Global warming began over 5,000 years ago: "A SINO-AMERICAN team of scientists has disputed the traditional thinking that global warming, partly resulting from excessive timber cutting, is a relatively recent modern phenomenon %u2014 they argue it's at least 5,000 years old." (emphasis added)
Reading this article, distributed by the Chinese news agency Xinhua, I couldn't understand what it had to do with global warming. This confusion resulted in spite of, or maybe because the article expressly ties archaeological data about the use of plants in Chinese towns 5000 years ago to carbon dioxide emissions.
The argument in the article says that "prehistoric" humans burned lots of wood for cooking, lighting, and making things. This required a lot of wood, requiring a lot of lumbering. Someone referred to as "Luan" says that the increase in carbon dioxide probably started before the industrial age.
Now, this was hard for me to believe. There are just so, so many things wrong with this story. Thinking maybe it had just slipped through the cracks, I looked around a little bit, and found that the story had made it onto Yahoo! News and also some site called ArchaeologyNews.org. It was also slightly rewritten on a site called sina.com [LINK], starting with the bold statement: "It is common sense nowadays that excessive carbon dioxide in the air caused by excessive lumbering leads to global greenhouse effects" (emphasis added). A search through GoogleNews shows 4 articles (Times of India, Xinhua, Shanghai Daily, People's Daily Online) carrying the same story.
What is wrong here?
First, there is the issue of "scientists" overstepping their expertise. This is an archaeology project, not a paleo-climate reconstruction. They are perfectly welcome to explore how plants were used in ancient China; that is a great project, and is probably very interesting for archaeology and sociology, and maybe even as an application of geochemistry and geochronology, but it is a far cry from doing a paleo-reconstruction of the composition of Earth's atmosphere. In fact, we have very good reconstructions (cf., the Mann et al. papers), which don't show much change in the pre-industrial years. There is some before the 1800s, but I don't think it is statistically significant.
Second, the report is focused on global warming attributable to cutting down trees. It goes further, suggesting that ancient people could have cut down enough trees to change atmospheric concentration of carbon dioxide. Okay, burning biomass releases carbon dioxide into the atmosphere, but that carbon dioxide came from the atmosphere in the first place... there isn't much contribution unless you get carbon out of the lithosphere (rocks, like coal). It is still uncertain how much carbon ecosystems can suck out of the atmosphere and put into the lithosphere (by dying and rotting). Most people who think about these issues are dealing with areas like the Amazon rainforest and huge coral reefs, not the edges of forests in ancient China. The amount of wood harvested by ancient peoples, even integrated over all societies from 10,000 years ago to 1000 years ago, can't compete with what modern humans are doing. We have industrialized deforestation, whereas ancient people used what they could by chopping down each tree and dragging it back to the village. The assertion in the article is ludicrous.
Third, the article gives no reference and few hints for finding the study itself. In the Xinhua article, one name appears, "Kuan Fengshi," and one other one ("Luan") which after some investigation must be referring to Luan Fengshi, the actual name of someone at the university cited. I was able to find a web page in english that describes the project [LINK]. There are two English and two Chinese publications, but they are both about surveying the area, not about plants used by the ancient inhabitants. So there's no credibility here.
Finally, is there some connection between this disinformation and a Chinese interest in climate change being discredited (or at least weakened)? Afterall, China is a huge energy user, and to keep their economy growing at the crazy rate it has achieved lately, they can't stop to make things too green. I don't have any evidence that this is the case -- i.e., that China is purposely releasing misleading news about climate science -- but I think it is worth putting out there for now.