Florissant Scientific Society notes—Aug 1, 2004
Speaker: David Atkins
Location: Florissant Fossil Beds (open FFBNM seminar)
Topic: Global Climate Change
Quote of the day: “How can we produce more methane than carbon dioxide? We breathe more than we fart.”
David spent about 2 ˝ hours presenting the very controversial topic of global climate change, primarily through the use of many charts and graphs. He explored the various postulated causes of climate change, generally grouped into astronomical, solar activity, tectonic, and atmospheric. It is the latter that considers the impact of greenhouse gases, the thrust of so much debate today.
Milankovitch cycles consider astronomical motions of eccentricity (100,000 yrs), obliquity (41,000 yrs), and precession (19,000-25,800 yrs). These are generally agreed to impact climate change.
Solar activity is a primarily forcing factor for climate change. About 1370 w/sec/m2 strike the earth. Fifty one per cent of solar radiation is actually absorbed at the surface; the remainder is reflected back into space. Sunspot activity has an 11.1 yr cycle.
Tectonic activity has some influence on climate through changes in water volume in the oceans, the building of mountains as topographic circulation barriers, etc. The world’s oceans currently store 97% of the water on planet Earth. Circulation patterns clearly change due to plate tectonic motions through time. How the water in oceans is connected, and moved along global currents, impacts climate. For example, the Gulf Stream moves 15 million cu m/sec water. It has been periodically shut off, probably due to fresh water dilution from Siberia. This process can rapidly cool the climate of northern Europe.
Carbon isotope analyses of ice cores since 1890 show a surprisingly high frequency record of change. This is probably reflective of Earth’s long-term history: the only thing constant is change. Ice cores are stored at the USGS facility, Federal Center, Denver. Today we are cold in terms of earth history. It is likely misleading to take decades of warming, coupled with data from the last few thousand years, and conclude we are approaching a disaster the industrial revolution has produced.
With respect to greenhouse gases, GWP (global warming potential) is a key parameter to evaluate specific gases. GWP is normalized to carbon dioxide:
Carbon dioxide 1
Many charts considering the impact of greenhouse gases on climate change do not address water vapor. Since the GWP for water vapor is so high, this is a major mistake! Certain charts are also extremely misleading because they choose a period coming out of the last ice age maximum of 18,000 yrs. That shows significant warming, but does not put the big picture in context, that the earth has generally been much warmer than today. Cooling cycles seem to happen rapidly—possibly within a matter of decades—but recover long term.
Hydrates—frozen methane ice just below the sea floor—make up a large methane budget that potentially could add to green house gases if they were to be added to the atmosphere via a sudden sea level drop or some other change to their stability field.
In conclusion, solar variability, rather than changing carbon dioxide content, appears to be the primary forcing factor for climate change. However, this is not the conclusion of parts of the scientific community; research on the man-made influence on climate change brings in the dollars because it is politically popular. Could man-made green house gases be THE trigger for climate change? Possible, but highly unlikely. Good science strongly suggests that the earth has experienced many episodes of warming and cooling, long before humans populated the planet. There are too many potent natural factors impacting climate.
WIPS next year is conducting a symposium on a similar theme: Extinctions, Punctuations, and Time, about March 12-13.