I have undoubtedly made clear my opinion on global warming, but indulge me as I reiterate my view as introduction.  I agree that climate change is in fact taking place right now.  Denying that would be like denying ice is frozen water.  What I will not acquiesce to is the hype and alarmism that our planet’s climate is changing because of human intervention.  There is insufficient support for that conclusion in the data currently available, although mounting evidence suggests a possible causal relationship, one that at present shows only that greenhouse gases from human industrialization may play a part in atmospheric physics and weather patterns.  The data as yet are unclear and fail to provide the irrefutable link between one and the other.  If in fact we do play a role in climate change, our part may only be minor, or it could be major, or it could all just be coincidence, ultimately confirming we are only along for the ride.  At present, there exists no smoking gun, and as a scientist, I do not believe in jumping to conclusions without verifiable and repeatable bases in fact.

Why am I on the fence and not radically in support of or against the idea of human-induced global warming?  There are plenty of reasons, some of which I have addressed here before.  Examples include evidence showing that natural climate change 45,000 years ago caused mass extinctions in Australia, clear proof that up to 25% of air pollution is naturally occurring, the natural oscillations and cycles that helped spawn Hurricane Katrina and her friends, the discovery of natural climate change on Mars, the clear misrepresentation and incorrect extrapolations from climate data as reported by BBC News, our claims of understanding global climate when we still can’t predict smaller weather patterns with any accuracy, the truth that we don’t know why polar ice sheets are retreating in such a hurry, blatant misrepresentation of the Texas drought as proof when it was much worse a hundred years ago, the discovery of natural rapid climate change, and the real science that rebuts dire warnings that climate change is responsible for the recent Amazon drought.  These are only some examples of my own attempts to address the issue.

The keen student can find many more paradigms with only basic internet research, although they increasingly are shrouded behind alarmist media hype and scientists leaping to conclusions that go well beyond the purview of available data.  For even a cursory understanding of how complex the climate is and why there are more considerations than just greenhouse gasses, you need only look into the impact of solar variability, oceanic oscillations, historical rapid climate shifts and long-term changes, the application of chaos theory to models as large as Earth’s climate, localized meteorology, atmospheric physics, oceanic currents and saline content, Earth’s orbital changes and wobbles, volcanic eruptions, meteorite impacts, and a great many other stimuli provided independent of human activity.

Two recent announcements from the scientific community lend credence to my skepticism and support of true scientific methods and objectivity as opposed to conjecture and misguided supposition.

First, Vladimir Shaidurov of the Russian Academy of Sciences announced a new theory about global warming that is controversial because it has nothing whatsoever to do with burning fossil fuels.  To fully appreciate his theory, you should be familiar with the Tunguska event in 1908.  Believed to be a meteorite airburst 6 to 10 kilometers above what is now Evenkia, Siberia, the Tunguska event was a massive explosion in the remote Siberian wilderness estimated to be between 10 and 15 megatons.  Given the time in which the event occurred, there is as yet no conclusive evidence of what caused the explosion, yet it is believed that it felled some 60 million trees over 2,150 kilometers.  The shockwave broke windows hundreds of miles away from the actual explosion, knocked people from their feet, registered on seismic stations throughout Eurasia, left the night sky bright enough to read by for weeks afterward, and caused atmospheric pressure fluctuations measured as far away as Britain.

Shaidurov’s new theory on global warming is based on the Tunguska event and explains how the cataclysm changed the amount of ice crystals at high altitudes.  This change could negatively affect the formation of clouds in the mesosphere, and this damage might have increased* the amount of solar-induced heat that could reach the surface.  His detailed analysis of global mean temperature changes over the last 140 years seems to indicate that global warming began in the period between 1906 and 1909, thereby providing a correlative relationship between climate change and the Tunguska event.  Should it be proved that global warming began 100 years ago as his model indicates, it contradicts the premise that it began more recently and as a direct result of increased burning of fossil fuels.

It is of course important to note that this is a new theory that requires diligent evaluation and research.  The findings to date, however, are compelling, and his theory certainly raises more questions about global warming being a product of greenhouse gasses created by humans.

Second, NASA recently announced that global warming is in fact taking place and is at least a probable cause of the rapid demise of polar and Greenland ice sheets.  (Note: You’ll want to at least take a look at the top picture from that link as it’s stunning.  Click on it for a larger version.)  While NASA did not link this evidence to any phenomenon like the burning of fossil fuels, it is the most comprehensive study of global freshwater ice melt and indicates a rapidly growing problem.  As I indicated above, saline content in the oceans plays a role in climate as does oceanic currents and the amount of water.  Significant influxes of freshwater into the oceans are proved by climate proxies to be a major component in historical shifts of the planet’s weather.

NASA’s findings provide fodder for concern about a natural climate change, rapid or long-term, as more ice melts.  That water entering the oceans raises oceanic water levels, pulses massive amounts of freshwater into salt-water bodies, changes currents and density, and finally the whole system is modified.  The scale of such changes to the oceans has dramatic effects on weather patterns in both local and global ways.  The announcement by NASA that global warming is taking place and impacting the Earth’s ice reservoirs has implications well beyond what might be causing present temperature changes across the globe.

Taking both of these announcements into account, one cannot help but see that global warming is a question, not an answer, and claims of knowing definitively that fossil fuels are the cause can be irrefutably denied as blatant misrepresentations or misinterpretations of the facts.  What we see is that the climate is changing, but we know from our own records that this happens all the time independent of human activity (in both near- and far-term analyses).  It cannot be concluded that we have had no impact whatsoever on the Earth’s climate.  Likewise, it cannot be concluded that we have had an impact.  The system in question is simply too complex and misunderstood for us to be able to answer the question with veracity.

It cannot be denied that our climate is changing.  It cannot be denied that it has changed in the past, and many times long before we were more than quadruped apes struggling to make our first tools from bone, wood and stone.  In the final analysis, there remain more questions than answers in this debate, and only politically-motivated individuals will claim to know with certainty that we are to blame.

* [UPDATE 4/2/2006 @ 2:04 PM CST]: Thanks to Russell’s comment for pointing out that the analysis of Vladimir Shaidurov’s Tunguska theory I read incorrectly stated that the amount of sunlight reaching the Earth’s surface was reduced when in fact it was increased.  I’ve now updated that statement to read as such.