Of course, it's not possible to travel back in time and verify the reconstructed temperature changes. There may be blips that we can't account for. However, Professor Michael Mann (best known for his "hockey stick" graph illustrating human-made climate change) tells the Independent that the data appears "sound," and the analysis is "quite defensible." And if it is, that suggests that the need to reduce harmful emissions is that much more urgent -- politicians can't ignore science in the name of propping up coal and oil companies. While there's no guarantee that we'll trigger an inescapable cycle that leads to Venus-like heat, higher average temperatures could spark additional flooding and desertification.

[Thanks, Kristy]