Why is West Antarctic ice sheet in irreversible decline?

Media have been reporting this week on the massive glacier system in West Antarctica that has started collapsing and will contribute to significant worldwide sea-level rise over the next two centuries. The glaciers contain enough ice to raise global sea level by 4 feet (1.2 meters). This melting appears to be happening faster than anyone realized. Here’s an explanation of the science behind the news, from NASA.

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