Take frogs.  While some people eat their legs; others study them.  Back in 1995, for example, schoolchildren in Minnesota discovered a number of specimens that had more than their normal complement of hind appendages.  Further investigations revealed other abnormalities: missing limbs, twisted jaws and declining populations all around the globe.  Was it checkout time for toads?  The end of the world for amphibians?  A harbinger of even more terrible things about to descend on the rest of the biosphere?

No speculation was too great for the fertile imaginations of scientists and journalists alike.  The resultant and ever-so-popular frog-as-canary-in-a-coal-mine hypothesis linked the observations of deformed and dying swamp things to all sorts of environmental perturbations: to the widespread pollution of lakes and rivers by pesticides, to enhanced and more-hazardous ultraviolet radiation caused by presumed CFC-induced thinning of the ozone layer, to even the has-to-be-happening warming of the globe believed to be driven by mankind's CO2 emissions.

Stepping back from this particular problem, it is almost axiomatic that when knowledge is lacking in any given area, hypotheses abound; and a theory may be as great a prod to remedial action as are facts.  That is why a little knowledge is a dangerous thing; it can mistakenly point one in the wrong direction, giving an urgent sense of righteous zeal to a course of action that in a more enlightened environment might even be realized to be inimical to one's own welfare.

Fortunately, there is a proven means for dealing with such problems: science.  Plodding along, one observation after another, experiment after experiment, and meticulous measurement after meticulous measurement, its trained practitioners slowly but surely acquire new facts that either buttress or bulldoze initial ideas relative to perceived problems.  And in the case of the frenzy over frogs, new information is beginning to constrain the types of hypotheses that may logically be offered as explanations for the creatures' sad and sorry state.

In a News Focus story in the 30 April 1999 issue of Science, contributing correspondent Virginia Morell asks "Are Pathogens Felling Frogs?"  Her comprehensive survey of scientific studies being conducted at various sites around the world answers this question in the affirmative.  Based upon work in the United States, Central America, and Australia, Morell notes that, although "massive frog die-offs have for years been linked to environmental conditions," that hypothesis is beginning to look less and less tenable.  Instead, she reports, "new data from Australia suggest that the real killer may be a deadly fungus."

This particular frog pathogen - Batrachochytrium dendrobatidis - was recognized as a lethal disease only nine months prior to the publication of Morell's report and was not even given a name until the month before her story appeared in print.  Already, however, it has been proven to kill healthy frogs in the laboratory; and by studying preserved specimens, it has been implicated "in some of the very die-offs that first raised the amphibian alarm in the United States."

So what about its link to global warming?  That possibility now seems pretty tenuous, especially in view of the fact that both Australian and American laboratory studies show that the "chytrid," as it is called, is hard to grow above 30°C and that it normally wrecks its havoc in cold and wet habitats.  In fact, the decline of the once-common lowland leopard frog in Arizona remained a mystery for many years, until researchers extended their normal summer studies into the winter, when the then-unnamed pathogen was found to be decimating whole populations of the species.

No, global warming does not appear to be the cause of the dwindling frog and toad numbers it was once opined to be; and other recent studies have also lessened the likelihood that it could be the cause of the amphibian deformities observed around the world.  In another News Focus story that appeared in the very same issue of Science, news writer Jocelyn Kaiser recounts how trematodes, a type of parasitic flatworm, have recently replaced various types of environmental change as the prime suspect in this case as well, based upon two research reports also published in the 30 April 1999 issue of Science.  In the first of these studies (Johnson et al., 1999), the researchers demonstrated that the kinds of limb abnormalities and other deformities seen in frogs in natural settings could be precisely duplicated by infecting tadpoles with the trematode parasite; while the second study (Sessions et al. 1999) demonstrated that the pattern of duplicated limbs found in five species of frogs from twelve different localities in California, Oregon, Arizona and New York was consistent with a purely mechanical effect that has been induced in the laboratory and shown to be nearly identical with the physical perturbation caused by the presence of trematode infestation.

As nice as it is to see that global warming has thus been largely "let off the hook" with respect to the mysterious amphibian maladies that have been observed around the globe in recent years, the demonstration of that fact was not the main reason for writing this essay.  Rather, it was to illustrate the ancillary fact that initial thinking on a topic is not always correct, especially if the subject is complex.  And when comparing the difficulty of determining the cause of the frog die-offs and deformities with that of determining the cause or causes of past and future climate change, the former more focused task would appear to be much easier than the latter, which includes the development of an integrated understanding of an enormous number of diverse and complicated subsystems.

Clearly, the cause of the warming that has allowed the earth to recover from the global chill of the Little Ice Age has not been satisfactorily established (see our Vol. 2, No. 10 Editorial Commentary Human Contribution to Climate Change Remains Questionable).  To attribute the temperature rise of the past century to the concomitant buildup of atmospheric CO2 at this stage of our understanding of global climate dynamics is truly on a par with accepting the frog-as-canary-in-a-coal-mine hypothesis.  It is premature at best and may even be totally wrong (see our Vol. 2, No. 7 Editorial Commentary CO2 and Temperature: The Great Geophysical Waltz).  We should therefore let science continue its course, until the answer to the climate conundrum is at least as close to being obtained as is the answer to the mystery of the dying and deformed frogs, before we attempt to play doctor with the biosphere (see our Vol. 1, No. 6 Editorial Commentary First, Do No Harm!).  The hurried judgments of learned scientific bodies have been wrong in the past; and history has an uncanny way of repeating itself (see our Vol. 2, No. 6 Editorial Commentary It's Happened Before ... It Can Happen Again).

So where does this all leave us?  Perhaps with something all sides could actually agree upon.  Just as most people at both poles of the CO2-climate issue spectrum are willing to accept that the historical rise in the air's carbon dioxide concentration has probably been driven by anthropogenic CO2 emissions (but which is not an absolutely proven fact), so too do nearly all of them realize that postponing action on the issue for another decade of additional research will not materially alter the final outcome of whatever plan may ultimately be deemed appropriate to deal with the problem, if it truly is a problem.  There is no compelling need to rush to judgment on so weighty a matter.  Let's let science run its course before we act.