What’s the science behind what’s causing the record heat?
The short version is, we have this big ridge of high pressure that’s retaining heat over much of the central and southern US, which isn’t unusual to see happen in the middle of the summer.
However, these typical midsummer conditions are getting taken up a level due to the fact that the climate is warming.
So, what would’ve been a more typical heat wave in the past is becoming more intense and lasting longer, and all of these impacts are starting to emerge – not just in the US, but around the world, including the recent record heat in the UK
How this comes out in a climate change context is the weather is always changing, and you can have a hot day or a cold day still, even in this changing climate, but we’re seeing a lot more record heat than record cold.
There are many studies coming out now showing that these extreme heat waves like the one in the Pacific Northwest last summer and the one in Europe right now would not be reaching the level they are reaching in terms of temperatures without the changing climate.
Beyond the phenomenon of climate change, is there anything else linking the record heat in the US to the UK?
We’ve been in La Niña conditions for the past two years, and it looks like it could persist for a third year. La Niña years are warm and dry, especially in places like eastern Colorado, Oklahoma and Texas.
El Niño and La Niña are the variations that occur in water temperatures in the Pacific Ocean. That affects where jet streams tend to go, which affects the weather even far from the Pacific. In Colorado, La Niña years tend to be drier than average, especially in spring, summer and fall.
The jet stream affects the weather, and during La Niña, what tends to happen is the northern states are wetter, the southern states are drier.
When you look at the record books for extended periods of hot conditions in the central United States, the years that pop out are in the mid-1930s, which was the Dust Bowl era, the mid-1950s, and now several recent years.
In Colorado, 2002, 2012, 2020 and 2022 are all showing up for years where we had extreme heat in different parts of the state. What it shows is that in areas already prone to hot and dry conditions, records are coming more frequently.
The good news we’ve had this summer is that there have been pretty active monsoon rains in the mountains. I think that has helped temper the fire danger a bit, but that’s not to say we can’t still get a big wildfire this year.
In 2020, the fires didn’t get started until August, but the rain has been more active in the mountains this year, which has been good for the wildfire situation. And we’ve also unfortunately seen deadly flash flooding on the burn scars from previous fires again this year.
The Eastern Plains have been feeling the brunt of the heat wave in Colorado, rather than the mountains, and the outlooks so far point to the monsoon being fairly active, so I’m hopeful that fire danger is not as bad as it’s been in the past years.