To those who are enjoying the unit root saga, I’ve generated some synthetic temperatures by forcing “Lumpy” with forcings similar to those used to drive GISS Model E, plus some “mystery” noise. (The mystery noise is uncomplicated.) These data are provided at the bottom of this post. The synthetic temperatures resemble earth surface temperature because [...]
I’m not going to go through all the math that has been posted elsewhere on unit roots. This will be much more practical. I’ll treat the climate system as a black box that just adds noise to the input signal. I can add more complexity like time constants for a two box model later. As [...]
I’m not embarked on tracing back. I came across a VS comment made on March 23 which strikes me as important. It’s posed after my questions. VS does a test that checks whether the trend in the data from 1900-1935 is real. He finds that trend is not statistically significant. Thereafter, he appears to assume [...]
Several readers, most recently Alex Heyworth, have been asking me to jump into the VS/Bart/Dave Stockwell/Tamino fray. It appears VS is making some sort of claims in comments at Bart’s blog. The claims and clarifications are spread out over 760 or so comments, with various interjections. I have been alerted that these claims all a [...]
In discussions of the application of the Hansen/Lebedeff gridding method to “toy planet” data, a few people noted that the “toy” data used did not hightlight a known way bias can be introduced into a computed temperature trend as a result of dropping out a whole bunch of stations. This can give the false impression [...]
There has been some excitement over statements made by Phil Jones in an interview with the BBC. In particular, when asked, Phil Jones admitted no statistically significant warming since 1995. In comments, Zeke asked: Lucia, I’d be interested to see what type of correction for autocorrelation Jones used in the “no (significant) warming since 1995″ [...]
In today’s post, I’m going to describe how I correct for the serial correlation in my recent comparison of multi-run means to observations of surface temperatures from Hadley. Data are only approximately AR(1). To estimate uncertainty intervals in a computed trends, we must first assume we know something about the time series that generated the [...]
The problem: Testing whether IPCC simulations faithfully reproduce the climate trends exhibited by earths temperatures is complicated by stochastic variations (i.e. noise) overlying the climate (i.e. deterministic) response. These stochastic variations appear in both the simulations and observations and arise from the earth’s own internal variability and the stochastic external forcings. Because these exist, evaluation [...]
It has come to my attention that a certain blog-climate warrior has now decided to get back to work adjusting analysis to include factors that will widen error bars while doing things in ways that do a poor job of incorporating explanatory factors that would narrow the error bars. So, I decided I might as [...]
No fancy statistics in this post! I’m just going to show 5 year running means of observations by GISSTemp and the average over all runs from A1B and A2 scenarios: The 5 year running mean for GISS temp is computed by taking the average over the 60 months prior to the date. The 5 year [...]
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