These threats remained idle due to obvious problems with causation and attribution, that is, establishing that company A’s emissions caused a specified portion of B’s damages. Regardless, for years both in-house and outside corporate counsel have been confronted with the threat, and occasionally the actual lawsuit, that their activities caused climate change. Indeed, even the United States Supreme Court directly if disappointingly took on the issue in 2006.

That latter development threatens less to open floodgates of global warming litigation than to impact the regulatory climate. The justices ruled 5 to 4 that the Environmental Protection Agency must treat CO2 (and presumably all greenhouse gases, including water vapor) as a pollutant under the Clean Air Act.

Environmental groups have long challenged energy exploration and production on public lands or offshore, even where otherwise permissible. This decision, along with a pending Fish and Wildlife Service proposal to declare the polar bear “threatened,” offer litigious environmentalists new opportunities to use global warming to sand the economy’s gears with delays and prohibitions on domestic E&P.

This campaign and its enormous direct, indirect, and opportunity costs to the economy now threaten to take on a new significance. This, despite a rare setback last month when the U.S. District Court for the Southern District of Mississippi threw out a class action lawsuit that essentially blamed 26 energy companies for Hurricane Katrina. The Biloxi court dismissed Ned Comer, et al. v. Murphy Oil USA Inc., et al., on the grounds that the plaintiffs identified no “standing” to sue and that this question is better left to the political process.

Notwithstanding this spasm of judicial sensibility, all signs show that the courts will soon be swamped with global warming plaintiffs suing under a variety of theories. These include further attempts at suing under tort law, unique claims over a 225-year-old law, a collaborative effort among pressure groups, trial lawyers, and states’ attorneys general, and suing under a specific cause of action that activist members of Congress seek to create for just this purpose.

First, it is clear that the Katrina suit in tort was not a one-shot effort, if only from the fact that noted class-action lawyer Gerald Maples seeks to create a new litigation industry akin to his successes suing over asbestos. His law firm’s Web-site offers an entire section dedicated to promoting the catastrophists’ claims.

Second, for years environmental groups have struggled to exploit a one-line provision in the First Judiciary Act of 1789, the Alien Tort Claims Act, which provides primary jurisdiction in the U.S. federal courts for aliens suing only in tort. To date the courts have wiggled out from having to enter this swamp by invoking doctrines such as forum non conveniens, “act of state,” and comity (in short, it is better for everyone if you try your luck in the other countries’ courts first).

Third, apparently several state attorneys general are investigating collaboration with green groups and trial lawyers to reproduce the master tobacco settlement, but extracting settlements from energy companies. Following up on this, I filed and await responses to requests of seven AGs under their respective freedom of information acts seeking internal discussions on this agenda.

Finally, the House of Representatives’ energy bill – now awaiting conference with the Senate version – creates a new cause of action for “aggrieved parties” to sue for damages from the U.S. government. The lack of such an entrée into the courts had been problematic, with only the odd 9th Circuit judge willing to grant standing to sue over global warming (for example, seeking to block OPIC/ExImBank loan guarantees for energy projects overseas under the National Environmental Policy Act, on the grounds that the plaintiffs uniquely appreciate national parks). Clearly, until the scientific battle is resolved against catastrophism, global warming lawsuits are here to stay.

Christopher C. Horner is a Senior Fellow at the Competitive Enterprise Institute in Washington, D.C., and author of the New York Times best-seller, The Politically Incorrect Guide to Global Warming and Environmentalism.