As Roger Pielke Jr. points out at Prometheus, there is a scientific error in Justice Stevens' Massachusetts v. EPA opinion:

there is a science error in the majority opinion, though it seems clear that it would not change their judgment of injury. It states:

. . . global sea levels rose somewhere between 10 and 20 centimeters over the 20th century as a result of global warming.

According to the IPCC's Third Assessment Report this value is more like 3 to 5.5 centimeters (from figure 11.10b here) with the rest of the 10 to 20 centimeters total due to natural causes. The Supreme Court has attributed all sea level rise to global warming which is incorrect.

As Pielke goes on to note, this error is not particularly material to the majority's conclusions — it would have found standing even had it relied upon the correct estimates for warming's contribution to sea-level rise — but it is worth noting nonetheless.