Is It Warm in Here?

May 18, 2013

The May 11 issue of The Economist has an interesting, though disturbing, short article on one measure of global climate change: the percentage of carbon dioxide [CO2] in the atmosphere.  This has recently reached a new high in recent history.

AT NOON on May 4th the carbon-dioxide concentration in the atmosphere around the Mauna Loa Observatory in Hawaii hit 400 parts per million (ppm).

Now, 400 ppm does not sound very high; after all, it is only 0.04%.  However, as the article goes on to point out, this concentration of CO2 has not been routinely present since the Pliocene epoch, about 4 million years ago.

The data series  is from the observatory at Mauna Loa in Hawaii, run by the Scripps Institution of Oceanography, part of the University of California at San Diego.  This series (sometimes called the Keeling Curve in honor of the scientists who initiated the project) is of particular interest for two reasons:

  • The observation site is remote from large centers of human population, minimizing fluctuations due to temporary pollution spikes.
  • The observations have been made consistently, at the same place, since 1958.

There is a regular seasonal fluctuation in CO2 levels, tied to plants’ growth cycles.  In the northern hemisphere, levels tend to peak in May, and then fall until about October, as plants’ growth removes carbon dioxide from the atmosphere.

Carbon Dixoide Levels at Mauna Loa

Source: Scripps Institution of Oceanography

The seasonal pattern is clearly visible in the graph.  The more striking thing, of course, is the steady rise in the carbon dioxide levels, an increase of more than 25% over the observation period.  And there is no evidence that the rate of increase is getting smaller.


Still Getting Warmer

July 29, 2012

Back in October of last year, I posted a note here about a new study that examined historical records for evidence of global warming.   The study, which confirmed previous results that the global average temperature had increased by 1°C since 1950, was somewhat noteworthy, because it was led by a self-described former global warming  skeptic, Prof. Richard A. Muller, who is a professor of physics at the University of California, Berkeley, and a Faculty Senior Scientist at the Lawrence Berkeley National Laboratory.  The research work, which is available at the BerkeleyEarth.org project site, examined some potential methodological problems with earlier research — notably the “urban heat island” hypothesis, and the questionable quality of some of the historical data — and found that correcting for them did not have any significant effect on the result.  (My earlier post, linked above, has a more complete discussion of the research.)  That study, though, did not address the question of why the warming was occurring.

Now Prof. Muller has published an Op-Ed column in the New York Times, in which he describes some new research that provides some significant evidence that the human-caused increase in atmospheric “greenhouse gases” (such as carbon dioxide and methane) is the cause of the warming.

Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause.

The historical pattern observed by the team (the data are also available at the project web site) shows some expected short temperature dips, following large volcanic eruptions, which eject large amounts of particulate matter into the air, thereby shading the Earth’s surface from some solar radiation.   There are also some small, short-term variations in temperatures that can be attributed to fluctuations in ocean currents, such as El Niño and the Gulf Stream.  But there was only one indicator that was strongly correlated with the long-term temperature trend.

We tried fitting the shape to simple math functions (exponentials, polynomials), to solar activity and even to rising functions like world population. By far the best match was to the record of atmospheric carbon dioxide, measured from atmospheric samples and air trapped in polar ice.

Prof. Muller notes that their historical data covers a long enough period that by analyzing it in connection with sunspot data, changes in solar activity can be essentially eliminated as a cause of global warming.

… our data argues strongly that the temperature rise of the past 250 years cannot be attributed to solar changes. This conclusion is, in retrospect, not too surprising; we’ve learned from satellite measurements that solar activity changes the brightness of the sun very little.

Prof. Muller further notes, correctly, that the strong correlation observed between carbon dioxide levels and temperature increases does not prove that the latter are caused by the former.  However, any posited alternative explanation should explain the historical record at least as well if it is to be taken seriously.   (There is, in the greenhouse effect, a plausible physical / chemical mechanism by which increased carbon dioxide levels could cause warming.)

Prof. Muller also says (and I agree) that many of the claims made about global warming are “speculative, exaggerated, or just plain wrong”.  The real point, though, is that there is more and more evidence that the average temperature on Earth is rising, and that it is being caused as a by-product of human activity.


Legislative Lunacy, Revisited

July 5, 2012

Glendower:   I can call spirits from the vasty deep.
Hotspur:       Why, so can I, or so can any man;
But will they come when you do call for them?
— Wm. Shakespeare, Henry IV Part I, III:1

From time to time, I have posted here about some of the more exotic efforts of some US state legislatures, such as the statute in South Carolina (since repealed) that required subversive organizations to pay a $5 fee to register with the state, or the Louisiana legislation which would require additional penalties if a crime involved the use of maps.  It sometimes seems that at least some of these legislative bodies are engaged in a contest to see which can produce the most ridiculous legislation.  Of course, Indiana has long had a strong position in this contest, with its attempt in 1897 to set the value of the mathematical constant, pi [π], by legislation.

Blog posts at The Economist‘s site report a couple of new entries to the contest.   The first entry, reported on the “Babbage” science and technology blog, is from North Carolina.  It seems that a state scientific commission released a report saying that, based on climate change predictions, the sea level  at the state’s Atlantic coast might rise by more than three feet.

Aghast at a state commission’s scientific findings about the local sea level rising 39 inches (or one metre, as it is known to the rest of the world) by 2100, coastal business leaders and property developers pressured the state’s legislators into banning all sea-level projections based on climate-change data. As a result, House Bill 819 would require future projections to use only historical data.

Now it is certainly true that a one-meter rise in sea level would have a grave economic effect on the state.  It derives a good deal of tourism income from vacationers that visit the coast, especially along the chain of barrier islands called the Outer Banks.   (The Wright brothers made their famous first flight there, near Kitty Hawk.)   I’ve visited there; it is a very pleasant place, and there is no doubt that a good deal of it would be decidedly damp if the sea level rose by three feet.  I guess the legislature can forbid the state’s agencies from publishing studies.  But do they think that they can legislate a higher sea level out of existence?

The second entry, from the “Democracy in America” blog, is from Georgia.  It seems that the state’s voters are to be asked to approve an increase in the sales tax, in order to fund transportation projects.

On July 31st, Georgia’s voters will decide whether to impose upon themselves a one-cent sales tax for the next ten years to fund transportation projects. Voters in each of Georgia’s 12 regions will have seen (or at least, will have had the opportunity to see) the list of projects their tax will fund; money collected in that region will be spent in that region.

There are, as one might expect, a variety of projects that are proposed under this initiative; there is also debate about the merits of the various proposals.  Most of this debate is relatively rational, but unfortunately some of it is not.

It also raises an insane question: are Atlanta’s Democratic mayor, Kasim Reed, and Republican attorney-general, Sam Olens, both agents of the United Nations determined to advance the cause of one-world government and outlaw private property?

The issue apparently arises because some of the proposed plans include provision of paths for pedestrians and cyclists alongside highways.   According to some local politicians, this is the thin edge of the wedge for an attempt, known as Agenda 21,  by the United Nations to take away Georgians’ freedoms.

That’s Agenda 21. Bicycles and pedestrian traffic as an alternative form of transportation to the automobile.

The scope of this UN conspiracy is breathtaking.  Just think, back when our distant ancestors first walked upright on the African savannah, they were preparing for this dastardly plot.   And everyone knows that people who ride bicycles are bound to be socialist atheist terrorists.  (There might even be a connection with the events in North Carolina.  After all, the Wright brothers were bicycle mechanics — what more do you want?)

My grandfather was fond of saying, “Most people are dumber than average.”  I am beginning to be convinced that he was right.


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