Most people will know very well why Bob Tisdale uses a 61 month running filter when he compares HadCRUT4 temperature anomalies with CMIP5 model mean (as archived here). It's so he can string out his false claim that there is a "growing difference" between model projections and observations. He's lying. There is now practically no difference.
Let me illustrate. In all these charts except the one down the bottom, the CMIP5 projections are as for the IPCC report, using RCP8.5. That is, they don't have the actual forcings from 2006 onwards, only estimates. The actual forcings would have made the projections lower from 2006.
Below is a chart showing GISTemp vs CMIP5 model mean.
That's why Bob Tisdale's chart has been drawn like that instead of using the annual data. Here is his actual chart:
If you look at the monthly charts, it shows even more starkly how the observations have gone from being lower to running ahead of the CMIP5 models. First GISTemp, which includes January 2016:
Then HadCRUT4, which goes to December 2015:
And here's a chart showing the February to January average, with the CMIP5 multi-model mean shown in white:
So when Bob Tisdale writes nonsense like this, he's telling a big fat lie.:
Considering the uptick in surface temperatures in 2014 (see the posts here and here), government agencies that supply global surface temperature products have been touting record high combined global land and ocean surface temperatures. Alarmists happily ignore the fact that it is easy to have record high global temperatures in the midst of a hiatus or slowdown in global warming, and they have been using the recent record highs to draw attention away from the growing difference between observed global surface temperatures and the IPCC climate model-based projections of them.He's lying to his conspiracy crowd. The difference isn't growing. It's shrinking, and on the monthly charts, the difference has already gone the other way. The observations are higher than the modeled projections!
He does it again, writing:
It’s very hard to overlook the fact that, over the past decade, climate models are simulating way too much warming and are diverging rapidly from reality.
What's very hard to overlook is that Bob is a science disinformer by profession. A con man. A pseudo-science crank. Climate models are not simulating "way too much warming". It's the planet itself that's doing way too much warming. More even than what was projected.
It gets even worse. Bob put up a chart where he plotted the difference between HadCRUT and CMIP5 and wrote:
In this example, we’re illustrating the model-data differences in the monthly surface temperature anomalies. Also included in red is the difference smoothed with a 61-month running mean filter.The chart he put up is below. I've animated it, and added some annotations. I've highlighted the zero line. Above the line observations are less than projections, below the line observations are hotter than projections:
The greatest difference between models and reconstruction occurs now.
Bob tries to delude his readers by adding that big red line, hoping they won't notice that the model minus observations is now negative. In other words, with the latest observations added, the actual temperatures are hotter than what was projected.
Model projections are accurate when the actual forcings are included
As you know if you've been keeping up with climate science, the models were constructed back around 2005/06 so they didn't have the actual forcings of solar radiation, volcanic aerosols etc. When you plug in the actuals into the models, the difference between models and observations disappears. Here's a chart I posted that Stefan Rahmstorf put together, showing more clearly how the observations are consistent with the CMIP5 projections. In this last year they've been higher than projected:
Bob's conspiracy theory widens to scientists the world over
Bob insists on repeating his lie about the latest data, too. He knows he's wrong because lots of people have told him so, but he insists there's a vast conspiracy. He's now had to rope in the UK Met Office into his conspiracy of coordinated fraud, writing:
The impacts of the unjustifiable adjustments to the ERSST.v4 reconstruction are visible in the two shorter-term comparisons, Figures 7 and 8. That is, the short-term warming rates of the new NCEI and GISS reconstructions are noticeably higher during “the hiatus”, as are the trends of the newly revised HADCRUT product.He didn't mention the other main surface dataset, Berkeley Earth. If he had, he'd no doubt have added the Berkeley Earth people to his growing list of conspirators. Here's a table showing the trends from 1970 to 2015:
Bob's conspiracy is based on his false assertion that global sea surface temperatures should be identical to night time marine air temperatures. He's wrong. As well as the fact that night time marine air temperatures are air temperatures, not sea surface temperatures, there is a lot more of the ocean covered by buoys than by ships taking air temperature. Bob has been told all that but he continues to promote his conspiracy that scientists all over the world are fudging temperatures. He's a crank, a nutter as well as a climate disinformer. He knows he'd never get anyone but science deniers to buy his "books", so I guess he figures he has to keep lying to keep the funds flowing. Or maybe his motivation is different. He might just be a pathological liar - who knows.
Addendum with further illustrations
Here are some charts which further illustrate how Bob is deceiving his readers. They show variously the LOESS smoothing using (Bob's) 61 data points, the simple moving average, CMIP5 and the final chart includes observations (monthly). The period is on the charts. Click to enlarge them.