Ignorance of systems has its way of plowing forward, juggernaut-like. Nordhaus has opined that agriculture is “the part of the economy that is sensitive to climate change,” but because it accounts for just 3 percent of national output, climate disruption of food production cannot produce a “very large effect on the U.S. economy.” It is unfortunate for his calculations that agriculture is the foundation on which the other 97 percent of GDP depends. Without food — strange that one needs to reiterate this — there is no economy, no society, no civilization. Yet Nordhaus treats agriculture as indifferently fungible.