Who exactly can you trust when it comes to climate science? In her 2010 keynote speech at the Canadian Society for History and Philosophy of Science, Evelyn Fox Keller called upon scientists and philosophers of science to engage the public in critical discourse regarding the issue of climate change. She claimed that scientists and HPS’ers (those that study history and philosophy of science), who are best suited to talk about the myriad of complex issues surrounding the subject, have traditionally been reluctant to take their expertise into the mainstream. This blog post, the first in an ongoing series, is designed to answer Fox Keller’s challenge.
As the introductory blog in the series, this entry will be an overview of the multifaceted scientific and political challenges that climate change poses. My goal here is somewhat modest. Simply put, in this post I want to give the basic background needed to enter into a discussion on climate change. Please use the comments section to ask questions about this information. If you already know this information, skip right down to the comments section and ask a question about climate science that you don’t know the answer to. I’ll respond, and maybe even answer it!
Subsequent posts will give more depth to the issues summarized here. I will also attempt reach out to guest authors with more expertise than I, to chime in along the way. On that note, it should be disclosed that I am not a climate scientist (although I studied with one), nor a full-blown environmental ethicist. My attraction to this topic is generated primarily from an academic interest in epistemic issues in scientific modeling, and secondarily from my love of outdoor sports (backpacking, mountain biking, and skiing). I should also disclose that I believe anthropogenic climate change is occurring, and something needs to be done about it – fast. With that being said, I don’t believe that every bit of science that supports this conclusion is correct; in fact, I am sure many of our assumptions are wrong. So with all the disclaimers out of the way, let’s get through the basics.
How do we know climate change is occurring?
The IPCC (Intergovernmental Panel on Climate Change), a group of scientists and legislators from around the world tasked with reporting on climate change, has concluded that warming of the climate system is unequivocal. For the IPCC, climate change is a change in the state of the climate that persists for an extended period, usually decades or longer, and is the result of natural variability or human activity. This kind of change has been detected in global air and ocean temperature, the widespread melting of snow and ice, as well as a rising sea level. Global temperature data from 1995-2006 indicates that 11 of the last 12 years were the warmest on record when compared to instrumental data. This trend has and is expected to continue. Very few people, even climate skeptics, deny that the climate has gotten warmer.
What is responsible for the warming?
What people tend to fight over is whether or not the warm temperatures are the result of human activity or natural causes. If there is scientific consensus on climate change, it comes at this level: the warming has been caused by human activity, most notably the release of CO2 from the burning of fossil fuels.
Carbon dioxide is one example of what is called a greenhouse gas. When the sun’s light reaches the Earth, some of it is reflected off the atmosphere, and some of it penetrates. The penetrating light hits the Earth’s surface and is turned into thermal radiation (heat). The thermal radiation is then emitted back up into the atmosphere where some of it escapes through the atmosphere into space, and some of it reflects back down. When large amounts of green house gases are present, the amount of thermal radiation that can exit the atmosphere is reduced, and much more is kept within our atmosphere. Simply put, this leads to warming. Of course there are some other factors too, factors that exaggerate or mitigate the effects of greenhouse gases, but no factor is as significant to climate change as the release of CO2. We will get into more detail about these other factors in a follow-up post on climate modeling.
So what of it?
This is where things get interesting. So the Earth is getting warmer, why is that a bad thing? Heating of the Earth’s atmosphere, it is predicted, will lead to some long term negative effects, and a few positive ones. It is predicted that with warmer temperature comes increased snow and glacier melting. The beginnings of this process have already been observed. This melting will lead to higher sea levels, which could put seaside counties like Bangladesh underwater, displacing hundreds of thousands, if not tens of millions, from their homes. As seas rise, many believe there will be a loss of fresh drinking water (the scarcest resource on the planet, way scarcer than oil). Where there is fresh water, the higher temperatures are likely to cause increased breeding of insects, and with that increased rates of disease, most notably in countries where there is no money or infrastructure to handle an outbreak. Some species, particularly those in the arctic, are likely to lose their habitats, while others are likely to spread. On the plus side, countries like Russia and Canada are likely to gain arable land, and of course, there is always that battle over the new arctic passageway.
You keep saying that people predict…but how?
The answer is climate models. Scientists have been working hard to create large scale computer models that will help predict the changes in climate 50 to 100 years from now. The models are immense and run on very powerful computers. It is not like sitting down on your laptop, but, you can help that way. In order to reach any conclusion from the models, they are first tuned to known data, then run hundreds of times, and then compared to other models. If this makes them reliable, no one really knows (after all, the test of their results is 50 years away). This issue however, will be another post on its own.
So ah, it sounds bad, what do we do?
Of course, this question is the most important. Most people believe the drastic negative effects mentioned above can be prevented if drastic changes are made now. Many think that we need to prevent more than a 2.5 degree C rise in global mean temperature from current levels. Of course, it seems that we are slow to action. What do we do? Why haven’t we done it yet? Who is responsible for doing it? And what are the moral implications of our (in)actions? That, my friends, is yet another blog entry.