Hunga-Tonga Mysteries

Guest Post by Willis Eschenbach

Yesterday, Anthony Watts posted a most interesting discussion of the Hunga-Tonga volcano, entitled “Record Global Temperatures Driven by Hunga-Tonga Volcanic Water Vapor – Visualized“. I found some curiosities worth discussing in the post.

First was the delay between “cause” and “effect”. Here’s Ryan Maue’s graph showing the conundrum:

Figure 1. Output of a climate reanalysis model of the 2-meter surface temperature. This shows a big jump in mid-March.

Now, the Hunga-Tonga volcano erupted on 14 January 2022. My questions are … why is there a ~ 14-month delay before the mid-March 2023 temperature jump shown in the red square in Figure 1?

And why does the eruption have no visible immediate effects?

I mean, we’re talking about changes in radiation due to water vapor, and they are instantaneous—as soon as the water vapor concentration changes, the radiation changes.

And why is there nearly as much warming from November 2022 to the mid-March date of the purported “jump” as there is after the date of the “jump”?

Some folks have said that it’s because it takes time for the water vapor to spread around the stratosphere. In his post, Anthony quoted from a study entitled “Global perturbation of stratospheric water and aerosol burden by Hunga eruption” regarding the huge quantity of water vapor injected into the stratosphere. But here’s another quote from that same paper:

Owing to the extreme injection altitude, the volcanic plume has circumnavigated the Earth in only one week and dispersed nearly pole-to-pole in three months.

So we should have seen some kind of change within a few months of the eruption … but there’s no sign of that in the data above.

Now, Ryan Maue’s graph doesn’t show observed temperatures. Instead, it’s the output of a climate “reanalysis” model. So I thought that in addition, I’d look at, you know … actual observations. I was going to start with the Berkeley Earth temperatures. But they only extend to March 2023, so they wouldn’t show the purported jump in temperatures.

So instead, I looked at the UAH MSU satellite atmospheric temperatures. Let me start with the temperature of the lower stratosphere because it’s there that the water vapor was injected, so it’s there that we should see the main effect.

Figure 2. UAH MSU lower stratosphere temperatures.

You can see the effect on the stratosphere of the large eruptions of the late 20th century, Pinatubo and El Chichon. The temperature peak just before the Hunga-Tonga eruption is likely a combination of the White Island and Taal eruptions in December 2019 and January 2020.

But there’s no sign at all of the Hunga-Tonga eruption. Nor is there any sign of the purported jump in temperatures in mid-March 2023.

Moving down in altitude, here’s the temperature of the tropopause, which is the altitude where the stratosphere meets the troposphere.

Figure 3. UAH MSU tropopause temperatures.

The signals of the earlier eruptions are less distinct at this lower altitude … and again, no sign of any effect from Hunga-Tonga.

Moving lower still, here’re the mid-troposphere temperatures.

Figure 4. UAH MSU middle troposphere temperatures.

The signs of the big eruptions are pretty much lost in the noise … and still no sign of Hunga-Tonga.

Finally, here are the UAH MSU lower troposphere temperatures:

Figure 5. UAH MSU lower troposphere temperatures.

Same story. No sign of any effect of Hunga-Tonga.

So I figured I might be looking in the wrong place. Where would we expect to see the changes from a volcano in Tonga?

Well, in Tonga, maybe? … unfortunately, there’s no daily temperature data from Tonga. However, here’s data from some of the nearby islands.

We’ll start with Fiji, a lovely place where I lived for nine years. Hey, those waves aren’t gonna surf themselves …

No immediate effect from the eruption, nor is there any sign of the purported jump in temperatures in mid-March. Next, here’s Tahiti:

Again, no sign of the eruption, nor of any sudden jump. It rose after the “jump” date, but it rose before that date by about the same amount.

Next, Pago Pago in American Samoa.

Looks like Tahiti, a whole lot of nothing going on. Next, here’s Auckland in New Zealand.

No immediate reaction to the eruption. And if Hunga-Tonga caused the warming in 2023 … did it also cause the preceding cooling starting at the end of 2022?

Moving on, here’s Honiara, my old hometown in the wonderful Solomon Islands where I lived for eight years.

Same lotta nothing going on there, temperatures rising both before and after the mid-March “jump” … finally, here’s Lord Howe Island off of the east coast of Australia.

A year of cooling after Hunga-Tonga, then warming … say what?

Next, to look at a larger area, here’s the North Atlantic Oscillation over the same period.

Still not seeing it. There is a rise starting around mid-March, but it’s indistinguishable from the previous rise and is much smaller than the rise pre-Hunga-Tonga.

Finally, here’s a different computer reanalysis model of the global temperature. To give a better view of the overall situation, I started the data in 2016 rather than 2022 as in Ryan Maue’s graphic above.

As with Ryan Maue’s graph, there’s warming both before and after the “jump”. However, it’s much smaller in total than the warming just before the eruption.

To close out, here are three different looks at the same post-2016 time span—ERA5, HadCRUT, and UAH MSU results.

Sorry, but I’m still not seeing any effect from the Hunga-Tonga eruption, nor any big jump in temperatures in mid-March 2023.

What do I conclude from this?

My guess, and it’s nothing but a guess, is as follows:

None of the above graphs, including Ryan Maue’s, show any immediate effects from the eruption. I suggest this is because estimates of the global effect of the injected water focus almost exclusively on the warming effects of the increase in downwelling longwave radiation from increased stratospheric water vapor.

But they seem to disregard the cooling effects of the decrease in downwelling shortwave (sunshine). This is likely to be significant, since stratospheric water is going to contain a lot of ice, and ice is a good reflector of sunlight.

In addition to reflecting sunlight, a second large issue is that water vapor, ice, and water droplets all absorb sunlight, which also cools the earth by reducing downwelling shortwave at the surface.

Also, I’m just not buying that an injection of water into the stratosphere that has “circumnavigated the Earth in only one week and dispersed nearly pole-to-pole in three months” would a) have zero immediate cooling or warming effects, zero six-month effects, and zero one-year effects … but b) would still cause an upwards step-change in temperature fourteen months later. I may be missing something, but I see no feasible physical process that would cause that.

w.

PS—As folks who regularly read WUWT likely know, I’m happy to defend my own words and I’m willing to admit when they’re wrong. I cannot do the same for your interpretation of my words. So when commenting, please QUOTE THE EXACT WORDS you’re discussing. Saves lots of problems.

PPS—For those who enjoy such things, here’s my story of one of my adventures in Tonga, entitled “Old Bill Rises From The Dead“.