Is it Hot in Here?

I remember running out the back door across the hot cement patio to the safety of the cool grass of the lawn. Going barefoot in Texas most summers made me extremely conscious of the surface I walked on. We learned where the patches of goathead stickers were, where the gravel was scattered on the sidewalk and the melted tar on the asphalt of the street. As summer progressed, our feet toughened up, and my older brother would show off to the neighborhood kids by putting out a cigarette, barefooted.

When I lived in Arizona, I joined some people on a camping and waterskiing trip to Lake Mead, one summer. I quickly learned that you kept your shoes on until you got into the boat, since the desert sand would scorch your bare feet. We filled buckets with lake water and poured it around the tents to cut the heat and raise the humidity before we tried to sleep.

Obviously, the sun is hot and sunshine can make things hot. Mother Nature uses that heat to support life. We use sunscreen to protect our skin, and window shades and air conditioning to keep our surroundings cool. However, in developed areas, that heat and other emissions combine to cause “heat islands” that can make temperatures unbearable.

Journalist Fred Pearce notes, “Summers in the city can be extremely hot — several degrees hotter than in the surrounding countryside … The urban heat island can be a killer. Counter-intuitively, the biggest effects are often at night. Vulnerable people such as the old who are stressed by heat during the day badly need the chance to cool down at night. Without that chance, they can succumb to heat stroke and dehydration. New research … underlines that temperature peaks can cause a spike in heart attacks.”

We also know that we can capture the sun’s heat for our own purposes. Solar panels collect that heat and convert it into energy. And there are other factors that can mitigate the heat effects.

Pearce continues, “The systematic replacement of dark surfaces with white could lower heat wave maximum temperatures by 2 degrees Celsius or more. And with climate change and continued urbanization set to intensify “urban heat islands,” the case for such aggressive local geoengineering to maintain our cool grows.”

“Another option is not to whitewash roofs, but to green them with foliage. This is already being adopted in many cities. In 2016, San Francisco became the first American city to make green roofs compulsory on some new buildings.

“There is a third option competing for roof space to take the heat out of cities — covering them in photovoltaic cells. PV cells are dark, and so do not reflect much solar radiation into space. But that is because their business is to capture that energy and convert it into low-carbon electricity.”

Solar panels are routinely established across unused spaces, but some people are concerned with the continued erosion of available vegetation for insects and animals. Ilana Cohen reports, “Pollinator-friendly solar provides an approach to both the pollinator crisis and the climate crisis that is attractive aesthetically and economically, and potentially scalable. By planting a deep-rooted mix of native flowers and grasses around and even between solar panels that can provide abundant and healthy food for pollinators, developers can provide clean energy while also expanding pollinator habitat.”

“Research … has found that pollinator-friendly solar can boost crop yields, increase the recharging of groundwater, reduce soil erosion and provide long-term cost savings in operations and maintenance. The research also found that by creating a cooler microclimate, perennial vegetation can increase the efficiency of solar panels, upping their energy output.”

Another approach is to place solar panels on already-disturbed lands, such as over artificial waterways. Reporter Matt Simon asks, “What if instead of leaving canals open, letting the sun evaporate the water away, we covered them with panels that would both shade the precious liquid and hoover up solar energy?”

A California feasibility study determined, “… that if applied statewide, the panels would save 63 billion gallons of water from evaporating each year. At the same time, solar panels across California’s exposed canals would provide 13 gigawatts of renewable power annually, about half of the new capacity the state needs to meet its decarbonization goals by the year 2030.” The canals would also provide the constant cooling that the panels require for higher efficiency.

Human ingenuity is being applied to solve or mitigate some of our greatest problems. The above ideas will be supplanted in the future by even more creative and effective ones. For example, in my childhood, our approach to the hot summer surfaces was simple — flip flops.

There is no end to our creativity when driven.

Additional information:

Ilana Cohen, Pollinator-Friendly Solar Could be a Win-Win for Climate and Landowners, but Greenwashing is a Worry, November 28, 2020, Inside Climate News

Matt Simon, Why Covering Canals with Solar Panels Is a Power Move, 3/19/21, Wired

Fred Pearce, Urban Heat: Can White Roofs Help Cool World’s Warming Cities? March 7, 2018, Yale Environment 360

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