Soon after it passed, the summer of 1988 was described as “the hottest in more than a century.” Researchers described the heat as consistent and used a (then) relatively new idea that carbon dioxide emissions from fossil fuels were building up in the atmosphere, causing the Earth to warm dangerously. Thirty years later, we are being told that the worst dreams of those early researchers have come true, causing temperatures to spiral out of control.
However tempting it may be to focus on frightful headlines, we should remember that climate is an ever-changing, dynamic, and highly complex system. We should resist efforts to reduce that system to a simplistic notion that carbon dioxide, or CO2, is the master control knob, leaving everything else, like the sun, as little more than statistical noise. Before we rush to implement potentially damaging or (at best) unsure fixes based on that notion, we should answer a few questions.
First, are increasing CO2 levels unprecedented? Second, will the measured warming be necessarily harmful? Third, how should we respond?
A telling quote from an early researcher into the nation’s changing climate can help to answer our first question. This researcher noted, “A change in our climate … is taking place,” causing snow to be “less frequent and less deep,” melting almost immediately after falling. He described how “rivers, which then seldom failed to freeze over in the course of the winter, scarcely ever do now,” and that an “unfortunate fluctuation between heat and cold” during spring was “fatal to fruits.”
These unnerving weather reports mirror anecdotal evidence we’re hearing from Michigan’s ski hill operators about the first snowfalls of the season coming later and melts coming earlier. But one key factor separates these disparate climate reports: time. The early researcher was Thomas Jefferson, in his 1787 book “Notes on the State of Virginia,” published long before any SUVs began rolling off Michigan’s assembly lines.
Atmospheric changes also occur on much longer timescales, and in a geologic sense, the level of CO2 in the atmosphere now (410 parts per million, or ppm) is certainly not unusual. In fact, Will Happer, a physicist from Princeton University, actually argued in his testimony before the U.S. Senate Subcommittee on Space, Science, and Competitiveness that the Earth is currently in a CO2 famine. Happer noted that the Earth has typically had atmospheric CO2 levels of “many thousands of parts per million.” Preindustrial levels of CO2 — 280 ppm — were, he added, dangerously close to 150 ppm, the point at which plants die from CO2 starvation and all life on Earth ceases to exist.
To answer the next question — whether a warming climate will be harmful — it is worthwhile to also ask, “How much warming do we expect?” For that answer, we typically look to climate models. But, the climate models relied on by researchers and governments have historically and chronically overpredicted the warming associated with human-generated greenhouse gas emissions. For example, one recently published study in the American Meteorological Society's Journal of Climate found that climate models routinely inflate the sensitivity of Earth’s atmosphere to CO2 emissions by as much as 45 percent.
That’s actually an important statistic, because most climate policy is based on something called Equilibrium Climate Sensitivity. If, as this paper found, the ECS is low, then climate change may not be much of a problem. It could even prove to be beneficial. But if it is high, as the climate models predict, it could be a much larger problem for humans and our environment.
If we do not have 100 percent certainty about the actual impacts of a changing climate, the question of what to do about the reported warming becomes more difficult to answer. Judith Curry, a former tenured professor and chair of the school of Earth and atmospheric sciences at the Georgia Institute of Technology, co-authored the previously mentioned study on climate models. She suggests that the best plan is to employ a pragmatic, “no regrets” style of energy policy. This policy recognizes that immediate and drastic cuts in our most reliable and affordable energy sources — like natural gas — would have massive and immediate negative effects on human health and well-being, because they would limit access to life-preserving energy.
Some groups say that our approach to fossil fuels should be “leave it in the ground” in the name of stopping climate change. Rather than follow that prescription, though, we should continue to develop and deploy more efficient and clean technologies and energy sources — like natural gas and nuclear energy. Doing so ensures we have affordable and reliable access to essential energy, and that we can continue to lead the relatively healthy and comfortable lives we now enjoy. It also ensures we can lead our lives in an increasingly clean environment, still protected from what has always been a potentially dangerous and volatile climate.