Articles by Andrew Dessler

One way or the other, we’re waiting for the next administration

If the Supreme Court rules that CO2 does not have to be regulated, it will give the present administration cover to do nothing for two more years. However, most serious candidates for president support action to curb greenhouse-gas emissions, so regardless, I suspect you'll see action in the next administration.

If the Supreme Court rules that CO2 can be regulated, the administration will ... do nothing for two more years. But again, the next president will likely take some action.

If the Supreme Court rules that CO2 must be regulated, the administration will drag its feet and ... end up doing nothing for two more years. But again, the next president will likely take some action.

Thus, regardless of what the court rules, we will have to wait for '09 to see any action on emissions reductions -- but we'll see action then regardless of what the court rules.

It’s likely not the primary cause

In climate change debates, one hears a lot about the Sun. A favorite argument of those opposed to action is that the warming we're presently experiencing is due to increases in solar output, also known as solar brightening, and not from greenhouse gases.

Before critiquing this argument, first remember what the IPCC says about human contribution to climate change:

There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.

Note that the IPCC says most of the recent warming is due to human activities. This leaves as much as 50% of the recent warming not attributed to humans.

It is certainly possible -- and fully consistent with the IPCC -- for solar to have contributed some part of the warming we are experiencing.

The real question is whether solar brightening could be the dominant cause of the recent warming, with humans playing a minor role. That is unlikely, for the following reasons:

It’s more complicated than you might think

Most people interested in climate change have seen the plots showing strong correlations between CO2 and temperature going back several hundred thousand years:

FIGURE: Data from the Vostok ice core in Antarctica, from 410,000 years ago to the present. The top curve shows abundance of CO2 (in parts per million) from air bubbles in the ice core. The bottom curve shows the temperature anomaly in the Antarctic region, relative to the present, from isotopic measurements of the ice. After Fig. 3-6 of my book.

Here’s why the scientific community thinks so

This is a "greatest hit" from my previous blog. It's a topic that comes up all the time, so I think it's worth a reprise.

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As George Bush said at a recent press conference: "the globe is warming. The fundamental debate: Is it manmade or natural?"

Why does the scientific community think humans are significantly contributing to today's warming?

To understand why, first recognize that whenever the climate shifts, there's a reason for it. It does not wander around like a drunken sailor.

Based on decades of research, we can identify the factors that have influenced climate in the past: