Climate Change, Texas, and the Limits of Confidence John Nielsen-Gammon Dept. of Atmospheric Sciences Texas A&M University
Global Surface Temperature (3)
Pattern of Temperature Trend
Regional Temperatures, 1-2000 (PAGES 2013)
Multiple datasets & analyses (AR5 WG1 FAQ2.1)
Mass change, ice sheets (AR5 WG1 Figs 4.13d-4.14d)
Changes in Water and Ice (AR5 WG1 FAQ2.1)
Global Surface Temperature (3)
Global temperatures 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 Global Surface Temperature Anomalies ( C) Base Period: 1980-1999 -1 1850 1880 1910 1940 1970 2000 2030 HadCRUT surface GISTEMP surface NGT surface BEST surface RCP8.5 avg
Global temperatures 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 Global Surface Temperature Anomalies ( C) Base Period: 1980-1999 -1 1850 1880 1910 1940 1970 2000 2030 HadCRUT surface GISTEMP surface NGT surface BEST surface RCP8.5 avg
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Scientific Principles Energy Imbalance implies a net gain or loss of energy Typical annually averaged energy imbalances are << 1% of the energy flow
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 1 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 2 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 2 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 2 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 2 Sun Atmosphere Earth Each arrow = 20 W/m 2
Global Energy Balance, Part 3 Sun Atmosphere Earth To maintain heat flow into atmosphere, Earth must warm too
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
Evolution of Estimated Forcings (AR5 WG1 Fig. 8.18)
Global temperatures 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 Global Surface Temperature Anomalies ( C) Base Period: 1980-1999 -1 1850 1880 1910 1940 1970 2000 2030 HadCRUT surface GISTEMP surface NGT surface BEST surface RCP8.5 avg
Texas vs Globe 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 Global Surface Temperature Anomalies ( C) Base Period: 1980-1999 -1 1850 1880 1910 1940 1970 2000 2030 HadCRUT surface GISTEMP surface NGT surface BEST surface RCP8.5 avg Texas
Texas 5-yr Avg vs Globe 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8 Global Surface Temperature Anomalies ( C) Base Period: 1980-1999 -1 1850 1880 1910 1940 1970 2000 2030 HadCRUT surface GISTEMP surface NGT surface BEST surface RCP8.5 avg Texas 5yr
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)
Melissa Phillip, Houston Chronicle
Rainfall (inches) 9 Waller County-Average 1-Day Rainfall (since 1950) 8 7 6 5 4 3 2 1 0
Rainfall (inches) 9 8 Waller County-Average 1-Day Rainfall (since 1950) April 18, 2016 7 6 5 4 3 2 1 0
Rainfall (inches) 9 8 Waller County-Average 1-Day Rainfall (since 1950) August 28, 2017 7 6 5 4 3 2 1 0
Rainfall (inches) 9 8 7 6 Waller County-Average 1-Day Rainfall (since 1950) August 28, 2017 August 29, 2017 5 4 3 2 1 0
Example #1: Heat and Cold IPCC SREX
The Three Pillars of Sound Attribution
The Three Pillars of Sound Attribution A clear historical trend
The Three Pillars of Sound Attribution A clear historical trend Consistent model projection s
The Three Pillars of Sound Attribution A clear historical trend Consistent model projection s A sound physical basis
Example #2: Heavy Rain
The Faucet Climate change s thermodynamic impact: the size of the pipe + 7% per C Climate change s dynamic impact: turning the handle
The Faucet The size of the pipe matters most when the faucet is wide open
99.98th %ile (14-yr return period) Change in Frequency 0.0x to 0.11x 0.11x to 0.25x 0.25x to 0.43x 0.43x to 0.67x 0.67x to 1.0x 1.0x to 1.5x 1.5x to 2.3x 2.3x to 4x 4x to 9x
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, 97-105, DOI: 10.1080/10824009909480519
1 Frequency (events per decade) Example: 20% increase 0.8 0.6 0.4 0.2 0 0 20 40 60 80 100 20% increase ~ 30% trend
Arid Wet
Alex 2010 Average Five Day Rainfall, 50,000 sq. mi. Georges 1998 NC Sep 2010 Beulah 1967 Harvey 2017 0.00 5.00 10.00 15.00 20.00 25.00
Claude e 1979 Average Five Day Rainfall, 2,000 sq. mi. Beulah 1967 TX Jun 1899 LA Aug 1940 Harvey 2017 0.00 10.00 20.00 30.00 40.00 50.00
Average Five Day Rainfall, 2,000 sq. mi. Claude e 1979 Beulah 1967 TX Jun 1899 LA Aug 1940 Harris County: 34 Harvey 2017 0.00 10.00 20.00 30.00 40.00 50.00
Example #3: Hurricanes
Hurricanes: The Balance of Evidence Increase in peak intensity (1.5 pillars) Decrease in frequency (1 pillar) but spatially variable (1.5 pillars)
Did Harvey stall because of climate change? 40 38 36 34 32 30 28 26 Lat H4 Harvey 2017 Aug TS Allison 2001Jun TS Allison 1989 Jun TS 1908#4 Jul H1 Juan 1985 Oct 2005 TS Alberto 1994 H3 1871#3 Aug 1980 1941 1938 1953 24 H1 1904#1 Oct Coast 22 20-100 -95-90 -85-80 -75
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
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?
Contact Information John W. Nielsen-Gammon n-g@tamu.edu 979-862-2248 http://climatexas.tamu.edu