Are we there yet?
If we haven’t entered a period of human-caused climate change yet, what will it take for us to agree that we have? Maybe events such as the following:
• Almost 1,500 U.S. high-temperature records fell in one week.
• Health-care specialists warn that Chagas’ disease, spread among humans by blood-sucking insects in tropical regions, might spread as temperatures rise in the United States.
• Biologists identify mechanisms by which earlier snow melts decrease populations of a rare Rocky Mountain butterfly.
• Agricultural specialists attribute global changes in crop maturation, for example early ripening of grapes, to increased global temperatures.
• NASA releases maps showing a reduction in snow cover for North America in 2012 compared with 2011.
• Studies suggest that the houses where 4 million Americans live on the coasts confront increased risk of storm-surge flooding by midcentury because of warming oceans.
• News reports say the iconic cherry trees in Washington, D.C., were in full bloom a week before the month-long National Cherry Blossom Festival started.All of these things occurred over just two days this month.No one seriously doubts that carbon-dioxide levels in the atmosphere are rising. Over the past 30 years, they have increased by 15 percent — a rate that continues to grow with no sign of stopping.No one seriously doubts that the increased carbon dioxide in the atmosphere is a result of burning fossil fuels and cutting and burning forests.And no one seriously doubts that global mean temperatures are rising. In the past 30 years, the global mean temperature has increased by about a half a degree Celsius.
Almost all scientists and related professionals who collect and analyze data about climate change or its effect on biological systems agree that the increased carbon dioxide levels cause much of the climate change and warming. The remaining climate skeptics tend to be policymakers who would rather not make policy.
So how do the hold-out skeptics propose to test their hypothesis that no link exists between carbon-dioxide increases and climate-change effects? Good science demands explanations and hypotheses that can be tested.
An explanation that can’t be tested isn’t an explanation — it’s a dream, a belief, a political position. It might make for good campaign rhetoric, but it makes for poor public planning.
The skeptics demand more science. Bring it on. What’s the red line for their “no effect” hypothesis? What has to happen for them to say: “We were wrong; there is an effect. You better do something about this.”Thomas Kuhn, a philosopher of science, noted in the middle of the last century that the ability and willingness to submit one’s hypothesis to testing and possible rejection formed a core component of effective science. Indeed, without it, one really isn’t practicing science; he or she is practicing advocacy at best, or maybe self-promotion.
The hold-out skeptics say they only want good science when it comes to climate change and planning for it. We all do.
How will we know we’re there? What will it take for them to abandon their “no effect” hypothesis? If they can’t answer that, they’re just adding even more hot air to the atmosphere.
Steve Rissing is a biology professor at Ohio State University.