Indonesia Issued the Highest Alert after Volcanic Eruption Near Bali

Bali flights cancelled after Indonesian volcano spews 11 km-high ash tower. Mount Lewotobi Laki-Laki on the island of Flores, east of Bali, erupted on Tuesday (June 17, 2025), afternoon, leading to several airlines canceling flights. The volcanic eruption near Bali has significant implications not only for Indonesia but also for people traveling to this region.

This incident highlights the ongoing geological volatility of Indonesia, a country located on the Pacific “Ring of Fire,” where tectonic activity frequently results in volcanic eruptions and earthquakes. The eruption of Mount Lewotobi Laki-Laki, which sent a 11-kilometer-high ash plume into the atmosphere, is not only a significant geological event but also a serious disruption to regional air traffic and tourism, especially given Bali’s heavy reliance on international travel.

One of Indonesia’s most active volcanoes east of Bali erupted at 5.35 pm local time on Tuesday and unleashed 11,000m (about 33,200ft) of grey clouds in the air that could be seen from 150km away.

Key observations:

1. Aviation Risk: Volcanic ash at such altitudes poses a severe threat to aircraft engines and safety. The decision to cancel flights reflects necessary caution and adherence to international aviation safety standards.
2. Economic Impact: The disruption of flights to Bali, a major tourist destination, can have ripple effects on local economies heavily dependent on tourism, particularly during peak seasons.
3. Environmental & Health Concerns: The ash plume may affect air quality on nearby islands, with respiratory health risks and potential contamination of water sources and agriculture.
4. Preparedness and Monitoring: This event underscores the importance of Indonesia’s volcanic monitoring systems. Given that Mount Lewotobi Laki-Laki has erupted before, it’s crucial for authorities to maintain readiness for evacuations and hazard mitigation.
5. Broader Implications: Such eruptions serve as a reminder of the fragility of human infrastructure in the face of natural forces, urging continuous investment in disaster preparedness, regional coordination, and public education.

In summary, the eruption is a powerful reminder of the dynamic nature of Indonesia’s landscape and the need for resilience in both travel infrastructure and community response systems.

Impact on Climate

The impact of Mount Lewotobi Laki-Laki’s eruption on the climate depends on several key factors, especially the volume of sulfur dioxide (SO₂) and ash released into the stratosphere. A 11-km-high ash plume could have regional or minor global climatic effects, but the outcome hinges on the eruption’s duration, intensity, and chemical output.

Here’s what science tells us:

1. Local and Regional Climate Effects

• Short-term cooling: If significant SO₂ reaches the stratosphere (above ~10–12 km in the tropics), it can form sulfate aerosols that reflect sunlight and cool the Earth’s surface temporarily.
• Reduced rainfall: Aerosols can alter cloud formation, potentially reducing precipitation in the surrounding region.
• Ash and haze: Suspended ash can cause localized dimming of sunlight, especially within a few hundred kilometers.

2. Global Impact?

A global climate effect (like what occurred after Mount Pinatubo, 1991, which cooled the planet by ~0.5°C) would only happen if:

• The eruption is very large (VEI 5 or 6),
• Injects millions of tons of SO₂ into the stratosphere,
• And sustains this output over weeks to months.

As of now, there is no evidence that Mount Lewotobi Laki-Laki has reached that scale.

3. Key Questions for Climate Scientists

• Was SO₂ injected into the stratosphere?
• How much SO₂ was released?
• How long will the eruption last?

If reliable satellite data (e.g., from NASA’s Aura/OMI or ESA’s Sentinel-5P) shows a stratospheric SO₂ cloud, then even a modest regional cooling for a few months could occur.

✅ Summary

• Minor to moderate short-term regional cooling is possible.
• No significant global climatic impact is expected unless the eruption continues or intensifies.
• Monitoring by volcanic and atmospheric agencies in the coming days will clarify the actual climate risk.

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