This Earth Note is the final segment of a three-part series on the monsoon. View the first two here.
In May, the atmosphere’s concentration of carbon dioxide exceeded 430 parts per million for the first time in recorded history.
That’s bad news for many ecosystems and for human communities and societies that rely on them. But there might be a silver lining for residents of the Southwest who like rainy summers.
Climate change already affects summer conditions in the Southwest. Higher temperatures mean that moisture evaporates more rapidly, and soils and plants dry out quicker.
That’s in line with an overall shift to a drier landscape. And some climate models suggest climate change may diminish the North American monsoon long into the future.
But higher temperatures also pump more water into the air. In recent years, scientists have closely examined the Pliocene period, around 3 million years ago, when carbon dioxide levels were near those today. The climate was warm, and the global sea level dozens of feet higher.
By analyzing plant remains from that era, researchers learned southwestern Pliocene summers were wet, producing lush growth.
Today, quite a few climatologists believe we’re headed into a similar pattern, in which heavy but patchy rainfalls produce not only summer greenery but more intense flash flooding.
You might think of it as a monsoon on steroids — bringing not only the promise and benefits of warm-season rains, but also the dangers inherent under an atmosphere that simply holds more energy.
This Earth Note was written by Peter Friederici and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
