Mann must pay the full legal costs to the defendant. The ruling is explosive because it means that Ball's claim that Mann was a scientific fraudster is now supported by the court.
In 1999, Mann published a 1000-year-long global temperature reconstruction from tree rings that severely undercut the then-accepted knowledge of climate. IPCC's 1995 Second Assessment Report acknowledged that it was warmer during the Medieval Warm Period than today and that a significant cooling called the Little Ice Age followed and lasted until the end of the 19th century.
Mann's reconstruction demolished that view and replaced our climate history with something that looks like a hockey stick: For 900 years, the temperature was a slightly falling straight line and then, during the period of human activity, rapid warming in the 20th century.
Climate catastrophists immediately seized on this persuasive graph and made Mann the poster boy of the IPCC, which was now thoroughly controlled by radical greens appointed by leftist politicians.