Tectonic Icebreaker

… reports that beneath the volcanic surface of … are vast glaciers. They are encased in unusual rock formations composed of minerals with exceptional insulating properties. Tectonic activity is slowly degrading these insulating layers, and … predicts that if temperatures between the glaciers and the rest of the planet were to equalize, the planet would cool enough to be considered an arid world, rather than a volcanic one. We can speed up this process in order to make the planet somewhat more habitable. But the phenomenon is scientifically curious, and there may be value in allowing it to be studied as it proceeds naturally.

The command below will trigger the "Tectonic Icebreaker" event in Stellaris:

When this event fires, you can choose between these 2 options:

• Stabilize the tectonics
• Accelerate the melting