Resilient NJ Shore 12 7-12 broccoli

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An overview of the scientific evidence that climate change is occurring, and what was normal in the past is not going to be normal for the future. Recent extreme-weather events -- snowstorms, last summer's derecho, and two severe hurricanes in the space of just over a year, are harbingers of more to come. Because the future will be different, we must use future-based modeling rather than historical data to prepare.

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Resilient NJ Shore 12 7-12 broccoli

  1. 1. Climate Change and Extreme Weather: A New Normal? Anthony J. Broccoli Director, Climate and Environmental Change Initiative Department of Environmental Sciences Rutgers University “Rebuilding a Resilient New Jersey Shore” Monmouth University December 7, 2012
  2. 2. Mantoloking Ortley Beach
  3. 3. “Extreme weather is the new normal. In the past two years, we havehad two storms, each with the odds of a 100-year occurrence.” - Governor Andrew Cuomo“Our climate is changing. And while the increase in extreme weatherwe have experienced in New York City and around the world may ormay not be the result of it, the risk that it might be — given thisweek’s devastation — should compel all elected leaders to takeimmediate action.” - Mayor Michael Bloomberg
  4. 4. Four Questions• What do we mean by “normal” climate?• Is there a new normal?• If there is a new normal, were Sandy and other recent extremes harbingers of future events?• How can we prepare for future weather and climate impacts?
  5. 5. What do we mean by “normal” climate?• We use the term “normal” to describe the expected range of conditions, including averages and extremes, at a location.• This definition of normal arises from the concept of stationarity.• “Stationarity is the assumption that the future will be similar to the past, in a statistical sense.” (Milly 2007, Ground Water News and Views)• In a stationary climate, the weather events that occur would be drawn from an underlying probability density function with properties that could be determined from the observational record (for example, a “100-year storm”).
  6. 6. Is there a new normal?
  7. 7. Climate Change 101: The Basics• Combustion of fossil fuels (coal, petroleum, natural gas) emits carbon dioxide into the atmosphere (currently about 9 billion tons of carbon per year).• Slightly less than half of the carbon dioxide remains in the atmosphere; most of the remainder goes into the ocean (causing ocean acidification).• Increasing carbon dioxide heats the earth; global temperatures have risen by 1-1.5°F during the past century.• Increasing temperatures also cause other changes in climate and sea level.
  8. 8. Climate change alters the probability ofextreme eventsProbability of summertemperature over allNorthern Hemisphereland grid boxes (using1951-1980 baseline)[Hansen et al. 2012, PNAS]
  9. 9. New Jersey summer temperature trends [Source: National Climatic Data Center]
  10. 10. Were Sandy and other recent extremesharbingers of future events?“Boxing DaySnowstorm” Irene
  11. 11. Millstone, NJNew Brunswick, NJ Manville, NJ Paterson, NJ
  12. 12. October 2011 Snowstorm
  13. 13. Hurricane/Superstorm Sandy Sandy All previous tropical cyclones passing within 50 miles of Atlantic City
  14. 14. Storm surge at The Battery
  15. 15. What the science tells us…• We do not know if tropical cyclone activity (i.e., intensity, frequency, duration) has changed systematically in the past. In the future, tropical cyclones will probably increase in strength but their number will either decrease or remain essentially unchanged.• We do not know if severe thunderstorms and tornadoes have become more frequent (because observational methods have improved) and future trends are uncertain.• Many areas have experienced upward trends in the number of heavy precipitation events and it is likely that such trends will continue throughout the 21st century.• Record high temperatures and heat waves have been occurring more frequently and they are expected to increase further during the 21st century.• The ongoing rise in sea level has raised the baseline for coastal flooding from storm surge and the rate of sea level rise will likely accelerate during the remainder of the 21st century.
  16. 16. Sea level trends along NJ coast 16 inches in 100 years Projection for 2050: 11-25 inches (best estimate of 16”) Projection for 2100: 27-67 inches (best estimate of 43”) [Source: R. Kopp and K. Miller, Rutgers University, paper in prep.]
  17. 17. Historic water levels at Sandy Hook• >13.2 FT — October 29, 2012 (Sandy)• 10.1 FT — September 12, 1960 (Hurricane Donna) / December 11, 1992.• 9.8 FT — August 28, 2011 (Hurricane Irene).• 9.7 FT — November 7, 1953.• 9.4 FT — September 14, 1944 (Hurricane) / March 6, 1962.• 9.0 FT — November 25, 1950.• 8.9 FT — January 23, 1966.• 8.8 FT — November 12, 1968.• 8.7 FT — MAJOR TIDAL FLOODING BEGINS.• March 29, 1984 / March 13, 1993.• 8.6 FT — September 27, 1985 (Hurricane Gloria) / January 2, 1987 / October 31, 1991.• 8.5 FT — April 13, 1961.• 8.3 FT — February 19, 1972 / March 19, 1996 / March 13, 2010.• 8.2 FT — October 18, 2009.• 8.1 FT — January 31, 2006 / April 16, 2007.• 8.0 FT — October 14, 1955 / December 26, 1969 / December 2, 1974 / April 16, 2011.• 7.9 FT — August 31, 1954 (Hurricane Carol) / December 22, 1972 / October 25, 1980 / February 24, 1998 / December 25, 2002 / November 14, 2009.• 7.8 FT — October 14, 1977 / November 8, 1977 / March 3, 1994 / December 20, 1995 / January 29, 1998 / March 30, 2010.• 7.7 FT — MODERATE TIDAL FLOODING BEGINS.• March 20, 1958 / October 22, 1961 / November 10, 1962 / December 25, 1978 / December 3, 1986 / January 4, 1994 / December 13, 1996 / November 14, 1997 / January 3, 2003 / January 3, 2006 / February 12, 2006 / October 7, 2006 / May 12, 2008 / December 12, 2008 / May 17, 2011.• 6.7 FT — MINOR TIDAL FLOODING BEGINS
  18. 18. The future will not be the same as the past• “We never had floods like this before. We made preparations but it didn’t do any good…”• “There was no reason for us to think that the kind of flooding that we actually experienced would happen there.”• “We had flooding in areas we never had flooding before.”• “...weve never had flooding before…The house has been in the family since it was built in 1964 and theres never been a problem with weather...ever.”• “They thought theyd be safe because theyd never had flooding before.”
  19. 19. How can we prepare for futureweather and climate impacts?• Recognize that the past is not an adequate guide to what will happen in the future (finite sample size, changing climate).• Use information from climate model projections, with careful interpretation, to develop an understanding of the effects of a changing climate baseline.• Focus on aspects of climate change that we understand with high confidence (such as sea level rise) rather than those that are more uncertain (such as changes in storm frequency/intensity).• Develop improved methods for making projections of the effects of climate change on high impact weather events.
  20. 20. Example: Estimating future flood return levels Black curve is for present climate; red and blue curves depict estimated flood return levels for period 2081-2100 under IPCC A1B emissions scenario. (Lin et al. 2012)
  21. 21. Example: Projecting changes in severe weather Severe thunderstorms and tornadoes occur where moisture is abundant , the atmosphere is unstable, and vertical wind shear is large. Convective available potential energy and specific humidity increase Vertical wind shear decreases Net result: Increase in severe thunderstorm environment days Source: Trapp et al. (2007, PNAS)
  22. 22. Four Questions• What do we mean by “normal” climate? Implicit assumption: Climate is quasi-stationary• Is there a new normal? Stationarity is dead.• If there is a new normal, were Sandy and other recent extremes harbingers of future events? Yes for some types of extremes; uncertain for others.• How can we prepare for future weather and climate impacts? Use best available science.

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