Earlier this year, a comparison was done using the GISS global temperature observations dataset versus an earlier version of the NASA/GISS computer climate model output, as of 2015 year-end. That comparison can be viewed here.
It is now 4 months later with the current powerful El Niño producing some very high global temperature averages.
So, how does the GISS dataset, as of March 31, 2016, compare against a newer climate model, specifically, the IPCC's modern CMIP5 model using the supposed business-as-usual greenhouse gas scenario (RCP8.5)?
The adjacent chart tells the story, but we add some more content below:
- The current El Niño appears to have peaked (maybe not, though) with a strong and rapid rising of GISS global anomalies over the 6-month period ending in March
- The 6-month surge in anomalies placed the Feb. and Mar. observations above the model output
- Despite this huge 6-month surge, the GISS linear trend is still well below the model's simulated linear trend since 1988
- Despite this huge 6-month surge, the 3-year (36-month) simple GISS moving anomaly average remains well below what the CMIP5 climate model produces for the same 3-year period
- The sharp uptick of the blue GISS 3-year moving average, after 2012, reveals the power of this recent El Niño on global temperatures
- The 2013 to mid-2016 slow build-up of the current El Niño peak reveals its contribution to warming as the arithmetic mean of the anomalies stepped up considerably (see on the chart: the black dashed lines represent the anomaly arithmetic means for the periods 2000-2012 and 2013-2016/March - note the shift up)
- The stall (i.e. the 'Pause', the 'Hiatus') in significant global warming can be seen, both in the 3-year GISS moving average and in the underlying anomalies during the 2000s, prior to the 2013 uptick that leads into the powerful El Niño
- The December 2012 anomaly was only 0.05 degree higher than the December 1999 anomaly - that meager five one-hundredths increase is indicative of the lengthy 'Pause' that occurred
Speaking of the current El Niño (and prior El Niños and La Niñas): "What goes up up must.....?"
- The advanced climate model output clearly misses all the big extremes and wide variations of observed global temperatures, including this El Niño's recent incredible burst of warming
- Per the official NOAA definition of the Oceanic Niño Index (ONI), it has now been 48 periods (a period being 3 months) since the last La Niña ended in early 2012
- Since the beginning of 1988 (339 months thru March 2016), 23% of the 3-month periods have been a La Niña condition versus 24% for El Niño conditions
- At 13 periods in length, this El Niño is rather long-in-the-tooth compared to most since January 1988
- After a strong and long El Niño, it is common for the ONI Index to reverse directions, sometimes dramatically (i.e. a strong La Niña)
Whether its the old NASA computer model simulations or the newer variety of IPCC climate models, Hansen's 1988 prediction of rapidly accelerating and dangerous global warming from human CO2, and other greenhouse gases, has done poorly in comparison to actual observed temps.
Although the recent spike in global temperatures from the current El Niño may provide some AGW alarmist bragging rights ("see, that clock is accurate"), it is highly probable the recent 6-month surge is a very temporary spike, entirely due to the natural ENSO phenomenon that climate models are incapable of predicting.
In fact, when viewing the future projections from the CMIP5 model, one sees the exact same pattern as above - a monotonous upward saw-tooth pattern of small ups and downs, completely unlike the chaotic conditions of real-world climate that is produced by all the conflicting natural feedback forces.
And the reversal from the current temp spike could well lead to another 'Pause' in any significant warming. If that happens, it will build on the growing consensus that climate models can't accurately predict squat, and should not be relied upon by policymakers for any reason - good for research but really terrible for reality-based policy.
Note: James Hansen's 1988 testimony took place in June 1998; this comparison used January 1988 as the starting point. The RCP8.5 scenario is considered by the majority of scientists seeking global warming research grants as the business-as-usual scenario. The climate model anomaly output for the CMIP5 RCP8.5 was adjusted to match the January 1988 anomaly for the NASA/GISS global dataset. Both the RCP8.5 and GISS dataset anomalies used in above chart were calculated by KNMI using the 1981-2010 span as the baseline. Both the model and observed datasets were downloaded after the baseline was chosen. Excel was used to plot chart and calculate all figures, including the linear trends and 3-year moving averages.