The volcanic island of Ambrym, located in the archipelago of Vanuatu in the South Pacific, was one of the most active volcanoes on Earth. What makes it particularly significant was its role as a major emitter of deep carbon dioxide (CO₂) and other magma-derived gases. Ambrym ranks among the top three volcanic emitters worldwide, highlighting its contribution to the global carbon cycle. The release of these gases plays a critical role in understanding volcanic processes and the movement of carbon between the Earth’s interior and atmosphere.
The Geological Setting of Ambrym
Ambrym was part of the Vanuatu volcanic arc, formed by the subduction of the Indo-Australian plate beneath the Pacific plate. The island was home to two persistent lava lakes—Benbow and Marum—which contribute to its continuous emission of volcanic gases. The volcano’s magma chamber connects deep within the Earth’s mantle, making Ambrym a key player in the deep carbon cycle by releasing CO₂ that has been stored for millions of years.
Volcanic Emissions from Ambrym
Ambrym emits an enormous volume of volcanic gases, primarily composed of:
- Carbon Dioxide (CO₂)
- Sulfur Dioxide (SO₂)
- Water Vapor (H₂O)
- Hydrogen Chloride (HCl)
These gases were released through eruptions, degassing from lava lakes, and fumaroles, with CO₂ being the most significant in terms of its impact on the carbon cycle.
Key Role of Deep Carbon Dioxide (CO₂)
- Ambrym’s CO₂ emissions were directly sourced from magma deep in the mantle, making it one of the world’s most prominent volcanic contributors to the global deep carbon cycle.
- It releases approximately 10,000–30,000 metric tons of CO₂ per day, rivaling other major volcanic emitters such as Mount Etna (Italy) and Kīlauea (Hawaii).
- These emissions provide critical insights into how carbon stored in the Earth’s mantle was transferred to the atmosphere.
Impact on the Global Carbon Cycle
Ambrym’s emissions represent an essential component of the decade-deep carbon cycle, which regulates Earth’s climate over geological timescales. While most atmospheric CO₂ comes from human activities, volcanic sources like Ambrym release ancient carbon that has been sequestered deep within the Earth. The study of these emissions helps scientists better understand:
- Long-term climate stability: How volcanic CO₂ contributes to Earth’s natural carbon balance.
- Volcanic climate feedbacks: The impact of large-scale eruptions on atmospheric CO₂ levels and global warming.
- The mantle’s carbon budget: How much carbon was stored, transferred, and released from deep within the Earth.
Volcanic Activity and Degassing at Ambrym
Ambrym’s continuous lava lake activity drives its exceptional gas output. Unlike explosive eruptions, which release gases in sudden bursts, Ambrym’s lava lakes emit gases steadily over time, contributing to sustained high levels of CO₂ and other volatiles. This consistent degassing makes Ambrym a crucial site for monitoring volcanic carbon emissions.
Monitoring and Scientific Research
Given its significance, volcanologists and climate scientists closely monitor Ambrym’s volcanic activity and emissions. Advanced tools such as:
- Satellite-based measurements (like NASA’s OCO-2)
- Ground-based infrared spectrometers
- Volcanic gas sampling drones
These tools allow researchers to track gas emissions in real time, helping improve volcanic hazard assessments and climate models. Understanding Ambrym’s gas output also contributes to refining predictions about the role of volcanic CO₂ in climate change.
Comparison with Other Major Volcanic Emitters
Ambrym stands alongside Mount Etna in Italy and Kīlauea in Hawaii as one of the top three volcanic sources of deep CO₂. Here’s a comparison:
| Volcano | Location | Average Daily CO₂ Emissions | Primary Gas Source |
|---|---|---|---|
| Ambrym | Vanuatu | 10,000–30,000 metric tons | Mantle magma |
| Mount Etna | Italy | 10,000–20,000 metric tons | Mantle plume |
| Kīlauea | Hawaii, USA | 5,000–9,000 metric tons | Basaltic magma |
Ambrym’s high emissions result from its persistent lava lakes and open vent structure, making it a continuous emitter of CO₂ even during non-eruptive phases.
Environmental and Climate Implications
The continuous release of volcanic CO₂ from Ambrym and other active volcanoes plays a complex role in Earth’s climate. While volcanic CO₂ emissions contribute to long-term warming trends, they were relatively small compared to human-made emissions. However, volcanic activity has historically triggered climatic shifts over geological timescales, such as during periods of increased volcanic eruptions in Earth’s past.
