Guest post by Bob Tisdale
Near the current end of the thread titled National Post: Thirty years of warmer temperatures go poof Allan asked, “What is your global average temperature prediction for the next several decades?” There were a few responses, including Allan’s. I sent an email to Anthony, letting him know I believed it would make a fun thread. He agreed and asked me to write up a starter post to get the ball rolling.
So, here’s Allan’s original group of questions:
What is your global average temperature prediction for the next several decades?
– warming or cooling?
– for how many years?
– on what technical basis?
– for the dataset provided (UAH Global anomaly) how would you extrapolate, if at all – linear, polynomial, or ???
– does anyone believe that a linear extrapolation is valid? If yes, how do you reconcile with the cyclical nature of the PDO and global avg. temperatures?
Let’s hear what you believe, not just what you don’t believe.
I didn’t want to repost the comments of the others without their okay. If they wish, they can add them and identify themselves, or you can go back to the thread and see who they were. Here’s my response, edited with the correction already included:
Allan: I’ll join in the predictions, but I’ll use the slow cycle in the Southern Ocean SST anomalies as my base.
Cooling for 50 to 60 years, counteracting most if not all of the warming over the last 60 years. There will be amplification then dampening of the cooling due to Thermohaline Circulation/Meridional Overturning Circulation in the North Atlantic and North Pacific. They’ll run in synch at first, but then the cycles will counteract one another. The intermittent positive step changes resulting from large El Nino events (82/83 and 97/98 magnitude) will disappear, since the additional heat supplied to the equatorial Pacific by the Southern Ocean and the THC/MOC in the North Pacific has been dissipated. They’ll be replaced by larger and more frequent La Ninas.
We’ll check back here on this thread in 20 years, see how we’re doing.
My prognostication is based on too many hours spent looking at graphs of sea surface temperature, many of which I post at my blog: http://bobtisdale.blogspot.com/
So, as Allan said, “Let’s hear what you believe, not just what you don’t believe.” There are no right or wrong answers. Twenty to fifty years from now some of you will be able to claim you predicted what happened.