Change, and Harvey John W. Nielsen-Gammon, Texas A&M University - PowerPoint PPT Presentation

Extreme Weather, Climate Change, and Harvey John W. Nielsen-Gammon, Texas A&M University Texas State Climatologist

Upper� Coast� Seasonal� Temperature� Anomalies� � Tmax� +� &� solid,� Tmin� -� &� do ed� ( ° F)� Average� 8� 6� Century� 4� 2� 20th� � 0� from� -2� -4� Difference� -6� -8� 1895� 1915� 1935� 1955� 1975� 1995� 2015� DJF� MAM� JJA� SON� DJF� MAM� JJA� SON� DJF� MAM� JJA� SON� DJF� MAM� JJA� SON�

Basis of Climate Prediction • Past observed changes • Climate model projections • Basic physical understanding of climate system

Three out of three • Higher temperatures – More extreme highs – Fewer extreme lows • Extreme rainfall – More extreme rain – More dry days, droughts • Sea level rise

IPCC sensitivity range Global� Surface� Temperature� Anomalies� ( ° C)� Base� Period:� 1980-1999� +4.5 °F 2� Local Lewis & +3.4 °F increase? 1.5� Curry range 1� +2.2 °F HadCRUT� surface� 5-year GISTEMP� surface� 0.5� Average Texas NGT� surface� +1.1 °F Temperatures BEST� surface� RCP8.5� avg� 0� Average Texas� 5yr� 0 °F model -0.5� output -1.1 °F -1� 1850� 1880� 1910� 1940� 1970� 2000� 2030� 2060�

Other Relevant Changes • Decreased soil moisture (2 out of 3) • Increased flooding (it depends) • Decreased streamflow (it depends)

John Nielsen-Gammon, Texas A&M 7 University

Probability of Harvey • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

Probability of Harvey (blue = less likely, red = more likely) • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

Probability of Harvey (blue = less likely, red = more likely) • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

Probability of Harvey (blue = less likely, red = more likely) • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

Probability of Harvey (blue = less likely, red = more likely) • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

Probability of Harvey (blue = less likely, red = more likely) • Probability of a tropical cyclone in southeast Texas • Given a storm, the probability that such a storm will be a major hurricane • Given a major hurricane, the probability that the hurricane will stall • Given a stalled hurricane, the probability of massive rain

The climate change debate • A: “It’s all bad” • B: “It doesn’t exist, the science is wrong, and it’s good anyway” • Reality : We’ve figured out a lot of stuff. Deal with it.