We can’t afford to wait

In his column Sunday (May 22), Jonah Goldberg accuses liberals of being the real science deniers. Goldberg touches on a litany of issues, including global warming, abortion rights and transgender bathroom laws. Let’s focus here on his remarks about global warming.

Goldberg suggests that climate scientists resort to claims of “settled science” in order to avoid having to make their case explicitly. He argues that the term is really a misnomer: “Scientists are constantly questioning their understanding of things; that is what science does.” Well, yes, scientists do that, but this is not the real issue.

What Goldberg fails to understand is that the corpus of scientific knowledge consists of matters that are “settled” and matters that are not. None of us question the theory of gravity. The fact that it causes unsupported objects to fall in Earth’s near-surface environment has been settled back to the time of Isaac Newton, if not earlier. (Newton merely explained why they fall.) Yet, wide open questions still remain. For example, scientists have yet to reconcile Einstein’s theory of general relativity (our most general theory about gravity) with quantum mechanics (our most general theory about the nature of matter). The fact that there are still open questions about the theory of gravity doesn’t make it safe to jump off a cliff.

Yet that is essentially what Goldberg is asking us to do when it comes to human-caused climate change. Certain aspects of climate science — e.g. the existence of the greenhouse effect, the fact that Earth is warming, and that we cannot explain that warming in terms of natural factors — are indeed “settled,” by any reasonable definition of the word. They are no longer actively debated by mainstream climate scientists. Other factors, such as the precise amount of warming we can expect, the subtle role of changes in clouds, and how things like tornadoes might be impacted, still are. But when it comes to making national and international policy, we cannot afford to wait for every aspect of the science to be completely settled. Much as the only way to confirm the danger of jumping off a cliff is to see what happens when you hit the bottom, waiting 50 years to see how much warming results from the continued burning of fossil fuels will likely commit us to the most severe consequences of climate change. We need to heed the advice of the U.S. National Academy of Sciences and the (international) Intergovernmental Panel on Climate Change. Starting with the first IPCC report in 1990, both organizations have consistently warned that the climate is warming and that humans are largely to blame. To back this up, the global surface temperature record has been broken the last two years in a row, and this year is shaping up to be hotter yet. The predictions are already being fulfilled.

Goldberg also argues, unconvincingly, that climate activists say their preferred remedies are irrefutable. In fact, there is ongoing, vigorous debate within the climate/energy community as to what the best mitigation strategies might be. This debate includes consideration of geoengineering — actively cooling the climate by increasing Earth’s reflectivity — although the proposed mechanisms are less attractive, and more expensive, than Goldberg makes them out to be.

Most of the discussion within the climate community centers on how best to reduce CO2 emissions. Some advocate policies that explicitly incentivize renewable energy to increase its competitiveness in the energy marketplace. Others advocate a “cap-and-trade” system of tradable permits designed to cap carbon emissions at some level. This isn’t a “liberal” idea. It was first introduced by George H.W. Bush to deal with the problem of acid rain, where it proved extremely effective.

Yet others (including some prominent Republicans) prefer taxing carbon emissions instead. Taxing carbon, they argue, is more efficient than subsidies or regulations, as it addresses the problem in a holistic manner. A gas tax, for example, would encourage all of us either to drive a fuel-efficient vehicle or to live closer to where we work or to use mass transit. Taxing CO2 emissions from electric power plants would level the marketplace to allow renewables and other non-fossil sources of energy to better compete. Any hardship of such a tax could be lessened or offset entirely by, for example, returning some or all of the money raised as rebates on people’s income taxes — something conservatives ought to support.

Unfortunately, these sorts of proposals are anathema to those who still don’t accept the overwhelming scientific consensus that underlies human-caused climate change. If we can get past the current, unworthy debate about whether a problem exists, and onto the worthy debate about what to do about it, we can join with the rest of world in finding a way to keep the Earth safe and habitable for future generations.

Jim Kasting is an Evan Pugh professor of geosciences at Penn State and an associate in the Earth and Environmental Systems Institute. Michael Mann is a distinguished professor of atmospheric science at Penn State, director of the Earth Systems Science Center and an associate in the Earth and Environmental Systems Institute.