August 8, 2023 Hurricane Season

Hunga Tonga volcano influence on global climate

A new paper was submitted to Journal of Climate using a Whole Atmosphere CCM to model the effects of a Hunga Tonga like volcanic eruption on the Earth’s climate.

The volcano launched or spewed 40 Trillion gallons of water or about 150 Tg of water vapor (ocean water) into the stratosphere where it will stay for perhaps 7-years as a potent greenhouse gas blanket.

Check out that significance statement:

Volcanic eruptions typically cool the Earth's surface by releasing aerosols which reflect sunlight. However, a recent eruption released a significant amount of water vapor-a strong greenhouse gas-into the stratosphere with unknown consequences. This study examines the aftermath of the eruption and reveals that surface temperatures across large regions of the world increase by over 1.5°C for several years, although some areas experience cooling close to 1°C. Additionally, the research suggests a potential connection between the eruption and sea surface temperatures in the tropical Pacific , which warrants further investigation.

The regional warming (or cooling) signals are larger than I expected. Initial papers calculated a global impact of a few hundredths of a degree based upon simple radiative transfer, but did not discuss the dynamical regional changes due to adding another 13% to the entire stratosphere’s water vapor load.

Some thought a tenth of a degree (0.1°C) but this modeling experiment by serious people suggests 1.5°C to 2°C additional warming over Canada and Arctic. This modeling experiment did not exactly replicate Hunga Tonga, meaning the climate at the time was not matched e.g. transition to El Nino, global SST patterns, or stratospheric warming episode. So, the method is to run a model [with an injection of 40 Trillion gallons of water vapor into the stratosphere] many times with ensembles like I show with ECMWF hurricane forecasts, and then look at the responses. The result is a generally warmer Arctic for the next 3-7 years (!) on the order of 1.5°C. That’s an enormous signal.

There's a lot of weird climate stuff going on right now that's unexplainable by just waving your hands and saying climate change. But, add 40 trillion gallons of water in the upper atmosphere, and that should raise eyebrows. Of course, there are skeptics of warming volcanic influences, so we will wait patiently while more high quality modeling evidence accumulates — or watch Mother Nature run her experiment.

Hat tip to Roger Pielke Jr @ Honest Broker Substack for first Tweeting out this paper, which I did not read until late evening Monday.