The science revealing rising risks of disruptive human-driven climate change has accumulated like dots added to a pointillist painting, but the resulting image still lacks clarity. The result is one of the great paradoxes of the early 21st century: a potential planet-scale threat that perpetually hides in plain sight. Parts of the climate picture are visible now in high resolution. There is no longer any reasonable way to explain recent changes in atmospheric and ocean temperatures without a substantial contribution from accumulating human-generated greenhouse gases. Arctic sea ice in summer is dwindling. Tropical climate conditions are expanding. The stratosphere is cooling, as predicted, while lower atmospheric layers warm.
For many of the most consequential climate impacts, though, the picture remains fuzzy. Rising sea levels are certain in a warming world, but there is still substantial uncertainty about the extent of the increase in this century, mainly because the dynamics that could erode the ice sheets of Greenland and Antarctica remain poorly understood. Other worst-case outcomes also remain primarily in the realm of the plausible, as opposed to the probable. That may be one reason why work toward a meaningful climate treaty and national climate legislation has sputtered. But there are others.
The disconnect between information and action is less surprising when you examine two other trends of the past 30 years. One is in research in behavioral science, illuminating our tendency to sift facts using emotion-based filters and to deeply favor short-term payoffs. The second is the sustained disinvestment in basic energy-related R&D that began with the election of Ronald Reagan in 1980 and has continued until now, with bipartisan support.
Some analysts call for a focus on adaptation and innovation: helping vulnerable communities develop ways to deal with climate extremes and reviving research budgets to raise the odds of energy breakthroughs. Even pessimists point to climate countermeasures, dubbed geoengineering, as a vital insurance policy. Still, the core challenge remains as Ralph Cicerone, president of the National Academy of Sciences, described it to me in 2007: “Does it take a crisis to get people to go along a new path, or can they respond to a series of rational, incremental gains in knowledge?” Given the persistent gap between climate data and behavior, we may not like the answer.
Andrew Revkin writes the "Dot Earth" blog for The New York Times and was a senior editor at DISCOVER. He has written three environmental books.