WEEKLY CLIMATE NEWS

WEEK TWO: 10-14 September 2012

ITEMS OF INTEREST

One for the record books -- If you would like more background information concerning how various temperature and precipitation extremes are identified as record events from a station's climate record, please read this week's Supplemental Information…In Greater Depth.
Typical peak in the Atlantic hurricane season reached -- The historic or statistical annual peak in the Atlantic hurricane season will occur early this week (10-12 September), as determined as the date during the entire season with most frequent number of named tropical cyclones (tropical storms and hurricanes), based upon over 100 years of record. This date corresponds closely with the time of peak sea-surface temperatures across those sections of the North Atlantic considered hurricane-breeding areas. [NWS National Hurricane Center] [Note: So far this Atlantic hurricane season, which commenced on 1 June 2012, twelve tropical cyclones have reached tropical storm or hurricane status. Of these thirteen named tropical cyclones, seven (Chris, Ernesto, Gordon, Isaac, Kirk, Leslie and Michael) have become hurricanes. EJH]
Hurricanes are no strangers to central Gulf Coast residents -- Motivated by the landfall of Hurricane Isaac over one week ago, the NOAA Environmental Visualization Laboratory produced a map showing the plotted paths of 140 tropical cyclones, with intensifies ranging from tropical depressions to category 5 hurricanes (on the Saffir-Simpson Scale) that have passed across the states of Louisiana and Mississippi between 1850 and 2011. The hurricane track plots were from data available from the NOAA Coastal Services Center. [NOAA Environmental Visualization Laboratory]
Celebrate International Day for the Preservation of the Ozone Layer -- The United Nations Environment Programme has proclaimed that this upcoming Sunday 16 September 2012 to be the International Day for the Preservation of the Ozone Layer, a commemoration of the day in 1987 when nations commenced the signing of the Montreal Protocol to limit and eventually ban ozone-depleting substances such as chlorofluorocarbons (CFCs) and other chlorine and bromine-containing compounds. This year marks the 25th anniversary of the event. The theme for Ozone Day 2012 is "Protecting our atmosphere for generations to come." [United Nations Environment Programme: Ozone Secretariat]
Education material available for space weather -- NOAA Education recently produced a webpage that contains information on space weather and resource material that can be used by educators for such topics as the NOAA Space Weather Prediction Center's space weather forecast models and the anticipated 2013 solar maximum. [NOAA Education Resources]

CURRENT CLIMATE MONITORING

Voyage commences to explore link between sea saltiness and climate -- A research voyage embarked last week from Woods Hole, MA to commence that will deploy a variety of instruments in different regions of the oceans, including the saltiest spot in the North Atlantic to obtain a detailed three-dimensional picture of how the salt content or salinity of the ocean's upper layers varies and how these variations are related to global rainfall patterns. This research voyage, known as the Upper Ocean Regional Study (SPURS), is sponsored by NASA, NOAA and the National Science Foundation the data collected will be used to help calibrate the salinity measurements made by NASA's Aquarius/SAC-D (Satelite de Aplicaciones Cientificas-D) spacecraft since August 2011. [NASA Earth Science News Team]
Melting of Patagonian ice field accelerates in last 25 years -- Researchers from Cornell University report their analysis of digital elevation models of the Southern Patagonian Ice Field in the South American Andes obtained from NASA satellite data indicates that this ice field lost its ice volume between 2000 and 2012 at a 50 percent faster rate than during the interval between 1975 and 2000. [Cornell University Chronicle Online]
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

Evaluation of trade-offs needed in combating urban heat islands -- Finding that urban warming in the expanding megapolitan area of the Arizona Sun Corridor appears to be seasonally dependent, researchers at Arizona State University claim that evaluation of the trade-offs used to combat this warming due to urbanization (or heat island effect) is needed. They note that increasing the reflectivity of roofs with a white color can reduce the temperature, but it disrupts the regional hydroclimate to decrease rainfall. [Arizona State University News]
Destruction of coastal habitats could increase greenhouse gas release -- According to a recent study led by scientists from Duke University, destruction of coastal habitats globally could release as much as one billion tons of carbon into the atmosphere annually, which would be ten times greater than previous estimates. When coastal wetlands are drained and destroyed, the sediment layers release into the atmosphere "blue carbon" or carbon that had been sequestered by the coastal-marine ecosystems. [Nicholas Institute, Duke University]

CLIMATE FORECASTS

Updated national drought outlook issued -- Forecasters at NOAA's Climate Prediction Center recently released their updated Seasonal Drought Outlook that is to cover all but the first five days of meteorological autumn that will run through the end of November 2012. Although these forecasters foresee a persistence of the drought conditions across a large area of the nation extending from the central and southern Plains westward across the central and northern Rockies and the central Intermountain West to California, they also believe that improvement in the drought conditions should occur across sections of the Mississippi Valley, the northern Plains, the Midwest and the Middle Atlantic States. Some of the improvement appears to be associated with the recent rains from the remnants of Hurricane Isaac, as well as the anticipated precipitation patterns that would accompany the developing El Niño episode. Sections of the Southwest, primarily across Arizona and sections of adjoining states, could experience improvement in the drought conditions. [NOAA Climate Prediction Center] Note: a Seasonal Drought Outlook Discussion is included describing the forecasters' confidence.

CLIMATE AND THE BIOSPHERE

Tropical forest loss could reduce rainfall -- A team of scientists from the United Kingdom's University of Leeds and the NERC (Natural Environment Research Council) Centre for Ecology & Hydrology warn that deforestation of the tropical forests could cause a significant reduction in tropical rainfall. Their findings based on NASA satellite observations of rainfall and vegetation indicate that tropical forests produce nearly twice as much rain as air flowing across surfaces with little vegetation. Using numerical models to predict atmospheric wind flow patterns, they estimate that the projected destruction of tropical forests would reduce dry-season rainfall across South America's Amazon basin by at least 20 percent as of 2050. [University of Leeds]
Sea otters could help fight global warming -- Researchers at the University of California, Santa Cruz claim that a sea otters that have an appetite for sea urchins appear to have a sufficiently large population that could keep the number of sea urchins in check and allow kelp forests to prosper and sequester large amounts of atmospheric carbon dioxide. The researchers note that the spreading kelp could fix twelve times the amount of carbon dioxide than if the population of sea urchins ran rampant. [University of California, Santa Cruz]

CLIMATE MODELING

A new generation of advanced climate models are needed -- A new report entitled "A National Strategy for Advancing Climate Modeling" issued by the National Research Council calls for a new generation of climate models should be developed that would deliver more detailed, smaller scale climate projections than currently available. These new generation climate models should take a more integrated approach where common software infrastructure would be used to gain regional detail, additional simulation capabilities and new collaboration approaches with the user community. [National Academies News]

CLIMATE AND SOCIETY

International Great Lakes environmental pact renewed -- Last Friday, the US Environmental Protection Agency Administrator and Canada's Minister of the Environment renewed the 40-year old Great Lakes Water Quality Agreement that pledged to increase efforts to reduce pollution, cleanse contaminated sites and prevent exotic species in the waters of the North American Great Lakes shared by the two nations. This new version of the agreement also includes sections on emerging challenges that include climate change, loss of wildlife habitat and the appearance of new waves of invasive species. [Detroit Free Press]
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]

COMPARATIVE PLANETOLOGY

Variations in incident solar radiation appear to drive dramatic Martian climate variations -- Researchers at Denmark's Niels Bohr Institute-University of Copenhagen report that the dated layers of ice and dust in the ice cap over the North Pole of Mars for the last million years are related to the variations in the incident solar radiation received by Mars due to variations in the orbital elements of the Red Planet that include its axial tilt or obliquity. Some of the information on the ice layers were obtained from the HiRISE instrument on NASA's Mars Reconnaissance orbiter. These scientists claim that these variations in orbital geometry driving the Martian climate are analogous to the rhythmic changes in the Earth's orbital elements (known as Milankovitch cycles) driving the planetary climate on Earth. [University of Copenhagen]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Feedback in Earth's Climate System

In Earth's climate system, feedback consists of a process where a change in one variable interacts with other variables of the system to alter that original variable. If the change reinforces the original quantity, it is known as a positive feedback. If the change suppresses the original quantity, it is a negative feedback. Feedbacks in Earth's climate system are significant--thought to be responsible for more than half the global warming expected from human activities.

Consider examples of positive and negative feedback. A warming trend in climate is likely to accelerate the rate of melting of snow and ice, producing more bare ground that absorbs more solar radiation, further raising the air temperature. A cooling trend prolongs snow and ice cover in spring and summer so that less solar radiation is absorbed, more reflected to space, bringing about additional cooling. In both cases, feedback is positive because the initial change in temperature is amplified.

Consider an example of negative feedback. While feedbacks among temperature, cloud cover, and radiation are not well understood and depend upon circumstances (e.g., type and height of clouds), they could be either positive or negative. It is thought that a warming trend in climate should increase the rate of evaporation of water from Earth's surface and thereby increase low cloud cover. A thicker and more extensive low-cloud cover reflects more solar radiation to space thereby inhibiting a further rise in surface temperature. Hence, this negative feedback would dampen the initial temperature change.

Understanding feedback in the climate system is essential for modeling and predicting climate change. If some agent or mechanism alters the climate, then feedback may either amplify (positive feedback) or dampen (negative feedback) the change in climate. As demonstrated later in this course, many agents and mechanisms can bring about climate change (e.g., variations in solar energy output, regular fluctuations in Earth-Sun geometry). While these climate forcing agents and mechanisms drive climatic change, processes within the planetary climate system involving feedbacks significantly impact the magnitude of climate change.

Overall, which type of feedback prevails in Earth's climate system, positive or negative? A system in which positive feedback prevails is unstable. For Earth, this would move the climate regime toward an extreme characterized by excessive cold that would encase the planet in snow and ice ("snowball" or "ice ball" Earth) or toward the other extreme resulting in much higher temperatures--the product of a runaway greenhouse effect. Although Earth's climate has varied considerably over the billions of years that constitute geologic time, it appears likely that Earth's climate system has been nearly stable with negative feedbacks generally compensating for positive feedbacks.

Concept of the Week: Questions

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

The magnitude of a climate change [(largely depends upon)(is independent of)] positive and negative feedback phenomena operating in Earth's climate system.
Through much of Earth history, it appears that [(positive feedbacks)(negative feedbacks)(a general balance between positive and negative feedbacks)] have (has) prevailed.

Historical Events

10 September 1900...Elk Point, SD received 8.00 inches of rain that set a 24-hour maximum precipitation record for the state. (NCDC)
10-11 September 1963...A 24-hour rainfall record for the Northern Hemisphere was set at Paishih, Taiwan as 49.13 inches of rain fell as the result of Typhoon Gloria. (Accord Weather Guide Calendar)
11-12 September 1949...Early snowstorm dumped 7.5 inches on Helena, MT on the 11th, the earliest measurable snow for the city to date, then an additional 22 inches followed the next day. (The Weather Doctor)
11-12 September 1976...Japan's 24-hour rainfall record was set as 44.80 inches of rain fell at Hiso in Tokuhima Prefecture as a result of Typhoon Fran, which also was responsible for 167 deaths in Japan. (Accord Weather Guide Calendar)
11 September 1990...The high temperature at Phoenix, AZ reached 112, the highest ever for the date and for so late in the season. (Intellicast)
12 September 1987...Peak sustained winds in Hurricane Max reached 155 mph, the highest observed for an Eastern Pacific hurricane. (The Weather Doctor)
13 September 1922...The temperature at El Azizia in Libya soared to 136 degrees to establish a world record at a surface weather station. To make matters worse, a severe ghibi (dust storm) was in progress. (The Weather Channel) (NCDC)
13 September 1988...Hurricane Gilbert smashed into the Cayman Islands, and as it headed for the Yucatan peninsula of Mexico strengthened into a monster hurricane, packing winds of 175 mph. The barometric pressure at the center of Gilbert reached 26.13 inches (888 mb), an all-time record for any hurricane in the Caribbean, Gulf of Mexico, or the Atlantic Ocean. Gilbert covered much of the Gulf of Mexico, producing rain as far away as the Florida Keys. (The National Weather Summary) (Storm Data)
14 September 1937...The mercury soared to 92 degrees at Seattle, WA, a record for September. (The Weather Channel)
14 September 1970...The temperature at Fremont, OR dipped to 2 degrees above zero to equal the state record for September set on the 24th in 1926. (The Weather Channel)
14 September 1987...Barrow, AK received 5.1 inches of snow, a record for September. (Sandra and TI Richard Sanders - 1987)
14 September 1988...Pressure in the eye of Hurricane Gilbert moving across the Caribbean Sea fell to 885 millibars (26.17 inches of mercury), the lowest recorded barometric pressure in the Western Hemisphere. Ultimately, 318 died in seven countries across the Caribbean and Gulf of Mexico.
15 September 1939...The temperature at Detroit, MI soared to 100 degrees to establish a record for September. (The Weather Channel)
15 September 1982...A snowstorm over Wyoming produced 16.9 inches at Lander to establish a 24-hour record for September for that location. (13th-15th) (The Weather Channel)
16 September 1881...Iowa's earliest measurable snow of record fell over western sections of the state. Four to six inches was reported between Stuart and Avoca. (The Weather Channel)
16 September 1964...The temperature at Concord, NH dropped to 27 degrees ending the shortest growing season on record (100 days). (Intellicast)
16 September 1988...Hurricane Gilbert made landfall 120 miles south of Brownsville, TX in Mexico during the early evening. During its life span, Gilbert established an all-time record for the Western Hemisphere with a sea-level barometric pressure reading of 26.13 inches. Winds approached 200 mph, with higher gusts. Gilbert devastated Jamaica and Mexico's Yucatan Peninsula. (The National Weather Summary) (Storm Data) (The Weather Channel)
16 September 2004, Birmingham, Alabama: Birmingham, AL set two all-time records for the city as Hurricane Jeanne crossed the city: Lowest sea level pressure on record, 986.8 millibars (29.14 inches of mercury), and the greatest 24-hour rainfall event on record, 9.75 inches. (The Weather Doctor)

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