William Ruddiman, professor emeritus from UVA, has one of the more controversial theses out there in terms of climate science. He argues, based on long-term studies, that human-driven climate change is not a recent, post-industrial phenomenon, but rather began with the dawn of agriculture around 12,000 years ago. Clearing forests to plant crops began soon after, with the results that around 5-6,000 years ago, when methane and other carbon levels should have been decreasing in the run-up to another ice age, levels rose instead. In Ruddiman’s view, the past 5,000 years of relative climate stability “may actually reflect a coincidental near-balance between a natural cooling that should have begun and an offsetting warming effect caused by humans” (94).
The second-level controversial claim Ruddiman makes is that, since humans have been modifying the climate for millenia, it’s not possible under any regime to return to a “natural” path. Taking a geological approach to time, he instead suggests that we are in the middle of a 400-year carbon intensive period, during which humanity will exhaust first oil (almost now), then natural gas, and then finally coal reserves. At the end of that period, all the easily accessible carbon will be in gaseous form, and the end result of the experiment — can the world ocean absorb that much carbon, and what will the consequences of the resulting acidification be? — will slowly become apparent. In the medium term, he’s more worried about topsoil and water shortages than fuel, though he does think that oil is nearly depleted now.
With curiosity, some abstraction, and a general desire to caution against alarmism on the green or brown sides, Ruddiman suggests that climate modification is what humans do. Interesting stuff.
This is the World just before men. Too violently pitched alive in constant flow ever to be seen by men directly. They are meant only to look at it dead, in still strata, transputrefied to oil or coal. Alive, it was a threat: it was Titans, was an overpeaking of life so clangorous and mad, such a green corona about Earth’s body that some spoiler had to be brought in before it blew Creation apart. So we, the crippled keepers, were sent out to multiply, to have dominion. God’s spoilers. Us. Counter-revolutionaries. It is our mission to promote death. (Thomas Pynchon, Gravity’s Rainbow 720).