The Great Pacific Climate Shift

My meteorologist friend Randy Baker mentioned to me at church. I stuck a note in my blogging files and don't remember exactly what he said-- except that this is a significant piece of the puzzle. (Perhaps he'll comment and elaborate.)

Here's an excerpt from Sallie Baliunas' paper posted at the Heritage Foundation.

Every 20 to 30 years, the Pacific Ocean changes sharply. The sudden shift is called the Pacific Decadal Oscillation, or PDO, and produces an ocean, air, and wind current shift. Fishermen will notice, for example, migrations of fish species along the West Coast.

In 1976-1977 the Pacific Decadal Oscillation shifted, and is labeled the Great Pacific Climate Shift of 1976-1977. As a result, temperatures changed dramatically from their former average (since around 1946), and returned to warmth seen from around 1923 to 1946. So sharp is the shift that the appropriate thing to do is to look for a secular trend (which might be the human-made trend) before 1976-1977, and then after 1976-1977. But drawing a straight line through that natural event should be avoided.

The PDO is natural, because proxy records--of tree growth, for example--detail the oscillation going back several centuries, which is prior to human activities that significantly increase the content of greenhouse gases in the air.

And also known from computer simulations is that the human-made warming trend is supposed to grow steadily over decades. So, a shift all at once in 1976-1977 is ruled out by those two reasons. One, it's not what the models project; and two, we see this event before the build-up of human-made greenhouse gases, and it is therefore natural.

Here are two more papers by John D'Aleo-- the original paper and an addendum.