UPDATE: See below for more information and clarification by Jason Samenow of Capital Weather Gang. I got some bits right and one wrong. On balance more right than wrong :) Anthony got it all wrong!
Things amuse. Anthony Watts published a false accusation about the IPCC and wrote: Spot the difference. The IPCC can't. Well it turned out the IPCC could and did. And it was staring everyone in the face but Anthony Watts didn't see it.
Now let's play spot the difference with two quotes on WUWT.
First of all, Anthony Watts writes a wishful thinking headline with the word "Mann" and "Hockey Stick" - which are powerful words on WUWT. It's a signal to WUWT readers that Anthony is giving them very wide latitude in the comments section. They can make whatever accusations they like and be as irrelevant to the topic at hand as they wish, as long as they are taking pot shots at Michael Mann. The headline reads:
IPCC throws Mann’s Hockey Stick under the bus?Anthony then compares these two statements, the first from Capital Weather Gang reporting what is said to be in the current nearly final draft of the AR5 IPCC report, and the second from WG1 of the IPCC AR4 report. This is the part where you can play "spot the difference" if you want to. Anthony can't!
CWG: 7) The 30 years from 1983-2012 was very likely the warmest 30-year period of the last 800 years.
IPCC AR4: Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1,300 years.
As HotWhopper readers know, Anthony has some major difficulties when it comes to tackling logic. From the above two statements this is what he deduces:
So basically what they are saying is that at the year 1200 (2000AD minus 800 years), temperatures were warmer (or at least equal to) temperatures today.
- The CWG(AR5) statement is probably about global surface temperatures, the AR4 statement is more conservative and specific to the Northern Hemisphere only. (See update below - the CWG statement was about Northern Hemisphere too, not global temperature.)
- The AR5 statement is a comparison of a thirty year stretch, the AR4 a comparison of a less conservative fifty year stretch.
- The AR5 statement is "very likely" (ie 90-100% probable)
globalsurface temperatures are the warmest 30-year period in the last 800 years; the AR4 statement's "very likely" (ie 90-100% likelihood) relates only to the past 500 years
- The AR5 statement does not include a "likely" estimate; the AR4 statement says it is "likely" (ie 66-100% likelihood) that the past 50 years were the warmest of the past 1300 years in the Northern Hemisphere.
Bring back the MWP sez Anthony Watts
Globally, the average surface temperature wasn't higher in medieval times than it is today
Globally, the 30 year period from 1983-2012 was very likely the warmest 30-year period of the last 800 years and likely the warmest 30-year period of the last xxx years. (See update below.)
|Green dots show the 30-year average of the new PAGES 2k reconstruction. The red curve shows the global mean temperature, according HadCRUT4 data from 1850 onwards. In blue is the original hockey stick of Mann, Bradley and Hughes (1999 ) with its uncertainty range (light blue). Graph by Klaus Bitterman. |
Jason Samenow of Capital Weather Gang has written a comment at WUWT. Looks as if I got some bits right (eg there is an additional "likely" statement) and one bit wrong - his original statement was northern hemisphere only, not global. Here is his comment:
August 21, 2013 at 8:48 am
I’m the author of the blog post on the IPCC report. My post just featured a handful of findings… it’s not at all comprehensive…just a teaser.
As I note in my post, I’ll dig deeper into the report once it’s finalized. As for the MWP, the IPCC says a couple things:
“Analyses of paleoclimate archives indicate that in the Northern Hemisphere, the period 1983–2012 was very likely the warmest 30-year period of the last 800 years (high confidence) and likely the warmest 30-year period of the last 1400 years (medium confidence).”
“Continental-scale surface temperature reconstructions show, with high confidence, multi-decadal intervals during the Medieval Climate Anomaly (950−1250) that were in some regions as warm as in the late 20th century. These intervals did not occur as coherently across seasons and regions as the warming in the late 20th century (high confidence).”
The IPCC stresses these statements are draft and subject to change via the government review.
Thanks for reading…
Correction: I originally attributed the AR5 statement to Grist. It was published by Capital Weather Gang of the Washington Post.