Climate activists make a lot of nonsensical claims about their beliefs. Like any religious group they testify to their unthinking and unshakable convictions, their absolutism and desire to exterminate heretics. This, even more than climate change, is the greatest threat we face. It's more than a character defect and ethical poverty. Mental disease seems a more apt diagnosis, and it is at epidemic levels.

These zealots have a lot in common with environmental activists of every stripe, and are often the same people. They're the same ones who fall for various food cult claims, organic gardening, fear of chemicals and nuclear power, and oppose liberty in all of its forms. They want strict religion, harsh punishment for unbelievers, even harsher punishment for apostates, and minute regulation of everyday behavior.

Fortunately, there are many who are still making open minded inquiry in the ongoing attempt to better understand natural systems rather than just giving up on comprehension and adopting superstitious beliefs. Their findings are less satisfying since they lack the certainty that zealots require for comfort, but I find them to be more interesting.

One strand of inquiry deals with agriculture and its long term effects on climate through land use change. Like every other species humans engineer their environment and have global effects. The earth has gone through massive changes over the millenia due to life. Our oxygen atmosphere is perhaps the classic example, which would not exist in the absence of life. Humans have increased carbon dioxide and methane, and it didn't begin with the industrial revolution and the use of fossil fuels.

This notion has been around for a while. It was discussed some last year in Soil Mining and People Power. The thrust of the argument is that rice paddies and deforestation to clear land pumped massive amounts of methane and carbon dioxide into the air beginning 8,000 years ago, and that this is what has prevented a return to ice age conditions that would otherwise be the case due to the Milankovitch cycles that regularly plunge the planet into general glaciation. It is even speculated that the Medieval Warm Period (~800-1300 AD) and the Little Ice Age (1500 to 1750) resulted from the world wide boom in population and agricultural activity - which warmed the world - followed by the bust in population in the Americas after the population was all but exterminated by Eurasian disease.

Critics of such ideas cite the comparatively small human population of those times as defects since they would not have used land on the scale required, but that assumes no change in agronomic methods.

early populations likely used a land-clearing method that involved burning forests, then planting crop seed among the dead stumps in the enriched soil. They would use a large plot until the yield began to decline, and then would burn off another area of forest for planting.

They would continue this form of rotation farming, ever expanding the cleared areas as their populations grew. They possibly cleared five or more times more land than they actually farmed at any given time. It was only as populations grew much larger, and less land was available for farming or for laying fallow, that societies adopted more intensive farming techniques and slowly gained more food yield from less land.

Ruddiman notes that with the highly efficient and intensive farming of today, growing populations are using less land per capita for agriculture. Forests are returning in many parts of the world, including the northeastern United States, Europe, Canada, Russia and even parts of China. . .

"Many climate models assume that land use in the past was similar to land use today; and that the great population explosion of the past 150 years has increased land use proportionally," Ellis said. "We are proposing that much smaller earlier populations used much more land per person, and may have more greatly affected climate than current models reflect."

Ruddiman and Ellis based their finding on several studies by anthropologists, archaeologists and paleoecologists indicating that early civilizations used a great amount of land to grow relatively small amounts of food. The researchers compared what they found with the way most land-use models are designed, and found a disconnect between modeling and field-based studies.

"It was only as our populations grew larger over thousands of years, and needed more food, that we improved farming technologies enough to begin using less land for more yield," Ruddiman said. "We suggest in this paper that climate modelers might consider how land use has changed over time, and how this may have affected the climate."

Interesting, and there are implications for current agronomic practice as population continues to rise along with GHG concentrations. Even if we develop better energy systems and reduce fossil fuel use emissions from land use change will continue to increase. If, as claimed, this has had large effects on climate then we won't dodge climate change problems unless we also greatly improve our agronomic systems to be more productive on less land, and restore soil carbon to near pre-agricultural levels. We wouldn't want to do this too well since the threat of the Milankovitch cycles remains.

It may be that some of the environmental heresies that are gaining support - nuclear power, GMOs - and emerging agronomic hacks such as pyrolysis to produce biochar and bioammonia deserve more attention. The hunker down primitivism of paleo-environmentalists is precisely the wrong thing to do at this time, and may have been a cause of earlier problems.

A better attitude is to focus on improved practices that increase productivity and reduce costs. Using less land, less water, and fewer costly inputs for greater production makes good sense. It's good business practice, and when business is not distorted by thoughtless regulation, including subsidies, this is a helpful guide to generally beneficial systems. Some of this will appeal to enviro-nutters and some won't, but it's the beliefs of the nutters that need to become more rational.