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To what extent is climate change actually occuring? Late last year, climate researchers were accused of exaggerating study results. SPIEGEL ONLINE has since analyzed the hacked "Climategate" e-mails and provided insights into one of the most unprecedented spats in recent scientific history.

Is our planet warming up by 1 degree Celsius, 2 degrees, or more? Is climate change entirely man made? And what can be done to counteract it? There are myriad possible answers to these questions, as well as scientific studies, measurements, debates and plans of action. Even most skeptics now concede that mankind -- with its factories, heating systems and cars -- contributes to the warming up of our atmosphere.