The recent IPCC 'AR5' summary report was essentially an admission of failure for the catastrophic human-induced global warming hypothesis. The admission was blatantly obvious as the IPCC bureaucrats did not deliver an adequate explanation for the last 15+ years of non-warming, plus they were unable to even establish what current climate science believes the critical climate sensitivity measure to be.
As result, the IPCC had to resort to lame, non-scientific descriptors such as "unequivocal" and "unprecedented" that were without meaningful empirical evidence. Below is an analysis of their supposed "unprecedented" decadal warming, that when dissected, is beyond lame. (click on charts to enlarge)
These two graphs plot decades-ending global temperature and atmospheric CO2 levels. The graph on the left represents decades prior to the 1950s, and the second graph, those decades subsequent to the 1960s.
Some observations based on this empirical evidence:
#1. From the decade ending in 1909, there were 4 decades in a row that the average global temperature was higher at decade-end (the increase from 1909 to 1919 was indeed very small but nevertheless, it was a warming.).
#2. In the modern era, since 1979, there has been only 3 decades in a row that the average global temperature was higher - ergo, the warming prior to the 1950s remains "unprecedented" in terms of decadal duration.
#3. Clearly, the modern era decades (1980s, 1990s, 2000s) CO2 levels jumped dramatically, approximately 50 points, which is over 6 times greater than the CO2 increase during the pre-1950s decades (1920s, 1930s, 1940s)
#4. If the warming trend of the early 20th century had continued (it didn't) until the end of the 21st century (2099), global temperatures would have increased by +1.92°C; yet despite the huge modern era CO2 spike, if the warming trend represented by the last 3 decades continued (it won't), the increase by 2099 would only be +1.72°C.
#5. The IPCC states that prior to 1950 any global warming was due to natural forces - thus, the +0.41°C decadal increase during the early 20th century was due entirely to natural climate forces.
#6. The IPCC states that the modern warming decadal warming, +0.55°C, was at least 50% caused by humans - thus, it is highly likely that natural climate forces were responsible for the other 50%, say a +0.27°C of the modern warming.
#7. If only half of the modern decadal warming is due to human influences, then it is also likely that the human-caused linear trend would represent a warming rate of only +0.89°C, half the modern 3-decade full-linear trend rate of 1.78°C/century.
#8. Put another way, the pre-1950, the all-natural decadal trend rate of +1.30°C exceeds the +0.89°C modern decadal trend attributed to anthropogenic forces (including land-use, the UHI effect, and of course, greenhouse gases).
#9. If one assumes that the modern decadal warming in reality was simply a cyclical repeat of the early 20th century decades of natural warming, then in actuality, at best, the gigantic increases of CO2 levels were only responsible for maybe a mere +0.14°C increase (+0.55°C - +0.41°C = +0.14°C) over the 3 decades ending in 2009.
Summary: After 7 years of research and billions of dollars on the 'AR5' report, the best that the IPCC can come up with is the thin gruel of "unprecedented" decadal warming, which when examined closely, is a false representation of the makeup, duration and the size of the anthropogenic component of modern warming. Since the last 15 years have proven that natural climate forces simply overwhelm the CO2 impact, the likelihood that modern decadal warming is more a result of natural (non-human) climate forces is the more probable "95% certainty".
Note: Data sources for above Excel charts can be found here.