1. What Do We Know About Climate Risks Facing Philadelphia and the Urban Northeast? Daniel Bader Columbia University May 30, 2014

2. An important distinction “Weather is what you get; climate is what you expect.” Climate describes weather patterns over a longer term Weather describes current and near- term conditions 2

3. Question What does the local climate record tell us?

4. What’s already happened locally? Temperature has risen, but the trend varies year-to-year A century of local data tells us the climate is changing Sea Level has risen over decades, though individual years vary somewhat Trend = 1.1 in / decade Trend =.24 F / decade

5. Question What is the basis for climate projections?

6. What’s behind this? Scientists have understood this pattern for over a century

7. Building on a strong foundation Powerful computer models let us test and refine hypotheses

8. Question What is projected for Philadelphia?

9. What is projected locally? Sea Levels are projected to rise Sea Level Rise Low- estimate (10 th percentile) Middle range (25 th to 75 th percentile) High- estimate (90 th percentile) 2020s 2 in4 to 8 in10 in 2050s 8 in10 to 20 in29 in 2080s 12 in17 to 36 in54 in Projections are based on a 6-component approach that incorporates both local and global factors. The model-based components are from 24 GCMs and two Representative Concentration Pathways Shown are the low-estimate (10 th percentile), middle range (25 th to 75 th percentile), and high-estimate (90 th percentile) 10-year mean values from model-based outcomes. Projections are relative to the 2000-2004 base period.

10. What is projected locally? Average temperatures are projected to rise Average temperature Baseline (1971-2000) 55.9 °F Low- estimate (10 th percentile) Middle range (25 th to 75 th percentile) High- estimate (90 th percentile) 2020s + 1.1°F + 2.1°F to 2.9°F+ 3.3°F 2050s+ 3.5°F+ 4.0°F to 5.7°F+ 6.7°F 2080s+ 3.8°F+ 5.0°F to 8.6°F+ 9.9°F Based on 33 GCMs and two Representative Concentration Pathways. Baseline data are from NOAA NCDC. Shown are the low- estimate (10 th percentile), middle range (25 th to 75 th percentile), and high-estimate (90 th percentile) 30-year mean values from model-based outcomes.

11. What is projected locally? Average precipitation is projected to increase Average preciptation Baseline (1971-2000) 41.5 inches Low- estimate (10 th percentile) Middle range (25 th to 75 th percentile) High- estimate (90 th percentile) 2020s -1 % + 2 to 11 %+ 14 % 2050s+2 %+ 4 to 13 %+ 18 % 2080s+3 %+ 6 to 17 %+25 % Based on 33 GCMs and two Representative Concentration Pathways. Baseline data are from NOAA NCDC. Shown are the low- estimate (10 th percentile), middle range (25 th to 75 th percentile), and high-estimate (90 th percentile) 30-year mean values from model-based outcomes.

12. New Average What can a few degrees warmer do? Average Action Point A small average change can mean a big effect on extremes Days with Extreme Heat Very Likely Increase: By the 2050s, days over 90 ° F are projected to occur approximately 2 times more often, or another 24 times each year

13. What is projected locally? Days with maximum temperature at or above 90 °F Baseline (1971-2000) 26 Low- estimate (10 th percentile) Middle range (25 th to 75 th percentile) High- estimate (90 th percentile) 2020s 33 36 to 4448 2050s4352 to 6675 2080s5160 to 94104 The number of hot days is projected to increase Based on 33 GCMs and two Representative Concentration Pathways. Baseline data are from NOAA NCDC. Shown are the low- estimate (10 th percentile), middle range (25 th to 75 th percentile), and high-estimate (90 th percentile) 30-year mean values from model-based outcomes.

14. What is projected locally? The number of cold days is projected to decrease Days with minimum temperature at or below 32 °F Baseline (1971-2000) 87 Low- estimate (10 th percentile) Middle range (25 th to 75 th percentile) High- estimate (90 th percentile) 2020s 63 65 to 7275 2050s4550 to 5966 2080s3034 to 5363 Based on 33 GCMs and two Representative Concentration Pathways. Baseline data are from NOAA NCDC. Shown are the low- estimate (10 th percentile), middle range (25 th to 75 th percentile), and high-estimate (90 th percentile) 30-year mean values from model-based outcomes.

15. Question What other changes are projected?

16. What other changes are projected by the end of the century? There’s more to consider than averages Precipitation extremes -Heavy rainfall events and flooding ↑ -Drought ↑

17. What other changes are projected by the end of the century? There’s more to consider than averages Winter Storms -Snowfall frequency and amount ↓

18. 18 National Climate Assessment Northeast Region Heat waves, coastal flooding due to sea level rise, and river flooding due to more extreme precipitation events will pose a growing challenge to the region’s environmental, social, and economic systems. Infrastructure will be increasingly compromised by climate-related hazards including sea level rise and coastal flooding, and intense precipitation events. Agriculture and ecosystems will be increasingly stressed by climate-related hazards, including higher temperatures, sea level rise and coastal flooding, and more extreme, precipitation events. While a majority of states and several municipalities have begun to incorporate the risk of climate change into their planning activities, implementation of adaptation measures is still at early stages. NCA, 2014 2014 National Climate Assessment

19. Question What can we do to respond?

20. Responding to Climate Risks Mitigate to reduce our impact on natural systems… …and adapt where we nevertheless expect impacts. 20