By Emily Williams
It’s a simple rule of physics--so simple it is easy to hear it and forget it. Now, during the hottest decade on record and in the wake and presence of climate disasters, it cannot be ignored. It goes like this:
Hotter air holds more water vapor than colder air. For every 1 degree Celsius of warming (how much we’ve warmed the earth so far on average), the atmosphere can hold about 7% more moisture.
This simple physical relationship manifests in some of the most complex, destructive, and heartbreaking disasters. Over the past two weeks, cities across the Western US have broken temperature records and wildfires surpassed acres burned from this time last year. The Western US is also deep into an exceptional drought, which both provides ample fuel for blazes and can act to further increase temperatures with the lack of cooling from evaporation.
At the same time, historic and disastrous flooding has hit multiple European countries, killing more than 120 people.
This is climate change. A detection-and-attribution study (which detects whether an extreme event was ‘abnormal’, and attributes how much climate change made it worse) found that the extreme heatwave that plagued the Pacific Northwest -- and preceded the blazes -- was made 150 times more likely by climate change. Another has found that the Southwest is deep into a climate-fueled megadrought, in part due to higher temperatures. And while no formal study has yet been conducted for the flooding, scientists are making the links with climate change.
There are complex meteorological dynamics at play -- such as the weakening and increasing waviness of the jet stream -- that bring about these events. But, less blatant, yet ever present just beneath these dynamics, we can turn back to that physical principle.
If temperatures increase, warming the air, that air will act like a sponge and soak up any available moisture. In semi-arid areas of the Western US where moisture is limited, that ‘thirsty’ draws from the precious few water resources -- in turn, desiccating plants, evaporating rivers and lakes, and drying the soil.
In wetter places, likely at least part of what happened in Europe, the air will soak up all that extra moisture, and that heavily laden, warm air will eventually precipitate out and rain.
This physical principle is one of the things that makes climate change so dangerous. And as we continue to emit greenhouse gases, we’ll continue giving the atmosphere that much more capacity to hold water vapor--which can translate to more intense droughts and more severe floods.
The solution is about as simple as the physics of the problem. When your house is on fire, you get yourself somewhere safe and you turn off the gas. We cannot keep extracting and burning fossil fuels without leading to more warming.
This begins at home -- elected officials here in California have a choice of whether to approve new oil permits and keep relying on gas. We will keep having to cope with climate-change fueled heatwaves, fires, droughts, and floods, but moving away from fossil fuels will avoid a whole new scale of climate-fueled disasters.