Global Warming Redux Paleo-climate clues to today's climate change
Without the slightest evidence of an interest in understanding historic climate change - change that puts their current projections to shame - the IPCC drones on with the same flawed message: humans are destroying the planet (see "chicken little" and "Al Gore" for more). This, from the same "scientists" who predicted just thirty years ago (1) we had only a 10-year supply of known oil reserves, and, (2) the human population bomb would overwhelm the planet by the year 2000. You sure you want to buy into their claims about climate change?
Who decides which is the "correct" global temperature? That is: radical environmentalists claim that the CO2 released into the atmosphere by our techno-industrial society has caused the global climate to warm, thereby portending catastrophic consequences for us all. Yet, over the eons, absent homo sapiens, Mother Earth has experienced wide swings in temperature. For example: except for a few short cold-spells, the period between about 3.0 billion and 40 million years ago found both poles ice-free. (See Fig 1, below) Then, about 40 million years ago, temperatures plunged into an unexplained cold-snap that has continued until today, culminating in the last couple of million years - the Pleistocene Epoch - in the regular advance and retreat of the great polar ice-sheets (See Fig 2 below).
Historically, closer to home, during the pre-industrial era, paleoclimatologists have identified four distinct climatic periods: the Roman Warm (circa the 1st to 5th centuries), the Dark Ages Cold (circa the 5th to 8th centuries), the Medieval Warm (circa the 10th to 14th centuries), and the Little Ice Age (circa the 16th to 19th centuries). Each of these periods exhibited temperatures a degree or 2° C above or below the current period. Therefore, one might ask:
What point on the global temperature curve is the "correct" point? That is, which is the "correct" global temperature?
And, who decides these things?
To get a feel for the blizzard of direct and inferential evidence existing out there for the post-ice-age climate (ranging from about 11,000 years ago to the present), "google" for "Holocene climate". Pay special attention to the "Pre-Boreal" period, when the climate, at least in the British Isles, might have warmed by as much as 7° Celsius in as little as seven years. And, while you're at it, check out the "Climatic Optimum", also referred to as the "Holocene Maximum", the time period between 4,000 and 7,000 years ago when global temperatures reached as high as 2.0° C warmer than present.
In the mid-1990s, the idea that the climate sometimes changes suddenly and dramatically generated a new field of study: "RCCEs" ("Rapid Climate Change Events"). Both the beginning and the end of the "Younger Dryas" are RCCEs (See Fig. 4, below) For many more RCCEs, find the Greenland Ice Sheet Project Two (GISP2) and the Greenland Ice Core Project (GRIP).
Or, for starters, you might hit: Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event, published in, Nature, 1993 - (362: 527-529), by Alley, Meese, Shuman, Gow, Taylor, Grootes, White, Ram, Waddington, Mayewski, and Zielinski.
Or, for a quick overview, see Earth's Climatic History: The Last 2,000,000 Years, from the Center for the Study of Carbon Dioxide and Global Change - (www.co2science.org), which relates:
Large and rapid shifts in climate have been detected in areas of the North Atlantic, Greenland, and in Antarctica from deep-sea sediment cores, ice cores, lake sediments, and pollen series that cover this period of time. Most of these records provide climatic descriptions of the last glacial cycle, with some continuing on through the Emian interglacial over 120,000 years ago.
In Greenland, rapid warming - approximately 7° C in a few decades - was observed around 11,500 years ago (Dansgaard et al., 1989; Johnsen et al., 1992; Grootes et al., 1993). Alley et al. (1993) also report evidence of even more rapid shifts in precipitation patterns, and other authors have noted swift changes in atmospheric circulation (Taylor et al., 1993; Mayewski et al., 1993). Sea surface temperature changes of around 5° C, associated with sudden changes in oceanic circulation, also occurred in a few decades in the Norwegian Sea (Lehman and Keigwin, 1992). Similar warming following the latest deglaciation occurred in regions of the Southern Hemisphere, though the warming there was less abrupt (Suggate, 1990; Denton and Hendy, 1994; Salinger, 1994; Jouzel et al., 1995).
During the last glacial cycle, large warm-cold oscillations have been detected in central Greenland ice cores (Johnsen et al., 1992). Rapid warmings of between 5° and 7° C occurred in a few decades, followed by periods of slower cooling and then a rapid return to glacial conditions.
Around 20 such interstadial events occurred during the last glacial period and lasted between 500 and 2000 years (Dansgaard et al., 1993). Similar rapid changes have been discovered in North Atlantic deep-sea cores, indicating massive iceberg discharges from the Northern Hemisphere ice sheets (Bond et al., 1993; Mayewski et al., 1994; Bond and Lotti, 1995); and they were followed by abrupt shifts to warmer sea surface temperatures. Additional records from Western Europe, North America, and China (Grimm et al., 1993; Guiot et al., 1993; Porter and An Zhisheng, 1995) document rapid shifts in climate during the last glacial period; and such records have prompted the IPCC to categorize these interstadials as "at least hemispheric in their extent" (Houghton et al., 1996).
All charts below come from J. D. Macdougal's, Frozen Planet, the Once and Future Story of Ice Ages, University of California Press, 2004.
Periods of Significant Global Ice Coverage
In Figure 1 above, the spaces between vertical lines represent periods during which both poles remained ice free. The vertical lines approximate the times at which previous ice-age events might have occurred, and the height of the lines approximates the intensity of these events. One current theory holds that, during the "Snowball Earth" Period, on more than one occasion, ice might have covered the entire planet.
Global Temperature Change, Past 70 million Years From Deep Sea Core Analyses
Figure 2 was constructed from data collected from the isotope oxygen analyses of fossils recovered from deep-sea coring. The sharp drop at the right denotes the Pleistocene Epoch, the last few million years during which the advance and retreat of the ice sheets have occurred.
Global Temperature Change, Past 600 Thousand Years From Deep Sea Core Analyses
Figure 3 was derived from oxygen isotope analysis of deep-sea cores. Note the valleys, the coldest years, occur at about 100,000 year intervals, and the peaks, the warm spells, like the one we're in now, do not last long - perhaps ten or fifteen thousand years. The last ice-sheet began retreating about 11,000 years ago. Thus, if the pattern holds, you might want to start looking at Florida property.
Global Temperature Change, "Younger Dryas" Period From Central Greenland Ice Core Analyses
Figure 4 was constructed from data collected from central-Greenland icecores as published by P. M. Grootes and M. Stuiver in Journal of Geophysical Research 102 (1997): 26455.
Note the dramatic drop in temperatures at the start of the Younger Dryas followed about 1,200 years later by a sudden rise that the data suggest was 8° Centigrade in less than a decade!
Point: Until we understand events like the Younger Dryas, does anyone out there seriously believe that we ought to throw in with Al "I-am-NOT-crazy" Gore and board up the factories?
Biography - Bernard Switalski
Graduated high school, 1953. U.S. Army lab technician, Bell Telephone Labs guided missile R&D, White Sands Proving Ground, NM, 1954-1957. Railroad freight conductor, Chicago, 1958-1963. Petroleum products quality/quantity surveyor, mostly in Venezuela, 1964-1965. Blast furnace foreman, Chicago,1966-1968.
After that damn blast furnace put me in the ER, got into the heavy industrial construction industry, 1969. First job, laborer. Last job, general construction superintendent, contracted by a Spanish consortium to oversee the construction of a 4 billion dollar grassroots petroleum refinery in Sumatra.
Somewhere in there, picked up a BA in philosophy. Traveled a lot. As old Cap'n Bill Jensen used to say back there on the Orinoco, "Been round the world two dozen times, first time in a baby buggy, twice in a submarine." Jigged for cod from a dory off Newfoundland; ran like a sissy from an irate cobra in Brunei. Met lots of good people along the way.
Switalski died, April 13, 2009 in Riverdale, Illinois.