Mid-August on a university campus is a time of greeting among people who are returning after months away.
“How was your summer?” I ask a student who works at the circulation desk in the library.
“Hot,” he says.
The hottest in U.S. history, as a matter of fact. Temperatures in June broke or tied 3,215 records. According to the National Oceanic and Atmospheric Administration, July 2012 was the all-time warmest month since national record-keeping began in 1895. At the end of July, according to the U.S. Drought Monitor, 62.9 percent of the continguous U.S. was experiencing moderate to exceptional drought.
Everyone, it seems, has stories of extreme weather. The soil in our small vegetable garden turned hard as concrete. Blackberry brambles I planted last spring fruited for the first time, but the berries shriveled in the scorching 103 degree heat. A colleague vacationing in Colorado brought news of the wildfires, and many have witnessed the devastation of crops in America’s Heartland. Agricultural losses will mean a rise in food prices at a time when millions of Americans are already hungry or food insecure.
There is a natural variability to the weather. Scientists therefore have not typically attributed any one particular weather event to global climate change. Rather, they explain that heat waves, droughts and more intense storms are consistent with the kind of things we can expect to experience in a world warmed by greenhouse gases. (See, for example, this article on recent droughts by Drs. Christopher Schwalm, Christopher Williams, and Kevin Schaefer: Hundred-Year Forecast: Drought ).
This month, however, the National Academy of Sciences published a peer-reviewed study that concluded that global warming has changed the bell curve of weather variability such that extreme heat is much more probable than it was just 40 years ago. Between 1951 and 1980, extremely hot temperatures covered only about 0.1 to 0.2 percent of the globe in any given year. Now annual heat extremes are covering a much broader range: a dramatic 10 percent of Earth’s surface. James Hansen, one of the study’s co-authors and Professor of Earth and Environmental Studies at Columbia University, spoke about the study in this segment on the PBS News Hour: Extreme Heat Events Connected to Climate Change.
How does one make policy decisions in the face of the probabilities in which climate science deals? In 2001, the United States Conference of Catholic Bishops issued the statement Global Climate Change: A Plea for Dialogue, Prudence, and the Common Good. “The virtue of prudence,” they affirmed, “is paramount in addressing climate change. The virtue is not only a necessary one for individuals in leading morally good lives, but is also vital to the moral health of the larger community. Prudence is intelligence applied to our actions. It allows us to discern what constitutes the common good in a given situation... In facing climate change, what we already know requires a response; it cannot be easily dismissed. Significant levels of scientific consensus—even in a situation with less than full certainty, where the consequences of not acting are serious—justify, indeed can obligate, our taking action intended to avert potential dangers. In other words, if enough evidence indicates that the present course of action could jeopardize humankind’s well-being, prudence dictates taking mitigating or preventative action.”
Congress and the U.S. electorate failed to take preventive action in 1988 when Dr. Hansen first testified on climate change before the Senate. In each ensuing year, we have continued to fail to act with the virtue of prudence. We are now going to need as never before the cardinal virtue of fortitude to give us the courage to enact the changes in our personal lives and public policy necessary to address the climate crisis at a time when the probability of climate catastrophes increases with each day we delay.