Volcanically Triggered Ocean Warming Near the Antarctic Peninsula

Area of Science:

• Climate Science
• Oceanography
• Glaciology

Background:

• Explosive volcanic eruptions inject sulfate aerosols into the stratosphere, causing global surface cooling.
• The Southern Ocean's response to volcanic eruptions is critical for Antarctic ice sheet mass balance but remains poorly understood.
• Observations after the Mt. Pinatubo eruption showed cooling in most of the Southern Ocean, but unexpected warming off the Antarctic Peninsula.

Purpose of the Study:

• To investigate the physical mechanisms behind the observed warming off the Antarctic Peninsula following low-latitude volcanic eruptions.
• To determine if this warming is a direct or indirect consequence of volcanic aerosol injection.
• To assess the potential impact of future volcanic eruptions on Antarctic ice shelves.

Main Methods:

• Combined observational analysis of the Mt. Pinatubo eruption (1991).
• Utilized the Last Millennium Ensemble (850-1850) from the Community Earth System Model.
• Analyzed changes in Southern Ocean temperature, Weddell Gyre outflow, and Southern Hemisphere polar westerlies.

Main Results:

• The observed warming off the Antarctic Peninsula is consistent with the forced response to low-latitude eruptions.
• This warming is associated with a 16% weakening of the subsurface Weddell Gyre outflow.
• The weakening of the gyre outflow is triggered by a southward shift of the Southern Hemisphere polar westerlies by approximately 2° latitude.

Conclusions:

• Volcanic eruptions can induce regional ocean warming in the Southern Ocean, counteracting global cooling trends.
• Weakened Weddell Gyre outflow and shifted polar westerlies are key mechanisms driving this Antarctic Peninsula warming.
• Future volcanic eruptions may exacerbate the vulnerability of Antarctic Peninsula ice shelves due to induced warming.