Saturday, February 28, 2009

Global Warming #4: More problems

While researching climate change I have discovered a host of new facts and observations. I have yet to synthesize it into something coherent, so most of it will have to wait. I will note a few interesting things though and then close with comments on science and policy.

Those of you who have seen Al Gore's An Inconvenient Truth (or turned on the TV or surfed the web) will likely have heard about two of global warming effects: increased hurricane activity and the drowning of polar bears. It turns out that while there is some truth in these claims, the reality is quite complicated.

Hurricanes are powered by warm ocean surface waters evaporating and then condensing, releasing latent heat. The warmer the water, the more evaporation, and therefore the more heat released to power the storm. As sea surface temperatures rise then, so should the number and intensity of hurricanes. Al Gore quite bluntly lays the blame for hurricane Katrina at the feet of global warming. Climatologists, however, point out that it is impossible to pin a local, specific event like Katrina as being caused by global warming. While it is true that some theoretical studies have linked rising water temperatures will increased hurricane activity, the observations are that the number of hurricanes have in fact not increased at all. What has increased is the relative number of intense (category 4 or 5) hurricanes. There has been some controversy over this claim, however, as our reliable records only go back around 30 years. In other words, how can we be confident that the number of intense storms has gone up when we don't have a reliable long term record to compare it to? In addition, several studies have shown that as the planet warms, wind shear over the Atlantic and East Pacific will increase. This atmospheric phenomenon prevents hurricanes from forming at all. Yet other studies have shown that this increased wind shear will result in less hurricanes making landfall in the U.S. So, the jury is certainly still out on exactly how global warming will affect hurricane activity.

As for polar bears, I have discovered that populations are indeed on the decline (down 20% or so in the last 30 years). While this is probably influenced by climate change and the decline of arctic sea ice, it is not yet true that we have found drowning polar bears because of a lack of sea ice. The study that seems to have sparked all the media interest (and led Al Gore in his movie to show a CGI clip of a polar swimming in an endless ocean searching for ice) is one where four polar bears drowned due to a fierce storm off the coast of Alaska. Not global warming; an intense storm. While it is hypothesized that the bears may have been swimming longer than usual due to less ice, Al Gore's portrayal hardly seems appropriate. This seems to be another example of misleading information around what will likely be a real issue. If global warming continues, polar bears will have to adapt or perish. It is disappointing though that the facts were twisted to support an agenda.

OK, so in this and the last three posts it will hopefully have become clear that much of the science surrounding past and current climate change is both complicated and tentative. So what should we do? There are those who advocate doing nothing in the interest of preserving our economy, and those who advocate radical change. For myself, the uncertainty of the science can be separated from policy decisions. Why? Consider our current source of energy, fossil fuels. These fuels formed during the Carboniferous period 300 million years ago. The processes that formed all of the coal and oil is slow, somewhat mysterious, and only seems to occur under certain conditions. This is why coal and oil are considered non-renewable resources. World population will likely hit 9 billion in the near future. Developing economies, like China's, are increasing consumption of fossil fuels at tremendous rates. Besides the fact that fossil fuel emissions are probably contributing to climate change, there is another perfectly good reason to develop alternative sources of energy: we are going to run out of fossil fuels (in as little as 30 years by some estimates).

You may have heard of Pascal's wager, a philosophical oddity that suggests that it is a better logical bet to believe in God than not to believe in God. After all, if you believe in God and you're wrong, nothing really happens to you when you die. But, if you don't believe in God and you're wrong, you may be sentenced to eternal damnation. Therefore, it is a safer bet to believe in God. Putting aside the merits of this theological wager for a second, consider the current crisis. If we act to stop global warming, and it turns out to be a complete hoax, what do we get? Some time and money will be spent, but we will also find ourselves with reduced pollution (fossil fuel combustion results in environmental damage besides global warming), zero dependence on oil of any sort (plus it will run out anyway), and the development of new, clean, efficient energy sources. Now, consider the flip side: if we do not act, and the less nice predictions about future warming are true, we could find ourselves with a host of problems, including: sea level rise, habitat devastation, increased floods and droughts, changing atmospheric and ocean currents, and others.

When it comes to modifying the Earth's climate with greenhouse gas emissions, an experiment in which the outcome cannot be predicted, it just seems to be to be a safer bet to start phasing out fossil fuels now and perhaps keeping reserves for emergency situations. I have called this "Gore's Wager" in the past, but as I find out more about climate change, the less enthusiastic I am about using his name. I'll have to think of something else...

Wednesday, February 18, 2009

Global Warming #3: New Territory

So we have seen that Earth has had dramatic climate changes in the past caused by both variation in the Earth's orbit and varying levels of greenhouse gases. Al Gore's attempts to link current climate change with past changes do not quite work. What is happening currently has no analogue; for the first time CO2 levels are rising on their own, ahead of other normally synchronous changes.

We are currently in the Holocene, which began around 11,000 years ago, marking the end of the last ice age. Glaciers covered many of the continents during the last glacial maximum, but beginning around 20,000 years ago Earth has warmed. The glaciers have retreated and left only arctic and Antarctic ice as well as mountain glaciers. The retreat of the glacier covering North America left behind the Great Lakes as well as the many kettle ponds here in New England. Cape Cod and Long Island are remnants of the debris left behind by the glacier's movement.

In other words, melting glaciers are nothing new. However, beginning with the industrial revolution humans have begun to add carbon dioxide to the atmosphere in appreciable amounts. From around 280 ppm (parts per million; within 1 million air molecules 280 of them would be CO2) before 1900 CO2 levels have risen to around 390 ppm. This is still an extremely small part of the atmosphere, but CO2 is a greenhouse gas that absorbs heat radiated from the Earth (originally from the sun). Venus, for example, has an atmosphere almost entirely made of CO2 and has surface temperatures around 400 degrees Celsius. While the Earth has many sinks for excess CO2 (only around half of total human emissions actually stay in the atmosphere), humans are adding enough to slowly but surely increase global levels.

Over the 20th century global temperatures have risen around 3/4 a degree Celsius or a little over one degree Fahrenheit. This may not sound like much, but remember, a lot of heat is needed to warm the entire planet by even 1 degree. Is all of this warming due to humans? Probably not; remember, Earth has been warming for the last 20,000 years (with a few notable exceptions), and sea levels have been rising steadily at about 2 mm per year over the same period. Most likely humans are accelerating the warming of the current interglacial period. And here we come back to the main point: this is essentially new territory. We simply do not know exactly what will happen as we add more and more CO2 to the atmosphere.

The Earth has various feedback mechanisms that have acted to stabilize climate throughout Earth's history. These seem to have prevented both an irreversible global icehouse as well as an irreversible runaway greenhouse effect. Can the Earth deal with the amount of CO2 we are adding? There are studies showing that even if we stopped adding CO2 today, climate change might continue for centuries. While modeling future climates is extremely difficult, there seems to be a general consensus that, in the words of the IPCC, "very likely" humans are contributing to the current warming and that warming will continue as long as we keep adding greenhouse gases.

Next: science vs policy.

Monday, February 16, 2009

Global Warming #2: Past climates

So last time I ended with the question of how to present complicated data to 9th graders. Global climate change involves extremely large amounts of complex data. The literature on past climate change is vast, but single or simple conclusions are absent. From what I can tell, climate change poses an ill-structured problem, the kind educational researchers tell us are important for students to be exposed to. Real world problems are complex and often lack a single answer or one correct approach.

Climate change in the past seems to have been caused by a combination of orbital variations of Earth (Milankovitch cycles) internal forcing by greenhouse gases (including water vapor, CO2, methane, ozone, etc.), and various feedback mechanisms. Scientists disagree about the relative importance of each. It is clear from ice cores and other records that CO2 and methane vary along with global temperature, but a clear cause and effect relationship is absent, despite what Mr. Gore might tell us. We are also led to believe that CO2 levels are off the chart compared to Earth's past. This is not quite correct. Current levels of CO2 (around 385 parts per million) are certainly the highest in the last 650,000 years, and while this might seem like a long time, it is very brief compared to the 4.6 billion year history of planet Earth. There is evidence that CO2 levels have been up to 15 times higher than current levels around 400 million years ago and at least 5 times the current levels more recently (geologically speaking). Of course, people weren't around back then, and there were no coastal cities, but still, sometimes Mr. Gore makes it sound like planet Earth itself couldn't survive. This is of course nonsense; as recently as 60 million years ago Earth likely had average temperatures 15 degrees Celsius higher than current averages. And Earth survived, as did its plants and animals. There have been times where there haven't been any glaciers anywhere, and as recently as 120,000 years ago sea levels were 4 to 5 meters higher than current levels.

So if you hear that current warming is unprecedented, that is simply false. Point this out to 9th graders, though, and you see some of them glaze over and start to dismiss the possibility of anthropogenic climate change. The problem is that Mr. Gore and others try to use past climate change as a simple analog to explain what is happening now. This doesn't work for several reasons; as mentioned above, past climate change involves dozens of factors that are not fully understood by any climate scientist. The current scenario is actually new in the history of the world.

Next: uncharted territory

Sunday, February 15, 2009

Teaching Global Warming #1

I'm researching global climate change, ill-structured problem solving, and constructivist methodology for a paper/project. I know a decent amount about climate change, but expect I will learn a lot more over the course of the next few months. I think I will post a series of posts on what I find.

As of now I am kind of torn over this issue and how to teach it. It is one of my favorite parts of the year for several reasons: I find it fascinating, and most of my students find it interesting as well. The problem is that climate change has become a partisan issue. Democrats and liberals tend to believe every word Al Gore says about global warming, while conservatives dismiss it as junk science. As usual, neither are correct. My dilemma is how to teach a nuanced view of climate change to my 9th graders, or rather, to have them arrive at a nuanced view through critical thinking.

I usually start our time on climate change with a viewing of Al Gore's An Inconvenient Truth. The reason is that Mr. Gore actually does a pretty good job explaining much of the science of global warming and its potential effects on Earth. The collection of images and animations are top notch, and Al Gore seems to sincerely care about our planet. Most students are impressed and come away totally convinced that anthropogenic (human-caused) global warming is real and that we must act swiftly or else the world will end. This sort of thinking is encouraged by junk science movies like The Day After Tomorrow. Al Gore isn't quite that far down the alarmist spectrum, but he's pretty close.

After the video (my students take notes) we summarize as a class the various current and future effects global warming may have on the only habitable planet that we know of. These include glacial ice caps melting (which are an important source of fresh water), sea levels rising, a redistribution of precipitation patterns, ocean current changing, and many others. We discuss the basic science of the greenhouse effect (various gases, including CO2, absorb infrared light radiated from Earth and warm the atmosphere) and that humans contribute around 6 gigatons of CO2 to the atmosphere each year (for reference, around 3 million fully loaded 747's would equal 1 gigaton). Then I go on to point out some of Gore's mistakes and/or glossed over complexities.

For example, Gore's first illustration of massive glacial retreat is atop Mt. Kilimanjaro. Unfortunately, studies published by reputable scientists in peer-reviewed journals have shown conclusively that global warming is not the cause of the retreat. Rather, it is a pre-industrial revolution change in atmospheric moisture patterns that is responsible (also, the temperatures at that altitude never rise above freezing). This is not to say that other glaciers are not retreating due to warming temperatures, but Mt. Kilimanjaro was a poor choice by Mr. Gore, and in the interest of truth I feel compelled to point this out.

One example of uncertainty/complexity that Gore overlooks is the relationship between past CO2 levels and temperature. We are shown the data from ice cores from Antarctica that show the past several ice ages and the correlation between CO2 and temperature over the past 650,000 years. When CO2 levels are high, temps are high, and when CO2 levels are low, temps are low. You see, says Gore, CO2 levels control climate, and he goes on to show how our current CO2 levels are rapidly going off the chart in a vertical direction. The problem is that the published studies of these ice cores show that historically temperatures always rise first, followed around 800 years later by a rise in CO2 levels. Also, it is fairly well accepted that these climate changes, the change from ice age to interglacial period and back again, are ultimately caused by variations in the Earth's orbit, known as Milankovitch cycles (though various other factors also come into play). Gore's point though, or so it seems to me, is that in these ice cores we have clear evidence that CO2 has caused drastic climate change in the past and that we are about to experience apocalyptic levels of change due to anthropogenic CO2 emissions. This, to me, is a gross misuse of the ice cores to argue for a valid point: that rising CO2 levels likely will contribute to global warming. How do you explain this to freshmen in high school?

More coming soon.

Saturday, February 7, 2009

Multiple Realities?

I'm taking a research class and the professor reviewed qualitative and quantitative approaches and the thinking behind them. Quantitative analysis of course involves variables that are strictly measurable; everything must be measured using numbers. The qualitative approach is more personal and may rely on data like recorded interviews. She explained that the qualitative approach emerged in the '60's as a counter to the quantitative, masculine, everyone can be explained as a number approach adopted first by the military and then everyone else. A qualitative approach recognized that it is difficult to reduce people to numbers and statistics, and that maybe research should start collecting data directly from the people instead of inferring data from quantitative tests. This would allow researchers insight into the people themselves and allow us to recognize the multiple realities of peoples' experiences.

The quantitative approach assumes a single reality, an external reality that is independent of people's experiences. There is a right answer to every question, and a quantitative approach allows access to that solitary truth. Qualitative researchers on the other hand assert that there is not one reality, but multiple realities that we can only discover through a qualitative approach. Each person has their own reality, and these would be missed or ignored through a strictly quantitative approach. This thinking is part of what might be considered postmodernism (or relativism): the belief that there is no absolute truth but instead there are multiple truths. For example, many see Thomas Kuhn's work, The Structure of Scientific Revolutions, as showing that even scientific knowledge of that one reality is suspect and that therefore not one reality but multiple realities exist. The reality of any given person then depends on culture, language, and so on.

I believe that the language used in this sort of dialogue is all wrong. When relativists (or qualitative researchers) say that there are multiple realities they are simply mistaken. What they should say is that there are multiple perspectives. For example, on an episode of the radio program This American Life the story of a missing boy was told. When a boy was found, two families claimed it was their boy, as both had indeed lost their son. Each were convinced that the boy belonged to them; in other words they each had their own realities. But clearly the boy could only have been from one family and not both, and therefore perspective is the more appropriate term. I think perhaps the fear is that perspective is not a strong enough word, and that different people's experiences will be ignored unless they are described as a reality. I hope no relativist would actually claim that the boy actually was both of the boys that had gone missing. It seems clear that there is only one external reality: the boy could have only been from one family or the other.

How then do we interpret the clear value of qualitative research and ideas like those of Kuhn's? The answer is that relativists were wrong about what is relative. They would claim reality itself is not singular. They are making a claim about ontology, or what actually exists. The proper claim should be about epistemology, or what we can know. There is one reality, but our access to it is fuzzy at best. Even scientific knowledge, which usually enjoys a vaulted epistemic status, is far from certain, as the work of Kuhn and others has shown. It is a mistake however to confuse what I will call epistemological relativism (the uncertainty of all knowledge; even scientific, quantifiable knowledge) with ontological relativism (that there actually exists more than one reality).

To sum up, we should replace talk of "multiple realities" with talk of multiple perspectives, being sure to appreciate and take seriously how people perceive reality. For example, my perspective right now is that it's time to order a pizza. How can I be sure that this is actually a reality, not just my perspective? My wife has told me so.