While preparing a lit review for a recent paper, I ran across this article that makes clear at least some scientists still doubt the man-made link to global warming. Published in the peer-reviewed scientific journal “Renewable Energy,” the author could find no evidence that man-made pollution has led to the global temperature changes. Here’s part of the abstract (italic added for emphasis):

Mathematical expressions which represent possible human influence on global temperature variations are developed, analysed and discussed … This establishment implies that, contrary to previous expectations and opinions, anthropogenic [human-caused] activities hardly generate significant net alterations in global temperature or solar energy patterns. … This is apparently the first scientific finding in the open literature which tends to support the consistent disputing of the human element in climate change by the USA and Australia as well as the views of the “climate skeptics” which heavily supported the September 2003 World Climate Change Conference held in Moscow.

The author is Ernest C. Njau, chair of the physics department at the University of Dar es Salaam in Tanzania. Njau elaborates in the full-text of the article:

One of the implications of the contents of this paper is that anthropogenic [man-made] activities are not the dominant force behind the post-1800 global warming trend. Atmospheric CO2 [carbon dioxide] is the primary greenhouse gas that is believed to have contributed to global warming since the beginning of the industrial revolution. The use of fossil fuels (e.g. oil, coal, natural gas, etc.) is the dominant source of anthropogenic CO2. In line with the implications of this paper, Ryabchikov shows that the main source of supply of CO2 to the atmosphere is not anthropogenic activities, but tropical regions of the ocean. These regions supply 2×1010 tons of air-borne CO2 annually to the temperate and circumpolar latitudes of the northern hemisphere.

I don’t claim to understand the science behind this author’s conclusions. But, I can read an academic article, and I know that at least three other scientists had to review and approve of its methods before publication. I also know that the Earth has warmed many times in the past, so there’s little face validity in assuming that its latest warming cycle must be due to human activity.

Njau’s article does not represent the first time that the man-made link to global warming has been questioned in the academic press. In 2005, in the peer-reviewed journal “Pure and Applied Geophysics,” three authors concluded that the current scientific literature did not support the theory that man-made pollution was causing global warming. From their abstract:

Our review suggests that the dissenting view offered by the skeptics or opponents of global warming appears substantially more credible than the supporting view put forth by the proponents of global warming. Further, the projections of future climate change over the next fifty to one hundred years is based on insufficiently verified climate models and are therefore not considered reliable at this point in time.

Given this literature, I feel comfortable saying that I still hold some skepticism regarding global warming.

Furthermore, future research may want to examine whether the reason so many scientists appear eager to assume that man is behind global warming has more to do with ideology than scientific method.

UPDATE: Here’s another peer-reviewed journal article that questions the science: “An Inconvenient Maybe” (2008) in the journal Estudios de Economia.