A warming world could leave cities flattened

[Still Waters]

EARTH is starting to crumble under the strain of climate change.

Over the last decade, rock avalanches and landslides have become more common in high mountain ranges, apparently coinciding with the increase in exceptionally warm periods (see "Early signs"). The collapses are triggered by melting glaciers and permafrost, which remove the glue that holds steep mountain slopes together.

Worse may be to come. Thinning glaciers on volcanoes could destabilise vast chunks of their summit cones, triggering mega-landslides capable of flattening cities such as Seattle and devastating local infrastructure.

For Earth this phenomenon is nothing new, but the last time it happened, few humans were around to witness it. Several studies have shown that around 10,000 years ago, as the planet came out of the last ice age, vast portions of volcanic summit cones collapsed, leading to enormous landslides.

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