Explanation #10 for the pause …”coincidence” has just completed the top 10 list, thanks Gavin! Party on! Excellent!
There is a new paper by Gavin Schmidt et al that comes in as #10 in the growing list of explanations for ‘the pause’. Now that we have a top ten list, let’s review:
- New study claims low solar activity caused “the pause” in global temperature – but AGW will return!
- THE OCEANS ATE OUR GLOBAL WARMING! Trenberth and Fasullo, 2013. But the heat will come back when you least expect it.
- Chinese coal caused the ‘pause’, published in the proceedings of the National Academy of Science. The study blamed Chinese coal use for the lack of global warming. Global warming proponents essentially claimed that coal use is saving us from dangerous global warming. Kaufmann et al 2011.
- The Montreal Protocol caused the ‘pause‘, which reduced CFC’s – but warming will return soon. Estrada 2013.
- Cowtan and Way’s (2013) underrepresented Arctic stations get adjustment to fiddle the numbers so that ‘pause’ never existed, but not so fast. It seems all isn’t quite as it seems. Dr. Judith Curry doesn’t think much of it either.
- Volcanic aerosols, not pollutants, tamped down recent Earth warming, says CU study – Neely et al March 2013: A team led by the University of Colorado Boulder looking for clues about why Earth did not warm as much as scientists expected between 2000 and 2010 now thinks the culprits are hiding in plain sight — dozens of volcanoes spewing sulfur dioxide.
- Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming. Solomon et al, 2010 Science Magazine.: Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000–2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases.’
- Slower Pacific Trade winds caused the pause England Et al 2014. A paper published today in Nature Climate Change adds the eighth excuse for the ‘pause’ in global warming: strengthened Pacific trade winds, which according to the authors, were “not captured [simulated] by climate models.” On the basis of those same highly-flawed climate models, the authors predict rapid global warming will resume in a decade or so when those trade winds abate. But in 2006, we were told the opposite.
- Stadium Waves. Wyatt and Curry 2013. ‘Stadium waves’ could explain lull in global warming. Not un-plausible.
- “Coincidence, conspired to dampen warming trends” Schmidt et al 2014. NASA’s Gavin Schmidt et al says: ‘Here we argue that a combination of factors, by coincidence, conspired to dampen warming trends in the real world after about 1992. CMIP5 model simulations were based on historical estimates of external influences on the climate only to 2000 or 2005, and used scenarios (Representative Concentration Pathways, or RCPs) thereafter.’
More on #10, from Andrew Montford, who writes in The mind-boggling coincidence hypothesis:
Schmidt and his colleagues are looking at the hiatus in surface temperature rises and considers why the CMIP5 ensemble all got it so wrong. In their new paper they explain that the reason for this is not – as wild-eyed readers at BH might think – that the models are wonky. In fact it’s all down to an incredible, incredible coincidence
Here we argue that a combination of factors, by coincidence, conspired to dampen warming trends in the real world after about 1992. CMIP5 model simulations were based on historical estimates of external influences on the climate only to 2000 or 2005, and used scenarios (Representative Concentration Pathways, or RCPs) thereafter4. Any recent improvements in these estimates or updates to the present day were not taken into account in these simulations. Specifically, the influence of volcanic eruptions, aerosols in the atmosphere and solar activity all took unexpected turns over the 2000s. The climate model simulations, effectively, were run with the assumption that conditions were broadly going to continue along established trajectories.
Apparently, if you go back and rework all the forcings, taking into account new data estimates (add half a bottle of post-hoc figures) and ‘reanalyses’ of old data (add a tablespoon of computer simulation) you can bridge the gap and explain away the pause.
We conclude that use of the latest information on external influences on the climate system and adjusting for internal variability associated with ENSO can almost completely reconcile the trends in global mean surface temperature in CMIP5 models and observations. Nevertheless, attributing climate trends over relatively short periods, such as 10 to 15 years, will always be problematic, and it is inherently unsatisfying to find model–data agreement only with the benefit of hindsight.
So, with the benefit of hindsight, the climate modellers can fit their square peg into a round hole. It wasn’t that the models were running too hot, it was just that nature has got it in for climate modellers.
You can see Schmidt et al Reconciling warming trends here