Jochem Marotzke, Director, Climate Research, Max Planck Institute for Meteorology, Hamburg, Germany: Aren't you worried about thawing permafrost? No, quantitatively the contribution is relatively small. And as a general rule, it always says: Methane is a much more powerful greenhouse gas than CO₂, which is of course true: Overall, methane has a lower greenhouse gas effect than CO₂. Even if the permafrost thaws, it is uncertain how much of the methane really arrives in the atmosphere. Bacteria can convert methane to CO₂. I'm not worried about the methane. I am not concerned about any catastrophic climate tipping point from use of fossil fuels. What does this mean for all the teachers and professors who for forty years have been preaching climate catastrophes from use of fossil fuels? What does it mean for the politicians doing the same?