Extremes

The year of extremes
Climate changes already apparent; Northeast should be prepared for its turn

By Richard A. Rehberg, Ph.D.
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Extreme weather has made the Weather Channel a source of unending fascination this year.

In North America, Texas and Oklahoma experienced record rainfall. Searing heat, severe drought, and intense brush and forest fires plagued the West and the Southwest. Georgia, Alabama, the Carolinas, and Virginia experienced prolonged drought. Atlanta, Ga., worries whether it will have drinking water beyond the New Year. Record 100-year floods plagued parts of the American Midwest. A tornado struck Brooklyn, New York. Severe thunderstorms shut sections of the New York City subway system. Intense hurricanes swept the Caribbean and Central America, and floods have just inundated much of the Mexican state of Chiapas. Fortunately, in the Southern Tier, we enjoyed a rather pleasant summer.

Europe and Asia have experienced extreme weather as well. May, June and July were the wettest in England and Wales since records began in 1766. Rainfall in Germany was the highest in May since observations began in 1901. Southeastern Europe suffered record-breaking heat during June and July. Heavy rains ravaged areas of Southern China, bringing hardship to almost 14 million people, with more than 120 deaths. Long-term drought threatens to cut farm output in Australia by up to 20 percent and economic growth by 1 to 2 percent.

Weather is what we experience today, this month, and this year. No single weather event -- for example, Hurricane Katrina -- can be attributed to climate change. However, when we average weather over longer periods of time, say over 30 years or more, we have what scientists call climate. Actual weather measurements, including temperature and precipitation extend back 100 or more years. Cores drilled from Greenland and the Antarctic as well as from the ocean beds enable scientists to infer the Earth's climate 300,000 to 400,000 years into the geological past. By studying climate over these periods, scientists are able to understand how our climate is changing.

Climate change over the planet

That the Earth's climate is changing is regarded as "unequivocal" by the Intergovernmental Panel on Climate Change. Since the 1800s, the average temperature of the planet has risen by almost 2 degrees Fahrenheit. More than half of that increase has occurred since the late 1970s. Carbon dioxide (CO2) is the greenhouse gas responsible for about 50 percent of observed human-caused climate change. Since the Industrial Revolution began in the early 1800s, atmospheric concentrations of CO2 have risen from 280 parts per million (ppm) to over 385 ppm today. Methane, nitrous oxide and other trace gases also contribute. Greenhouse gases are the "trapdoors" of our atmosphere: open to the shorter wavelengths of the sun's incoming energy, energy that warms the surface of the Earth, but closed to the longer wavelengths (infrared) of that energy that is reradiated to our atmosphere. Once trapped within the atmosphere, that energy warms our planet. The more fossil fuel we burn the more greenhouse gases we emit and the warmer the planet becomes. Absent substantial reductions in our burning of fossil fuels and forests, atmospheric CO2 is projected to rise by 2050 to 450 to 550 ppm and by 2100 to 900 to 1,000 ppm. During this period, average global temperatures are projected to increase by between 4 and 10 degrees Fahrenheit.

Other evidence confirms the changing of Earth's climate:

* Ocean temperatures to depths of 10,000 feet are rising, indicating that the oceans have absorbed more than 80 percent of the heat added to the climate system;

* Ice sheet losses are accelerating both in Greenland and the Antarctic;

* Arctic temperatures have risen at almost twice the global rate in the past 50 years;

* Atmospheric water vapor is increasing (warmer air holds more moisture);

* Global precipitation is increasing;

* Periods of intense rainfall are becoming more frequent;

* Severe droughts occur more often;

* Cold days and nights are decreasing; warm days and nights are increasing, spring arrives almost a month earlier and fall a month later;

* Heat waves are rising in frequency and intensity; and

* Hurricanes in the Atlantic and typhoons in the Pacific are becoming more intense.

Climate change here in the Northeast

We in the Northeast should not expect our weather good fortune of this past year to continue. Our region already has been affected by climate change. Since 1970, the Northeast has been warming at a rate of nearly 0.5 degree Fahrenheit per decade with winter temperatures rising even more rapidly at a rate of about 1.3 F per decade from 1970 to 2000.

Indeed, "Confronting Climate Change in the U.S. Northeast," a report released in July of this year by the Northeast Climate Impacts Assessments (NECIA) team notes that warming over the past 40 years or so, our region has been marked by:

* More frequent days with temperatures above 90 F;

* Longer growing seasons;

* Less winter precipitation falling as snow and more as rain;

* Reduced snow pack and increased snow density;

* Earlier ice breakups on rivers and lakes;

* Earlier spring snowmelt resulting in earlier river and stream peak flows.

Moreover, because of the heat already stored in the oceans and the heat trapping gases now in the atmosphere, NECIA projects that by mid-century and beyond temperatures in the Northeast will rise another 2.5 to 4 F in winter and 1.5 F to 3.5 F in summer.

If United States, China, and India continue their "high emissions" of carbon and other greenhouse gases, then we may anticipate a "starkly" different climate future. Under this "high emissions" scenario, the NECIA projects for the Northeastern United States that by 2100 (when our children and grandchildren shall have inherited our future):

* Winters in the Northeast will warm by 8 to 12 F and summers by 6 to 14 F above historic levels;

* The snow season in northern New York, Vermont, New Hampshire and Maine will be cut in half;

* Northeastern cities will average 20 or more days of 100 F-plus temperatures compared with only a few such days at present;

* Short-term droughts (one to three months) could occur as often as once each summer in the Catskills and the Adirondacks and across New England;

* Extreme coastal flooding that now occurs only once a century could strike New York City on average once a decade;

* Hemlock stands that shade and cool Northeast streams could be lost to pests that thrive in warmer weather with the result that many steams will lose their shade, thus raising their temperatures and threatening native brook trout and other favorite species;

* As forest habitat changes, migratory songbirds such as the Baltimore oriole, American goldfinch and song sparrow may become less abundant;

* Parts of the Northeast may become unsuitable for growing certain varieties of apples, blueberries and cranberries. Milk production will be subject to decline significantly in the warmer months.

Immediate and substantial action by the world's major economies, including the United States, India and China, could and would avoid Northeast climate change of the magnitude we have just described. NOTE: With a lower-emissions scenario, projected changes might be only half the magnitude of those described for the higher-emissions scenario.

In California, both Governor Arnold Schwarzenegger and the Legislature, informed and inspired in part by examples set by the European Union, have committed the state to reduce its greenhouse gas emissions to pre-1990 levels by the year 2020. They have set an even more ambitious goal of an 80 percent reduction below 1990 levels by 2050. New York state is considering similar ambitious reductions. Almost all scientists believe that such dramatic reductions must be achieved by all of humanity if we are to avoid potentially catastrophic climate change.

Which leaves us with this critical question: if California, New York, and a number of other states, along with much of Europe, recognize the severity the challenge posed by climate change and appear to be acting rather decisively to address that challenge, why is there so little evidence of bold and decisive leadership in Washington?