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Attribution of Extreme Weather

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What is extreme weather? How can it be attributed to climate change? Two NOAA scientists explain how and what kinds of weather is attributed to a changing climate.

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Attribution of Extreme Weather

  1. 1. 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 Boulder
  2. 2. Questions? climatewebinars@gmail.com Background Info and Links: http://ow.ly/uhaY6 Twitter @CUclimate #climatechat
  3. 3. What is Extreme Weather?
  4. 4. Extreme Weather is in the Fabric of Earth’s Atmospheric Circulation
  5. 5. Extreme Weather is not Necessarily the Same as Extreme Events
  6. 6. What is an Extreme Event?
  7. 7. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N What are ‘extreme events’? NOAA uses a broad definition Meteorologically Rare AND/OR High Impact “Extreme events are those that rarely occur at a given location or have significant impacts on society or ecosystems.” 7
  8. 8. 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 probability of extreme values (or events) is changing over time.
  9. 9. Why is it important to understand extreme events and their change?
  10. 10. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N The Nation Is Conscious of Extreme Events because of Impacts U.S. Billion-Dollar Weather and Climate Disasters: 1980 – 2011 Drought and Heatwaves Hurricanes and Tropical Storms Winter Storms and Crop Freezes Flooding Wildfires Severe Local Storms Figures: NOAA’s National Climatic Data Center
  11. 11. How Do we Know if Extremes are Changing?
  12. 12. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N Observational Record • NOAA archives the nation’s climate data and information about observed extremes at the National Climatic Data Center. – http://www.ncdc.noaa.gov/climateinformation/extreme-events • Modeling can also tell us about changes we expect in the future. 13
  13. 13. Extreme Values of Atmospheric Carbon Dioxide Concentration
  14. 14. Extreme Energy Input to Earth’s Surface
  15. 15. Extreme Heat Content of the World Oceans
  16. 16. Extreme Values for Ocean Acidity ~1/3 of emitted carbon dioxide dissolves in the oceans (pH less than 7 is Considered “acidic”)
  17. 17. Extreme Values of Global Mean Surface Temperature
  18. 18. An Extreme Value of Arctic Sea Ice Extent
  19. 19. How Do we Determine the Effect of Human Influences on Climate and Extremes?
  20. 20. Simulated Global Temperature with and without Anthropogenic Greenhouse Gas Forcing
  21. 21. Simulation of the Future Change in Global Temperature, Assuming Emissions Scenario
  22. 22. Are Extreme Events Changing over Time, and if so Why? 23
  23. 23. Extremes & Climate in Context 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” 24
  24. 24. 2013 IPCC AR5: Synthesis on How Extreme Events Have Changed, and Will Change
  25. 25. Can Individual Events be Attributed to Climate Change? 26
  26. 26. Intensity vs. Frequency • 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. Climate change can influence an extreme event’s intensity and frequency. 28
  27. 27. Communicating an NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N Evolving Science • 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. 29
  28. 28. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N In Response to Considerable Interest in the Topic NOAA (Herring, Hoerling& Peterson) and UK Met Office (Peter Stott) co-led the development of annual BAMS report, Explaining Extremes from a Climate Perspective. 30
  29. 29. Why do attribution science? • Public Interest • Adaptation Strategies • Improving Predictions • Understanding 31
  30. 30. What is your perspective on communication of science knowledge about extremes to the general public? 32
  31. 31. References • 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/climateinformation/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 33
  32. 32. 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
  33. 33. 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 Boulder climatewebinars@gmail.com

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