PERVASIVE WARM BIAS IN CMIP6 TROPOSPHERIC LAYERS
John Christy and I have a paper forthcoming in Earth and Space Science comparing tropospheric warming rates in the new generation CMIP6 climate models to observations from satellites, weather balloons and reanalysis systems.
Every model overpredicts warming. It has long been known that climate models on average overstate warming in the troposphere over the tropics. This was flagged as a serious inconsistency in 2005 in the first US Climate Change Science Program report and has been mentioned in every IPCC report since. But instead of the problem being corrected, it's gotten worse over time, and the bias is now global. We examined runs over the post-1979 interval in the first 38 climate models made available in the CMIP6 archive, looking at the lower- and mid-troposphere in the tropics and globally. Every model over-predicted warming in both layers, both globally and in the tropics. In most individual cases the bias is statistically significant and on average it is highly significant. We also show that the bias is larger in high-ECS models, but even the models with lower average ECS predict too much warming. If a group of models were to appear that had a realistic representation of global tropospheric warming, it would likely have to have a lower ECS than even the low-ECS members of the CMIP6 ensemble. Data and code here.
July 13 2020
THE WARM BIAS IN CMIP6 CLIMATE MODEL TROPOSPHERIC LAYERS IS PERVASIVE AND GLOBAL IN EXTENT
Newspaper Columns, Commentary and Other
CLIMATEGATE: UNTANGLING MYTH AND REALITY 10 YEARS LATER
Steve McIntyre and I have written a retrospective and evaluation of the issues raised by Climategate and the inquiries that followed from it:
It's hard to believe that a decade later the controversies are still resonating, even to the point of having bearing on a decision of the US Supreme Court last week (via a point made by Justice Alito in his dissent), as well as a decision this past summer in a BC court pertaining to the dismissal of a defamation case. We discuss these things and many many more. We had hoped to write a short summary of a few key items, but ended up going deep into some topics that are still pertinent and subject to widespread misunderstanding and misinformation.
The idea of this site is very simple: to build the complete environmental record of every community across Canada. The site currently shows air emissions by source (back to 1990), air contaminant levels (back to 1974), monthly average high temperatures (back to 1900) for hundreds of places across the country, and water pollution records for several provinces.
The layout is self-explanatory and it's very easy to use. The data are all from government agencies, but most of it has not hitherto been disseminated in a usable form to the public. All my sources are linked and the data I use are easily-downloadable.
So the next time you find yourself in a conversation about some aspect of the environment and you wonder what is actually going on, look at yourenvironment.ca to find out.
AN OPEN LETTER TO LISA RAITT, MP
Like many MPs, Lisa Raitt finds herself asking some legitimate and reasonable questions about what we're being told about climate change. And like many MPs, when she does so out loud, she comes face to face with an increasingly angry climate mob. I got wrapped up in this situation when she retweeted an op-ed of mine, then was quickly bullied and harassed into deleting the tweet and apologizing for it. What was my op-ed about? A scientist who published research contradicting some aspects of climate alarmism, who was eventually bullied and harassed into leaving the field. There's a pattern here, and an important lesson that we all need to learn while there's still time.
Journal Articles and Discussion Papers
CLIMATE SENSITIVITY, AGRICULTURAL PRODUCTIVITY AND THE SOCIAL COST OF CARBON IN FUND
I have published a new paper with Kevin Dayaratna and Pat Michaels on the Social Cost of Carbon taking account of updated evidence on aerial CO2 fertilization and Equilibrium Climate Sensitivity.
Suppose we take a standard model of the Social Cost of Carbon (same as the EPA uses) and the latest mainstream science literature estimates of climate sensitivity to greenhouse gases (based on IPCC forcing estimates) and the mainstream measurements of crop/grassland responses to rising CO2 levels (based on satellites and experimental measurements) and put them together. Do we get evidence of a climate crisis? No, the opposite. We get evidence that the marginal damages of CO2 emissions are basically zero through the mid-21st century. In other words even if you accept mainstream climate science it still doesn't justify costly policy measures.
ASSESSING LONG TERM CHANGES IN US REGIONAL PRECIPITATION
John Christy and I have published a paper in the Journal of Hydrology:
The published version is temporarily available at this link. If that does not work a pre-print is available here. The Supplement is here. We look at the claim (made by the recent US National Climate Assessment) that US precipitation increased over the 20th century, that precipitation extremes did likewise and that confidence is high that this is due to greenhouse gases. We discuss 2,000 year drought proxies that reveal Hurst behaviour (long term persistence) which means spurious trend detection is a risk. We replicate the NCA finding on 2 regional data sets, both for average precipitation and for various measures of extreme rainfall. We then show that the trend inferences don't hold up when the data are extended back into the 1800s and that the trend signs reverse on the last 4 decades of the sample, which is the opposite of what should happen if GHG's are driving the changes. We conclude that natural variability is likely the dominant driver of historical changes in precipitation and hence drought dynamics in the US regions we examine.
TEMPERATURE TRENDS IN CANADA SINCE 1888
We hear a lot about climate change. Would someone who lived in, say, 1918 notice much change in the average weather conditions compared to today? Once you delve into temperature data you will see that it's very hard to offer a simple answer to such a question. Patterns vary over time, by season and by place. For those Canadians who are curious about how the climate might have changed near where they live, I have written a rather lengthy report on the subject.
Or rather, I wrote an R program that generated a lengthy report. I analyze long term records on monthly average daytime highs in Canada, in various segments based on collections of stations available back 40, 60, 80, 100 and 130 years. There are also some nice graphs. If you think you know what "climate change" looks like in Canada, now you can test your perceptions against the data. The R program is here.