Earth Brightening as a Solution to Global Warming
(Hot Black Roofs and Roads Compared to Gasoline and Solar Farm Energy)
Alec Feinberg, DfRSoft Research, Northeastern University
Geoengineering solutions are needed. Since CO2 is estimated to linger in the atmosphere for over 100 years, it is
difficult to reverse global warming by trying to reduce fossil fuel usage. Yet, solar geoengineering solutions provide
an opportunity to lower global temperature quickly and are needed as warming is escalating faster than expected
(Hugonnet, 2021). Here we illustrate how an acre of black roads or roofs equates to 75,000 gallons of gasoline or 7.5
times as much energy as a solar farm showing the ongoing heat pollution that must stop and the need for solar
Heat Pollution and Earth Brightening
Our estimates find that black roads, black rooftops, and cities (the UHI effect) contribute a major portion to Global
Warming. We term this heat pollution in Feinberg (2022) which is a stronger and broader term than what
climatologists typically call land-cover/land-use.
Feinberg 2022 in modeling and Zhang et al. (2021) in measurements find that heat pollution shows that
7.6% and 12.7% (corresponding to forcing percentages of 16% to 27%) of global warming is likely due to the
urbanization effect, respectively. It is difficult to make projections, but one might anticipate that heat pollution's
influence on global warming will increase further by 2050 along with the UHI footprint (FP) as Yang et al. (2018)
reported FPs rapidly growing at a rate of 4.4% per year in China. The FP is defined as the continuous extent
emanating outward from urban centers to rural areas that have an evident UHI effect. Its assessment is important. It
helps in identifying possible UHI heat pollution amplification estimates that are needed in modeling and assessing
the FP environment. This further illustrates the strong current growth of heat pollution and the need for solar
geoengineering of urbanization (Feinberg, 2022).
Example of the Serious Issue of Heat Pollution from Black Roads and Roofs
Considering the land albedo to average about 25% reflectivity (He et al., 2014), one definition of heat pollution is
that any manmade surface or combination of surfaces with resulting lower reflectivity than 25% yields improper
land-cover and land-use contributing to global warming.
To understand how heat pollution makes incremental warming contributions and the importance of key
parameters, a comparison can be made between the energy from heat pollution due to black roads and roofs, to solar
cells and gasoline energy. Consider an acre (4046m2) of black roads or roofs with an average albedo of 0.125
(Ramirez et al., 2014) compared to the average land albedo of 0.25 (He et al., 2014) so that
0.25 0.125 0.125
. Then using the relation
it is found that (Feinberg, 2022)
( ) ( ) ( )
P P P X
Where Xc is the average irradiance on the Earth taken as 47% sunlight, A is the area of interest, and AE is
the area of the earth. Since
( ) ( )
p watts A P Wm
( ) ( / ) ( ) 340 (4046 )(0.47)(0.125) 80,820
E C T T
p watts P watts m A A X m watts
Then in a year, the total watt-hours are 80,820 watts x 24hrs/day x 365 days=0.71 GWh per acre per year.
If we include key parameter secondary effects from GHG re-radiation (1+f)=1.62 and feedback AF=2.15 (see
Feinberg, 2022), it increases this estimate to 2.5GWh. This is about 7.5 times more energy in heat pollution than a
solar power plant produces where studies have found they average about 0.33GWh per acres per year (Ong et al.,
2013). Furthermore, a gallon of gas equates to 33.6 kWh (Wikipedia, 2021). Then this heat pollution equates to
74,200 gallons of gasoline energy per year per acre.
This illustrates the enormous energy in an acre of heat pollution and how black roads and roofs make
significant incremental warming contributions. This offsets much of the benefits created by solar power plants and
produces a large amount of heat pollution energy up to 2.5GWh per year per acre (with secondary effects are
included). In work supported by the EPA, Cambridge Systems (2005) showed the ease of increasing the albedo of
roads. However, to date, very little work has been done by agencies like the Department of Transportation (DOT) in
the US, for example. From this example, we see that the DOT is a main contributor to heat pollution.
To offset the effect of black roofs, cool roofs in a mixture of climates across the U.S. has been studied by
Levinson et al. in 2010 with a “ heat transfer module to simulate in each of 236 US cities (well distributed in many
climates in the U.S. see their Fig. 5) the annual heating and cooling energy uses of new and old office and retail
building prototypes…. when roof solar reflectance is increased to 0.55 (weathered cool white roof) from 0.20
(weathered conventional gray roof)”. They reported results showing, “an annual CO2 reduction … offsetting the
annual CO2 emissions of 1.20 million cars or 25.4 peak power plants; an annual NOx reduction offsetting the annual
NOx emissions of 0.57 million cars or 65.7 peak power plants; an annual SO2 reduction offsetting the annual SO2
emissions of 815 peak power plants; and an annual Hg reduction of 126 kg.”
Example 2: What percent of the Earth do we need to brighten to reverse global warming?
The current estimate to reverse the global warming that occurred from 1950 to 2019 is 1.47Wm-2. To understand this
estimate and how it converts to solar geoengineering area and the albedo increase needed, please see the author’s
reference Feinberg (2022).
Governments need encouragement for Earth brightening and sun dimming. Most governments and politicians have
little idea that other solutions besides CO2 reduction exist. CO2 while important is also somewhat of a distraction to
these alternate needed solutions as time is running out.
Cambridge Sys (2005) Cool Pavement Report, Heat Island Reduction Initiative (PDF), Environmental Protection
Agency, Cambridge Systematics, available online at:
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.648.3147&rep=rep1&type=pdf, (accessed January 5,
2022). Also see: U.S. Environmental Protection Agency. 2012. "Cool Pavements." In: Reducing Urban Heat
Islands: Compendium of Strategies, available online at: https://www.epa.gov/heat-islands/heat-island-
compendium, (accessed March 24, 2022).
Feinberg A. (2022) Solar Geoengineering Modeling and Applications for Mitigating Global Warming: Assessing
Key Parameters and the Urban Heat Island Influence, Accepted for Publication in Frontiers of Climate on
3/21/2022 https://www.frontiersin.org/articles/10.3389/fclim.2022.870071/abstract. Also see research gate preprint.
He T, Liang S, and Song DX (2014), Analysis of global land surface albedo climatology and spatial-temporal
variation during 1981–2010 from multiple satellite products, J. Geophys. Res. Atmos., 119, 10,281–10,298,
Levinson, R, Akbari, H (2010) Potential benefits of cool roofs on commercial buildings: conserving energy, saving
money, and reducing emission of greenhouse gases and air pollutants. Energy Efficiency 3, 53–109,
Ong S, Campbell C, Denholm P, Magolis R, Heath G (2013) Land-use requirements for solar power plants in the
United States, NREL, Technical Report NREL/TP-6A20-56290, https://www.nrel.gov/docs/fy13osti/56290.pdf
Ramirez AZ, Munoz CB. (2014) Sustainable Development – Energy, Engineering and Technologies –
Manufacturing and Environment. Albedo Effect and Energy Efficiency of Cities, (Polytechnic University of
Madrid Press, Madrid Spain) 1-18, available online at: http://cdn.intechopen.com/pdfs/29929/InTech-
Albedo_effect_and_energy_efficiency_of_cities.pdf (accessed March 4, 2021)
Wikipedia (2021), Gasoline gallon equivalent, https://en.wikipedia.org/wiki/Gasoline_gallon_equivalent
Zhang P, Ren G, Qin Y, Zhai Y, Zhai T, Tysa, Xue S, Yang X, Sun X (2021). Urbanization Effects on Estimates of
Global Trends in Mean and Extreme Air Temperature, Journal of Climate, 34, 5, 1923-1945 doi:10.1175/JCLI-