Saturday, September 21, 2013

Climate Change Workshop, part 2.

Saturday morning, after a good cafeteria breakfast (the OU Biological Station is famous for its food), and everyone is in a good mood to start the first full day of the climate change workshop sponsored by Oklahomans for Excellence in Science Education (OESE) and the Oklahoma Climatological Survey. About 30 middle school and high school teachers are participating.

"Welcome to the second most unpopular talk in Oklahoma," said Gary McManus, Associate State Climatologist (the most unpopular talk was one about how Texas beat Oklahoma in football) as he began our first session. Since there is so much opposition to climate science in Oklahoma, he always tells his audiences (which can range from environmental groups to petroleum engineers) that he is just going to present the facts; he is not, he said, a scientist telling people how to live their lives. (In contrast, I am a scientist who does tell people how to live their lives.) The Oklahoma Climatological Survey remained neutral on climate change until the 2007 International Panel on Climate Change (IPCC) report, which made climate change undeniable, and they finally had to take a stand.

Climate change, driven largely by human activity, is a consensus position of all the major scientific organizations in the world, and of nearly all climatologists. One occasionally sees lists of "thousands of scientists" who dispute global warming, but these lists often have a lot of petroleum geologists on them. Not that petroleum geologists are not scientists, but their job is to get oil for us to burn. Being good people, petroleum geologists and engineers do not want to believe that their jobs are putting the world in danger.

Global warming does not affect only the averages, but the extreme weather events. But it is these extremes that people notice. In Oklahoma, 2011 had the hottest summer on record, not just for Oklahoma but for any state, as measured by the number of days on which the temperature exceeded 100 F. In some places in southwestern Oklahoma, there were over 100 such days in 2011. But late winter 2011 also had the lowest temperatures recorded in state history.  These are the events that catch people's attention. We have had long droughts, but when it rains, it often rains very heavily. But we need to pay attention to the averages, lest our views are determined solely by the extremes.

Climatologists use computer models to estimate global temperature, based on information about sunspots, volcanic eruptions, etc. (For example, volcanoes eject smog and cool the Earth.) Models that use only natural processes (e.g., not including carbon from human activity) fit the observed temperature patterns from the 19th century, but in the twentieth century global temperatures increased far beyond what the "natural" temperature would have been.

But quite apart from temperature measurements, there are thousands of independent lines of evidence to confirm that global warming is occurring: the arctic ice is melting; spring is coming earlier; species migration patterns are changing, etc. We will encounter more of this evidence in later sessions, especially on Sunday the 22nd.

Some of the evidence can be misinterpreted by those who are inclined to do so. The upper atmosphere is getting cooler. Does this contradict global warming? No, because the carbon dioxide in the lower atmosphere is trapping the heat in the lower atmosphere, which makes the upper atmosphere cooler. Also, if you choose your years correctly, you can "prove" global warming has stopped. Global temperatures decreased from 1998 to 2000, for example. Denialists can extrapolate this into the future and conclude that we will all be freezing in a few decades. But this is invalid; it is just like saying that, if you paid a big bill from your checking account, causing the balance to decrease for a few days, then you will obviously be bankrupt within a year.

The Earth is losing its air conditioning system, said McManus. It is the arctic sea ice that is the a/c system for the Northern Hemisphere; it cools the Earth when it melts. The ice is melting rapidly, reducing its ability to absorb future heat from the Earth's atmosphere.

Climate scientists use estimates and projections, and sometimes these projections are wrong. But in most cases, the climatologists have underestimated the problem: sea ice is melting faster than the earlier IPCC reports had predicted. Furthermore, much of the remaining ice is new ice rather than old ice, which means that it cracks and crumbles more easily--and melts more easily--than old ice. Oh, and by the way, global warming is occurring more rapidly than even the most extreme prediction that the IPCC made back in 2007. The truly extreme results will be felt at the end of the 21st century, when we will all be dead, but our descendants at that time will, I suspect, hate us for the carbon we have foisted upon them.

The hottest day in Oklahoma on record was August 12, 1936, where some places reached 120 degrees. The difference between then and now is that we have a lot more hot days now than there were back then, even though we have had no days quite as hot as that August day in 1936.

If our rain comes in short intense bursts rather than frequent rains, we could have the anomalous result that we would have more total rainfall but less of it penetrating usefully down into the soil and aquifers!

Some people might actually benefit from global warming. Can you imagine, perhaps, that Oklahoma will mostly raise tumbleweeds, while Russia might become the wine capital of the world? The Russians might welcome global warming (unless they get a repeat of 2010, in which drought and heat made them lose much of their wheat crop).

We cannot easily predict what global warming will do to Oklahoma. Eastern Canada will get wetter, the Southwest will get drier, but it could become either drier or wetter in Oklahoma, halfway between the two easily-predictable geographical extremes.

A great deal of the information Gary presented to us is very useful to physics and chemistry teachers. It is not necessary to understand the absorption spectrum of the atmosphere in order to understand global warming; but if physics and chemistry teachers are introducing students to absorption spectra anyway, why not use the atmospheric absorption spectrum as a real, and very important, example?

The weather almost never gradually changes. Our long heat wave in Oklahoma ended suddenly just today, for example. Many of us wished that we could have part of our workshop outdoors, in the beautiful cool morning, but this is not possible. What would Gary do? Point to the blue sky and say, look at the invisible carbon dioxide?

One final thought. High school students may grow weary of learning the science of global warming. How can you engage them? Try this. "America produces a huge amount of greenhouse gas, but much of the resulting drought and famine will occur in Africa. Is that fair?" So, if you are not "into" environmental issues, just remember that (as I have elsewhere written), the environment is the medium through which we relate to other people.

No comments:

Post a Comment