Where What When

Should We Be Worried About Global Warming?

Facts, Theories, Politics And What Should We Do About It? Beyond Politics

Most of you have heard or read about global warming; it’s been all over the media lately. But you are probably confused about whether it is really occurring and poses a danger to us or whether it is merely another form of extreme environmentalism of the kind favored by those who throw paint on people wearing fur coats.

Before I start to explain, perhaps a little self-examination would be in order. So let me ask you, what would be your reaction if, at the outset, I claimed to be a Republican who didn’t believe in global warming? What if I claimed to be a liberal Democrat who did believe in global warming? Would either one of these statements turn you off so much that you would be unwilling or unable to read the rest of this article with an open mind?

If so, you can relax. Let’s try to leave our politics at the door when discussing what is a scientific question. Let’s also take the word “belief” out of this conversation and try, rather, to come up with some useful ways to think about the issue of global warming.

You might ask, fairly, what are my credentials to lead an examination of this issue? For the past 15 years I have worked with a group in the Climate and Radiation Branch at the NASA Goddard Space Flight Center doing earth science research. While our research isn’t directly on the topic of “global warming,” it is an integral part of the bigger picture of understanding the earth’s climate. I have had the privilege during this time to work with some of the brightest and best people I have ever known.

Fact and Theory

I’ll review some of the basics of the science of global warming. To be perfectly honest, it should be called “global climate change.” But whatever the name, here is how it works, in a nutshell.

The earth has a balance of energy. The energy “in” is provided by the sun. That energy is either retained by the planet’s atmosphere, absorbed by the land and ocean, used by plants, or returned out into space. The overall balance is determined by the fraction that stays here compared to how much is sent back out into space. Some of the gases in the atmosphere – the so-called “greenhouse gases,” carbon dioxide chief among them – are very efficient at retaining this solar energy as heat. This is a fact. Another fact which no one, not even the skeptics, disputes is that human activity has tremendously increased the amount of carbon dioxide in the atmosphere over the last 50 years.

The theory part is that, because we have drastically changed the makeup of the atmosphere to increase the heat-retaining gases, the earth will warm as a result.

No Crystal Ball

There is a growing body of scientific observations indicating that the global climate is in fact warming. This ranges from global satellite measurements of increased ocean and atmospheric temperatures, to increased length of the growing seasons in the polar areas, to increased rates of melting of permafrost and ice sheets. Assuming for the moment that warming is happening, the principal point of debate is then this: Can we say that global warming is caused by human activity, or is it within the normal range of climate variability? If it is caused by human activity, why can’t the scientific community clearly prove this?

The earth’s climate is determined by an extremely complex web of relationships involving not only the atmosphere but also the ocean and land surfaces. We have no laboratory where we can do experiments to prove these ideas one way or another. What we have to do in order to try to understand the issue is rely on computer simulations.

Imagine the task at hand being to build an accurate computer model of the entire earth. To build a perfect model would require two things: 1) a complete understanding of how all of the processes in the climate work, for example how and where clouds form, and 2) a complete and accurate set of observations as to exactly what is being put into the earth’s environment, for example exactly how much carbon dioxide.

We don’t have perfect models, nor do we have perfect observations. We don’t even have simple models that are correct all of the time in the things they do attempt to do. However, a good friend of mine who has worked as a chemical transport modeler for many years says, “No model is true, but some models are useful.” We can’t get a complete answer from the models, but they can help us learn about what is happening.

Another Ice Age?

One result you may have heard reported from some of the models is that global warming could lead to an ice age. On the surface, this sounds like a ridiculous contradiction, to the extent that it may cause you to want to disregard anything the scientists report. Well, here’s how this could work: There are now ocean currents that carry warm water from the equator into the North Atlantic Ocean. As the water goes north, some of the heat gets transferred into the atmosphere. When the ocean water gets far enough north and has lost enough heat, it sinks to the bottom of the ocean, since cold salty water is much more dense than warm water or fresh water. The cold salty water is transported back towards the equator deep in the ocean. The overall result is that the heat from the equator is redistributed towards the pole and warms the northern hemisphere. (So far, this is all fact, not speculation.)

For the past few years, observations indicate that the Greenland ice sheets are melting at an accelerated rate. These are fresh water ice sheets. Some of the models predict that if enough fresh water gets added to the North Atlantic, where the cold salty water is sinking, it will mix with the salt water so that it will no longer be dense enough to sink, and this current will be broken. The heat at the equator will thus stay at the equator, and the North Atlantic will become very cold and experience an ice age.

Will this happen? Who knows? Could it happen? It’s possible. How likely is it? Again, who knows? Why can’t we be more certain? Because we don’t have a lab where we can test this, we don’t have records from the past to check, and because this is a non-linear process.

What’s that? A linear process means put-one-in-get-one-out or put-one-in-get-five-out. If I double the pressure on my gas pedal, I’ll go twice as fast. In a non-linear process, you may get one-in-one-out for a while, but you reach a critical point where you get a lot more out than the one you put in. It’s kind of like playing tumbling tower. You know that each block you pull out is making your tower weaker, but you can never be sure which one will make it fall. Our modelers have a hard time predicting non-linear processes.

The bottom line is that models can help us to learn about what is happening so that we can make the best educated guesses possible. The models, combined with the observations, have convinced the vast majority of climate scientists that we have a real problem.

A Parable

Rather than continuing a discussion of the science, I’d like to give you some food for thought by adapting a parable (mashal) from a shiur by Rabbi Dovid Gottlieb of Ohr Someyach in Yerushalayim. Many of the non-observant young people he talks to about faith and belief ask him, “Rabbi, how can you expect me to change my lifestyle if you can’t prove to me that G-d exists and gave us the Torah?”

He answers with an example: Let’s suppose you have a fatal disease, and if you sit around and do nothing about it you will die. There are two possible medicines to treat the disease, medicine A and medicine B. The right medicine cures you, and the wrong medicine kills you. If you go to a doctor and he says there is a 51 percent probability that medicine A is the correct one, which one would you take? I’m sure we would all choose medicine A (after getting a second opinion, of course, and maybe a third and a fourth). The point, says Rabbi Gottlieb, is that in our daily lives we always make calculations of probabilities and act on them without absolute proof.

Let’s apply this story to think about global warming. The vast majority of scientists –let’s compare them to the doctors in the story – say we have a disease. They say we need to reduce our production of greenhouse gases to reduce the impact of the disease. In order to accomplish this, we will need to change our lifestyles somewhat.

Without debating the correctness of the predictions on either side of the debate, let’s look at the potential fallout by following either course of action. What is the cost if the scientists are wrong but we take their advice to change our lifestyles to reduce emissions? Some critics say it will put us at a competitive disadvantage economically. We could lose jobs and market share to those countries that aren’t attempting to reduce greenhouse gas emissions.

If the scientists are correct, what is the cost if we ignore their advice and do nothing? It won’t kill us as a species, but it will cause major changes in climate that in some locations (for instance the semi-arid U.S) will severely reduce food production, cause more local droughts and flooding, and will eventually flood enough coastal areas (including the East Coast and most of Florida) that hundreds of millions of people will be forced to move. In addition, there are predictions that 10 to 50 percent of animal and plant species globally will become extinct.

There was a report released recently to the government of the UK compiled by Sir Nicolas Stern, the former chief economist of the World Bank. This report warns of a 20 percent drop-off in world economic activity if we do nothing about global warming. On the other hand, this report contends that each pound invested now will yield five pounds of economic activity down the line.

It seems to me that a prudent approach that minimizes our risks argues strongly for taking this threat seriously and attempting to minimize our continued over-production of greenhouse gases. While this may mean some self-sacrifice in how we live our lives, I think the rewards far outweigh the risks. I believe we are obligated to participate and not stand idly by in the hopes that this is an overblown power play by some scientists who just want additional funding for their research. As is says in Mishlei, the one who is lazy is a brother to the one who destroys.

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Article List - April 2007