The climate change debate

I’ve noticed over the years that the popular debate on a subject (among people who aren’t experts) is often miles away from the professional debate (among experts) on the same subject. For example, on the nature-nurture question, the popular debate hinges around whether genetics has anything at all to do with people’s abilities, while the expert debate (based on data, not political correctness) is about whether genetics accounts for 40% or 60% of the outcome.

So too with the climate change debate. The popular debate (among people with strong views but no data), now fueled by some intemperate but not especially incriminating e-mails between a few British climate scientists, is about whether there is any real climate change at all. The expert debate (among climate scientists who study the field and have data) is about just how much and how fast the effects of climate change will be felt.

There are four data-supported indisputable facts that support the argument that the climate is changing:

1. From chemistry we now know that the surface temperature of the Earth is roughly 60º F higher than it would otherwise be thanks to greenhouse gasses that collectively make up about 3 percent of the mass of our atmosphere. The two most important of these are carbon dioxide and methane.

2. From several different sources (air samples trapped in glaciers, plant growth rates, the rate at which shells (calcium carbonate) are dissolved in sea water, etc) we know that carbon dioxide levels have increased sharply by about 40% since the beginning of the industrial revolution.

3. From what we now know of chemistry and physics, in the absence of any feedbacks except for temperature itself, doubling carbon dioxide would increase the global average surface temperature by about 1.8º F.

4. Global temperatures have been rising for roughly the past century and have so far increased by about 1.4º F.

In addition, there is observational data to support this warming. The story that the Himalayan glaciers were disappearing may have been incorrect, but there is no doubt that the arctic ice sheet and winter sea ice are disappearing. There is no doubt that the permafrost is disappearing in large areas of northern tundra (releasing yet more methane, by the way). There is no doubt that some deposits of frozen methane hydrates in shallow portions of the ocean are melting (releasing yet more methane).

So while there may be a good deal of disagreement among experts as to how much and how fast our climate will warm, there is almost no disagreement that warming is occurring. Of course, data means little to those who are emotionally attached to a contrary position.