Category Archives: Mathematics

Hockey Sticks And “Fraud”

Some reflections from Judith Curry on Professor Mann’s latest court filing.

[Update early afternoon]

Oopsie:

After being caught out claiming he was a “Nobel Prize recipient” in his original complaint (then having to retract it), it seems Mann and his lawyers just don’t have the good sense to know when to stop. In this case Mann has been “hoisted by his own petard”. His very own words condemn him. Again.

No comment.

The “97%” Nonsensus

As I noted on Twitter:

Judith Curry explains:

I think we need to declare the idea of a 97% consensus among climate scientists on the issue of climate change attribution to be dead. Verheggen’s 82-90% number is more defensible, but I’ve argued that this analysis needs to be refined.

Climate science needs to be evaluated by people outside the climate community, and this is one reason why I found Kahan’s analysis to be interesting of people who scored high on the science intelligence test. And why the perspectives of scientists and engineers from other fields are important.

As I’ve argued in my paper No consensus on consensus, a manufactured consensus serves no scientific purpose and can in fact torque the science in unfortunate ways.

And José Duarte is appropriately brutal:

Continue reading The “97%” Nonsensus

The 50-50 Argument

It’s not logical to state that most warming since 1950 has been caused by man (or Mann):

The glaring flaw in their logic is this. If you are trying to attribute warming over a short period, e.g. since 1980, detection requires that you explicitly consider the phasing of multidecadal natural internal variability during that period (e.g. AMO, PDO), not just the spectra over a long time period. Attribution arguments of late 20th century warming have failed to pass the detection threshold which requires accounting for the phasing of the AMO and PDO. It is typically argued that these oscillations go up and down, in net they are a wash. Maybe, but they are NOT a wash when you are considering a period of the order, or shorter than, the multidecadal time scales associated with these oscillations.

Further, in the presence of multidecadal oscillations with a nominal 60-80 yr time scale, convincing attribution requires that you can attribute the variability for more than one 60-80 yr period, preferably back to the mid 19th century. Not being able to address the attribution of change in the early 20th century to my mind precludes any highly confident attribution of change in the late 20th century.

In other words, we shouldn’t and can’t have as much confidence as many would like to push their policy agenda.