Earth's Energy Balance

You have probably noticed it is getting hotter, as if the weather is out of balance. Earth’s energy flow is always in balance, but the planet-wide thermostat is now set to keep more heat. The energy retained on Earth’s surface has doubled between 2005 and 2019, thus the planet heats up. You can blame the sun, if that makes you feel better, but in fact human activity is the culprit.

Energy comes to Earth in the form of sunlight. Earth is storing more of this energy in the form of warmer land and especially warmer ocean water. This simply continues a warming trend that started with the industrial revolution in the late 19th century. Sadly, because of changes to the mix of gases in our atmosphere, the planet can’t get rid of the energy that comes naturally from the sun fast enough. There is a lot of water on Earth, so it’s getting warmer everywhere.

It’s simple, really. The oceans are warming because there are fewer clouds and less sea ice that would otherwise reflect the sunlight away. More significantly, the levels of heat-trapping gases, especially methane and carbon dioxide, are rising because of human activity. Carbon dioxide in the atmosphere has almost doubled since the time of Shakespeare. Water vapor in the air also contributes to the greenhouse effect, but its level is not changing much. Increasing levels of methane and carbon dioxide are thus the biggest drivers of the recent natural anomalous events such as record-shattering high temperatures in the American West and episodes of heavy rainfall, droughts, floods and extended hurricane seasons everywhere else.

How can gas way up in the air worsen weather down on the surface?

Carbon dioxide due to its molecular structure is naturally able to absorb sunlight, especially heat radiation. When heat radiation comes back into the air from Earth’s land or oceans, it is absorbed by the carbon dioxide and re-emitted. Sometimes the re-emitted heat goes off into space, but increasingly the heat is returned to Earth’s surface. That’s the problem: We are now at the point where there is so much carbon dioxide in the air that it’s hard for heat energy to escape back into space and our planet heats up.

It could be worse. Neighboring Venus has an atmosphere that’s mostly carbon dioxide. Venus enjoys a surface temperature of about 800 degrees C. This is hot enough to melt metals like lead, magnesium or aluminum. No wonder our favorite space cadets Elon Musk, Jeff Bezos and Richard Branson have announced no plans to visit our nearest planetary neighbor.

So why did temperatures in Portland hit 116 and 121 F in British Columbia recently? It was a heat dome — the fancy name for a huge thick blanket of hot air that formed and didn’t budge for days. The National Oceanic and Atmospheric Administration says a heat dome forms when strong high-pressure circulation in the atmosphere traps rising warm air from large areas of the ocean, especially from the periodic influences from La Niña. The main trigger for heat domes is a strong gradient in ocean temperatures from west to east in the tropical Pacific during the preceding winter.

NOAA explains: “The western Pacific’s temperatures have risen over the past few decades as compared to the eastern Pacific, creating a strong temperature gradient … that drive(s) wind, across the entire ocean in winter. In a process known as convection, the gradient causes more warm air, heated by the ocean surface, to rise over the western Pacific and decreases convection over the central and eastern Pacific. As prevailing winds move the hot air east, the northern shifts of the jet stream trap the air and move it toward land, where it sinks, resulting in heat waves.”

Here are some personal actions you can take, or at least ponder, as we all talk about the weather: take fewer trips on jet planes; plant trees and support reforestation; support companies that capture carbon dioxide before it gets into the air. You can also urge lawmakers to switch subsidies and tax credits from nonrenewable energy sources like fossil fuels to renewables; make all public transit free; mandate that all new construction must have solar panels; and implement a carbon tax.

Richard Gelinas, Ph.D., whose early work earned a Nobel Prize, is a senior research scientist at the Institute for Systems Biology. He lives in Lakebay. Suggestions for further reading are at keypennews.org.