Earth Sciences Forum

Andre · Posted: Sun Apr 13, 2008 10:42 am Post subject: How El Nino and La Nina diddit

This is a first. This has not posted anywhere before.

We're experiencing a bit of a cold spell now which is attributed to La Nina like the big warm spike of 1998 was attributed to a strong El Nino. Sure enough the alarmists recognise this but it seems that an occasional spike up or down does not a trend make.

Let's see about that and let's plot the EL Nino Southerly Oscilation (ENSO) index againt the HADCRUT3T surface temperatures of the last 50 years in monthly increments, then we get this:

Indeed the ENSO index does not show a trend and a correlation squared (R2) of 13% (in the X-Y scatter plot on top) is not very overwhelming.

But wasn't there something with a delay? The global temperatures reacting a bit slower on the ENSO activity? What, if we did not only look at the immediate correlation but also at the cumulative effect of the previous months? So we add the previous value of the ENSO index to the next month and we get this:

Hmmm, The correlation squared drops even one percent but we also see a trend now, especially after 1975, nicely matching the trend of HADCRUT3 global temperatures. Are we getting somewhere?

Actually by adding the complete former trend we weight older months just as heavy as the last month. That can't be quite correct but if we multiply the accumulated ENSO index with a factor a little smaller than one, then the effect of the older months diminish gradually

So let's try a factor 0.995:

Now look at the r2: 53% !

I'm not sure if I'm doing the right thing but it certainly appears that the cumulative effect of the ENSO index is for a large part responsible for the general trends. This of course leaves less and less trend to be explained by enhanced greenhouse effect.

_________________
Moderator of http://tech.groups.yahoo.com/group/climatesceptics/

"Don't worry about the world coming to an end today. It's already tomorrow in Australia."

Charley Brown