claim: Thus rather than a "doomsday" cycle of runaway warming, Mother Earth appears surprisingly tolerant of carbon, decreasing atmospheric levels of water vapor -- a more effective greenhouse gas -- to compensate.
evidence: The last time the Earth was 2 °C (3.6 °F) warmer than pre-industrial temperatures, sea levels were at least 5 metres (16 ft) higher than now: this was when warming because of changes in the amount of sunlight due to slow changes in the Earth's orbit caused the last interglacial.