Things Can Only Get Wetter

In the UK, things can only get wetter. It’s a law of physics, not a matter of opinion, that warmer air holds more moisture.

From high school physics, warmer air holds more water because the water vapour molecules in the air are moving at a higher average speed than those in colder air, making them less likely to condense back to liquid. The result? For each degree Celsius rise in air temperature, saturated air contains 7 percent more water vapour.

End of physics lesson, and starting point for the ensuing consequences. An atmosphere with more water vapour can make more precipitation. How this translates into changes in precipitation is not so linear, but the total volume increases and its uneven distribution becomes more exaggerated. Heavier rainfall is produced by fewer, more intense events that in turn lead to longer dry spells elsewhere.

Things will only get wetter in regions that are already wet and drier regions will only get drier. The UK could face water shortages and hosepipe bans in parts of the country if this summer is hot and dry, despite having experienced the wettest 18 months since records began. So let’s prepare ourselves now, because there are things we can do collectively to make the places where we live more resilient and to improve our capacity to adapt to our changing climate.