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Albedo Enhancement: Localized Change Adaptation with Substantial Co-Benefits

Sarah Pearl April 2019

Introduction

Pursuing localized (surface reflectivity) enhancement can be an important component of regional adaptation. Increasing surface reflectivity to reduce absorption of solar radiation can partially offset the local warming effects of increased atmospheric concentrations while also improving public health and conserving water resources.

This paper highlights the potential efficacy, costs, and risks of localized albedo enhancement for urban centers, deserts, farmlands, and water bodies. Current research suggests that urban and farmland albedo enhancements are particularly effective in moderating and local climate change that provide additional localized benefits, thereby incentivizing communities to pursue them. Albedo Enhancement Strategies

Scientists have studied several intriguing climate intervention (geoengineering) strategies for enhancing the planetary albedo as a means of counteracting global climate change. While these are potentially effective and will possibly be necessary to prevent a climate catastrophe, significant research into each approach is needed. Governance mechanisms also remain a significant challenge.

There is considerable knowledge about how local temperatures and other climate features are affected by the local albedo. This understanding makes clear that increasing the local albedo can affect the local and , leading to generally beneficial outcomes. These outcomes are dependent on both their unique characteristics and how they are implemented. The following subsections describe a few examples.

Urban Albedo Enhancement

Painting surfaces such as roofs and pavements white or otherwise adding a reflective coating can be an effective way to increase the albedo of urban areas. Doing so has been demonstrated to reduce the effect, which leads to cities experiencing temperatures above those of surrounding areas due to the heat-absorbing characteristics of buildings and infrastructure along with

1 The Climate Institute| Albedo Enhancement: A Localized Climate Change Adaptation Effort with Substantial Co-Benefits

reductions in air circulation and evaporative cooling due to sparse greenery.1 As more people are projected to move into cities in the coming decades,2 urban albedo enhancement seems likely to be a particularly important adaptation strategy for cities to pursue.

While there is considerable potential for reducing the absorption of solar radiation, estimates vary as to how much albedo could realistically be increased and over what percentage of urban surfaces. An experiment conducted in western Athens found that brightening of asphalt and pavements reduced ambient temperature by 7.5 degrees and 6.1 degrees Celsius respectively.3

Such large reductions in temperature would dramatically improve the living environment for urban residents. Among all types of events, heat stress is a leading cause of mortality4 and is projected to become even more intense as a result of global warming.5 A recent Scientific American article provides a moving description of how heat waves have become a major source of human health risks, especially in urban areas,6 and these risks have been increasing over the last decade. Effective approaches for reducing temperatures in densely populated areas are thus becoming more critical.

Because higher temperatures speed up chemical reactions, urban albedo enhancement would also reduce the concentrations of photochemically generated (smog).7 As improved air quality is known to reduce rates of respiratory diseases and other ailments, urban albedo enhancement would contribute to improved human health.

Energy consumption is projected to increase significantly in urban areas as air conditioning becomes more widely available. Urban temperatures can sometimes become so dangerously high that air conditioning is a life-saving as well as comfort-enhancing technology. Increased use of cooling systems, however, can lead to both warmer outdoor temperatures and more air due to the heat from the running of the systems themselves and from the electric generating facilities.8 Urban albedo enhancement could help moderate these effects by reducing city temperatures in a way that does not require a cooling system. A study conducted in Andalusia, Spain found that the widespread implementation of cool roofs would lower emissions by

2 The Climate Institute| Albedo Enhancement: A Localized Climate Change Adaptation Effort with Substantial Co-Benefits

135,000 metric tons annually as a result of the reduced energy use,9 equivalent to removing almost 29,000 passenger vehicles from the road for an entire .10

A recent study in Los Angeles County analyzed the energy savings of modestly increasing roof albedo, finding that this could produce savings from reduced energy use of 23% to 40%,8 making cool roofs a financially attractive option. Others have found that, as a result of their energy savings, cool roofs pay for themselves within five to seven .11

Energy savings and improved comfort from installation of cool roofs are even more significant in the low-performance, outdated, and inefficient buildings8 that are often found in low- income areas where residents are likely to suffer most during extreme heat. Subsidizing albedo enhancement projects in these areas, thereby overcoming the inability to cover upfront costs, could thus have beneficial public health outcomes.

Agricultural Albedo Enhancement

Choices of plants in vegetated areas can also affect the local albedo. Crops absorb electromagnetic radiation both inside and outside the photosynthetically active region (PAR), or the window of radiation that actually contributes to growth.12 The radiation absorbed outside this window contributes nothing to productivity but still heats the plants and , leading to higher evaporative losses and earlier water stress.

Biologists and engineers have considered a variety of approaches to decreasing water usage and reflecting away more non-PAR radiation. This may involve adjusting leaf canopy structure or genetically modifying plants’ cuticles, hairs, or glaucousness.12, 13

It is estimated that crop albedo could be increased by as much as a third without reducing plant productivity.13 This could have significant regional effects by reducing temperatures on the hottest days.14 The Scientific American article mentioned earlier also noted that 80% of the billions of hours of labor lost due to dangerously high temperatures are in .6 It therefore seems plausible that increasing crop albedo to moderate local temperatures could reduce health risks and lost work hours, substantially improving agricultural market efficiency.

3 The Climate Institute| Albedo Enhancement: A Localized Climate Change Adaptation Effort with Substantial Co-Benefits

In addition, crops are harvested and re-planted so frequently that implementing such changes could be relatively quick. The main tenets of climate effective management are currently conservation tillage and improved irrigation techniques,14 but crop albedo enhancement also merits being included as a plausible approach.

Albedo Enhancement of Water Bodies

Just as air jets in bathtubs and spas create bubbles that make the water more reflective, microbubbles injected into water bodies such as water , aqueducts, streams and have the potential to reduce the absorption of , thus cooling the waters and leading to less evaporation.15 Freshwater is a vital resource under increasing strain from agricultural production and climate change. The increasing frequency of and heat waves, along with escalating pollution of freshwater sources, is leading to stricter and stricter rules governing water use. A recent study based on data from a NASA satellite identified nineteen hotspots that may face catastrophic water scarcity in coming years.16 Given this growing concern, the potential to alleviate pressure on freshwater sources merits further investigation. Current Applications

Use of the suggested albedo enhancement techniques does not require international or national approvals. Cities, states, and businesses can take the lead on these adaptive strategies. Urban, crop, and water albedo enhancement investigated here provide localized adaptation benefits, improving livelihoods and conserving precious resources.

Some cities are already implementing the urban strategies outlined here, albeit on a small scale. In April of 2018, Los Angeles started using CoolSeal, a white coating, on roads and pavement to reduce urban heat island effect.17 Mayor Eric Garcetti says this is part of the city’s plan to bring greenhouse gas emissions 45% below 1990 levels by 2025.17

State and municipal governments seem to have the authority to take actions to incentivize albedo enhancement measures and encourage their widespread implementation. Just as California has recently approved a regulation that all newly built homes must install solar panels or purchase

4 The Climate Institute| Albedo Enhancement: A Localized Climate Change Adaptation Effort with Substantial Co-Benefits

solar power from developers,18 similar governance frameworks could be used to promote albedo enhancement measures by, for example, requiring that newly built buildings and homes and newly paved streets be highly reflective. The co-benefits of albedo enhancement measures could also be bolstered and legitimized through information campaigns that point out the potential benefits of energy savings and more comfortable daytime temperatures. By doing so, use of reflective materials in urban environments could gradually become the new norm, displacing the widespread use of heat-absorbing dark pavements and roofs. Promoting the widespread use of reflective crops would likely require a different path, less focused on consumers and instead oriented toward the agricultural industry and farmers, encouraging expansion of the definition of climate effective land management to include reflective crops. Evaluating Albedo Enhancement Options

Urban and farmland albedo enhancement are compelling forms of local- to regional-scale climate change adaptation if used to complement overall efforts to reduce the increasing

atmospheric concentrations of CO2 and other greenhouse . In large population centers, reflective roofs and pavements, if widespread, offer the potential to moderate peak daytime temperatures, lessen the use of cooling systems, and reduce greenhouse gas emissions. In agricultural areas, use of more reflective crops could lower water use and regional temperatures while reducing the amount of work hours lost to extreme heat. Cost-benefit studies are needed to better understand the potential for these approaches to strengthen regional climate adaptation plans. Further research into the potential for microbubble injection into localized water bodies is needed to determine the role that this strategy could play in helping to conserve freshwater resources. As governments move to establish, formulate, and take actions to meet the time-sensitive emissions reductions goals that can moderate the consequences of climate change for their communities, albedo enhancement would seem to offer a compelling opportunity to bolster localized efforts.

Sarah Pearl is a student at Dartmouth College pursuing a Bachelor’s Degree in Physics and Environmental Studies.

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Notes

1. Santamouris, Mattheos. "Cooling the cities–a review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments." Solar Energy 103 (2014): 682-703. [There are also articles about this by Art Rosenfeld and colleagues on this—see article at https://grist.org/climate-energy/cool-roofs-offer-a-salve-for-hot-cities-and-the-climate- too/] 2. "68% of the World Population Projected to Live in Urban Areas by 2050, Says UN | UN DESA Department of Economic and Social Affairs." Department of Economic and Social Affairs. May 16, 2018. Accessed March 18, 2019. https://www.un.org/development/desa/en/news/population/2018-revision-of-world- -prospects.html. 3. Kyriakodis, G. E., and M. Santamouris. "Using reflective pavements to mitigate urban heat island in warm -Results from a large scale urban mitigation project." Urban Climate 24 (2018): 326- 339. 4. Centers for Disease Control and Prevention. "Heat-Related Deaths--United States, 1999-2003." MMWR: Morbidity and mortality weekly report 55, no. 29 (2006): 796-798. 5. Oleson, K. W., A. Monaghan, O. Wilhelmi, M. Barlage, N. Brunsell, J. Feddema, L. Hu, and D. F. Steinhoff. "Interactions between urbanization, heat stress, and climate change." Climatic Change 129, no. 3-4 (2015): 525-541. 6. Lewis, Tanya. "Climate Change Is Having a Major Impact on Global Health." Scientific American. March 01, 2019. Accessed March 24, 2019. https://www.scientificamerican.com/article/climate- change-is-having-a-major-impact-on-global-health/. 7. Stathopoulou, E., G. Mihalakakou, M. Santamouris, and H. S. Bagiorgas. "On the impact of temperature on concentration levels in urban environments." Journal of System Science 117, no. 3 (2008): 227-236. 8. Baniassadi, Amir, David J. Sailor, Peter J. Crank, and George A. Ban-Weiss. "Direct and indirect effects of high-albedo roofs on energy consumption and thermal comfort of residential buildings." Energy and Buildings 178 (2018): 71-83. 9. Boixo, Sergio, Marian Diaz-Vicente, Antonio Colmenar, and Manuel Alonso Castro. "Potential energy savings from cool roofs in Spain and Andalusia." Energy 38, no. 1 (2012): 425-438. 10. “Greenhouse Gas Equivalencies Calculator.” EPA, Environmental Protection Agency, 15 Oct. 2018, www.epa.gov/energy/greenhouse-gas-equivalencies-calculator.

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11. Levinson, Ronnen, Hashem Akbari, and Joseph C. Reilly. "Cooler tile-roofed buildings with near--reflective non-white coatings." Building and Environment 42, no. 7 (2007): 2591-2605. 12. Zamft, Bradley M., and Robert J. Conrado. "Engineering plants to reflect light: strategies for engineering water‐efficient plants to adapt to a changing climate." Plant biotechnology journal 13, no. 7 (2015): 867-874. 13. Drewry, Darren T., Praveen Kumar, and Stephen P. Long. "Simultaneous improvement in productivity, water use, and albedo through crop structural modification." 20, no. 6 (2014): 1955-1967. 14. Hirsch, Annette L., Micah Wilhelm, Edouard L. Davin, Wim Thiery, and Sonia I. Seneviratne. "Can climate‐effective land management reduce regional warming?." Journal of Geophysical Research: 122, no. 4 (2017): 2269-2288. 15. Seitz, Russell. "Bright water: hydrosols, water conservation and climate change." Climatic Change 105, no. 3-4 (2011): 365-381. 16. Rodell, M., J. S. Famiglietti, D. N. Wiese, J. T. Reager, H. K. Beaudoing, F. W. Landerer, and M- H. Lo. "Emerging trends in global freshwater availability." 557, no. 7707 (2018): 651. 17. Fedschun, Travis. "Los Angeles Painting City Streets White in Bid to Combat Climate Change." Fox News. April 10, 2018. Accessed March 24, 2019. https://www.foxnews.com/us/los-angeles- painting-city-streets-white-in-bid-to-combat-climate-change. 18. Chappell, Bill. "California Gives Final OK To Require Solar Panels On New Houses." NPR. December 06, 2018. Accessed March 24, 2019. https://www.npr.org/2018/12/06/674075032/california-gives-final-ok-to-requiring-solar-panels- on-new-houses.

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