Turning Point

It has dawned on me over the past year, after a winter that didn't occur and as one month after another rolled in as the warmest on record, that right now, this very year, humanity's fortunes may have begun to shift and that a story was beginning to unfold that would dominate the news for the next few centuries. It won't be a happy story. And I think future generations will hold us in deep contempt if we don't at least begin to make the effort to alleviate the disaster that awaits them.

I wrote those words eight years ago in a Science Insights essay titled "Wintertime Reflections on Global Warming" (C&EN, Jan. 25, 1999, page 45). Two events in the past two weeks indicate that we have arrived at the point I alluded to eight years ago. According to the UN Intergovernmental Panel on Climate Change (IPCC), global warming is now affecting Earth's physical and biological systems, and the impacts will increase in severity in coming decades. And the U.S. Supreme Court has ruled that the federal government has the authority to regulate carbon dioxide, the principal greenhouse gas.

The IPPC report—"Climate Change Impacts, Adaptation & Vulnerability"—is the second installment of the group's Fourth Assessment Report (see page 14). The first installment, issued in February, concluded that global warming due to human activity has occurred in the past 50 years (C&EN, Feb. 12, pages 3 and 17). The current installment is based on more than 29,000 observational data sets from 75 studies that "show significant change in many physical and biological systems," with "more than 89% ... consistent with the direction of change expected as a response to warming."

C&EN Senior Editor Bette Hileman wrote this week's news story on the IPCC report. She quotes Martin Parry, cochair of the working group that produced the report, as saying: "At the global level, there is a man-made climate signal coming through on plants, animals, water, and ice. For the first time, we are no longer arm-waving with models saying this might happen. "

An important conclusion in the report is that the spatial corelation of warming and various changes make the observations "very unlikely to be due solely to natural variability of temperatures or natural variability of the systems."

One of the infuriating things about those who would deny the reality of global warming caused by humans is the convenient evolution of their argument. Ten years ago, most simply denied that Earth was warming. The data that suggested otherwise was derided as "just noise." Five years ago, when the data was even stronger and we had lived through several of the warmest years in recorded history, doubters conceded that, perhaps, Earth was warming, but they insisted that humans were not the cause. "Just natural variation," their argument went. Today, a few former skeptics concede that humans may, in fact, be contributing to global warming. But guess what? It's too late to do anything about it, they insist. "Just get used to it, enjoy the warmth, adapt," goes their refrain.

But that is just not true. Some degree of global warming has already occurred and more is going to occur. We know that. But the amount of warming-and the amount of concomitant ecosystem destruction, species extinction, and human dislocation that goes with it-can very much be affected by the decisions we make today about future energy use.

That is where the Supreme Court ruling that CO₂ is an air pollutant as defined by the Clean Air Act comes in (C&EN, April 9, page 9). One of the principal functions of government is to regulate behavior for the common good. The Bush Administration has been adamant about not regulating greenhouse gases, insisting in this case that EPA did not have the authority to control CO₂. Turns out, that's not true. In a 5-4 ruling, the court found that CO₂ is, indeed, a pollutant and that EPA has authority to regulate its emission from new cars and trucks. The ruling opens the door to regulation of CO₂ from all sources.

The IPCC report and the Supreme Court's ruling mark an important turning point in addressing the challenge of global warming. I hope we are ready to begin meeting that challenge.

Thanks for reading.