attribution of extreme weather

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

Questions?climatewebinars@gmail.com

Background Info and Links:http://ow.ly/uhaY6

Twitter @CUclimate#climatechat

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