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Course of American History Shaped by Mysterious Deep Freeze

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Course of American History Shaped by Mysterious Deep Freeze Page Climate10 1st e dition Cyan M agenta Yellow Black 10 OUR CHANGING WORLD, Thursday, January 12, 2006, Bangor Daily News Continued from Page 4 kind of evidence telling the whole Today, climate is the provenance story,” Jacobson said. Only from all long before our cities were built and ice age, a period of alternating of scientists, not philosophers, these stories from ice cores, lake sedi- that very likely will happen again. ments, fossils, tree rings, coral reefs, And once the natural systems are warm and cool phases that began Four times over the past 500 mil- although this gumbo of disciplines lenniums, ice has advanced, as rocky cliffs and even old diaries will a defined, the role that we play in trans- 2½ million years ago. — incorporating geology, biology, though on a regular schedule. The full picture of the past emerge. forming the climate will become clear, “We’re still in the ice age, and oceanography, chemistry and, most recent glaciation, which ended “The data becomes so diffuse and Jacobson said. most people don’t know what the ice increasingly, social sciences such as between 12,000 and 17,000 years ago, broad and plentiful that one person “It’s only in understanding the age is,” Borns said. history and archaeology — requires formed Maine’s landscape. Glaciers more than a little faith. can’t handle it all,” said Hal Borns, natural variability that we can see The woolly mammoths that once marched over the sheets of scraped over the rocky ground, Mayewski travels the world, sav- founder of the multidisciplinary Cli- what’s happening today,” he said. ice atop what is now Bangor are chiseling the peaks and valleys of ing ice cores from rapidly melting mate Change Institute. long gone, but millions of years of Baxter State Park and the White glaciers in hopes that they can “All the knowledge just can’t be ‘We’re still in the ice age’ climate data indicate that the Mountains. reveal the history of the world. locked up in one or two people,” Mainers joke about the brevity of a world may be poised on the edge Then, as the ice receded, melting Other scientists hunt messages in Borns said. New England summer, claiming that of the next glaciation, or cool water rushed over the land, leav- rock formations. Jacobson seeks At the University of Maine, one of all they have to do is blink once and phase of the ice age. Of course, to ing long, narrow deposits of sand knowledge in ancient pollen several centers for climate research the snow is falling again. But warm climate scientists, who think on and gravel that snake across the trapped far beneath lake waters. around the country, scientists are periods of time in which the state mind-boggling time scales, that state. Each believes that the information piecing together the history of the experiences anything that can be natural world in hopes of someday called a summer have been tremen- edge could last for many human “Over a period of just 4,000 or is there, waiting to be tapped. 5,000 years, there was an incredibly being able to predict the sorts of dras- dously rare — just 10,000 years of generations. “It’s not a simple matter of one rapid change from Maine being cov- tic changes that affected the planet heat for every 100,000 years of snow. “Some people say we’re 500 to 1,000 Earth is still in the throes of an years overdue,” Borns said. “We’ve ered by ice to being covered by for- been through the warm spell.” est,” Jacobson said. Continued on Page 11 Changes in temperature, salinity, currents mean ripple effects elsewhere When the wind starts to blow and the rain starts to fall, most people don’t nor’easters to Maine are also at blame the oceans for their plight. the whims of global climate. But the waters that cover more than Currents are put in motion by 70 percent of Earth’s surface are inti- cold water sinking to the sea bot- mately linked to the planet’s climate. tom in the polar regions because “Many people think climate is the it becomes more dense and holds weather. In fact, the ocean is the more salt as it loses its heat to largest driver of climate,” said Fei the air. The cold water moves Chai, an oceanographer with the Cli- downhill along the sea bottom mate Change Institute at the Universi- toward the equator, where it ty of Maine. warms and returns to the sur- In the real world, the oceans and the face. Prevailing winds then atmosphere lack the distinct boundary drive the warm surface water lines depicted in textbooks. Water, car- back toward the poles. The bon dioxide, oxygen and other mole- result is continual motion cules constantly travel back and forth throughout the oceans. between the air and the sea. This system was dubbed “the Most coastal residents understand great conveyor belt” by climatol- how the oceans help to moderate tem- ogist Wallace Broecker of the perature by warming or cooling Lamont-Doherty Earth Obser- breezes that pass over the water en vatory at Columbia University, route to land. because it drives much of the The oceans play a similar role on a world’s weather. Scientists cite Arctic Ocean global scale. The sea can absorb or changes in the circulation pat- release a tremendous amount of tern as a major factor in past ice heat, slowing the impact of a climate ages. The system has been rela- shift. tively stable for the past 200-300 The oceans also hold a great deal of years, after likely playing a role Pacific Atlantic Ocean carbon dioxide, one of the most abun- in the cold phase known as the Ocean dant greenhouse gases. Carbon is pres- Little Ice Age between the 14th ent in all living things — including and 19th centuries. t But if Earth becomes too Heat released Indian urren plankton and the calcium carbonate ace c to the atmosphere Ocean surf structure of clams and corals — which warm, millions of gallons of Warm will eventually decompose, creating fresh water from melting polar gla- more carbon dioxide. ciers and icebergs could pour into “A cooler ocean tends to hold carbon the sea, interfering with the tem- dioxide — like a can of Coke,” Chai perature and salt balance, or ther- explained. “When you have warmer mohaline, that maintains the cur- Deep cold current Cold saline water, the CO2 starts bubbling out of rents. deep current the water into the air. “The ocean transports a lot of This is just one of the many climate heat from the western side of the Great Ocean Conveyor Belt: Thermohaline circulation phenomena that concern scientists, Atlantic to the eastern side,” Chai An ocean circulation pattern known as the “conveyor” moves heat around Earth through a like Chai, who produce models predict- said. globally interconnected movement of ocean waters primarily driven by differences in heat and salt ing what might happen if the climate Without this conveyor belt, the content known as thermohaline circulation (“therm” for heat and “haline” for salt.) Warm, low-salini- Gulf Stream, which carries warm ty water, flows north along the surface of the Atlantic, becoming saltier (red path). Cooling of this changes. For example, high levels of saltier water in the North Atlantic produces high enough densities for the water to sink and flow CO2 in the atmosphere could warm water to the United States and West- southward in the deep ocean and into other ocean basins (blue path). If Arctic ice melts and the the oceans, prompting the release of ern Europe, could weaken or change North Atlantic waters grow warmer and less salty, they will no longer sink. Some scientists specu- still more CO2 and spurring further path. late the conveyor might suddenly shut down, slowing the Gulf Stream and dropping temperatures warming. Broecker and some other scientists significantly across Europe and the Northeast United States. And as Hurricane Katrina so aptly believe they have evidence from ice demonstrated, warm oceans also can cores that suggests that this system has changed in the past, bringing ice To better understand, and predict, trigger more immediate effects. Mon- University of Maine ster storms will happen occasionally and snow to the temperate regions. the behavior of these systems, scien- 256 high-powered PCs, showing how the oceans change over time, their oceanographer Dr. Fei in any climate, but warmer water has The disaster movie “The Day After tists have deployed a small army of Chai (left) and Professor the potential to breed more ferocious Tomorrow” was based on Broecker’s buoys and free-swimming rovers to warm and cold currents strengthening Huijie Xue (seated) hurricanes. theory — albeit in a dramatically exag- monitor the high seas, transmitting and dissipating. explain an ocean circula- The ocean currents that bring mon- gerated form that depicted the start of their data by satellite. Internationally, the goal is someday tion model they have a new ice age in Manhattan over a Chai uses this and historical climate to have thousands of live data collec- extrapolated from a soons to India, El Ninos to Peru, and dozen remote moorings period of a few days. data to create complex models on a tors, drifting in all of the world’s oceans, searching for the signals that with cell phone and supercomputer with the capability of satellite uplinks from the the climate is beginning to change. Gulf of Maine. Next to them is research associ- IMPACT: ate Steve Cousins and LITTLE ICE AGE post-doctoral researcher Course of American history shaped by mysterious deep freezeMasa Fujii.
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