Climate Change is Upon Us
When I was a graduate student in the 1960s researching how the earth’s atmosphere generates hurricanes and other severe storms, climate models weren’t very good. But they’ve gotten a lot better, thanks to much faster computers and more knowledge about the physics and chemistry of the atmosphere. We also have a lot more data, including very careful measurements over 50 years of how carbon dioxide levels in the atmosphere have steadily increased, along with corresponding data about the increasing human use of coal, oil, and other fossil fuels that emit carbon dioxide when burned.
One result is a much-improved assessment of how—and how fast—the climate is changing. Three recent reports by scientists and by 13 U.S. government agencies ( https://nca2018.globalchange.gov ) underscore these changes and their impending impact on our lives and our economy. One finding is that far from slowing down, carbon dioxide emissions are accelerating, up 2.7% worldwide in 2018. China and the U.S. are the largest emitters. In cumulative global emissions—perhaps a better measure, since carbon dioxide persists in the atmosphere for more than a century—the U.S. is by far the largest source, responsible for about one-third.
The mechanisms of climate change are pretty well understood. Carbon dioxide in the atmosphere captures reflected solar radiation leaving earth, in effect trapping its heat in the atmosphere and warming the planet. That leads to more frequent heat waves and drought, and to larger and more intense forest fires. Warmer air also warms the top layers of the oceans, causing more evaporation and putting additional moisture into the atmosphere, leading to more intense rainfall and flooding from coastal storms, and more severe storms generally. Warmer water contains less oxygen, which means many marine species grow more slowly or have to migrate northward to survive, a phenomenon that is already disrupting fisheries.
On a continental scale, the warmer atmosphere shifts the pattern of the high-altitude jet stream, causing larger and more persistent waves or fluctuations and leading to prolonged summertime high pressure areas over California (worsening drought and fires), similar low pressure areas over the east coast (more rainfall and flooding), and often more intense winter cold waves. Globally, the warmer climate is hastening the melting and collapse of ice sheets, leading to rising sea levels.
The reports highlight both the severity of the impacts of such changes and the magnitude of the required adaptations. Those changes especially pertinent to the Eastern Shore include:
- Abandoning low-lying coastal areas or hardening them with seawalls.
- Rebuilding ports, marinas, waterfront sewage systems, and coastal highways.
- More frequent crop failures as yields fall and shortages of irrigation water occur, and as heat waves affect livestock—or else major changes in farming practices.
- Accelerated decline of local fisheries.
The reports also make clear that these impacts are likely to occur sooner than expected—perhaps as soon as 2030. And outside the U.S., especially in tropical areas, the impact from such changes will be even more severe and may lead to major food shortages and increased social/political instability—and, likely, massive waves of refugees—as early as 2040.
Since it takes decades to shift energy sources and adapt to a warmer climate, failure to start now will simply make things more severe and more difficult later. If there is to be an effective global effort to mitigate climate change, the U.S. (as the largest cumulative emitter) will need to play a leading role. It is notable that the Trump Administration has withdrawn from the global climate treaty and is removing regulations on auto emissions and boosting coal use. On a local level, very few U.S. counties have adopted and are implementing plans both to mitigate and to prepare for climate change.
Common Sense for the Eastern Shore
