How Trees Can Save Lives: New Research from the Urban Climate Program of the CRC for Water Sensitive Cities

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1 How Trees Can Save Lives: New Research from the Urban Climate Program of the CRC for Water Sensitive Cities Nigel Tapper Program Leader, CRC for Water Sensitive Cities and Director, Monash Water for Liveability Centre Monash University, Melbourne, Australia Key Contributors to Our Program: Margaret Loughnan, Andrew Coutts, Thu Phan, Rick Harris, Rose Andrykanus, Jill Pettigrew, Emma White, Jason Beringer, Matthias Demuzere, Luke Gebert, Devna Pankhania, Laura Downs, Sultana Nury, Kerry Nice, Ashley Broadbent, Nadine D Argent, Charlie Lam, Edoardo Daly, Darren Hocking, Asieh Motazedian, Stephanie Jacobs

2 Origins of our Heat-Health Work and Interest in Urban Cooling Pre-dates our CRC Program 1 st decade of 21 st Century saw increased concern about climate change at State (and eventually Federal) level In 2007 the Victorian State Government, as part of their climate change adaptation planning asked our group to assist in the development of a heat warning system The research became a key element of our CRC program when it initiated in 2012

3 Melbourne Heat Threshold for Excess Deaths in >64 year olds Mortality anomaly Threshold Temperature Suggested that even a slight temperature reduction in EHEs (i.e. heat mitigation) would be sufficient to save many lives, also that forecasts based on this relationship would be of value in emergency Incr ~17% management in Melbourne 35 C=95 F Nicholls, Skinner, Loughnan and Tapper, 2008

4 Potential Reductions in Mortality for Each C (1 3 F) Reduction in Mean Daily Temperature So a 1-2 C temperature reduction under extreme conditions would be sufficient to save many lives we believe increased tree cover, especially if supported by irrigation 35 C=95 F Loughnan and Phan, 2013

5 Heat-Health Forecasting in Melbourne So the heat-mortality relationship has become the basis for heat-health forecasting in Melbourne Simple, requiring only forecast maximum daily and minimum overnight temperatures. Avoids problematic humidity forecasting Can be issued as an advisory 5 days out (from BoM 5 day forecast) Used to advise local government and emergency management authorities to mobilize resources Tested by DoH in summer of (unfortunately too late for the 2009 heat wave) and implemented in the following summer

6 Black Summer of 2009 in Victoria 547 people died in weatherrelated events in and around Melbourne Indications are that in the recent 2014 heat wave (4 days > 106 F [41 C], 173 on Black Saturday, but 374 during the 5-day heat wave that preceded Black Saturday 66% of the excess heat-related deaths were in the 75+ age group Clearly spatial dimensions to patterns with night temperatures remaining above 80 F [27 C]) mortality and morbidity were reduced over the 2009 event by ~50% - a result of better warnings and emergency management?

7 Threshold Temperatures (Best Predictors of Mortality/Morbidity) for Australia s Capital Cities Final report Loughnan, Tapper et al., 2013 SPATIAL VULNERABILITY TO EXTREME HEAT EVENTS IN AUSTRALIAN CAPITAL CITIES. National Climate Change Adaptation Research Facility, Gold Coast, pp146

8 Future Climate Change Using CCAM CSIRO Model - Adelaide as an Example From: SPATIAL VULNERABILITY TO EXTREME HEAT EVENTS IN AUSTRALIAN CAPITAL CITIES. Loughnan, Tapper et al., 2013 Report to National Climate Change Adaptation Research Facility, January 2013.

9 Why the Interest in Urban Heat and the Role of WSUD in Heat Mitigation?

10 Mapping the Vulnerability Index (VI) Critical risk factors identified a priori from the literature Hot days (EHEs) were defined for each city and associated adverse health outcomes (AHOs) identified Stepwise regression used to select best variables (risk factors) for each city. Appropriately weighted values applied to define VI for each city postcode An alternative, but similar VI for each postcode was defined using Principal Components Analysis PCA Ability of both approaches to predict AHOs at the postcode level was assessed

11 Melbourne ambulance callouts hot days Melbourne - Heat Vulnerability Indices and Emergency Highly relevant for prioritizing Presentations implementation of urban design features that can cool the urban landscape as well as for Report to NCCARF, January 2013 mobilization of emergency services Melbourne heat vulnerability map

12 Vulnerability Maps Now Online Overlay on Google Maps Final report Loughnan, Tapper et al., 2013 SPATIAL VULNERABILITY TO EXTREME HEAT EVENTS IN AUSTRALIAN CAPITAL CITIES. National Climate Change Adaptation Research Facility, Gold Coast, pp146 (

13 ~4 C Important urban design features that influence urban climate (Oke,1982): Albedo (surface reflectance) High imperviousness Thermal adsorption Urban canyon morphology (shading, heat trapping) Coutts et al., 2010 Airflow (ventilation) Waste heating (vehicles, air conditioners) Vegetation cover Water availability Stormwater runoff Irrigation Excess heat exposure

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15 Evaporative fraction - 50% Storage in urban materials + 250% Restoring tree/vegetation cover and hydrology Bowen is Ratiopivotal to restoring to a more natural Sensible heating of air + 30% climatic environment Increasingly urbanised Radiation available at the urban surface = energy used in heating air + energy used in heating substrate + energy used in evaporating water Critical urban indicators Coutts, Beringer and Tapper, 2007

16 Benefits of Storm Water Harvesting and WSUD for Hydrology and Climate Return to the Natural

17 Broad Research Objectives of CRC Project B3 Green Cities and Urban Microclimates Research Program How effective are storm water harvesting technologies, tree cover, green infrastructure and WSUD in improving urban climates at a range of scales? What are the key configurations required to reduce temperatures to save lives under heat wave conditions and to enhance human thermal comfort and liveability?

18 Coutts et al., 2012

19 CRC Project B3 Observational/Empirical Work Street tree cooling, , 2014 Street tree pit / tree physiology, 2012, 2014 Green roof/green wall performance Parkland irrigation influence on local climate, 2012, 2013, 2014

20 Heat wave conditions Feb 2012 Physiological Equivalent Temperature (PET) Trees = Reduction in mean radiant temperatures during the day Slight decrease in wind speed Reduced level of heat stress during day Net Benefit over the diurnal cycle White et al., 2012 Street trees study - PET

21 CRC Project B3 Remote sensing Land cover land surface temperature relationships at city scale Landscape irrigation and regional (city) cooling Microscale controls on urban air and surface temperature Prioritizing areas for implementation of water sensitive urban design

22 CRC Project B3 Remote sensing LST and Land Cover in Metropolitan Melbourne

23 CRC Project B3 Remote sensing Dubbo Landscape Irrigation Landsat TM images and transect for 13 th January Below right -Spatial variation in LST exhibits a surface cooling of up to ~5.0 C (suggesting air temp differences of ~2.0 C, Top right). Below The inverse relationship between LST and NDVI along an eastwest linear transect.

24 Prioritizing areas for implementation of WSUD and GI A = Highest priority B = Medium priority C = Moderate priority C Areas with observed or perceived: High air/surface temperature Daytime areas with: High imperviousness Little or no shade Dry, barren surfaces Night-time areas with: Dense streets Poor ventilation Exposure of the population Key influences of vulnerability Age Socio-economic status B A B Areas of high population concentration and risk of exposure Population density Ethnicity Pre-existing medical conditions Areas with potentially vulnerable populations: Aged care homes Schools / Education centres C B C Key locations o o o o Shopping precincts Train stations, transport corridors Walking routes Recreational Spaces Norton, Coutts et al., 2013

25 CRC Project B3 Remote sensing Prioritizing Heat Mitigation (City of Port Phillip)

26 Role of Melbourne s Inner City Parks and Pocket Parks in Cooling Summer

27 Errol St Pocket Park 10 March 2014 Weather Conditions 33 C (91 F), cloudy 100 x 30 m

28 Errol St Pocket Park 10 March 2014 Weather Conditions 33 C (91 F), cloudy L1 Path Roadway Tree WSUD bed 48 C = 118 F

29 Lincoln Square March 4 and ~100 x 130 m Weather Conditions C (91 95 F), clear to cloudy

30 Lincoln Square 10 March 2014 Weather Conditions 33 C (95 F), cloudy L1 Path/unirrigated grass Roa d Tree Irrigated grass Shadow 48 C = 118 F

31 Lincoln Square 4 March 2014 X upwind Weather Conditions 34 C (93 F), clear Wind direction Cooling below 30 m of up to 2-5 C (3-9 F) X downwind Most cooling below 10 m

32 CRC Project B3 Heat, Health and Thermal Comfort Vulnerability mapping for extreme heat (with NCCARF) Human thermal comfort and urban climates in public spaces Heat wave preparedness and household adaptation

33 CRC Project B3 Modelling (ramping now) Mesoscale Urban Climate Modelling CLMU within CLM4 and CESM (with Demuzere, KUL) WRF model for WSUD climate sensitivity and human thermal comfort Microscale Urban Climate Modelling Integrating vegetation and water balance Various urban design scenarios Estimation of HTC SURFEX (TEB) and SUESS model evaluation using high resolution data

34 Current Work for OLV Outcomes related to Liveability 4 & 5 - exploring the utility of NDVI measurements from satellite imagery. 4. Parks, gardens and green open-space meet community needs and remain healthy for use year round 5. Increase tree canopy cover, vegetation cover and soil moisture to ameliorate the effect of urban heat Normalised Difference Vegetation Index (NDVI) = (NIR-Red)/(NIR+Red)

35 NDVI From Landsat Seasonal Variation (Nov 2013 and Feb 2014) Normalised Difference Vegetation Index (NDVI) = (NIR-Red)/(NIR+Red)

36 NDVI From Landsat Seasonal and Longer Term Differencing Normalised Difference Vegetation Index (NDVI) = (NIR-Red)/(NIR+Red)

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