Plows, Plagues, & Petroleum

Great book.

Best of my Christmas books thus far. William Ruddiman, an environmental sciences professor at UVA, has a breakthrough concept book about man and the environment. He is very persuasive. He notes wryly that both sides of the climate change debate will pick out things from this book to buttress their claims, and that has already proved true. His side, he insists, is the science side, of hypothesis, research, challenge, test, reevaluate, and rework. As such, he is annoyed with both sides of the political debate, though recently he has become more annoyed with the climate change deniers (skeptics he’s still okay with).

He believes in anthropogenic climate change because he can demonstrate it has been happening. For 8,000 years. Most climate scientists have focused on the last 200 years of slight, but rapid, warming. Ruddiman shows that when we abandoned hunting and gathering and started farming, we started to slowly warm the environment. We have done this so effectively, in fact, that we should have already begun a glaciation, or Ice Age since then, but haven’t.

We were due for one because of cycles of tilt, orbital shape, and precession of the earth. According to those long, long overlapping cycles, we should be halfway into a major glaciation at this point. If we hadn’t warmed the environment, we’d be real cold just now.

Farming led to deforestation, which slightly increased CO2. Three thousand years later, irrigation and domestication of animals led to methane increases which further warmed the environment. Because of the long-term cooling trend, however, the warming has mostly succeeded in keeping average temperatures stable. The cooling cycles in this trend have been comparatively brief – two or three centuries – resulting from massive epidemics. What we inaccurately call the Little Ice Age (1600-1800) was likely caused by the massive epidemics in the Americas when Europeans arrived. 10-20% of the population of the entire earth died 1500-1700. Epidemic causes widespread abandonment of farmland, which rapidly reforests, cooling the environment.

On top of this warming that has been an enormous positive for mankind, we started burning fossil fuels in quantity 200 years ago. That has created a more dramatic spike in CO2 and some warming. The value of this for humans is more ambiguous.

Ruddiman’s view is that warming is fine per se, it’s the speed that is worrisome. Climate change has a long delay time, and the die is already cast for future warming. The CO2 that will change the climate is already “in the pipeline” as he says, and we will continue to warm whether we abandon fossil fuels or not. What we can do now is slow the rate of warming, giving the deep ocean time to do its thing absorbing CO2. This will decrease the final spike in warming, and make it last longer as well. When the fossil fuels are burned up, in 200-400 years, cooling will resume, though from a high level. Even that prediction he makes with hesitation, because human actions can change.

His conclusion is that anthropogenic climate change is real and demonstrable, that it has mixed benefits and risks, and the primary danger for the next century is for places that have large populations in low-lying areas. We can address this by slowing the amount of CO2 being released into the atmosphere. He considers this quick warming a problem, but not the primary environmental problem we face. Using up our topsoil and fresh water is of greater concern to him. I would add fish to that.