IN THE SCIENTIFIC COMMUNITY THE DEBATE over the reality and cause of climate change is over. Not so in the popular press, especially here in the United States. Sarah Palin is a skeptic in the news lately. Being from Alaska, she has no doubt about our changing climate, but as best I can tell (sometimes she so unclear it sounds like she has lived in Washington all her life, doggonnit) she doesn't believe the process is caused by human activity. Skeptics, who don't see the effects of climate change right outside their window, won't even go as far as Governor Palin.
As with any topic, the popular press allows people to state their opinions and go on their way unchallenged. In a liberal, tolerant democracy perhaps they are a person's right to their own opinion. Senator Moynihan once said, "We all have a right to our own opinion, but we don't have a right to our own set of facts." For my part, I 'm not sure why I should care what your opinion is, if you are not willing to defend it in light of the facts. Unfortunately, the media seems more interested in opinions than the underlying facts. Reporting opinions on all sides while ignoring the facts may be fair and balanced, but it is also lazy and useless.
The current popular controversy over climate change could not survive in an environment where opinions had to be defended. At least that's my opinion. Now, let's review the facts.
Intuitively, it is easy to be skeptical of human involvement in climate change when you consider the difference in scale between tiny humans and our vast planet.
The most fundamental aspect of the climate change debate is the greenhouse effect itself. To many the greenhouse effect is a nuisance of nature, capable of bumping up global temperatures by a few degrees. Not so – the greenhouse effect is a powerful force which is responsible for life as we know it. Natural greenhouse gases, primarily water vapor and carbon dioxide with a little help from methane and ozone, make up less than one percent of the atmosphere, but they raise the earth's temperature by 50 degrees. Without greenhouse gases the earth's average temperature would hover around zero degrees Fahrenheit.
Water vapor, which makes up just under half a percent of the earth's atmosphere, is by far the most abundant greenhouse gas. It also makes the greatest contribution to the natural greenhouse effect, but it is not a primary player in climate change. Carbon dioxide (CO2) and methane are the culprits in climate change. These gases make up an even smaller percentage of the atmosphere, .0383% and .00017% respectively.
The fact that the atmosphere contains only trace amounts of these gases is a significant point which is often overlooked. Intuitively, it is easy to be skeptical of human involvement in climate change when you consider the difference in scale between tiny humans and our vast planet. But, being aware of the tremendous power that a tiny portion of the atmosphere exerts on the entire planet and realizing it is this tiny portion of the atmosphere being affected by human activity makes possibility of human induced climate change a good deal more plausible.
Since the beginning of the industrial revolution, concentrations of both CO2 and methane have been increasing. Direct observations show CO2 concentrations increasing from .0313% to .0383% since 1960, but it is the ice cores from Greenland and Antarctica that put this data into context. The ice record shows natural variations in CO2 concentrations between .0180% and .0300% during the last 650,000 years. Today's readings are over 25% higher than any level seen in the ice record. This increase started 250 years ago and is not part of any natural cycle ever seen. Likewise, the current level of methane exceeds anything seen in the ice record.
Greenhouse gases allow short wave radiation from the sun to pass to the earth's surface, but they absorb the long wave radiation emitted by the earth before it escapes into space. Rising levels of greenhouse gases will unquestionably result in the earth retaining more of the sun's energy - it's just physics.
In addition to the direct effects of greenhouse warming there are a number of feedback mechanisms, which could be triggered by increasing temperatures and would accelerate the process of climate change.
- Additional water vapor evaporating from warmer oceans will increase greenhouse warming, resulting in more evaporation.
- Diminishing sea ice will reflect less of the sun's energy back into space. More of that energy will be absorbed by the ocean, resulting in warmer oceans and further diminishing of sea ice.
- Thawing permafrost will allow previously frozen organic material to decay thereby releasing methane into the atmosphere.
On the other hand, cloud formation is a possible negative feedback mechanism. Additional water vapor in the atmosphere may result in more clouds, which will reflect heat away from the earth and tend to stabilize temperatures.
The real question is what this means to us – certain disaster or just a mild winter? Scientists try to answer that question with their global climate models. For those of us who don't have a global climate model or any objective basis to judge one, it's probably best to leave the conversation here. The earth's climate is incredibly complex and greenhouse warming is just one of the variables that drive it. Getting too wrapped up in how we think these models should work has been the source of much foolishness. One side points to every hurricane as proof of climate change while the other side feels vindicated by a snowy winter in Wisconsin.
As part of that decision we need to get in touch with our own predispositions. If we are constantly reacting to perceived dangers from every corner, we should probably require a little more certainty before we react.
Models may suggest the potential nature and magnitude of the consequences, but they don't provide any additional certainty. We are probably best off coming to a conclusion based on the facts on hand.
We know that, coinciding with the industrial revolution, a change has occured in the atmosphere which is unprecedented in modern geologic times. We are seeing clear evidence of long term changes in our environment: retreating glaciers and artic ice melting to the extent that northern nations are scrambling to lay claim to resources which have been inaccessible to us throughout human history. Finally, we know there are thresholds at which feedback mechanisms could kick off and make the situation much worse.
Once we face the facts, we need to decide whether all this represents a credible threat requiring action. As part of that decision we need to get in touch with our own predispositions. If we are constantly reacting to perceived dangers from every corner, we should probably require a little more certainty before we react. On the other hand, if we have just spent years watching our auto industry drive itself to the brink of destruction by rejecting all calls to design cars for a world with a limited supply of oil or if we have just watched our financial institutions implode after years of lending money to people with minimal prospects to repay it, then maybe we should resolve not to watch another obvious problem bloom into a certain disaster.