My work-out walk takes me through my neighborhood – a more suburban part of San Francisco. Today, i noticed something interesting – with scary implications for our climate. The weather is muggy – the sky is covered with fog, which adds a lot of moisture to the warmer air. Walking at about 140 beats per minute (using Earth Dance to pace myself), i work up a sweat even under cooler conditions. The muggy air today warmed me up well – i was longing for a breeze!

The first thing i noticed was that there was a breeze whenever i got to an intersection. I know that the grid design of our modern cities is redirecting the wind. In my neighborhood, that often translates into strong winds on the streets perpendicular to the ocean. Not today, though. I was walking on those and there was no wind. I decided to walk as close to the street on the sidewalk as i could hoping for a little bit of a breeze.

As i adjusted where i walked because of some grassy areas in the sidewalks, i felt the coolness from those patches of grass. The grass combined with the slightly moist soil cools the air. Something the sidewalk and the houses i was walking past does not do. This impact became very obvious toward the end of my walk. It goes past a couple of blocks with a mostly green park. I welcomed the colder air!

Struck by the difference of walking past those one-family houses and the park, i remembered a term from my permaculture class: Heat sink. The houses store the heat. The more little houses we build, the more heat we store. Another factor in global climate disruption…