For comparison: Global sea level is rising at about 2.1 millimeters per year, or a little over one-sixteenth of an inch.

Seasons: Winter, Spring, Summer, Fall

Sources: Overeem, I et al. “Sea ice loss enhances wave action at the Arctic coast.” Geophysical Research Letters 38 (2011): L17503 and National Snow and Ice Data Center: Arctic Sea Ice News and Analysis. Accessed Online 28 January 2011 <http://nsidc.org/arcticseaicenews/> and Francis, OP et al. “Ocean wave conditions in the Chukchi Sea from satellite and in situ observations.” Geophysical Research Letters 38 (2011): L24610.

Rains in East Africa primarily fall during the long rains (March through May) and the short rains (October through December). Understanding how climate and climate change influence these rains is particularly important for predicting drought in the region.  Conditions in the tropical Pacific affect weather throughout the world and the tendency for the tropical Pacific to persist in either cool La Niña phases or warm El Niño phases enable forecasters to predict whether seasonal temperatures or precipitation levels will be above or below average. In addition to local Indian Ocean sea surface temperatures, the short rains in East Africa are strongly influenced by conditions in the tropical Pacific, with La Niña phases leading to reduced precipitation. How the tropical Pacific affects the long rain season, on the other hand, is harder to identify. Recent work shows that since 1999, the long rains have been consistently weak and unable to compensate for reduced short rain precipitation during La Niña phases, leading to drought conditions like those experienced in 2011. Also since 1999, there has been a pattern of consistently elevated sea surface temperatures in the western tropical Pacific and consistently high rainfall levels in that region. The tendency of ocean surface temperatures to remain in particularly warm or cool conditions for relatively long periods of time, coupled with what is known about the atmospheric links between the western tropical Pacific and East Africa, enables forecasters to better understand and predict droughts there.

Seasons: Winter, Spring, Summer, Fall

Source: Lynn, B and DeWiltt, DG. “A recent and abrupt decline in the East African long rains.” Geophysical Research Letters 39 (2012): L02702. 

Earth’s ocean is mixed by a complex system of currents. Downwellings occur when currents move water from the surface to the depths and upwellings occur when nutrient-rich waters are pulled from the depths to the surface. Upwelling areas are some of the most productive waters in the world, including the California Coast where part of the California Current System upwells. The waters along the California Coast are more or less productive during some years, based on the strength and timing of this upwelling. Waters are less productive during years when the winter upwelling is delayed and weaker. This upwelling strength is indexed by the North Pacific Gyre Oscillation (NPGO) – in positive NPGO years, the upwelling starts about six weeks earlier than negative NPGO years. The NPGO is an expression of the variability in the pressure difference between a high pressure center located near Hawaii and a low pressure center in the Gulf of Alaska. This variability leads to changes in the strength and position of the winds that run along the California Coast and work to “pull” a current of water from the depths. Compared to negative NPGO years, average end of winter water conditions during positive NPGO years feature nitrate concentrations that are about 25 percent higher, chlorophyll concentrations about 15 percent higher and zooplankton numbers that are about 20 percent higher. These nutrients and zooplankton  feed commercially-important fish species and seabirds.

Seasons: Winter, Spring

Sources: Chenillat, F et al. “North Pacific Gyre Oscillation modulates seasonal timing and ecosystem functioning in the California Current upwelling system.” Geophysical Research Letters 39 (2012): L01606 and Di Lorenzo, E et al. “North Pacific Gyre Oscillation links ocean climate and ecosystem change.” Geophysical Research Letter 35 (2008): L08607.

AO: The Arctic Oscillation (AO) is the difference in atmospheric pressure between the Arctic and the mid-latitudes of the Northern Hemisphere. Upper-atmospheric westerly winds and mid-latitude winter storms are stronger during “positive phases” of the AO (when the pressure difference is greater), and these stronger winds serve as a “blocking” mechanism that keeps the frigid Arctic air in the Arctic instead of invading many midlatitude areas, particularly the Eastern United States, leading to milder winter temperatures there. Negative phases work the opposite way, with less blocking and a colder eastern United States.

So far, the Arctic Oscillation has favored mild winter temperatures in the Eastern United States (http://www.climatewatch.noaa.gov/image/2011/so-far-arctic-oscillation-favoring-mild-winter-for-eastern-u-s)

Useful Climate Analogy: The Arctic Oscillation and Your Refrigerator Door. 

http://www.earthgauge.net/2011/analogies-of-basic-physical-principles#arctic The El Niño-Southern Oscillation (ENSO) is a periodic shift in tropical Pacific sea surface temperature distributions. During cool La Niña phases, the northern hemisphere storm track tends to move farther north, leading to a wetter northern tier of the United States – particularly a wetter Northwest – and a drier southern tier. El Niño phases bring relatively the opposite conditions.

NOAA’s Winter Weather Outlook (http://www.climatewatch.noaa.gov/image/2011/2011-2012-winter-outlook) gives different regional probabilities for warmer/colder or wetter/drier conditions. Variation in this outlook is driven largely by differences in the state of the El Niño-Southern Oscillation.

Regional Outlooks:

Albany, Georgia Winter Outlook: The Albany area has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Albuquerque, New Mexico Winter Outlook: The Albuquerque area has equal chances of experiencing well above or well below normal winter temperatures and has a 33 to 40 percent chance of receiving below average precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Anchorage, Alaska Winter Outlook: The Anchorage region has equal chances of experiencing well above or well below normal winter temperatures and an equal chance of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Arizona Winter Outlook: Most of Arizona has equal chances of experiencing well above and well below normal winter temperatures and a 33 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Asheville, North Carolina Winter Outlook: The Asheville region has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Atlanta, Georgia Winter Outlook: The Atlanta area has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Bismarck Winter Outlook: The Bismarck area has a greater than 40 percent chance of experiencing well below normal winter temperatures and a 40 to 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

California Winter Outlook: Most of California has a greater than 40 percent chance of experiencing well below normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Carbondale, Illinois Winter Outlook: The Carbondale area has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Central Mississippi Winter Outlook: Central Mississippi has a greater than 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well below and well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Central North Carolina Winter Outlook: The Central North Carolina region has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Central Oklahoma Winter Outlook: Central Oklahoma has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Colorado Springs Winter Outlook: The Colorado Springs region has equal chances of experiencing well above and well below normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Dallas, Georgia Winter Outlook: The Dallas region has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well below and well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Dayton, Ohio Winter Outlook: The Dayton region has equal chances of experiencing well above and well below normal winter temperatures and a greater than 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Eastern Nebraska Winter Outlook: The Eastern Nebraska region has equal chances of experiencing well above and well below normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Eastern Tennessee Winter Outlook: Eastern Tennessee has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Fairbanks, Alaska Winter Outlook: The Fairbanks region has a greater than 40 percent chance of experiencing well below normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Fallon, Nevada Winter Outlook: The Fallon region has a 33 to 40 percent chance of experiencing well below normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Florida Panhandle Winter Outlook: The Florida Panhandle region has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Grand Forks, North Dakota Winter Outlook: The Grand Forks area has a greater than 40 percent chance of experiencing well below normal winter temperatures and a 40 to 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Iowa Winter Outlook: Most of Iowa has equal chances of experiencing well above or well below normal winter temperatures and equal chances of receiving well above or well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period. A predominately positive Arctic Oscillation has so far favored mild winter temperatures in the region.

Kansas Winter Outlook: Most of Kansas has a 33 to 40 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Little Rock, Arkansas Winter Outlook: The Little Rock region has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Louisiana Winter Outlook: Most of Louisiana has a greater than 50 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Lubbock Winter Outlook: The Lubbock area has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a greater than 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Memphis, Tennessee Winter Outlook: Memphis has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Minnesota Winter Outlook: Most of Minnesota has a 33 to 40 percent chance of experiencing well below normal winter temperatures and a 33 to 40 percent chance  of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Missoula, Montana Winter Outlook: The Missoula region has a 33 to 40 percent chance of experiencing well below normal winter temperatures and a greater than 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Missouri Winter Outlook: The State of Missouri region has a 33 to 40 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well below and well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Mobile, Alabama Winter Outlook: The Mobile area has a greater than 50 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Nashville, Tennessee Winter Outlook: The Nashville area has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Northeast Winter Outlook: The Northeast has equal chances of experiencing well above or well below normal winter temperatures and an equal chance of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period. A predominately positive Arctic Oscillation has so far favored mild winter temperatures in the region.

Northern Alabama Winter Outlook: Northern Alabama has a greater than 40 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well below or well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Northern California Winter Outlook: Northern California has a greater than 40 percent chance of experiencing well below normal winter temperatures and 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Northern Colorado Winter Outlook: The Northern Colorado region has equal chances of experiencing well above and well below normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Northern Florida Winter Outlook: The Northern Florida region has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a greater than 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Northern Mississippi Winter Outlook: Northern Mississippi has a 40 to 50 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well below and well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Ohio Winter Outlook: Most of Ohio has equal chances of experiencing well above and well below normal winter temperatures and a greater than 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Ohio Valley Winter Outlook: The Ohio Valley region has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a greater than 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Plentywood Winter Outlook: The Plentywood region has a greater than 40 percent chance of experiencing well below normal winter temperatures and a greater than 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Pocatello-Idaho Falls Winter Outlook: The Pocatello-Idaho Falls region has equal chances of experiencing well above and well below normal winter temperatures and around a 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Portland, Oregon Winter Outlook: The Portland region has a greater than 40 percent chance of experiencing well below normal winter temperatures and around a 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Rapid City, South Dakota Winter Outlook: The Rapid City region has equal chances of experiencing well above and well below normal winter temperatures and a 40 to 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Reno, Nevada Winter Outlook: The Reno area has a greater than 40 percent chance of experiencing well below normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Salt Lake City Winter Outlook: The Salt Lake City region has equal chances of experiencing well above and well below normal winter temperatures and around a 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

San Diego, California Winter Outlook: The San Diego region has a 33 to 40 percent chance of experiencing well below normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Sandpoint Winter Outlook: The Sandpoint region has a greater than 40 percent chance of experiencing well below normal winter temperatures and a greater than 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Santa Fe Winter Outlook: The Santa Fe region has equal chances of experiencing well above or well below normal winter temperatures and has a 33 to 40 percent chance of receiving below average precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Savannah, Georgia Winter Outlook: The Savannah area has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Socorro, New Mexico Winter Outlook: The Socorro region has equal chances of experiencing well above or well below normal winter temperatures and has a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

South Carolina Winter Outlook: Most of South Carolina has a 33 to 40 percent chance of experiencing well above normal winter temperatures and a 40 to 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

South Florida Winter Outlook: The South Florida region has equal chances of experiencing well above and well below normal winter temperatures and a greater than 60 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Spartanburg, South Carolina Winter Outlook: The Spartanburg region has a 40 to 50 percent chance of experiencing well above normal winter temperatures and a 33 to 40 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Springfield-Eugene, Oregon Winter Outlook: Most of Oregon has a greater than 40 percent chance of experiencing well below normal winter temperatures and a 40 to 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Texas Winter Outlook: Most of Texas has a greater than 50 percent chance of experiencing well above normal winter temperatures and a greater than 50 percent chance of receiving well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Twin Falls, Idaho Winter Outlook: The Twin Falls region has a 33 to 40 percent chance of experiencing well below normal winter temperatures and a 40 to 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Upper Midwest Winter Outlook: The Upper Midwest has equal chances of experiencing well above and well below normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Virginia Winter Outlook: Most of Virginia has a 33 to 40 percent chance of experiencing well above normal winter temperatures and equal chances of receiving well above and well below normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

Washington State Winter Outlook: Most of Washington State has a greater than 40 percent chance of experiencing well below normal winter temperatures and a greater than 50 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period.

West Virginia, Western New York and Western Pennsylvania Winter Outlook: The Western Pennsylvania and Western New York region has equal chances of experiencing well above or well below normal winter temperatures and a 33 to 40 percent chance of receiving well above normal precipitation levels. “Well above” and “well below” normal are defined by NOAA as conditions falling into the top or bottom third of climate conditions observed during the 1980 to 2010 period. A predominately positive Arctic Oscillation has so far favored mild winter temperatures in the region.

Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement of 177 out of 305 observed species was documented. Not all species moved north and a few may be wintering a little farther south, but the general trend has been an average northward movement of 35 miles. More than 60 species are now wintering at least 100 miles farther north than they did in the 1960s. General trends of species movement toward or away from the poles happen during periods of climate warming and cooling, as species seek their preferred conditions. The average temperature in January in the lower 48 states rose by over five degrees Fahrenheit from 1966-2005. This means that temperatures are now more tolerable in more northerly areas, letting birds stop their southerly migrations sooner and remain closer to the north pole during winter. In the eastern United States, the range of the Purple Finch has advanced by 433 miles over the past 40 years. This is about the distance from the Virginia-North Carolina border to southern Connecticut.

Want to help scientists collect more data about winter bird ranges? Participate in the Christmas Bird Count from December 14, 2011 to January 5, 2012.

Download image in high resolution
(1280 x 720)

Download image in low resolution
(640 x 360)

Purple Finch (click for image download from U.S. Fish and Wildlife Service)

Photo courtesy of Dr. Thomas T. Barnes, U.S. FWS

Source: The Audubon Society. “Birds and Climate Change: Ecological Disruption in Motion.” February 2009. Accessed Online 2 December 2011 < http://birdsandclimate.audubon.org/>

Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement of 177 out of 305 observed species was documented. Not all species moved north and a few may be wintering a little farther south, but the general trend has been an average northward movement of 35 miles. More than 60 species are now wintering at least 100 miles farther north than they did in the 1960s. General trends of species movement toward or away from the poles happen during periods of climate warming and cooling, as species seek their preferred conditions. The average temperature in January in the lower 48 states rose by over five degrees Fahrenheit from 1966-2005. This means that temperatures are now more tolerable in more northerly areas, letting birds stop their southerly migrations sooner and remain closer to the North Pole during winter. In the Midwest United States, the range of the American Goldfinch has advanced by 250 miles over the past 40 years. This is about the distance from the southern to northern border of Missouri.

Want to help scientists collect more data about winter bird ranges? Participate in the Christmas Bird Count from December 14, 2011 to January 5, 2012.

Download image in high resolution
(1280 x 720)

Download image in low resolution
(640 x 360)

Goldfinch (click for image download from U.S. Fish and Wildlife Service)

Photo courtesy of David Brezinski, U.S. FWS

Source: The Audubon Society. “Birds and Climate Change: Ecological Disruption in Motion.” February 2009. Accessed Online 2 December 2011 < http://birdsandclimate.audubon.org/>

Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement of 177 out of 305 observed species was documented. Not all species moved north and a few may be wintering a little farther south, but the general trend has been an average northward movement of 35 miles. More than 60 species are now wintering at least 100 miles farther north than they did in the 1960s. General trends of species movement toward or away from the poles happen during periods of climate warming and cooling, as species seek their preferred conditions. The average temperature in January in the lower 48 states rose by over five degrees Fahrenheit from 1966-2005. This means that temperatures are now more tolerable in more northerly areas, letting birds stop their southerly migrations sooner and remain closer to the north pole during winter. In the western United States, the range of the House Finch has advanced by 270 miles over the past 40 years. This is about the distance from Fresno, California to the California-Oregon border.

Want to help scientists collect more data about winter bird ranges? Participate in the Christmas Bird Count from December 14, 2011 to January 5, 2012.

Download image in high resolution
(1280 x 720)

Download image in low resolution
(640 x 360)

House Finch (click for image download from U.S. Fish and Wildlife Service)

Photo courtesy of Dave Menke, U.S. FWS

Source: The Audubon Society. “Birds and Climate Change: Ecological Disruption in Motion.” February 2009. Accessed Online 2 December 2011 < http://birdsandclimate.audubon.org/>

Dust suspended in the air and smoke from fires make up most of the aerosol concentrations found in the air around us. Aerosols affect how much sunlight reaches the Earth’s surface and how clouds form, which means they can have a strong influence over regional precipitation. Aerosols also link different parts of the world: winds can carry aerosols from fires and dust storms far away, even across oceans, affecting the climates of remote regions. This is particularly true for the Amazon rainforest. Dust storms in the Sahara Desert, combined with the smoke that is generated during Central Africa’s dry season when fires are common, are carried by northeasterly trade winds across the Atlantic to the Amazon. This transport is most common from January to May and takes approximately ten days to reach South America from Africa. The January through May period is the wet season in most of the Amazon, when there are few fires and dust generation is at a minimum. During this time, aerosols from Africa impact air in the Amazon – they are present in about one-third of aerosol measurements taken across the Amazon region.  Aerosols are considered a wild card in Amazonian weather and climate prediction. Variations in aerosol concentrations can make the difference between rainfall occurring or not. Generally, higher aerosol concentrations mean less rainfall. African dust does, however, provide a fertilizer for the soils of the Amazon, helping plant growth.

Seasons: Winter, Spring, Summer, Fall

Source: Baars, H. et al. “Further evidence for significant smoke transport from Africa to Amazonia.” Geophysical Research Letters 38 (2011): L20802.

Every place in the world has its own climate with its own average temperature and precipitation levels. Some places around the world, such as most equatorial rainforests, experience little seasonal variation and are hot and wet throughout the year. Locations closer to the poles have more seasonal climates. The Northeast United States, for example, has rainfall evenly spread throughout the year, but the summer months are much warmer than the winter months. In some locations in the tropics, temperatures don’t change much throughout the year, but there are defined wet and dry seasons. Similarly, from year to year some places have little rainfall variance while other locations can be considerably wetter or drier. Such inter-annual variability in rainfall can be particularly pronounced in parts of Amazon. Inter-annual rainfall variability in the Amazon is driven by surface temperature shifts every few years in the waters of the equatorial Pacific Ocean, and shifts on longer time scales in the tropical and subtropical Atlantic Ocean. These water temperature shifts move winds, affecting rainfall patterns on land. If it was not for the plants of the Amazon, however, this variability would be even greater. Wetter years, or years with wetter wet seasons and/or shorter dry seasons, are years when vegetation flourishes. More vegetation means more evapotranspiration, the movement of moisture from the soil through plants to the atmosphere. More evapotranspiration means more rainfall. This increase in rainfall helps to keep the wet conditions going into the next year, even if other factors would favor drier conditions. Drier years tend to stress vegetation, leading to less evapotranspiration and less rainfall, which perpetuates these dry conditions into the following year. This means that years following severe droughts, such as the “once-in-a-century” 2010 Amazon drought, may be more susceptible to further droughts. It also means that there is more year-to-year continuity of rainfall levels than there would otherwise be.

Seasons: Winter, Spring, Summer, Fall

Source: Wang, G et al. “Vegetation dynamics contributes to the multi-decadal variability of precipitation in the Amazon region.” Geophysical Research Letters 38 (2011): L19703.

The glaciers that make the peaks of the Western United States white year round are located almost exclusively within National Forests and National Parks. In addition to providing scenery and tourist attractions, these glaciers partially melt during the summer months, feeding streams and rivers that bring waters to cities and farms in the West. In fact, most of the West’s water comes from mountain snowpack or glaciers. As long as the glaciers accumulate enough snow during the wet and cold winter months to offset the summer melt, they persist. When temperatures warm however, as they have over the past century, summertime melt exceeds winter freeze, and the glaciers shrink in size. Warmer temperatures over the past century have resulted in melting glaciers across the National Parks and Forests of the West:

• North Cascades National Park has 40 percent less glacial mass than it did in 1850, and Lewis Glacier disappeared in 1990. Streamflow in the watershed fed by Lewis subsequently declined by 40 percent.
• In Alaska’s Glacier Bay National Park, Muir Glacier, one of the Park’s best recognized, is a mile shorter and 600 feet thinner than it was in 1980.
• The glaciers of Glacier National Park have been some of the hardest hit in the West: Today, about 27 percent of the area of Glacier National Park that was covered by glaciers in 1850 is still covered. The number of glaciers has been cut from 150 to 37.
• In the past 110 years, the seven largest of Mt. Hood’s eleven glaciers in Oregon’s Mt. Hood National Forest have each lost more than 30 percent of their masses. Sandy Glacier, which faces downtown Portland, has retreated by 60 percent during this period.

Sources: “Most Alaskan Glaciers Retreating, Thinning, and Stagnating, Says Major USGS Report: Press Release.” U.S.G.S. Newsroom. 2008. U.S. Department of the Interior, U.S. Geological Survey: Office of Communication. 6 October 2008 < http://www.usgs.gov/newsroom/article.asp?ID=2033> and United States. National Park Service. Climate Monitoring in Glacier Bay National Park and Preserve: Capturing Climate Change Indicators. 2007 Annual Report. Washington, GPO, 2007. Accessed Online 3 November 2008 and Sources: United States Geologic Survey. “Fifty-Year Record of Glacier Change Reveals Shifting Climate in the Pacific Northwest and Alaska, USA.” 6 July 2009. Accessed Online 7 August 2009 and The National Park Service. “North Cascades National Park Complex: Glacial Monitoring Program.” Accessed Online 10 July 2007 and Global Glacier Retreat Project. Nichols College. Accessed Online 5 July 2007 and Jackson, K.M. and Fountain, A.G. “Spatial and morphological change on Eliot Glacier, Mount Hood, Oregon, USA.” Annals of Glaciology 22 (2007): 222-226 and Fagre, DB. “Adapting to the Reality of Climate Change at Glacier National Park, Montana, USA.” Proceedings I Conferencia Cambio Climático 2005.

The 2007 September Arctic sea ice minimum extent was the smallest on record. This ice has been in a declining trend since 2002, with warmer temperatures favoring melt and prevailing winds favoring ice transport out of the Fram Strait between Greenland and Scandinavia. There has been a slight recovery in ice levels since 2008, although the multiyear ice extent in March 2011 was lower than it was in any year prior to spring 2008, following the fall 2007 record minimum. The measurement of multiyear ice, or ice that has survived at least one melt season, is important for assessing the robustness of the Arctic sea ice, which has traditionally been a permanent, not seasonal, feature of the North Pole. Between 1980 and 2011, the percent of multiyear sea ice present in March declined by 33 percent, while the percentage of multiyear ice at the September minimum declined by 50 percent. In March 2011, only about 45 percent of the ice present in the Arctic was multiyear ice, compared with 75 percent in 1980. Additionally, in March 1980, about 50 percent of the ice cover was particularly old ice (older than five years), whereas by this March that number had declined to 10 percent. The last four years have seen a marked decline in the survival rate of multiyear ice, which is now at 74 percent, compared to the 1980 to 2006 period when the survival rate was 90 percent.

Seasons: Summer

Source: Maslanik, J et al. “Distribution and trends in Arctic sea ice age through spring 2011.” Geophysical Research Letters 38 (2011): L13502.

After the snow melts in high-elevation meadows of the central Rocky Mountain region, pollinators hatch and flowers bloom. Flowers need pollinators for reproduction and pollinators need flowers for food via the nectar they provide. Many species of pollinators are generalists, meaning that they can feed on a variety of flowers, as opposed to specialists which usually rely on only one species. Generalists typically have longer lifecycles that extend throughout the warm season. They rely on a staggered system of flowering for a consistent supply of food, with different species of flowers growing on different sites and blooming at different times throughout the season. Sites include dry, rocky areas with shallow soils, wet soil sites at lower elevations often adjacent to streams, and mesic sites that are dryer than wet sites but have more developed soils than dry sites. Traditionally, the wet and dry sites have had two peak periods of flowering, one in the late spring and one in the late summer, with flowering that takes place on the mesic sites bridging the gap between these two peaks. A study of flowering behavior and temperature based on observations from Rocky Mountain Biological Laboratory collected between 1974 and 2009 showed that when compared to the seven years with the lowest July-August temperatures, the seven years with the warmest July-August temperatures featured second, late-season flowering peaks on the dry and wet sites that were an average of 25 days later in the season. These peaks tended to be smaller with fewer flowers. Warmer years also exhibited the development of a mid-season “valley” at the mesic sites when less flowering occurred. This means that warm years tend to include a mid-summer period where there is a lack of flowers and nectar that generalists like bumblebees and the broad-tailed hummingbirds need to survive. The average July-August temperature at the study site has increased by 2.5 degrees Fahrenheit since 1974.

Season: Summer

Source: Aldridge, G et al. “Emergence of a mid-season period of low floral resources in a montane meadow ecosystem associated with climate change.” Journal of Ecology 99 (2011): 905-913.

Water conditions along the Pacific Northwest coast are controlled by the Northern California Current (NCC) system, which features a strong alongshore northward flow of warm waters during winter and a southward flow of cool waters during the summer. On longer time scales, the Pacific Decadal Oscillation (PDO) is a cycle where abnormally warm and abnormally cool conditions shift across the North Pacific. During positive PDO phases, warm conditions in the northeastern Pacific accompany a stronger wintertime northward flow in the NCC that favors the survival of warm water plankton, fish and even seabird species in places as far north as Vancouver Island, Canada. Negative phases with cool conditions feature stronger summertime southward flows that favor the survival of cool water plankton, which tend to be richer in fats and more nutritious than their warm water counterparts. This variability in nutrition levels in the waters influences the survival rates of juvenile salmon, which enter the ocean and begin feeding on plankton in April and May, just after the current shifts. These salmon return upstream a year and a half later in the autumn to spawn in the place they were born. Water samples taken off the coast of Newport, Oregon during different phases of the PDO were used to analyze associated changes in plankton community compositions and then compared to Coho salmon survival rates. Years when more fat-rich plankton species were present were years when juvenile Coho salmon survival rates were the highest.

Seasons: Winter, Spring, Summer, Fall

Source: Hongsheng, B et al. “Transport and coastal zooplankton communities in the northern California Current system.” Geophysical Research Letters 38 (2011): L12607.

Range, the geographic area where a species is located, can shift in response to habitat changes such as land use changes, the introduction of a new species, the elimination of a competitor or internal species dynamics such as a genetic mutation that allows individuals to tolerate new conditions. It can also shift in response to climate change. Birds in midlatitude areas like the United States generally move their ranges closer to the Equator when Earth cools, such as during the ice age thousands of years ago, and closer to the poles as the Earth warms. While not all birds that have shifted their ranges in recent decades have moved northward, most species that have expanded their ranges have expanded them in that direction. This has been observed in both Europe and North America over the past five to six decades. The only factor that is consistent across both Eastern and Western Hemispheres since 1950 that could account for the general northward shift is a multi-seasonal warming with northern hemisphere spring maximum temperatures increasing by two degrees Fahrenheit. This has likely prompted Northern Hemisphere birds to travel farther north on their spring journeys to warm season breeding grounds. An analysis of similar bird taxa (several orders of arboreal and semiarboreal insectivores and granivores) demonstrates a northward range expansion at a rate of about 1.5 miles each year since the 1970s for southern species formerly limited by cool temperatures.

Two warbler species have been particularly quick to take advantage of the warmer conditions: the Kentucky Warbler and the Golden-Winged Warbler. The Kentucky Warbler’s mean breeding range latitude is now about 88 miles farther north than it was in the 1970s, while the mean latitude of the Golden-Winged Warbler is about 136 miles farther north.

Above: Mean range shifts for the Kentucky and Golden-Winged Warblers since the 1970s. This image is provided by Earth Gauge and is free for distribution and use on-air.

Download image in high resolution
(1920×1080 jpg file)

Download image in low resolution
(640×360 jpg file)

Season: Summer

Source: Hitch, AT and Leberg, PL. “Breeding Distributions of North American Bird Species Moving North as a Result of Climate Change.” Conservation Biology 21 (2007): 534-539.

Range, the geographic area where a species is located, can shift in response to habitat changes such as land use changes, the introduction of a new species, the elimination of a competitor, or internal species dynamics such as a genetic mutation that allows individuals to tolerate new conditions. It can also shift in response to climate change. Birds in midlatitude areas like the United States generally move their ranges closer to the Equator when Earth cools, such as during the ice age thousands of years ago, and closer to the poles as the Earth warms. While not all birds that have shifted their ranges in recent decades have moved northward, most species that have expanded their ranges have expanded in that direction. This has been observed in both Europe and North America over the past five to six decades. The only factor that is consistent across both Eastern and Western Hemispheres since 1950 that could account for the general northward shift is a multi-seasonal warming with northern hemisphere spring maximum temperatures increasing by two degrees Fahrenheit. This has likely prompted Northern Hemisphere birds to travel farther north on their spring journeys to warm season breeding grounds. An analysis of similar bird taxa (several orders of arboreal and semiarboreal insectivores and granivores) demonstrates a northward range expansion at a rate of about 1.5 miles each year since the 1970’s for southern species formerly limited by cool temperatures.

In the Great Lakes region, two species have been particularly quick to take advantage of the warmer conditions: the Swainson’s Thrush and the Blue-gray Gnatcatcher. The Swainson’s Thrush mean breeding range latitude is now about 88 miles farther north than it was in the 1970s, while the mean latitude of the Blue-gray Gnatcatcher is about 195 miles farther north.

Above: Mean range shifts for the Swainson's Thrush and Blue-gray Gnatcatcher since the 1970s. This image is provided by Earth Gauge and is free for distribution and use on-air.

Download image in high resolution
(1920×1080 jpg file)

Download image in low resolution
(640×360 jpg file)

Season: Summer

Source: Hitch, AT and Leberg, PL. “Breeding Distributions of North American Bird Species Moving North as a Result of Climate Change.” Conservation Biology 21 (2007): 534-539.

Boreal (Northern Hemisphere) spring is here. Even in the high northern latitudes, temperatures are beginning to warm and plants are beginning to come out of dormancy and photosynthesize, using the Sun’s energy to turn water and atmospheric carbon dioxide into sugar and grow. Snow cover may seem like a relic of winter, but snow also effectively reflects sunlight off the ground. In the boreal forests of the Northern Hemisphere, snow still covers much of the forest floor. Gaps in the tree canopy allow sunlight to hit snow on the ground, which reflects sunlight back towards the trees above. The amount of energy the trees receive from this reflection can even exceed the amount of energy they get from the initial downward wave of sunlight! It is likely that this reflection gives the trees a boost of energy, giving them the kick they need to “wake-up” and photosynthesize. This boost may be diminishing in importance as the duration of Northern Hemisphere snow cover has been shrinking at a rate of 5.5 days per decade over the past 40 years. Most of this decline in snow cover duration is due to melting in the late winter and early spring period.

Seasons: Spring

Sources: Choi, G et al. “Changing Northern Hemisphere Snow Season.” Journal of Climate 23 (2010): 5305-5310 and Pinty, B et al. “Snowy backgrounds enhance the absorption of visible light in forest canopies.” Geophysical Research Letters 38 (2011): L06404.

Trivia Question: Why does Earth have seasons?

a) Because the Earth is far away from the Sun in December and close to the Sun in July
b) Because the Sun is stronger during different times of the year
c) Other planets get between the Earth and the Sun during winter
d) Because Earth tilts on its axis

The correct answer is d. The Earth is tilted at an angle of about 23.5 degrees. The part of the Earth that leans toward the Sun changes over the 365.25 day period it takes for Earth to make one complete orbit. On June 21 the Northern Hemisphere is tilted towards the Sun and is gets lots of daylight and more solar energy, while the Southern Hemisphere is tilted away from the Sun.  The opposite is the case on December 21. On March 21 and September 21, the angle between the Sun’s rays and the Earth’s surface is 90 degrees and everyplace on the globe has an equal number of hours of day and night.

Season: Spring

Source: Strahler, A and Strahler, A. Physical Geography: Science and Systems of the Human Environment. New York: John Wiley and Sons, Inc., 2002.

The 2010 Atlantic hurricane season ended on November 30th, but Earth’s climate still “remembers” the tropical storms that formed during the Northern Hemisphere warm season. Far from being just passive products of heat in the tropics, tropical cyclones cool sea surface temperatures while warming sub-surface waters. They transport heat up into the atmosphere and towards the poles, and dry the tropical atmosphere by encouraging rainfall. These effects “linger;” sea surface temperatures can remain anonomalously cool for 50-60 days after the passage of a category three or greater hurricane. Weather conditions and sea surface temperature distributions in the tropics affect the variability of the weather in mid-latitude regions, and the lingering effects of tropical storms can be felt in the United States as late as March. Each year, there are on average 63 tropical cyclones in the Northern Hemisphere. Active tropical cyclone years, or years with 68 or more storms, tend to be years with subsequent Northern Hemisphere winters that feature less of a temperature difference between the tropics and Arctic. The less this temperature difference is, the less potential energy there is to drive the mid-latitude storm tracks. Less active Northern Hemisphere tropical cyclone seasons, or years with 57 or fewer storms, tend to be seasons with more potential energy for the winter storm tracks.

Source: Hart, RE. “An inverse relationship between aggregate northern hemisphere tropical cyclone activity and subsequent winter climate.” Geophysical Research Letters 38 (2011): L01705.

Trivia Question: Why does Earth have seasons?

a) Because the Earth is far away from the Sun in December and close to the Sun in July
b) Because the Sun is stronger during different times of the year
c) Other planets get between the Earth and the Sun during winter
d) Because Earth tilts on its axis

The correct answer is d. The Earth is tilted at an angle of about 23.5 degrees. The part of the Earth that leans toward the Sun changes over the 365.25 day period it takes for Earth to make one complete orbit. Right now, the Northern Hemisphere is tilted away from the sun and is getting fewer hours of daylight and less solar energy. The Southern Hemisphere, however, is getting an abundance of sunlight and temperatures are warm. Thus, while December 21-22may be the shortest day of winter in the Northern Hemisphere, it is the longest day of the year in the Southern Hemisphere.

While the Earth is closer and farther away from the sun at different points in the year, it is actually closest during the winter and farthest away during the summer!

Above: A schematic diagram illustrating the differences in hemispheric orientation relative to the Sun at different points of the year, the mechanism behind Earth’s seasons. Image Courtesy of the National Weather Service.

Season: Winter

Source: Strahler, A and Strahler, A. Physical Geography: Science and Systems of the Human Environment. New York: John Wiley and Sons, Inc., 2002.

Trivia Question: As temperatures have warmed since the 1960s, birds in the United States birds have moved their wintering grounds…

a) farther north
b) farther south
c) closer to the ocean
d) to the east

The correct answer is a. As temperatures have warmed since the mid-1960s, most bird species that have shown significant changes in where they winter have moved farther north. Globally, species are moving their ranges – range being the geographic extent of where a species lives – towards the poles at a rate of 3.8 miles per decade. Because they are particularly mobile animals, birds are shifting their ranges particularly quickly. In North America, 60 percent of the 305 species tracked are on the move and spending their winters an average of 35 miles farther north than they did in the mid-1960s. Some species that are moving north particularly rapidly are the Wild Turkey, the Purple Finch and the American Robin.

Season: Winter

Sources: Parmesan, C and Yohe, G. “A globally coherent fingerprint of climate change impacts across natural systems.” Nature 421 (2003): 37-42 and The National Audubon Society. “Birds and Climate Change: Ecological Disruption in Motion.” February 2009. Accessed Online 3 December 2010 <http://birdsandclimate.audubon.org/>