A warm, stable greenhouse
Ice sheets retreat, seas rise, and climate settles into warmth after the Ordovician catastrophe.
- When
- Known to
- ± 10 million years
- Era
- Silurian, Paleozoic
The Hirnantian ice sheets melt early in the Silurian and sea level rises again, though far less steadily than in the Ordovician: carbon isotope excursions accompanying each anoxic event show a carbon cycle in repeated upheaval. Overall the period is warm, with no polar ice for most of its length, and broad shallow seas over the continents.