The Urban Heat Island in Phoenix: Impacts on Neighborhoods

Transcription

1 The Urban Heat Island in Phoenix: Impacts on Neighborhoods Sharon L. Harlan Arizona State University April 25, 2012 Prepared for Mitigating the Urban Island Planning in the West Webinar hosted by Western Lands and Communities, a joint venture of the Lincoln Institute of Land Policy and the Sonoran Institute National Science Foundation Grant No. GEO

2 It s Hotter in the City: Urban Heat Island The air in the urban canopy is usually warmer than that in the surrounding countryside... the horizontal gradient may be as great as 4 o C per km distance. Tim Oke 1978 Urban Heat Island expression in Phoenix Source: Joseph Zehnder

3 Phoenix Has an Expanding Heat Island Weather Research Forecasting Model 2 m air temperature simulations 1700 LST 14 July 2003 spatial resolution = 1 km Source: Susanne Grossman-Clarke

4 Environmental Injustice and Urban Climate Environmental injustices are uneven/inequitable distributions of environmental amenities, disamenities, and ecosystem services. Human-built environments green infrastructure fundamentally change urban climates and create widely variable microclimates within cities. The spatial ldistribution ib i of green spaces and temperature are significant environmental injustices and they are related to social inequalities. Reducing urban temperatures in vulnerable neighborhoods is possible with cooperation between decision-makers and neighborhoods.

5 Neighborhood Microclimates in Phoenix Census 2000 block groups selected for variation in income, ethnicity, location, and landscape. July 2003 heat wave temperature at 5 pm 118 o F 104 O F Each color band represents a distance of 5 miles. Harlan, Brazel, Prashad, Stefanov, Larsen (2006)

6 Environmental Gap Widens in Phoenix Wired, December 1, 2011 Change from 1970 to 2000 in the correlation between neighborhood median income and amount of vegetation July 2000: $10,000 increase in neighborhood h median income buys 0.5 o F decrease in temp Jenerette, Harlan, Brazel, Jones, Larsen, Stefanov (2007) Jenerette, Harlan, Stefanov, Martin (2011)

7 Quantification of Neighborhood Vegetation Historic Anglo Phoenix Black Canyon Freeway Object Based Image Classification National Agriculture Imagery Project, 1 m pixel (March 2007) UVCC Team Meeting, ASU, 4/17/09, Juan Declet-Barreto

8 Vegetation: Key Factor in Controlling Microclimate Temperatures Photo: Sharon Harlan Photo: Sara Grineski In poor neighborhoods, landscapes with sparse vegetation expose residents to higher temperatures for longer periods. Substandard housing, lack of air conditioning, and crowding g, g, g contribute to heat-related health problems.

9 Comparing Predicted Monthly Water Consumption in ,000 18,000 Historic Phoenix Mexican Neighborhood South Mountain Preserve Neighborhood ion (gal) Water Consumpti 16,000 14,000 12,000 10,000 8,000 January February March April May June July August September October November December Month Harlan, Yabiku, Larsen, Brazel (2009)

10 Trade off: More water for cooler temperatures Jenerette, Harlan, Stefanov, Martin (2011) Estimated additional irrigation water to generate a landscape with some proportion p of each neighborhood landscape below a critical surface temperature.

11 Benefits of improving ecosystem services with ihincreased vegetation in heat-vulnerable neighborhoods Psychological impacts: reduce stress, promote mental health Support sense of community empowerment and dfull citizenship rights Promote health and well-being: Recreational spaces for outdoor physical activities (reduce obesity) Improve air quality (reduce respiratory illness*) Lower temperatures (reduce heat stress, heat illness, and heat deaths) *increased allergies

12 ( ) Harlan, Declet-Baretto, Stefanov, Petitti (in review)

13 Climate Mitigation/Adaptation Strategies for Vulnerable People in Vulnerable Places 1. Top-down policies and programs: Warnings systems, water stations, AC shelter, emergency response City risk management plans for climate change Public climate education 2. Bottom-up organizing: ii Reclaim neighborhood landscapes Improve housing quality Secure food, transit, jobs, and health care Expand social networks Brian Garcia Escalante

14 ENVI-met Modeling: Sherman Park in South Central Phoenix Sherman Parkway. Dimensions: ~700 X 50 meters Declet-Baretto, Brazel, Martin, Chow, Harlan (in review)

15 A Way Forward... Sustainable Cities i and Just Communities i What are the social and environmental inequities that exist? How should we distribute limited resources to achieve the most ecosystem services from green infrastructure? How can we minimize i i the human health impacts of climate change? Apply principles of environmental justice to planning Distribution... Recognition... Participation

16 Publications cited Declet-Barreto J, Brazel AJ, Martin CA, Chow WTL, Harlan SL. n.d. Creating the park cool island in an innercity neighborhood: heat mitigation strategy for Phoenix, AZ. Under review. Harlan SL, Brazel AJ, Prashad L, Stefanov WL, Larsen L Neighborhood microclimates and exposure to heat stress, Social Science & Medicine 63: Harlan SL, Yabiku ST, Larsen L, Brazel AJ Household water consumption in an arid city: affluence, affordance, and attitudes. Society and Natural Resources 22: Harlan SL, Declet-Baretto J, Stefanov WL, Petitti D. n.d. Neighborhood effects on heat deaths: social and environmental determinants of vulnerability in Maricopa County, Arizona. Under review. Jenerette GD, Harlan, SL, Brazel A, Jones N, Larsen, L, Stefanov WL Regional relationships between surface temperature, vegetation, and human settlement in a rapidly urbanizing ecosystem. Landscape Ecology Jenerette GD, Harlan SL, Stefanov WL, Martin CA Ecosystem services and urban heat riskscape moderation: o water, green spaces, and social inequality in Phoenix, USA. Ecological Applications 21: Ruddell DM, Harlan SL, Grossman-Clarke S, Buyantuyev A Risk and exposure to extreme heat in microclimates of Phoenix, AZ. Pp in PS Showalter and Y Lu (eds.), Geospatial Techniques in Urban Hazard and Disaster Analysis. Springer. Contact information: [email protected]