Global temperature plateau

This morning I (somewhat unintentionally) continued researching the whole CRU email hack issue again, and stumbled upon this article from BBC about a recent plateau in temperature increases. Overall I don't find it to be overwhelming evidence against AGW (anthropogenic global warming) compared to the drastic temperature spike occuring post industrial revolution, and unfortunately it may just be one of those things that we'll have to "wait and see."

Personally, the issue of whether or not to take action to prevent AGW is pretty obvious to me, and is simply a matter of invoking the Precautionary Principle. In this case, the action(s) potentially causing harm are pumping out greenhouse gases, etc. Furthermore, reducing fossil fuel usage would have multiple positive effects regardless of whether or not AGW exists. To name a few, it would reduce mountaintop removal, reduce pollution, and reduce US dependency on foreign oil. Besides, it appears that there is much more evidence in support of AGW than there is refuting it. Also, a lot of studies contradicting AGW appeared in the journal Climate Research, which is said to have a dubious peer review process and is not JCR listed.

Anyways, going back to the BBC article I can't comment on solar radiation as I know exactly zilch about the science behind it. I will note this quote about ocean currents, specifically the Pacific Decadal Oscillation (PDO), which I was exposed to while working for the Stilly-Snohomish Fisheries Enhancemnt Task Force (it determines which Pacific salmon species are likely to be abundant). Here's a quote from the BBC article:

According to research conducted by Professor Don Easterbrook from Western Washington University last November, the oceans and global temperatures are correlated.

The oceans, he says, have a cycle in which they warm and cool cyclically. The most important one is the Pacific decadal oscillation (PDO).

For much of the 1980s and 1990s, it was in a positive cycle, that means warmer than average. And observations have revealed that global temperatures were warm too.

But in the last few years it has been losing its warmth and has recently started to cool down.

These cycles in the past have lasted for nearly 30 years.

Now, here's a quote about the PDO (for more information see this link):

Causes for the PDO are not currently known. Likewise, the potential predictability for this climate oscillation are not known. Some climate simulation models produce PDO-like oscillations, although often for different reasons. The mechanisms giving rise to PDO will determine whether skillful decades-long PDO climate predictions are possible. For example, if PDO arises from air-sea interactions that require 10 year ocean adjustment times, then aspects of the phenomenon will (in theory) be predictable at lead times of up to 10 years. Even in the absence of a theoretical understanding, PDO climate information improves season-to-season and year-to-year climate forecasts for North America because of its strong tendency for multi-season and multi-year persistence. From a societal impacts perspective, recognition of PDO is important because it shows that "normal" climate conditions can vary over time periods comparable to the length of a human's lifetime.

The causes for the PDO are not know, and therefore it can't be factually stated that the supposed correlation between the PDO and global average temperature implies a causation. Furthermore, the PDO has been in the warm phase since approximately 1980, when global temperatures were rising. However, the "hockey stick" graph showing the sharp (supposedly anthropogenically caused) increase in temperature also demonstrates relatively stable temperatures throughout the millenium (pre-industrial revolution). During this stable period, the PDO was presumably operating much as it has since it's been recorded (approximately 30 years between phase changes).

So with all of the uncertainty surrounding the PDO there doesn't seem to be much valid evidence for stating that it significantly influences average global temperature. There is much more evidence that humans are significant contributors, and so I once again invoke the Precautionary Principle. I'm not a climate scientist and I can't say that I'm 100% confident that GW is anthropogenically influenced, but the evidence does lead me to lean strongly in that direction. Besides, the burden of proof lies with those who wish to continue pumping out greenhouse gases (or, more realistically, pumping them out with weaker to no regulation) that they have no effect on climate. Especially considering what's at stake (predicted warming will have huge ecological consequences, especially given the habitat fragmentation caused by human impacts on the land, but that is a much more involved discussion than I would like to get into here).

I'll end this post on an unrelated note: Happy Thanksgiving!!!

References: embedded in text.