The LA `pLAn` mentions steps to reduce the urban heat island effect. One way to reduce heat in cities is to increase tree canopy cover. Here is recent lesson f

The LA `pLAn` mentions steps to reduce the urban heat island effect. One way to reduce heat in cities is to increase tree canopy cover. Here is recent lesson from the city of Melbourne, Australia, regarding drought and tree cover: * the city experienced a drought from 1999 - 2007 [1] * as a short-term measure to conserve water, a decision was made to stop watering the city's trees [2] * consequently, ~40% of the city's trees are dead, or are in decline. The council now expects that 27% of the trees will die in the next 10 years, and 44% of the trees will die in the next 20 years. Melbourne city now is aiming to improve tree canopy cover from 22% to 40% by 2040 [3], as a means to reduce the city's temperature by 4 degrees C. There is also work to capture storm water run-off from the city to use for irrigation. Note that this is only talking about Melbourne's city centre (0.12m residential population of 4.2m total) [4]. As an aside, outside of cities, there is a recent Nature Geoscience paper that links lethal tree water stress thresholds to long-term climate models, and forecasts tree deaths due to drought in the southwestern United States by ~2050, assuming the world follows a high-emissions business-as-usual scenario (RCP 8.5, i.e. uncontrolled emissions, which tracks reality to date) [5]. [1] https://www.melbourne.vic.gov.au/Sustainability/AdaptingClimateChange/Pages/Drought.aspx https://www.melbourne.vic.gov.au/Sustainability/AdaptingClim... [2] http://citiscope.org/story/2015/can-melbourne-lower-its-temperature-4-degrees http://citiscope.org/story/2015/can-melbourne-lower-its-temp... [3] https://www.melbourne.vic.gov.au/Sustainability/UrbanForest/Pages/About.aspx https://www.melbourne.vic.gov.au/Sustainability/UrbanForest/... [4] https://www.melbourne.vic.gov.au/AboutMelbourne/Statistics/Pages/MelbourneSnapshot.aspx https://www.melbourne.vic.gov.au/AboutMelbourne/Statistics/P... [5] http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2400.html http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo24...