Will PDO drive a cooler global climate?

Temp records show a recent dropoff in the past year, a downtrend that We've noted and Daily Tech and Anthony Watts and other Climate Skeptic blogs have as well. We are, this year at least, in Global Cooling. UPDATE: March sees an uptick with SH cooling and NH rebounding.



Two immediate questions are: Is this a blip for a season, i.e., just one anomalous cold winter and then back to 'global warming', or is it an indicator of a different trendline? And what is driving this change? It's too early to tell, but the answer may be "PDO". PDO stands for "Pacific Decadal Oscillation" and is a long-lived El Niño-like pattern of Pacific climate variability. Wikipedia PDO entry mentions that "Shifts in the IPO change the location and strength of El Niño (ENSO) activity."

In Climate Audit blog, commenter Ron Cram mentions that PDO has recently 'flipped' into cool mode:

You write that the recent cooling is driven by ENSO turning to La Nina. I disagree. While this has played a role, it is really the PDO turning to its cool phase in combination with La Nina. When PDO is in its warm phase, El Nino can be quite warm - such as in 1998. When the PDO is in its cool phase, the La Nina can be quite cool. But the opposite is not true. La Nina will never be this cool when the PDO is in its warm phase. ....
It takes four or five years for the PDO to shift from one regime to another. The Bratcher and Giese paper was written in 2002 and based on their observations they predicted the PDO would change regimes in “about four years.” It did not actually seem to shift until late 2007.

So while monthly values may fluctuate, I do not expect you will see any exceptionally warm El Ninos for the next 30 years or so. The exceptionally strong and cool La Ninas, which we have not seen in recent decades, will dominate this cool PDO regime.

The PDO history matches well with North American temperature history and drives mnay North American effects like salmon runs, and is linked to El Nino/La Nina cycle. If Cram's comment is right, then PDO cool phase may may lead to a stable-to-cooler temperature trendline for some time (decadal oscillation). This chart shows how 30 years of 'cool mode' PDO matched a cool trend in US temperatures from 1940-1970, while 30 years of 'warm' PDO matched recent warming:



A look at solar activity is also portending cooler trends.

Climate models that IPCC (and Gore) uses to promote the Global Warming 'crisis' are
overly simplistic and ignore decadal climate factors - at their peril:

Such predictions represent a huge gamble with public and policymaker opinion. If more-or-less steady global warming does not occur as forecast by these models, not only will professional reputations be at risk, but the need to reduce threats to the wide spectrum of serious and legitimate environmental concerns (including the human release of greenhouse gases) will be questioned by some as having been oversold. For better or worse, a failure to accurately predict the changes in the global average surface temperature, global average tropospheric temperature, ocean average heat content change, or Arctic sea ice coverage would raise questions on the reliance of global climate models for accurate prediction on multi-decadal time scales.

The failure of models to account for this trends leads them to overstate mankind's influence and understate natural variability. As natural variability rears up and potentially takes us in a cooler direction for a while, it will discredit the models that Global Warming fearmongering is based on.


I leave it as a question, not a statement, of whether PDO cycle will drive cooler global climate, since only time will tell whether cool PDO/ENSO effects will persist. But climate model teams should take this as a wake-up call to fix their models before reality overruns their credibility and leaves them falsified by data. Gore's claim that the science is 'done' and debate over is un-scientific bunk. There is plenty more to learn about earth's climate before we can declare certainty on these matters. But don't be surprised if the cool trend continues.