Saturday, March 30, 2013

FD: The risk of climate change, and its implications

originally published at Freedom Democrats, 12/19/2007
When dealing with an issue like greenhouse gas-induced climate change, productive discussion needs to stay focused on the practical questions: what is the general nature of the risk, and how can we mitigate the risk. Discussions of climate change often become sidetracked by non-productive investigations into the detailed nature of the risk, which are often initiated by individuals who are afraid that general recognition of risk implies that particular strategies/policies must be adopted. I hope to keep this discussion on track by starting with these two declarations:

 1. We don't know exactly how the climate will respond to our greenhouse gas emissions, and it doesn't really matter.
 2. There are many different strategies available to us.

Before getting into the details, let's consider the nature of risk and uncertainty with respect to climate change. We don't know what our climate will be like in the future. It might be similar to today's, or it might be worse. We often wish to refrain from developing plans/opinions until we have a clear sense of what to expect in the future, but this prudence becomes paralytic in situations where we will never have high confidence in our predictions. Some degree of uncertainty is unavoidable with any prediction, and this is especially true with climate predictions due to the complexity of the system. Just to become an expert on this topic would require about 10 years of full time study, and even the experts don't know what will happen. Obviously, most of us cannot become experts, yet we still need to decide how we will act. So, let us begin:

*Greenhouse gas emissions (GGEs) create a substantial risk of problematic climate change.*

1. Carbon dioxide is a greenhouse gas: it allows visible light to pass , but prevents the passage of infra-red light. The net effect is that energy from the sun can easily reach the surface of the earth, but it is hindered from leaving the earth.

2. Humans are drastically increasing the amount of carbon dioxide in the atmosphere (about 25% since 1900).

By themselves, these facts give us reason to consider how to reduce GGEs. But we still may wonder if these changes in atmospheric carbon dioxide levels can impact atmospheric temperatures. So we look at fact 3:

3. Atmospheric temperature is strongly correlated with carbon dioxide concentrations. This has been seen over the long term (ice cores ) and over the short term (modern monitoring).

3b. We also know that the size of glaciers is inversely correlated with atmospheric carbon dioxide, both over the long term and the short term.

This doesn't prove that carbon dioxide levels cause an increase in atmospheric temperature or glacier-melt, but the data is consistent with that proposal. Warming may have all types of side-effects, while excessive glacier-melt will impact the entire water system of the earth, ranging from glacier-fed rivers to the ocean itself. As a practical matter, we face a substantial risk that carbon dioxide emissions will cause global warming and climate change. If these facts aren't enough to convince you that we face a risk of GGE-induced climate change, here's one last fact:

4. The experts agree that we face a risk of GGE-induced climate change.

The Earth is warming. Glaciers are melting. It's time to admit that there is a risk of GGE-induced climate change, and figure out what we want to do about it:

*We have many options for dealing with the risk of GGE-induced climate change.*

 1. Reduce GGEs. This is the intuitive response, and has recieved the most attention over the past couple of decades, meaning that we have developed plenty of ideas of how to reduce GGEs. These options include personal, institutional, and governmental reforms. They exhibit a wide range of return on investment, as illustrated by abatement curves . These options include development of low-emission infrastructe (buildings, vehicles, cities), low-emission technologies, low-emission lifestyles, and carbon sequestration. These may be promoted by private initiative or governmental policies including subsidies, mandates, spending decisions, taxes, cap-n-trade, etc. The most drastic measures (immediate elimination of fossil fuels) could be as bad as global warming.
 2. Buffer the change on a global level (i.e. Geo-engineering , such as putting sulfur dioxide in the upper atmosphere)
 3. Do nothing/Deal with the symptoms directly: We may decide that other concerns are more pressing, and that the risk of climate change does not justify the expenditures needed to stop it. We may also find that we "can't put the geenie back into the bottle", since we've already changed atmospheric carbon dioxide concentrations. We may also find that it is easier to deal with the symptoms (both technically and politically) than it is to deal with the cause of climate change.

Personally, I favor a mix of options 1 and 3. Reductions in GGEs will reduce the severity of climate change -- both in its magnitude and its suddenness. Total elimination of GGEs in the near-future is possibly not worth the cost, and is probably politically impossible (considering the needs of developing countries). Finally, the climate change models are relevant to the extent that they help us to anticipate future challenges arising from climate change. Keep up the work guys!

/Inspired by discussion with John, and cross-posted to Swords Crossed and Daily Kos . /

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