1. The Hiatus The Pause The Thing John W. Nielsen-Gammon Regents Professor of Atmospheric Sciences, Texas A&M University Texas State Climatologist

2. Sen. Cruz vs. Mair, Oct. 8, 2015 https://youtu.be/Sl9-tY1oZNw [5:17 – 6:32]

3. IPCC AR5 WG1 Explanation of The Thing Natural variability does this sort of thing Radiative forcing was weaker Some models overestimate climate sensitivity Confidence levels: –Medium for explanations –Low for numbers Not discussed: was warming undersampled by observations? [1] [2] [3]

8. Trends: 0.08 °C/decade to 0.12 °C/decade

9. Trends: -0.01 °C/decade, -0.03 °C/decade, 0.08 °C/decade

10. Trends: 0.09 °C/decade, 0.07 °C/decade

11. Total Solar Irradiance

14. Natural Variability as an Explanation, not an Excuse What natural variations produced a slowdown in warming, and how? Did oceans continue uptake of energy, and how? What does this mean for climate predictions/projections?

15. ENSO/PDO/IPO: Fun in the Pacific Model with observed East Pacific SST simulates the Thing [1]

16. ENSO/PDO/IPO: Fun in the Pacific Model with observed East Pacific SST simulates the Thing [4] Same thing happens with observed enhanced trade winds [5] Modeled global temperature can be overly sensitive to tropical Pacific SST [6] Statistical allocation 2002-2011 [7] (also [8]): +0.19 °C anthro, -0.11 °C Pacific, -0.04 °C solar

18. Subsurface Ocean Warming Top 100 m cooled; 100-300 m layer warmed [9]

19. Subsurface Ocean Warming Top 100 m cooled; 100-300 m layer warmed [9] Warm water in West Pacific flows to Indian Ocean [10]

20. The Thing is Predictable Spin up model with observed winds, and decadal variability can be forecasted [11]

21. Short-range climate forecasts IPCC AR5 WG1 Fig. 11.9b

22. Short-range climate verification IPCC AR5 WG1 Fig. 11.9b, updated

23. IPCC AR5 WG1 Fig. 11.25a

24. IPCC AR5 WG1 Fig. 11.25a, updated

25. IPCC Model & Expert Judgment IPCC AR5 WG1 Fig. 11.25b

26. IPCC Model & Expert Judgment IPCC AR5 WG1 Fig. 11.25b, updated

27. Causes of the Thing Natural variability, mainly Pacific Ocean (likely, major) Reduced radiative forcing (solar + ?) (very likely, minor) Observational issues (likely, very minor) Are models overly sensitive? Quite possibly, but not because of The Thing

28. Contact Information John W. Nielsen-Gammon N-g@tamu.edu http://climatexas.tamu.edu http://climatechangenationalforum.org

29. References [1] Cowtan and Way, 2014, Quarterly Journal RMS [2] Saffioti et al., 2015, Geophysical Research Letters [3] Karl et al., 2015, Science [4] Kosaka and Xie, 2013, Nature [5] England et al., 2014, Nature Climate Change [6] Douville et al., 2015, Geophysical Research Letters [7] Johansson et al., 2015, Nature Climate Change [8] Dai et al., 2015, Nature Climate Change [9] Nieves et al., 2015, Science [10] Lee et al., 2015, Nature Geoscience [11] Thoma et al., 2015, Geophysical Research Letters

30. Bonus Slides

33. [7]