Invoking news coverage of recent extreme weather events, environmentalists are urging the public to sign a petition to pressure major television networks to do more coverage of climate change.

The petition, by the League of Conservation Voters, is aimed at executive producers of nightly news programs for major broadcast networks — ABC, CBS, and NBC — who the groups say don’t focus enough news coverage on climate change issues and, when they do cover the issue, portray the issue as a “two-sided debate” by featuring climate skeptics.