1. Climate Change, Texas, and the Limits of Confidence
John Nielsen-Gammon
Dept. of Atmospheric Sciences
Texas A&M University

2. Global Surface Temperature (3)

3. Pattern of Temperature Trend

4. Regional Temperatures, 1-2000 (PAGES 2013)

5. Multiple datasets & analyses (AR5 WG1 FAQ2.1)

7. Mass change, ice sheets (AR5 WG1 Figs 4.13d-4.14d)

8. Changes in Water and Ice (AR5 WG1 FAQ2.1)

9. Global Surface Temperature (3)

10. Global temperatures

11. Global temperatures

12. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

13. Scientific Principles
Energy Imbalance implies a net gain or loss of energy
Typical annually averaged energy imbalances are << 1% of the energy flow

14. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

15. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

16. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

17. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

18. Global Energy Balance, Part 1
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

19. Global Energy Balance, Part 2
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

20. Global Energy Balance, Part 2
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

21. Global Energy Balance, Part 2
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

22. Global Energy Balance, Part 2
Sun
Atmosphere
Each arrow = 20 W/m2
Earth

23. Global Energy Balance, Part 3
Sun
Atmosphere
To maintain heat flow into atmosphere, Earth must warm too
Earth

24. Detection and Attribution
Identify trend: detection
Compare with distinct patterns in space and time caused by different forcing agents
Apportion role of different forcing agents: attribution

25. Evolution of Estimated Forcings (AR5 WG1 Fig. 8.18)

32. Global temperatures

33. Texas vs Globe

34. Texas 5-yr Avg vs Globe

35. Short definition: Weather that’s newsworthy Long definition: two kinds
Extreme Weather
Short definition: Weather that’s newsworthy
Long definition: two kinds
Weather that’s extremely unlikely
Weather that’s unhealthy or damaging
(The same event often fits both definitions)

40. Melissa Phillip, Houston Chronicle

42. April 18, 2016

43. August 28, 2017

44. August 28, 2017
August 29, 2017

45. Example #1: Heat and Cold
IPCC SREX

46. The Three Pillars of Sound Attribution

47. The Three Pillars of Sound Attribution
A clear historical trend

48. The Three Pillars of Sound Attribution
Consistent model projections
A clear historical trend

49. The Three Pillars of Sound Attribution
Consistent model projections
A clear historical trend
A sound physical basis

50. Example #2: Heavy Rain

51. Climate change’s thermodynamic impact: the size of the pipe
The Faucet
Climate change’s thermodynamic impact: the size of the pipe
+ 7% per °C
Climate change’s dynamic impact: turning the handle

52. The size of the pipe matters most when the faucet is wide open

54. 95% confidence interval using effective degrees of freedom estimated following D. A. Griffith & Z. Zhang (1999): Computational Simplifications Needed for Efficient Implementation of Spatial Statistical Techniques in a GIS, Geographic Information Sciences, 5:2, , DOI: /

55. 20% increase ~ 30% trend

56. Arid  Wet

59. Harris County: 34”

60. Example #3: Hurricanes

61. Hurricanes: The Balance of Evidence
Increase in peak intensity (1.5 pillars)
Decrease in frequency (1 pillar)
…but spatially variable (1.5 pillars)

62. Did Harvey stall because of climate change?

64. National climate assessment News items
Resources
IPCC.ch
Special report on extremes (SREX)
Fifth assessment report, working group 1 (AR5 WG1)
National climate assessment
News items
AP + USA TODAY + NYTIMES ~ Network news

65. The climate is changing Over the long haul, it’s us
Summary
The climate is changing
Over the long haul, it’s us
Future changes are hard to pin down
Some impacts are easy
It’ll get warmer, it’ll rain harder
Some impacts are hard
More droughts? Fewer hurricanes?

66. John W. Nielsen-Gammon n-g@tamu.edu 979-862-2248
Contact Information
John W. Nielsen-Gammon