The media spin on science seems to hate nuance and love a the simplest interpretations. It is my opinion, and the opinion of virtually everyone in the climate research world, that we cannot now predict what will happen with our climate in the next 2 to 20+ years. The only skill we now have in making climate predictions comes from an ability to keep track of El Nino and then predict what it will do for about 1 year into the future. That skill is also limited, mostly to years when something especially strong develops in the tropics. Looking farther into the future (say a 30 to 100+ years), there is a growing body of evidence that increasing concentrations of greenhouse gases will warm the planet--"global warming". There is also a lot of evidence that we've already started to experience the early stages of global warming. It's not to say that the science of global warming is settled, but in most of science that's what we're faced with. Tough issues that require careful statements about what we know and what we don't know. So let me try and lay out a few things with regard to the Pacific Decadal Oscillation:

1. we know that Northwest climate over the past century had warm eras from ~ 1925-1946 and 1977-present, and relatively cold eras from ~1890-1924 and 1947-1976; coincident with these climate eras were changes in ocean temperature patterns: warm in the coastal waters when it was warm in the NW, and cool in the coastal waters when it was cool in the NW. The cool eras had relatively good salmon production in the NW (CA-OR-WA and Southern BC), but relatively poor salmon production for Alaska. The warm eras were especially good for salmon production in Alaska, but especially poor for salmon production in the NW. We don't know why the climate more-or-less got stuck in those patterns for 20 to 30 year periods.

2. In the past 5 years, the coastal ocean from around British Columbia south to California has been in a cooler period, especially compared to the exceptionally warm period that ran from 1991-spring 1998. This cool period has not consistently been seen in the Gulf of Alaska and Bering Sea. In fact, the past 5 years have seen a prevalence of very warm ocean temperatures around Alaska. The recent cool period is clearly different than the cool period that dominated from 1947-1976.

3. The "pattern" of salmon abundance of the past few years does not match the pattern observed in the previous cold period: Alaska salmon production has remained mostly high, while NW salmon production has also rebounded for many stocks that were in steep decline in the early-to-mid 1990s.

4. While our coastal ocean (Calif to BC) has been on the cool side most of the past 5 summers, NW temperatures over land have been either near-average or well above average.

All these observations suggest that the "Pacific Decadal Oscillation" pattern of the past century has not been a good model for explaining what's been happening since 1998. This issue will be the topic of a session in a national meeting of oceanographers and climate scientists in Portland next January. Unfortunately, we don't have a lot of answers for why these recent climate changes look the way they do, and we don't have any confident predictions for what our climate will do in the next 2 to 20 years or so.

What does this all mean for salmon recovery? Don't count on the ocean or climate to bail us out of the big problems created in our watersheds and estuaries, and with hatcheries and harvest.

Nathan Mantua, PhD
Joint Institute for the Study of the Atmosphere and Oceans
University of Washington