Thou cunning’st pattern of excelling nature,
I know not where is that Promethean heat
Othello. Act v. Sc. 2.
Here in the bottom of Tennessee, where the next county south is in Alabama, we have been watching the summers grow steadily hotter. When we arrived here, a band of ragtag hippies in 1971, the climate wasn’t as bad as rumors would have it. We were up on the rim of the Nashville Basin, and the reason the place is called Summertown is because it was where top-hatted and corseted city folk would come in the summers to cool off. There was once a resort hotel down by the rail track, and particularly when the Swamp°Fever was bad in the lowlands, the little highland town could expect to see a goodly number of wealthy tourists, people who would buy homemade corn ‘shine, quilts and wood furnerature.
The climate we had in 1971 is now up near Lexington, Kentucky. The local summer heat of ‘09 was what folks down in Nashoba County, Mississippi, had regularly in 1971.
At my house we swore off air conditioning in 1993 when we went to solar electric, choosing window fans and living roofs to keep us cool, especially at night. We have some picture windows that are replaced with large screens every year in May only to go back every October. We have some vents to the cellar, with a fan, to draw up the chill of the earth.
It’s still cool enough to work, or bike, or run around in the mornings, and when there is a breeze, usually before or after a rain, but days like we’re having this week are rough. Now it’s over 95°F every day, and humidity is well above 90 percent. There is no breeze, so you just learn to live with a layer of sweat. Clothing is minimal. Even taking a cold shower only lasts a couple of minutes, then you are all soaked in hot sweat again. At night it is still above 80°F at midnight, dropping only to the mid-70s by morning. By 8 am it is back above 80 in the sun. The sheets are stained with sweat and have to be washed more often.
We have taken to rising at sun-up, breaking for food at 8 am, working until noon, then taking off in the heat of the day, going for a swim, or just hanging out in the shade somewhere, trying not to work up a sweat. Even simple chores like weeding the garden or cleaning the house begin to bring on flushed foreheads and heavier breathing as the body’s air conditioning struggles to hold to 98.6. Our Amish neighbors are tougher than we are, but they vanish from the fields most afternoons now. It is too hot for the horses.
Reading the new federal report on “Global Climate Change Impacts in the United States” (http://www.globalchange.gov/publications/reports/scientific-assessments/…) we are particularly struck by the descriptions of what the temperature change will likely be by the time our grandchildren, just recently beginning to walk and talk, are middle aged. The report says:
The number of very hot days is projected to rise at a greater rate than the average temperature. Average temperatures in the [Southeast] region are projected to rise by about 4.5°F by the 2080s, while a higher emissions scenario yields about 9°F of average warming (with about a 10.5°F increase in summer, and a much higher heat index).
It is not easy to grasp those numbers, because we assume that global averages and daily or hourly temperature changes are equivalent, and they aren’t. Since 1970 our average temperature in this region has risen 2 degrees, which is roughly the same change for the Southeast as occurred between now and the last time glaciers extended below the Great Lakes. So, just to begin with, 2 degrees is huge. It is the difference between southern Mississippi and Nashville, Tennessee. Trying to grasp what “about 4.5°F by the 2080s” will mean, never mind 9°F… fuggeddaboudit.
One thing we can surmise is that farming will be harder. The report says:
Because higher temperatures lead to more evaporation of moisture from soils and water loss from plants, the frequency, duration, and intensity of droughts are likely to continue to increase.
That really only shows half the picture. If summer rains and the groundwater or rivers dry up, it will be hard to sustain field crops. If it is consistently above 95°F, corn will not generate ears, or the kernels will wilt on them. Above 102°F, soybeans will not set bean pods, or the seed will shrivel and die. Even our shiitake logs will lose the mycelium that makes the mushrooms grow.
Some crops are particularly sensitive to high nighttime temperatures, which have been rising even faster than daytime temperatures. Nighttime temperatures are expected to continue to rise in the future. These changes in temperature are especially critical to the reproductive phase of growth because warm nights increase the respiration rate and reduce the amount of carbon that is captured during the day by photosynthesis to be retained in the fruit or grain.
Snap beans will fail if nighttime temperatures are consistently above 80°F.
Lower soil moisture and higher temperatures leading to intense wildfires or pest outbreaks (such as the southern pine beetle) in southeastern forests; intense droughts leading to the drying of lakes, ponds, and wetlands; and the local or global extinction of riparian and aquatic species.
We are already watching our hardwood forests fall of their own accord. Last year it was the oaks. This year it’s the hickories. Loblolly pine, a species that favors the sandy soils of Mississippi, was planted abundantly back in the late 1970s, when we worked as tree-planters and had lots of leftover stock, and also the forest service and ag-extension agents gave them away for free. Those are now thriving, happy to have the climate they most favor come their way. Loblolly will now move up into Kentucky, Pennsylvania, and New York, even as the sugar maples, spruce, beech, and wild plum go extinct.
What will it be like for our grandchildren, we wonder, when we have 120-135 days per year above 90°F and perhaps a third of those topping 100°F? By mid-century, extreme heat events that used to occur every 20 years on average will have become annual affairs, like the drought in Atlanta. It is by no means certain that there will be energy to run air conditioners by then, but perhaps there will if the radioactive sediments are dredged from behind TVA’s dams and the plants that make nuclear fuel and weapons are closed.
Migration is an option. Our granddaughter has an aunt in Alaska who might take her in, not that Alaska will be exactly paradisical. Already droughts are becoming more common, forest fires spreading, lakes shrinking, and coastal storms increasing. Still, they may still be able to make a bean crop there by mid-century.
Right now it is approaching midnight on a Saturday night in June. The summer solstice is about an hour away, and after that our nights will start getting longer. The temperature is 89°F. Solar-powered fans keep the air moving but our MacBook is way too hot to rest wrists on. I’m feeling the need for another shower.