A recent visitor to the Academy brought this article from the National Post to my attention. After visiting our Altered State: California and Climate Change exhibit, reading the article raised some questions for our visitor. The article is very typical of a certain segment of the media that tends to politicize the science of climate change in a skeptical manner. I responded to both our visitor's questions and the article, and I've posted my response below. I should point out that there is also certainly politicization of climate change science on the other side of the issue, and I will take this up in another posting.
Thank you for your comments on the museum and the climate change exhibit.
And thank you for the link to Lorne Gunter's article in the National Post. I
will indeed comment on it, but first let me address your question about solar
inactivity and cooler temperatures.
Solar activity is indeed one of the major influences on global temperature
and climate (see my blog entry here).
This activity tends to wax and wane cyclically on a couple of different
frequencies. The first is a seasonal one and is very easy to understand; it's
based on the orientation of the Earth's northern and southern hemispheres as
it orbits the sun. The second is a frequency that is roughly decadal, and is
more difficult to understand. It obviously has something to do with the
internal fluid mechanics of the sun, which in turn is influencing how much
heat is produced, but we don't understand exactly why it cycles in such a
Now, what does this have to do with ongoing global warming? Not much. The
influence of the sun has not varied very much for a very long time, and while
the amount of heat that it contributes does indeed vary over time, the
Earth's warming trend is progressing independently of solar output. We have
considered solar activity very carefully, and it simply cannot explain the
observed warming. The fact that this keeps coming up again and again in
the "skeptics" media is, frankly, an annoying and dishonest misrepresentation
Mr Gunter's article...I'll pick this apart in a sequential manner. First,
notice that he refers to a string of news stories, not scientific articles.
He is simply wrong in implying that it is difficult to publish scientific
articles skeptical of global warming. A more accurate observation would be
that there are constantly articles questioning, checking, and re-checking
ideas and observations of the warming, and many of them run counter to our
current ideas. For example, it was recently demonstrated that the Greenland
ice sheet might not be melting as rapidly as previously thought (whew).
Another example would be the worry first raised a few years ago that deep
water circulation in the Atlantic was slowing down as the Arctic warmed. We
know now that the slowdown is part of a long-term cycle that is not being
driven by global warming (yay). And I could go on. What Mr. Gunter should
state is that the "string of news stories" really refers to the
self-perpetuating and unvetted output of an agenda-driven group of
journalists, himself included, and not the scientific literature.
The number of climate skeptics in the scientific community is not growing
at all. I believe that I am better informed of this than Mr. Gunter is. I do the science, I
read the journals, I write articles, I review articles, I go to conferences
and meet, chat and argue with colleagues. Mr Gunter does not.
The thrust of his article is summarized by the statement, "Because a funny
thing is happening to global temperatures -- they're going down, not up."
Well now, doesn't global temperature always go up and down on certain
timescales? Isn't is cooler in winter and warmer in summer? What he is
referring to is the recent discovery of a multi-decade trend in North
Pacific/northern hemisphere temperatures, the Pacific Decadal Oscillation,
and we are indeed entering a cool phase. So yes, we can expect a slight
cooling over the next 20 years (that's good news). However, and this is a
very important "however", this cooling trend is imprinted on a longer-term
and constant rise in temperature, the global warming trend. So while the
cooling will occur, it will not be as significant as it would be in the
absence of human-caused, greenhouse gas-driven warming, nor will it be
permanent. As soon as the cycle begins to wane, the global warming trend,
which will have continued in the background, will make itself felt.
And who ever said that the Medieval Warm Period (MWP) "had to be made to
disappear"? This one made me laugh. The MWP is an absolutely fascinating
paleoeclimatic episode, and lots of scientists study its causes and effects
every day. Just look it up on Google Scholar. But it's surrounded by
questions such as, how long did it last? How widespread was it? Did it occur
at the same time in all places? Whatever the answers, it seems that the MWP
was a real phenomenon, but that it was not a synchronous nor global event.
Note that even Mr. Gunter concedes, "...the period from 800 AD to 1300 AD was
unusually warm, particularly in Northern Europe." Ah, if only the world
consisted only of Northern Europe, how much easier it would be to understand.
I'll just skip ahead toward the end of the article where the NASA record is
discussed. Look at the graph. To draw the conclusion that global
temperatures "have given back" (whatever that is supposed to mean) most of
the warming that has occurred since 1980, from that graph, is a terrible
conclusion. I suppose that in the same way that some economists are
apparently inept at reading financial charts, there are apparently folks
applying the same ineptness to climate science.
In summary, let me just say that this non-scientific skepticism is
intellectually challenged. Scientists don't "believe" in this or that
conclusion (see this blog post,
June 2007). We observe, we measure, we
hypothesize and test, and we reject our hypotheses or we fail to reject them.
It is what we are trained to do. It underlies the care with which we designed
the Academy's climate change exhibit. If we did not discuss solar influence,
it is because it has no meaningful impact on the problem. Mr. Gunter and his
friends would do well to visit our exhibit with an open mind.
Again, thank you for visiting the Academy, and your kind words regarding our
efforts. And thank you for your questions. The Academy is here because we ask