3:05 p.m. | Updated |
Given the flurry of attention this week around what two batches of scientists of various stripes think of evidence that humans are exerting a growing and disruptive influence on climate, it’s worth checking in with two Nobel laureates who’ve long been focused on the atmosphere and climate.

As I’ve written before, whatever your view of the science and policy choices related to global warming, you can probably find a Nobelist with matching views. But Mario Molina and Burton Richter deserve a prominent place at this table given their sustained attention to relevant issues.

Mario MolinaMario Molina, a Nobel laureate in chemistry, uses this image representing a partially completed jigsaw puzzle to convey the state of understanding of human-driven climate change. CLICK TO ENLARGE

While participating in a November conference connected with the International Year of Chemistry, I spent time talking with Molina of the University of California, San Diego, a 1995 laureate in chemistry for his work (with others) on the atmospheric impact of ozone-destroying refrigerants and related chemicals. In a talk at the event, he conveyed his view of the incomplete, but compelling, picture of greenhouse-driven climate change with this photo illustration (right).

[3:05 p.m. | Updated | In a comment below, Laurie Dougherty helpfully pointed to 2010 congressional testimony by Molina in which he described his jigsaw analogy this way:

There appears to be a gross misunderstanding of the nature of climate change science among those that have attempted to discredit it. They convey the idea that the science in question behaves like a house of cards: if you remove just one of them, the whole structure falls apart. However, this is certainly not the way the science of complex systems has evolved. A much better analogy is a jigsaw puzzle: many pieces are missing, and some might even be in the wrong place, but there is little doubt that the overall image is clear, namely that climate change is a serious threat that needs to be urgently addressed. It is also clear that modest amounts of warming will have both positive and negative impacts, but above about 4 or 5 degrees Fahrenheit most impacts turn negative for many ecological systems, and for most nations. (Read the rest.)]

I’ve posted a lot on contrasting climate manifestos published in the past week by The Wall Street Journal, but it’s worth adding the perspective of Richter, a physics Nobelist who’s been deeply focused on humanity’s energy challenge, including the climate impact of greenhouse gases. As I’ve noted before, he’s the author of “Beyond Smoke and Mirrors,” a cogent road map for facing the daunting long-term challenge of cutting emissions of greenhouse gases even as humanity’s growth spurt crests in the next few decades.

Here’s a note Richter sent in reaction to the initial 16-author op-ed article in the Journal, which challenged the need for prompt action to stem emissions:

The letter of the 16 scientists (physicists, I am sorry to say) published in the Wall Street Journal on 1/27/2012 says that more and more scientists doubt the dangers of global warming.  That may be true of those who have not really looked at the issue, but it is certainly untrue of those that have.

There are two legitimate questions to ask about global warming.  First, is the temperature going up?  Second, if it is changing, what is causing it? The letter first casts doubt on the temperature rise, and then goes on to say even if it is rising, it is probably natural and has little to do with greenhouse gas emissions.  I suppose it is nice to try to have two strings for your bow.

On the first question, the average temperature of our planet has, in fits and starts, been going up for more than 100 years.  The average temperature each year fluctuates by a considerable amount and to see an effect one has to average over some period of time just as the technical analysts of the stock market look at the moving average over some number of day to discern trends.

Some of the authors of the letter know this; some do not.  That the temperature has not gone up for a few years is irrelevant. To those who are interested in the most recent analysis, I point them to the work of Dr Richard Muller and his group at Lawrence Berkeley National Lab.  Muller was a climate skeptic and pulled together a group of scientists and mathematicians and reanalyzed all the data.  He did an outstanding job and gets the same answer as the Intergovernmental Panel on Climate Change.

The letter quotes one of its authors, Nobel Laureate Ivar Giaever, damning the American Physical Society’s statement that the evidence for warming is incontrovertible.

Armed with my own Nobel Medal, I say if you can read a graph, the evidence is indeed incontrovertible because the temperature has gone up. The American Physical Society is right, he is wrong, and I can’t understand why he complains about the temperature rise issue when there is more to discuss on the second question; who is the villain?

We have seen in the past a temperature change of about the same amount as the current one and it was a cooling.  The Little Ice Age that began in the 14^th century reduced the temperature of at least the northern hemisphere by about one degree centigrade in a couple of hundred years, and CO-2 emissions had nothing to do with it.  The authors should be asking why today we are fairly sure the enemy is us.

In science we try analyze effects to discern their cause. When effects showed Newton was wrong on some things, Einstein put forward relativity which left Newton alone in his domain of validity and showed how new things happened when one left that domain.  That is also the story of climate change.

In the 1950s we learned that CO-2 was going up faster than assumed previously.  In the 1970s the World Meteorological Organization and the International Council for Science put together a group to try to understand what might happen if trends continued.  The UN took it over in 1988 and the Intergovernmental Panel on Climate change was born.  Its first report in 1990 said the temperature was going up and not enough was known to say if it was nature or us doing the driving.  In its 1995 report humans were said to be contributing.  In the 2001 report it said human activity was the likely cause.  In the 2007 report it said it was very likely that humans were the drivers.  The next report is due out in 2013.

As to the Little Ice Age, its origins were a mystery until very recently.  New research ties it to a series of violent volcanic eruptions that threw material into the sky leading to a cooling.  We will need more work to make sure this is true, but this is how science works; analyze effects to discern their causes and incorporate what you learn into a larger understanding.

The science is still evolving and new effects are being recognized and included.  It may be that some of them will lower the predicted greenhouse driven rise while some will increase it.  Meanwhile there are many things we can do that have multiple benefits.  Going to 54 miles per gallon as the E.P.A. and the car companies agree can be done lowers our oil imports and reduces greenhouse gases.  Switching from coal to gas to generate electricity eliminates a major harmful set of pollutants and improves health as well as reducing emissions.  Improved efficiency can lower energy use in buildings, saving money and reducing emissions.  It makes sense to do things that have economic benefits as well as potential climate benefits.

There is one place where the writers and I do agree.  There are lots of uncertainties in the climate analysis and more investment in reducing those uncertainties is certainly warranted.  Maybe we can at least get that done no matter who wins the next election.

Incidentally, The American Physical Society has started a Topical Group on the Physics of Climate.  The authors can join in the discussion without resigning from the society, and perhaps learn a few things.  Of course, polemical letters are more fun.

Article source: http://dotearth.blogs.nytimes.com/2012/02/02/two-nobelists-offer-views-of-human-driven-global-warming/