StoryImage( ‘/Images/Story//Auto-img-11690678064532.jpg’, ‘Image courtesy of www.wetwired.org’, ‘According to Dr. Carlson, the excessive levels of CO2 that have accumulated in the atmosphere since the onset of industrialization in the 1850s are sufficient in themselves to warm the planet and melt all the ice now covering North America and Greenland. Melted ice would raise the sea level around the world approximately 22 meters. Many of the worlds seaport cities, including Boston and New York, would be covered. ‘);
Thanks to the Burpee Museum and Museum President Lew Crampton, Rockford area residents had the opportunity to hear a prominent glacial scientist explain how evidence is gathered that links rising carbon dioxide (CO2)levels and global warming.
Anders Carlson, Ph.D., is a post doctoral scholar at the world-famous Woods Hole Oceanographic Institute in Massachusetts. This fall, he will become a faculty member at the University of Wisconsin. He specializes in glacial geology and ice sheet dynamics. As a youth in Rockford, Carlson nourished his budding scientific bent eagerly participating in Museum programs.
According to Dr. Carlson, the excessive levels of CO2 that have accumulated in the atmosphere since the onset of industrialization in the 1850s are sufficient in themselves to warm the planet and melt all the ice now covering North America and Greenland. Melted ice would raise the sea level around the world approximately 22 meters. Many of the worlds seaport cities, including Boston and New York, would be covered. If we stopped burning fossil fuels today, the ocean would gradually absorb the excessive levels of carbon dioxide over a couple of thousand years.
Carlson explained how scientists gather and analyze data, which enables them to reach conclusions on how rising CO2 levels impact ice sheets which, in turn, control the level of the seas. Air trapped between frozen crystals in core samples drilled from ice masses provides evidence of changes in atmospheric conditions. Such studies have established that over the last 650,000 years, prior to the onset of industrialization and burning of fossil fuels, carbon dioxide in the atmosphere has varied from a low of 180 ppm to a high of 280 ppm. These natural changes are controlled by the tilt of the earth and changes in the distance of its orbit from the sun.
Twenty-one thousand years ago, when the last continental glacier was at its maximum expanse, the sea level was roughly 450 feet lower than when the earth was warmer, and the atmosphere contained 280 ppm. Thirty-five million years ago, when CO2 levels reached 1,300 ppm, there were no ice sheets left on any part of the globe.
Dr. Carlson explained numerous other methods used to establish evidence supporting how rising CO2 levels affect ice masses and control the level of the oceans. Carbon dating establishes the age of glacial deposits, such as the Marengo moraine just east of Rockford. The age of exposed granite rocks deposited at the farthest reach of a glacier can be determined by measuring accumulated beryllium isotopes from quartz crystals shattered by protons and neutrons from the sun. Pollen samples from lake bottoms reveal which plants were in the area in earlier times. Their specific temperature and moisture requirements indicate the climate in which they grew. Cross section samples of silt and clay layers deposited on the ocean floor adjacent to the Greenland ice mass allow scientists to determine how fast the ice was melting and the temperatures on the surface of the ice mass at various times. Previous sea levels can be determined from the remains of specific coral reefs, which grow 16 feet below the surface. Coral reef remains on terraces above the ocean near Papua, New Guinea, are indicators of previous high ocean levels.
Using the data collected by scientific studies around the globe, the 2001 International Panel on Climate Change report developed computer models estimating that global temperatures would rise between 1 degrees C and 5 degrees C within the next 100 years. Resulting glacial meltwater would raise ocean levels between 2 and 5 feet.
Evidence accumulated after the 2001 report indicates the worlds ice sheets are melting at a much faster rate than originally thought. Data collected on the Greenland ice sheet from 2003 through 2006 documented the accelerated rate of melting. Water from the melting surface flows down crevasses and spreads across the base of the ice sheet, accelerating the rate at which the ice mass slides toward the ocean. The closer the ice mass is to the warmer ocean water, the faster it melts.
It has also been established that ice masses have melted abruptly twice in the past. About 19,000 years ago, ice equivalent to two Greenland ice sheets melted within 500 years, raising the sea level some 40 feet. About 14,500 years ago the equivalent of three Greenland ice sheets melted within 500 years, raising the sea level around 70 feet. If we are entering a period of abrupt ice melt, the results could be felt in hundreds of years rather than the thousands previously assumed. According to Carlson, we are just beginning to feel the impacts of global warming.
Extreme weather events are expected to be more intense and frequent with widescale destruction of buildings and infrastructure and disruption of agricultural output, placing large numbers of people at risk. This calls for a dramatic cutback in burning fossil fuels and increased carbon sequestration. According to some estimates, this combination could add 30 percent to the cost of electricity.
As pointed out in the recent Stern report on global warming, it is far cheaper to initiate action to cut carbon emissions now than wait until widespread damage occurs. The 2006 IPCC report, to be released in March, will further document the accelerated rate at which global warming is occurring. The time to act is now.
This column is based on a lecture by Anders Carlson, Ph.D., at the Burpee Museum of Natural History, Jan. 4.
Drs. Robert and Sonia Vogl are founders and officers of the Illinois Renewable Energy Association and coordinate the annual Renewable Energy and Sustainable Lifestyle Fair. They have 3.2 kW of PV and a 1 kW wind generator at their home. Forty acres of their 180-acre home farm are in ecological restorations. They are also active in preserving natural areas. They are retired professors from Northern Illinois University.
From the Jan. 17-23, 2007, issue