attribution of extreme weather
TRANSCRIPT
Attribution of Extreme Weather Events Webinar March 5, 2014 4:30 pm MST
Dr. Stephanie HerringNOAA Climatic Monitoring Division
Dr. Martin HoerlingNOAA Earth System Research Laboratory
Dr. Anne GoldCooperative Institute for Research Environmental Sciences
Deb MorrisonUniversity of Colorado BoulderProduced by Kit Seeborg, LearnMoreAboutClimate.orgBroadcast from ATLAS Institute, University of Colorado Boulder
What is Extreme Weather?
Extreme Weather is in the Fabric of Earth’s Atmospheric Circulation
GOES Full Disk Satellite Image
Extreme Weather is not Necessarily the Same as Extreme Events
What is an Extreme Event?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
NOAA uses a broad definition
“Extreme events are those that rarely occur at a given location or have significant impacts on society or ecosystems.”
What are ‘extreme events’?
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Meteorologically RareAND/OR
High Impact
Extreme Values (or Events)An extreme value (or event) can be thought of as the smallest or the largest
value in a sample of observations
There is great interest to know if, and by how much, the probabilityof extreme values (or events) is changing over time.
Why is it important to understand extreme events and their change?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
The Nation Is Conscious of Extreme Events because of Impacts
Drought and Heatwaves
Hurricanes and Tropical Storms
Winter Storms and Crop Freezes
Flooding Wildfires Severe Local Storms
Figures: NOAA’s National Climatic Data Center
U.S. Billion-Dollar Weather and Climate Disasters: 1980 – 2011
Lavell et al. 2012, IPCC
How Do we Know if Extremes are Changing?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• NOAA archives the nation’s climate data and information about observed extremes at the National Climatic Data Center. – http://www.ncdc.noaa.gov/climate-information/e
xtreme-events• Modeling can also tell us about changes we
expect in the future.
Observational Record
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Extreme Values of Atmospheric Carbon Dioxide Concentration
based on Etheridge et al., 1998, graph from Wikicommons
Extreme Energy Input to Earth’s Surface
Church et al., 2013, IPCC
Extreme Heat Content of the World Oceans
Rhein et al., 2013, IPCC
Extreme Values for Ocean Acidity~1/3 of emitted carbon dioxide dissolves in the oceans
(pH less than 7 is Considered “acidic”)
IPCC, 2013
Extreme Values of Global Mean Surface Temperature
An Extreme Value of Arctic Sea Ice Extent
NASA Image
How Do we Determine the Effect of Human Influences on Climate and
Extremes?
Simulated Global Temperature with and without Anthropogenic Greenhouse Gas Forcing
Solomon et al. 2007, IPCC
Simulation of the Future Change in Global Temperature, Assuming Emissions Scenario
IPCC, 2007
Are Extreme Events Changing over Time, and if so Why?
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IPCC AR5 WGI Chapter 2 • “Overall, the most robust global changes in climate extremes are seen in
measures of daily temperature, including to some extent, heat waves. Precipitation extremes also appear to be increasing, but there is large spatial variability”
• "There is limited evidence of changes in extremes associated with other climate variables since the mid-20th century”
Extremes & Climate in Context
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2013 IPCC AR5: Synthesis on How Extreme Events Have Changed, and Will Change
Can Individual Events be Attributed to Climate Change?
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• Attribution studies can look at two questions:– Did climate change make this event more likely?– Did climate change make this event more intense?
• The answers to these questions can be different.
Intensity vs. Frequency
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Climate change can influence an extreme event’s intensity and frequency.
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O NCommunicating an Evolving Science
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• We finally get reporters and politicians to repeat our mantra:– “You can’t attribute any single event to
global warming”• About the time that the science of
event attribution was moving on.– It is now widely accepted that attribution
statements about individual events are possible, provided proper account is taken of the probabilistic nature of attribution
The role of human-caused climate change can be evaluated for some specific extreme events.
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
In Response to Considerable Interest in the Topic
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NOAA (Herring, Hoerling & Peterson) and UK Met Office (Peter Stott) co-led the development of annual BAMS report, Explaining Extremes from a Climate Perspective.
• Public Interest
• Adaptation Strategies
• Improving Predictions
• Understanding
Why do attribution science?
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What is your perspective on communication of science knowledge about extremes to the general public?
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• IPCC SREX report: http://ipcc-wg2.gov/SREX/
• IPCC AR5: http://www.ipcc.ch/report/ar5/wg1/
• NOAA State of the Science Fact Sheets (extreme events fact sheet coming soon): http://nrc.noaa.gov/CouncilProducts/ScienceFactSheets.aspx
• NOAA’s National Climatic Data Center: http://www.ncdc.noaa.gov/climate-information/extreme-events
• Explaining Extremes from a Climate Perspective:• 2011: http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-12-00021.1• 2012: http://www.ametsoc.org/2012extremeeventsclimate.pdf
References
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Webinar: Extreme Weather Mitigation & Resiliency to Climate Change
Kathleen Tierney, Ph.D. and Kevin Trenberth, Ph.D.
April 16, 2014 4:30 – 6:00 PM MDT
Register: https://extremeweatherwebinar.eventbrite.com
Attribution of Extreme Weather Events Webinar March 5, 2014 4:30 pm MST
Dr. Stephanie Herring, NOAA Climatic Monitoring Division
Dr. Martin Hoerling, NOAA Earth System Research Laboratory
Dr. Anne Gold, Cooperative Institute for Research Environmental Sciences
Deb Morrison, University of Colorado Boulder
Produced by Kit Seeborg, LearnMoreAboutClimate.org
Broadcast from ATLAS Institute, University of Colorado BoulderClimatewebinars @ gmail.com
Twitter: @cuclimate