Think like a Sponge: Global warming intensifying rainstorms in North America

One of the effects of a warming world that has long been predicted, and has caused some confusion, is the way in which higher temperatures will mean more droughts and  more floods. The basic mechanics of it are pretty straightforward, if you learn to think like a sponge.

Image shows a bright orange and yellow sponge growing on the sea floor in a coral reef. It is made of several thick vertical tubes with a rumpled texture on the outside. There's a blue-gray fan sponge or fan coral between a couple of the tubes, and the reef in the background is tinted blue from the light filtering through the water. The color of the sponge is probably so bright from a camera flash.

”                                                                                                                                                         ” -From Thoughts of a Sponge, Volume 7, by A Sponge

Wrong kind of sponge, sorry.

Basically, hot air is like a dry sponge that’s being expanded. It sucks up any water with which it comes in contact. When it cools, it’s like squeezing out that sponge. So in a hotter world water in soil, rivers, lakes, and oceans will be absorbed rapidly by the air, and dumped out in other parts of the world when that air cools down. Because of how air moves around, that can mean that one location will both get bigger rainstorms, and be in a near-permanent state of drought compared to what we’re used to. That means all the harmful effects of heavy rainstorms, but also the harmful effects of water shortages. As with so much else in this field, this is entirely predictable based on things we’ve known for a very long time, despite what the Doubt Industry might do to confuse things, so it’s no surprise that, with the planet warming fast, the likelihood of intense rainstorms is increasing:

“The longer you have the warming, the stronger the signal gets, and the more you can separate it from random natural variability,” said co-author Megan Kirchmeier-Young, a climate scientist with Environment Canada.
Previous research showed that global warming increases the frequency of extreme rainstorms across the Northern Hemisphere, and the new study was able to find that fingerprint for extreme rain in North America.

“We’re finding that extreme precipitation has increased over North America, and we’re finding that’s consistent with what the models are showing about the influence of human-caused warming,” she said. “We have very high confidence of extreme precipitation in the future.”
At the current level of warming caused by greenhouse gases—about 1.8 degrees Fahrenheit above the pre-industrial average—extreme rainstorms that in the past happened once every 20 years will occur every five years, according to the study. If the current rate of warming continues, Earth will heat up 5.4 degrees by 2100. Then, 20, 50 and 100-year extreme rainstorms could happen every 1.5 to 2.5 years, the researchers concluded.
“The changes in the return periods really stood out,” she said. “That is a key contributor to flash flooding events and it will mean that flash flooding is going to be an increasing concern as well.”
The image shows a graph of extreme one-day precipitation events in the contiguous 48 states from 1900 to 2015. The image shows individual years as vertical gray bars, with a nine-year weighted average as an orange line. The X axis of the graph is time in decades, starting in 1910 and ending in 2020 (the vertical bars don't go that far). The Y-axis is

More often than not, when there’s a so-called “natural disaster”, the actual disaster is the result of human malfeasance or error. An event, like a storm, or an earthquake, or a drought, may be natural in origin, but the scale of disaster it causes is often a matter of how well the affected human population is prepared to deal with an event of that nature. Areas accustomed to dry weather aren’t bothered by what amounts to a catastrophic drought in other parts of the world. One of the bigger threats we face from climate change is that we are, increasingly, going to be seeing “the wrong weather” for what we’re used to in any given part of the world. This is something for which we can prepare, because we have enough understanding of how the temperature change is going to affect things.

The droughts could be significantly mitigated by a coordinated effort to capture, clean, and safely store rain water during the big rainfall events. Likewise, infrastructure could be designed to be able to handle a more monsoon-like annual rainfall pattern, while capturing the water needed. Doing all of this is not likely to be profitable, but it would dramatically decrease the need for drought-stricken areas to import water to deal with fairly predictable problems.

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  1. says

    I did see some idiot on YouTube arguing that more humidity in the air means there are no droughts in Europe. It was impossible to explain to him that that is not the case.
    Central Europe is currently experiencing a fourth dry year in a row. The underground water table is at 50% of its normal status. Rivers are drying up. And when the rain comes, it falls down all at once and runs away before seeping deep into the ground, so two days later it is as if there was no rain at all.
    And still a majority of people who could do something about either do not believe it is happening or do not want to do anything because it would cut into their profits.

  2. says

    The best real-world example I’ve seen is the 2010 combo of drought in Russia and flooding in Pakistan.

    A heat wave and drought led to wildfires and crop failures so bad they had to stop grain exports, on the one hand, and all that moisture was carried over and dumped on Pakistan, flooding a MASSIVE portion of the country, and also causing crop failures.

    If memory serves, one of the major driving factors was a wobble in the jet stream that more or less held the weather patterns in place, and carried all the humid air from Russia over to Pakistan.

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