For example, in January 2006, Andrew Revkin's report that NASA political appointees were blocking James Hansen's ability to make public statements ran as the lead story of the Sunday NY Times. For Times' editors, who earned their stripes covering politics, the story was probably a classic whistle-blower tale. It also fit with a larger narrative about the Bush administration favoring ideology and cronyism over expertise, while featuring as a central character Hansen, the climate saga's best known protagonist.
Vendantam's article at the Washington Post is more difficult to figure out, though it is likely the human interest (and impact) element that pushed it to the front page. The article leads with a local-area NASA computer programmer who moved his family to New Zealand, fearing climate's inevitable impact in the US (the web story includes a photo with his family, the print version does not). Vendantam then provides context by detailing statistics across the globe on climate-driven migration, quoting several experts on the topic. He closes the article by profiling several U.S. residents in hurricane zones who have moved or are planning on it.
For a review of the factors that shape journalistic decision-making, see this short article synthesizing previous research on what media scholars call "agenda-building," written for the International Encyclopedia of Communication.