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  • Putting Global Warming In Perspective

    Posted by Michael Hiteshew on January 16th, 2005 (All posts by )

    The graph below is what’s got everyone talking about global warming. It’s a graph of the change in average global temperature since the beginning of the industrial era.

    Average Global Temperatures Since 1861

    It shows, quite conclusively you’ll agree, that making steel, using a leaf blower and driving your SUV is raising carbon dioxide (CO2) levels in the atmosphere. And because CO2 is a greenhouse gas, carbon dioxide raises the average temperature of the Earth. So, when Kansas turns into a desert and Florida disappears under the ocean, it’s your American gas-guzzling fault. Correct?

    Not so fast, my media propagandized reader. The Woods Hole Oceanographic Institute (WHOI) has been doing extensive research on the question of global warming and have begun to weigh in with their results. Their verdict can be summed up in one sentence: The earth has been warming and cooling in regular cycles for hundreds of thousands of years. At least.


    What we’ve been seeing is what I’d term ‘cherry picked’ data, designed to support a particular political agenda. How many of us have been shown graphs like the following?

    Change In Average Temperature In Antarctica Over 450,000 Years

    Looks like a heartbeat doesn’t it? It’s quite regular. Whatever process is driving global warming and cooling has been doing it on approximately 110,000 year intervals for at least the last half million years. Other data shows similar changes over the last million years.

    So what process is driving this clockwork-like cooling and heating of the earth? One possible explanation is Croll-Milankovich Cycles, a combination of three things:

    A) Orbital Eccentricity – A slow change in the shape of Earth’s orbit from more circular to more elliptical on a time scale of approximately 100,000 years.

    NASA has a nice kids site with a really useful animation of the change in Earth’s orbital shape over time.

    B) Precession of the Equinoxes – The slow wobbling of the Earth on it’s polar axis. For example, think of the way a top slowly wobbles on it’s axis as it spins. The Earth does the same thing, taking about 26,000 years to make one wobble.

    (Off topic note: The Equinox is the name given to those two times each year when night and day are of equal length. It occurs once in the spring, the Vernal Equinox, and once in the fall, the Autumnal Equinox. The name literally translates as ‘equal night’. Over time, as the Earth wobbles on it’s axis, the point where the sun rises at Vernal Equinox moves backward as seen against the the constellations behind it. This is what is meant by the equinox ‘precessing’ (precess: to go before). When the study of astrology was begun, the Sun was rising against the constellation of Aries at the Vernal Equinox. That’s why astrological lists begin with Aries. The Sun is currently rising against Pisces and will soon (in about 200 years, IIRC) begin rising against Aquarius. That will be the “Age of Aquarius” for those old enough to remember the musical Hair. )

    C) Tilt – The Earth currently has a tilt of about 23 1/2 degrees with respect to it’s orbital plane around the Sun. The tilt of the Earth’s axis moves through range of 21.8 to 24.4 degrees over 41,000 years.

    On a finer scale, research into temperature patterns shows more confusing results. Lloyd Keigwin, Senior Scientist in the Geology and Geophysics Department, has a paper in Oceanus entitled Sedimentary Record Yields Several Centuries of Data in which he discusses the results of the study of a long series of measurements made at sea and the study of deep sea sediments. His result?

    “I found a consistent pattern of sea surface temperature change (see figure). The core-top data indicate temperatures of nearly 23 degrees, very close to the average temperature at Station S (Sargasso Sea) over the past 50 years. However, during the Little Ice Age of about 300 years ago sea surface temperatures were at least a full degree lower than today, and there was an earlier cool event centered on 1,700 years ago. Events warmer than today occurred about 500 and 1,000 years ago, during the Medieval Warm Period, and it was even warmer than that prior to about 2,500 years ago.

    Although this is not universally accepted, it is widely accepted that eventually changes to Earth’s atmosphere will cause climate warming. The message from the Bermuda Rise is that human-induced warming may be occurring at the same time as natural warming—not an ideal situation.”

    I think Lloyd Keigwin summed it pretty well. Carbon dioxide is a greenhouse gas (by the way, so is water vapor) and it probably is adding to the average global temperature to some degree. To what degree? I don’t think anyone knows. However, it is certainly not the primary engine of global warming, as some would have us believe.

     

    13 Responses to “Putting Global Warming In Perspective”

    1. The Sanity Inspector Says:

      Speaking of CO2, don’t forget the Keeling Curve This is the result of an ongoing measurement of the increase in that gas in the atmosphere since 1958. It’s a fact. The debate over global warming is over the interpretation of that fact, among others. Global warming holds that the increase in CO2 is a) real, b) growing, c) artificial, and d) a menace.

      My political leanings incline me to be skeptical of most environmental scaremongering. But the global warming thesis was not hatched by a small band of granola-gobbling Sixties flotsam. Many scientists working independently in different disciplines over the past several decades followed clues that led to this hypothesis. That’s how major earth science discoveries are frequently made, like plate tectonics. Speaking as someone who grew up reading science columns by Isaac Asimov, and knows little more about science than what I read in the popular monthlies and on PBS, I think there is more to global warming than can be dismissed with some smashing jeers by conservative commentaters. It bears watching, and study, though of course we shouldn’t allow ourselves to be buffaloed into precipitate action until we’re all convinced of the need for it.

    2. David Says:

      Sanity,

      I don’t get it. The Keeling Curve measures CO2 concentrations at one location on Earth, which just happens to be Mauna Loa, the largest, and one of the most active, volcanoes on the planet according to the USGS.

      The article you linked doesn’t explain how Keeling controlled for CO2 emissions from the volcano, or what rising CO2 measurements near a single active volcano over a 45 year period have to do with global CO2 concentrations or global warming.

      But there are two pictures of the plaque commemorating the “Keeling Building”.

    3. Craig R. Harmon Says:

      The message from the Bermuda Rise is that human-induced warming may be occurring at the same time as natural warming—not an ideal situation.”

      Not an ideal situation, indeed. The thing that struck me about the second graph was not just the regularity of the previous warming periods but the lack of regularity of the present one. That is, the previous three warming peaks reveal that we spent a very short period of time above the baseline relative to the current warming. We have spent more than half of the last 50,000 years at or above or only slightly below the baseline.

      It seems indeed true that global warming is a cyclical and naturally occurring phenominon. I have no doubt that we will, at some point take a nose-dive south, temperature-wise. Will our contributions to the natural effect cause the warming period to continue for an unnaturally long period of time? Will it have an effect on the steepness and depth of the cooling period? What will that mean for the future livability on earth?

      I don’t think anybody knows, either…that’s what troubles me.

    4. Michael Hiteshew Says:

      Sanity,

      Take a look at this graph. This is from the accompanying article:

      “Establishing the exact role that atmospheric CO2 played in past natural climatic oscillations, however, is not a simple matter. Changes in atmospheric CO2 may have been more a response to climate change than a forcing mechanism. On the other hand, while we know that the pace of Quaternary glaciations was primarily driven by variations in Earth’s distance from the sun and in the angle of Earth’s axis of rotation, the resulting changes in incoming solar radiation to the planet’s surface are too small to account for the large climate variability observed. This implies that the effect of these orbital parameters must have been amplified by some internal feedback mechanisms within the earth’s environment, and we suspect that atmospheric CO2 may be a major factor. In view of its obvious connection to present societal concerns, this particular problem has elicited a lot of attention in the paleoceanographic community.”

      It’s interesting that atmospheric CO2 seems to have peaked around 130,000 years ago. We haven’t yet matched that level.

    5. Bill Hight Says:

      A global warming period is easier to survive than an ice age. When given the choice between global warming and global cooling, always choose the warming. The next ice age will kill several billion people. Unfortunately, it is unlikely that humans can produce enough CO2 to ward off the next ice age. And no, it is very unlikely that global warming ever caused an ice age. That is a lively fantasy fit for movies. I understand the science very well, but the evidence doesn’t support the theory.

      Climatologist have to get funding. They have lives too, and need an income. The way to get funding as a climatologist is to appear as if you support the “human caused global warming disaster” thesis.

      These graphs look better than they actually are. You can look at them and think they are telling you something when they are not, or worse yet, they are misleading you.

      The problem is that we have good measurements for the last hundred years or so, fair measurements for the past few thousand years, mediocre measurements for the past tens of thousands of years, and absolutely atrocious measurements for greater than 50 or 100 thousand years ago.

      No wonder the graphs going back many hundreds of thousands of years appear so regular–they are based on so few data points as to be almost worthless.

    6. Michael Hiteshew Says:

      it is very unlikely that global warming ever caused an ice age

      That is correct. A short Q&A on the subject can be found here.

      However, the situation is complicated. The oceans are *the primary heat exchanger* for the entire planet. For that process to work properly, though, it’s necessary that the ocean be essentially homogenous in it’s salinity. Melting of arctic ices can cover key points in the ocean conveyer system with fresh water, shutting the heat exchanger down for landmasses warmed by the Gulfstream, mainly Europe.

      A surface layer of fresh water also interferes with the abiility of the ocean to exchange heat with the atmosphere. (Diagram here)

      However, I agree we don’t want a return of the Ice Ages. I support more research with the goal of moderating the climate to the best of our ability. Let’s see if we can break the cooling cycle without going overboard into a runaway greenhouse effect.

    7. Steve Says:

      The earth’s oceans also act as a biological “sponge” for CO2, via plankton blooms.

      A millenium after a remarkable rise in atmospheric CO2, sedimentary studies should reveal an increased layer of carbonate plankton skeletons on the sea-floor.

      As far as I know, no proponents of Global Warming have factored biological CO2 absorption into their models.

      -Steve

    8. jj Says:

      The atmosphere is so vast that any man induced co-2 is diluted to parts per bazillion, Plus in this dilution, the refractiveness of co-2 to cause the alleged greenhouse effect is non-existant.

      Same can be said of the hoax over CFC’s doing in the ozone, the concentrations of CFC vs. the vastness of the atmosphere make the theory bullshit.

    9. dick Says:

      What I can’t understand is that the same scientists who are complaining about this long global warming cycle are the same ones who were warning us about a coming ice age due to a global cooling cycle about 25-30 years ago. Which is it to be?

    10. MisterBixby Says:

      I could not recommend State of Fear by Michael Crichton more. Of course, he completely disagrees with the notion of global warming.However, he presents citations throughout the novel (which is actually a pretty gripping story in itself) to allow the reader to come to his own conclusions. In the end the case against global warming is:

      1. there is no real indication that anthropogenic CO2 levels are that high.
      2. it’s likely that a small net rise in CO2 would actually be beneficial to the biosphere.
      3. there’s no substantial warming over the last 150 years, and, in fact, temperatures seem to have declined since about 1940.
      4. the climate of the earth is so beyond complex that none of the claims of so-called climatologists ten to twenty years ago have even come close to coming true. If we can not accurately predict the weather for a given area for the next ten days, how can we possibly make a prediction about the next ten years, 100 years, 1000 years?
      5. despite the theory’s predictions, glaciers are advancing, not retreating. Antarctic ice is thickening.

      As they used to say in those time/life book ads, Read the Book!

    11. pat Says:

      There are many sources of information regarding global warming. WHOI, just one (although a good one). If u want to focus on its results, u summary totally misses the real story which is that in WHOI’s words “Earth’s climate repeatedly has shifted dramatically and in time spans as short as a decade. And abrupt climate change may be more likely in the future. ”

      The real summary isn’t that the scare mongers should be ignored, but that we need to double up our efforts to figure out what is happening and possible solutions (even if they are not man made).

    12. Fûz Says:

      I recall that some cosmic phenomena were also being associated with climate change. Radioactive particles entering Earth’s atmosphere can trigger cloud formation at high altitudes, altering how and where the atmosphere absorbs sunlight.

    13. Steve Says:

      It’s clear that when politics intersect with science, Junk Science is the result. Popular politics takes the science out of the infallible (almost) realm of Peer review, and experimental repetition, and throws it open to scientifically-ignorant journalists and politicians.

      A friend of mine was recently hired by Sonoma County Schools (in California) to teach eighth grade science. Prior to becoming unionized, he was a global warming skeptic. One year after gaining NFT union protection, his curriculum and his emails read exactly like Democratic Party talking points. I mean verbatim.

      If our secondary education system produced more critical thinkers, and the public school teacher’s unions were busted, the media and professoriat would not get away with this so easily.

      Thanks for your post, Michael.
      Steve