AMO

I regularly get comments claiming that ocean cycles are the cause of global warming. They couldn’t be more wrong.

Glacial Cycles, part 2

In the previous post (also this) we established that without doubt, astronomical cycles — in particular, changes of obliquity (earth’s axial tilt) and precession (the relationship between the seasons and closest approach to the sun) — are related to the growth and decay of glacial ice. The question remains, why?

Advertisement

Glacial Cycles, part 1b

This is just a “quickie” to show the results of Fourier analysis of a stack of delta-oxygen-18 records from benthic (i.e., ocean floor) sediment cores, which is not orbitally tuned.

Paul Nurse on science vs anti-science

Paul Nurse (nobel prize winner, and president of the Royal society) reports on the conflict between science and anti-science:

Glacial Cycles, part 1

There’s really no doubt that astronomical cycles have influenced the growth and decay of ice on planet earth for the last 5 million years or so. The subject came up recently, and there seems to be a lot of confusion on the issue, so let’s take a closer look at the influence of astronomical factors on earth’s cryosphere.

Milankovitch Cycles

James Hansen has a new paper (a draft for review), “Paleoclimate Implications for Human-Made Climate Change.” We’ll discuss it in a future post. There’s a so-called “review” by Martin Hertzberg at WUWT in which he claims that Hansen fails to understand the Milankovitch cycles. But it’s Hertzberg whose understanding is a failure.

Loaded Questions

When I chose the title for the last post, I didn’t really intend to stimulate discussion of the Phil Jones interview. I just thought it was a catchy title for a post about the fact that if you account for exogenous factors, you can establish a trend with less data than you’d need without accounting for exogenous factors.

Nonetheless, a lot of commentary mentioned the Phil Jones BBC interview. And that caused me to ponder such questions as “What should Jones have said?” and “What would I have said?” In fact, since I hadn’t done my recent analysis at that time, I might have responded very similarly to the way Jones did.

Phil Jones was Wrong

There. I said it.

Wrong about what, you wonder? During an interview for the BBC he was asked, “Do you agree that from 1995 to the present there has been no statistically-significant global warming?” Jones replied, “Yes, but only just.”

How Fast is Earth Warming?

We’ve already studied the rate of global warming in the GISS surface-temperature data and the two best-known satellite lower-troposphere data sets. We even removed approximations of the impact of exogenous factors (namely, the el Nino southern oscillation and volcanic eruptions) on the data, for a clearer comparison. Now that GISS, NCDC, and HadCRU have reported their year-end figures, let’s repeat the exercise using all five major global temperature records: GISS, NCDC, HadCRUT3v, RSS, and UAH. Also, let’s include another exogenous factor in our analysis: variations in solar output.

MLE

It’s routine practice in statistics to apply a statistical model to some process. Often (I’d even say, usually) the model depends on a certain number of parameters. Sooner or later, we’d like to know what the parameters are (or at least be able to estimate them). One of the most powerful methods in statistics for estimating the parameters of a model from a given set of data is called “MLE” for “Maximum Likelihood Estimation.”