Ph.D. Geophysics, University of Michigan, 1963-present
Global Climate Change
Ann Arbor Science & Skeptics Meet Up
Scientists have discovered ways to study the earth’s climate, going back millions of years and those who specialize in studying ancient climates are known as Paleoclimatologists. Paleoclimatologists use natural elements in the environment to find “proxy climate data” related to the past. Studies of these types use several different methods of collecting data, so they are assured of forming the most accurate analysis possible.
These principle data points come from:
Mountain Glaciers and the polar ice caps and ice sheets are a widely employed source of data in paleoclimatology. Recent ice coring projects in the ice caps of Greenland and Antarctica have yielded data going back several hundred thousand years—over 800,000 years in the case of the EPICA project.
Climatic information can be obtained through an understanding of changes in tree growth. Generally, trees respond to changes in climatic variables by speeding up or slowing down growth, which in turn is generally, reflected a greater or lesser thickness in growth rings.
Sediments, sometimes lithified to form rock, may contain remnants of preserved vegetation, animals, plankton or pollen, which may be characteristic of certain climatic zones.
Biomarker molecules such as the alkenones may yield information about their temperature of formation.
Chemical signatures, particularly Mg/Ca ratio of calcite in Foraminifera tests, can be used to reconstruct past temperature.
Isotopic ratios can provide further information. Specifically, the δ18O record responds to changes in temperature and ice volume, and the δ13C record reflects a range of factors, which are often difficult to disentangle.
On a longer time scale, the rock record may show signs of sea level rise and fall; further, features such as “fossilized” sand dunes can be identified. Scientists can get a grasp of long term climate by studying sedimentary rock going back billions of years. The division of earth history into separate periods is largely based on visible changes in sedimentary rock layers that demarcate major changes in conditions. Often these include major shifts in climate.
Coral “rings” are similar to tree rings, except they respond to different things, such as the water temperature and wave action. From this source, certain equipment can be used to derive the sea surface temperature and water salinity from the past few centuries.
Dr. Pollack’s specialties include:
Geophysics, tectonophysics, geodynamics, heat flow, Paleoclimatology, global change
Henry Pollack’s principal research efforts have been in geothermal and other geophysical studies as applied to the dynamics and evolution of the solid earth and its recent climate. He and his students have constructed a geothermal laboratory and conducted field measurement programs in Africa and South America. His geothermal research has contributed to an understanding of the thermal and petrologic evolution of continents and of the earth as a whole. Currently he is making use of subsurface thermal data to investigate climate change and global warming.
The Ann Arbor Science & Skeptics held a get together with guest speaker Dr. Henry Pollack to discuss the current trend in Climate Change and the effects on the world as we know it now and the future politically and socially.
Earth’s climate and the biosphere have been in constant flux, dominated by ice ages and glaciers for the past several million years. Approximately every 100,000 years Earth’s climate warms up temporarily. These warm periods, called interglacial periods, appear to last approximately 15,000 to 20,000 years before regressing back to a cold period. Global warming during Earth’s current interglacial warm period has greatly altered our environment and the distribution and diversity of all life. Approximately 15,000 years ago the earth had warmed sufficiently to halt the advance of glaciers, and sea levels worldwide began to rise. By 8,000 years ago the land bridge across the Bering Strait was melted, cutting off the migration of Homo sapiens and animals to North America. Since the end of the Ice Age, Earth’s temperature has risen approximately 16 f and sea levels have risen 390 ft.
One of the questions posed, was man actually contributing to Global Warming and how strong is the evidence:
Dr. Pollack brought up the CO2 concentration levels as evidence of our involvement. The concentration of carbon dioxide (CO2) in Earth’s atmosphere is approximately 390 ppm (parts per million) by volume as of 2010 and rising by about 1.5 to 2 ppm/yr. Carbon dioxide is essential to photosynthesis in plants and other photoautotroph, and is also a prominent greenhouse gas.
The most direct method for measuring atmospheric carbon dioxide concentrations for periods before direct sampling is to measure bubbles of air (fluid or gas inclusions) trapped in the Antarctic or Greenland ice caps. The most widely accepted of such studies come from a variety of Antarctic cores and indicate that atmospheric CO2 levels were about 260 – 280 ppm immediately before industrial emissions began and did not vary much from this level during the preceding 10,000 years (10 ka). In 1832 Antarctic ice core levels were 284 ppm. The longest ice core record comes from East Antarctica, where ice has been sampled to an age of 800 ka. During this time, the atmospheric carbon dioxide concentration has varied by volume between 180 – 210 ppm during ice ages, increasing to 280 – 300 ppm during warmer interglacial.
What this means to us is at the current trend of 1.5 to 2 ppm of CO2 increase, by 2040 we could see CO2 levels in the 435 to 450 range, thus increasing the greenhouse effect and in turn increase total global temperature averages.
Two significant effects of this greenhouse heating will lead to melting of many coastal and some intercostal glaciers. Melting of the Greenland ice sheet alone would produce 7.2 m or 23 ft of sea-level rise. This would displace as many as 100 million people just in the United States and with already scarce fresh water sources in the American west (notably the Arizona and Nevada aquifers as well as the Colorado river that no longer reaches it’s destination, the Gulf of California and stops short just few hundred miles south of Lake Havasu City, Arizona) the encroachment of sea water would invariably destroy already stressed fresh water sources.
The time is now to start making Manhattan Project style efforts and changes to our social and political atmosphere and move toward eliminating CO2 emitting energies and adding Wind Turbine, Photovoltaic and Thermal Convection energy sources, which in turn would project us into a leader in emerging technology’s and provide much needed jobs for our future.