The Fascinating Hunga Tonga-Hunga Haʻapai Eruption
The Hunga Tonga-Hunga Haʻapai eruption is an amazing event, and not just because of its potential impact on the climate. Find out why this eruption is so fascinating and why science is an important and interesting topic.
Gavin Schmidt
Climate scientist, occasional juggler, even more occasional author, curious about how the world works.
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These people are so predictable with their nonsense, and yet I can't quite get over how disappointing it is that they can't see science as something deeply interesting and important... pic.twitter.com/KW95IedZhY
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
The Hunga Tonga–Hunga Haʻapai eruption was (is) an absolutely fascinating event - not because it's going to make a big difference to the climate or the weather (it won't), but because we got to see something we hadn't seen before. I mean, isn't that cool? pic.twitter.com/jlovmj1qiv
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
We've been able to closely observe big eruptions into the atmosphere before of course - eg. Pinatubo (1991), El Chichon (1982). And we've seen that the SO2 in the plumes can cause sulfate aerosols to linger in the stratosphere for a few years - causing a net surface cooling. pic.twitter.com/MK7epLzaYJ
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
In the stratosphere though, the extra absorption of solar radiation and upward long wave radiation by the aerosols causes local warming - this is seen clearly in the lower to upper stratosphere. pic.twitter.com/kZ1FB3uXA9
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
But Hunga-Tonga was different. It didn't have a lot of SO2 in the plume, but it did have a huge amount of water vapor....
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023
[need to take a break from the thread - part ii to follow later....] -
[back]
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023
So the amount of water vapor was literally shocking. None of the previous eruptions in the satellite era like as much. Estimates suggest that this one eruption added about 10% to the total stratospheric water content. That’s huge. pic.twitter.com/vJEp4ZDdGq -
A thing you need to remember though is that the stratosphere is really dry - with around 4 to 6 ppm of water vapor - compared to the lower atmosphere which can have a thousand times more.
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
We talk a lot about (tropospheric) water vapor as a feedback to climate change - how warmer temperatures increase the specific humidity and then increase the greenhouse effect some more. pic.twitter.com/WJgaV2jax7
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
But stratospheric water vapor is different. First it has a much longer lifetime (up to 5 years or so) compared to 10 days in the troposphere. No rain in the stratosphere!
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
There are normally two sources of strat water vapor - large scale advection in the upward motion of the tropics - that goes through a cold trap (around -80°C) which squeezes most of the tropospheric water vapor out. And the oxidation of CH4.
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
Now CH4 (methane) is increasing because of human activity (landfills, agriculture, oil and gas operations. leaks, cow burps etc) and so (therefore) is stratospheric water vapor. This is considered to be a climate forcing that can increase surface temperatures.
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
But with Hunga-Tonga we now have a new significant source of stratospheric water vapor. How neat is that? pic.twitter.com/xi0u5PpFSw
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
Scientists from all over are trying to see what this means - for ozone, temperature, and climate. Lots of models being spun up, lots of observations being analyzed, and lots of assumptions - particularly associated with eruptions in paleoclimate - being reconsidered.
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023 -
For right now, this is a huge signal in the upper stratosphere, but not so much anywhere else. So it really doesn’t impact any of the issues related to global warming.
— Gavin Schmidt (@ClimateOfGavin) June 25, 2023
It’s only when you have a cartoon image of the science & the ‘debate’ that you can’t wrap your head around it!