texas at Austin advise that the scientific community, policy makers and the public should not attempt to separate out the specific contribution of greenhouse gas-driven climate change to the decline or extinction of plant and animal species at the local scale. [University of Texas at Austin]

• Slow recovery of marine life after ancient mass extinction explained --
Researchers at Stanford University claim that their analysis of the limestone beds in present day southern China indicate the slow recovery of marine life following the major Permian-Triassic mass extinction (approximately 250 million years ago) was due to the subsequent explosion of algae and bacteria. This explosion in marine algae and bacteria consumed essentially all the free oxygen in the ocean for several million years after the extinction event. This event, representing the largest known mass extinction in Earth history, may have been caused by massive volcanic activity. [Stanford University News]

CLIMATE AND SOCIETY

• Future large regional changes in farmland area predicted --
  Using climate and high-resolution land use data, researchers at the University of Illinois predict that the effects of climate change and population growth on the availability of agricultural land areas will vary regionally. Regions in midlatitudes, such as the US, Russia and China, could experience an increase in arable land, while Europe and some of the tropical and subtropical regions of Africa, India and South America could loose arable land. [University of Illinois]
• Website for human dimensions of climate change --
An interagency effort within the US federal government that included NOAA, the Bureau of Land Management and the US Forest Service, has resulted in a website called HD.gov (for HumanDimensions.gov) that provides users, such as natural resource managers, with information on the human dimensions on a variety of topics of interest such as climate change. [HD.gov]
• Earthweek --
Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Extending the Historical North American Drought Record

Through history, drought has been a major concern for many people as the lack of adequate water can adversely affect agriculture, and in the extreme case, the availability of potable (drinkable) water. The Case in Point for Chapter 9 describes the migration of ancient peoples across the semiarid Southwest due to what may have been major drought conditions. During the last century, the "Dust Bowl" era drought in the 1930s created many problems in this country. The effects of this seven-year long drought were made worse by poor agricultural techniques and land management. The effect of the drought on the nation was also exacerbated by the coincident Great Depression. Drought remains a problem today across Texas and the West Coast as we can see from inspection of the current weekly US National Drought Monitor produced by the National Drought Mitigation Center.

How do the current drought events compare with earlier droughts? A time series of computed Palmer Drought Severity Index (PDSI) values began in 1895 when a sufficiently dense climate network was established. During the 20th century, several episodes of drought have had a major national impact. The exceptional drought that developed in the early 1930s extended across much of the nation resulting in the "Dust Bowl" era. The PDSI time series shows that the 1930s drought was the worst in the last century, with nearly 80 percent of the nation experiencing moderate to extreme drought in 1934. During the 1950s, the southern Plains and the Southwest also experienced a major drought, when 50 to 60 percent of the nation was under drought conditions.

What about farther back in history? Sophisticated tree-ring analysis techniques allow researchers to extend the drought record across a large section of North America farther into the past. In 1998, Edward R. Cook at Columbia University's Lamont-Doherty Earth Observatory along with colleagues at Arizona and Arkansas reconstructed past drought conditions across the nation based upon annual tree-ring data obtained from a network of 388 climatically sensitive tree-ring sites. From these data, time series of annual summertime (June-August) PDSI values were determined back to 1700 at 155 grid points across the nation. These gridded tree-ring chronologies were calibrated with PDSI chronologies generated by instrumental records at selected Historical Climate Network stations commencing in the late 19th century. The researchers found that the 1930s drought was the most severe drought to hit the nation since 1700.

By 2004, the series was expanded to 835 tree-ring sites, primarily across the West, where exactly dated annual tree-ring chronologies were obtained. The new grid covered most of North America with a latitude-longitude spacing of 2.5 degrees. In addition to the 286 grid point PDSI time series, annual contour maps of PDSI were constructed that span much of the continent. This work permitted extension of the spatial and temporal coverage of the drought reconstruction not only into Canada and Mexico, but back 2000 years. From this more recent data set they produced an online "North American Drought Atlas." They found several "megadroughts" in North America that were even more severe than the 1930s drought. In addition to being more severe, some droughts extended over several decades, considerably longer than those of the 20th century. One such megadrought was in the 16th century, an event that along with another megadrought into the early 17th century has been implicated by some researchers in the hardships encountered by British settlers in the Virginia area, such as the disappearance of the Roanoke Colony.

Concept of the Week: Questions

(Place your responses on the Chapter Progress Response Form provided in the Study Guide.)

1. The 1930's Dust Bowl era drought [(does), (does not)] appear to be the most intense across the nation of any in the last two thousand years.
2. The "North American Drought Atlas" is based on 835 sites where trees in climatically sensitive areas produce [(monthly),(annual),(biennial)] growth rings.

Historical Events:

• 27-28 March 2009…A blizzard moving across the southern Plains was responsible for new 24-hour snowfall records for the states of Kansas, Oklahoma and Texas. A 30.0-inch snowfall at Pratt eclipsed the previous Kansas 24-hour record of 24 inches set at Norcator on 26 October 1996. Freedom and Woodward in Oklahoma replaced the 24.0-inch state snowfall record at Buffalo on 21 February 1971. In Texas, 25.0 inches fell at Follett, which broke the previous 24.0-inch record at Plainview set on 4 February 1971. (Accord Weather Guide Calendar)
• 28 March 1902...McMinnville, TN (elevation 900 feet) received 11.00 inches of precipitation, setting a 24-hour precipitation record for the Volunteer State. (National Climate Data Center).
• 28 March 1955…Florida's latest measurable snowfall occurred at Marianna when one inch of snow fell. Ground is whitened further south in Panama City. (The Weather Doctor)
• 29 March 1879...The temperature at Los Angeles, CA climbed to 99 degrees, which was 3 degrees higher than any other March day had ever reached in the city. (Intellicast)
• 29 March 1886...Atlanta, GA was drenched with a record 7.36 inches of rain in 24 hours. (The Weather Channel)
• 29 March 1920...Clear Spring, MD received 31 inches of snow in 24 hours to establish a state record. (Sandra and TI Richard Sanders - 1987)
• 29 March 1942...The "Palm Sunday snowstorm" buried Baltimore, MD under 22 inches of snow in 24 hours. This was the heaviest 24-hour snowfall ever for the city for the month of March as well as the heaviest snow for so late in the season. (Intellicast)
• 29 March 1945...Providence, RI hit 90 degrees to establish a March record for the New England area. (The Weather Channel)
• 30 March 1977...Hartford, CT hit 87 degrees to establish a record for the month of March. (The Weather Channel)
• 31 March 1890...Saint Louis, MO received 20.4 inches of snow in 24 hours, which was the worst snowstorm of record for St. Louis. (David Ludlum)
• 31 March 1954...The temperature at Rio Grande City, TX hit 108 degrees, which for thirty years was the U.S. record high for the month of March. (The Weather Channel)
• 31 March 1992...Seattle, WA closed out its first snowless winter ever (November through March). Las Vegas, NV recorded 4.80 inches of rain during the past month, which set 2 records -- the wettest March ever (old record 1.83 inches set in 1973) and the wettest month ever (old record 3.39 inches in September 1939). The normal yearly rainfall for the city is only 4.19 inches! (Intellicast)
• 2 April 1970...The last snowstorm of the 1969-70 winter season came to an end at Chicago, IL as 10 .7 inches of snow fell -- a final contribution to the season's amount of 77 inches, which set a new all-time snow season record for the city. (Intellicast)
• 2 April 1975...A severe storm over the northeastern US began on this day and blasted the area for the next 3 days. Wind gusts reached 87 mph at West Harpswell, ME and Boston, MA recorded its lowest April pressure on record (28.68 inches). Tides along the coast ran 2 to 4 feet above normal and anywhere from 1 to 4 feet of snow fell from western New York to northern Maine with the higher elevations receiving the most. (Intellicast)
• 3 April 1955…Record snow fell across north-central Wyoming and south-central Montana as Sheridan WY established a 24-hour snowfall record with 26.7 inches. (The Weather Doctor)
• 3 April 1996...Marquette, MI recorded 12.6 inches of snow on this day to raise its seasonal snowfall to 250.8 inches -- the city's snowiest winter ever. The old record was 243.8 inches set back in 1981-82. The snowfall for the month now stood at 43.4 inches -- the snowiest April on record for the city as well. (Intellicast)

Return to DataStreme ECS website

Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2011, The American Meteorological Society.