The submarine Hunga Tonga volcano in the South Pacific erupted violently on 15 January 2022. Tonga produced a massive volcanic plume that briefly reached 58 km (36 miles), touching the mesosphere. Below we have infrared satellite imagery of the eruption. We can see the warmer (green-yellow) cloud in the stratosphere and the colder (black-white) cloud in the troposphere.

And

Like sulfur, water vapor has a cooling effect, but not at the surface. Instead, it actually cools the stratosphere because it reflects the incoming solar radiation. It also prevents the heat from escaping, thus actually warming the surface.

So how much water was injected into the stratosphere? Based on observations and measurements, the normal amount of water in the stratosphere is around 1560 Teragrams.

Following the eruption of Hunga Tonga, the total amount of water increased to over 1700 Teragrams, which is a 10% increase in total stratospheric water vapor content. This is a large amount, coming from just one event.

And

The image below was made by Simon H. Lee and also shows the July 2022 mid-stratosphere temperature anomaly. The cross markings in the southern hemisphere mark the record minimal temperatures, which span in a belt around the whole southern hemisphere.

And

A negative NAO pattern means higher pressure over the north Atlantic and Greenland and lower pressure to the south. The image below shows the temperature pattern of a negative NAO winter season. You can see colder temperatures over the northern and eastern half of the United States and Europe.

Eoin Treacy's view

This Tonga volcanic eruption is likely to have a multi-year effect on the weather. The southern hemisphere is already experiencing a colder than normal winter. If that translates into a colder winter for Europe it will contribute to even more volatile energy pricing.