Let me try to explain

Two recent Facebook topics and their associated discussions have inspired me to offer two short pieces to try to explain some current issues.

Linking specific weather events to climate change

Advocates for anthropogenic global warming (AGW) often criticize those AGW deniers who cite recent blizzards, cold snaps, etc. as counterexamples to AGW, and rightly so.  But recently, some AGW advocates have at least hinted at the Sandy "megastorm" as being linked to AGW.  Folks, anyone making such a linkage is being hypocritical and is, in fact, dead wrong.

There can be little doubt that a warmer climate will have some impacts on the weather.  However, the primary thing to keep in mind is that the climate is the time average of the weather over many years (there is no specific number of years, of course).  If we wish to examine the record of global temperature, we can use various sources to produce a record thousands of years in length, and it turns out that there is unmistakeable evidence for global warming in recent years.   If we were to choose a single year as a proxy for that long-term record, what would we have?  We'd have precisely nothing of value in anticipating the future.  It makes no sense to choose a particular year as the prototype for what is to come - the weather (as well as the climate) has been changing all the time, going back to the development of the atmosphere in the very distant past.  No single data point on that long trend tells us anything about the long-term averages (i.e., the climate)!

In the same way, no single weather event (e.g., an outbreak of tornadoes in 2011, or a powerful storm bringing storm surge onto the East Coast in 2012) tells us anything about how climate might be changing.  What makes this even more problematic is that our record of storm events doesn't begin to sample the full range of what is possible, and is plagued with a host of "secular" changes in the way storms are observed and recorded.  Our knowledge of storms going backwards in time becomes unreliable long before our knowledge of global temperature becomes unreliable.

The challenge is to know just how AGW might alter the associated weather events.  If we had a reliable record of storms comparable to the global average temperature records we can construct, then there might be some hope of anticipating what AGW might do to the frequency or intensity of storms.  But the fact is that no such record exists and any linkage of a specific storm to global climate is just as stupid as picking a particular year to represent that global climate.  That is, it's just plain stupid! 

Is CO₂ a pollutant?

We generally consider pollutants to be noxious substances in the environment.  There are many natural processes that produce carbon dioxide (CO₂), including animals breathing, volcanic eruptions and fumaroles, etc.  At the moment, the percentage of CO₂ in the global atmosphere is about 0.04 percent (about 4 parts per 10,000) - it is properly referred to as a trace gas.  Whereas some compounds like nitrous oxides (NO_x) or sulphur dioxide (S0₂) are toxic even at relative low concentrations, CO₂ must reach levels of about 5 percent to be toxic (more than a thousand times the current global atmospheric value).

However, CO₂ need not be toxic for it to have a deleterious impact.  CO₂ is one of several "greenhouse gases" that act to inhibit the radiation of longwave infrared (thermal) energy from the Earth back into space.  This greenhouse effect is what makes the Earth habitable for us - without it, our temperature changes between night and day would be much larger!  The role of manmade CO₂ on the global average temperature is clearly discernible from existing records of CO₂ and temperature.  The growing concentration of CO₂ in the atmosphere is beyond reasonable doubt a primary driver in the existing undeniable global warming trend.  Thus, although CO₂ is not thought of traditionally as a "pollutant", the increasing levels of atmospheric CO₂ (as a result primarily of burning fossil fuels of all sorts) are being reflected in the current warming trend.  Thus, CO₂ is becoming a "pollutant" in the sense of having (unintended) noxious effects, even though it remains at levels well below human toxicity.

The human species is addicted to the use of energy and has been since the prehistoric discovery of fire.  We extract energy in a variety of ways, and in our modern technological civilizations, we pay for the cost of extracting energy in terms of our electricity and fuel bills.  These prices pay for the infrastructure that allows us the luxury of having that extracted energy on demand, with the flip of a switch.  And as the world supply of fossil fuels diminishes, the infrastructure costs will increase.  And an undiminished demand in the face of decreasing supply also drives the price upward.

However, we're not yet paying for the environmental degradation associated with extracting and using that energy.  We all want cheap energy (yes, me, too!), but eventually the price of environmental degradation will come due - and some forms of energy extraction have a much higher environmental impact than others.  The Second Law of Thermodynamics can be interpreted as an old saying:  There ain't no free lunch!   However, although no form of energy can be entirely free of cost, the environmental costs we eventually will have to pay are higher for some forms of energy extraction than for others.  The choices are ours.