The park insisted these were emitted by a "former employee." The tweets were removed.
There were rumors that climate change was now a verboten subject in President Donald Trump's administration.
Why, on Wednesday, the Associated Press reported the Environmental Protection Agency had been forbidden from releasing scientific research until a political appointee had reviewed it.
Some people claiming to be employees at the National Park Service, however, decided to bite, rather than bark. They created a new Twitter account, using the currently popular "Alt" prefix. The AltUSNatParkService account describes itself as "the Unofficial 'Resistance' team of U.S. National Park Service."
It began tweeting on Tuesday. One of its first missives was aimed at the president: "Mr Trump, you may have taken us down officially. But with scientific evidence & the Internet our message will get out."
In 24 hours, the tweets have flowed like executive orders. As well as offering science, they've become a touch personal.
For example: "Trump knows climate change is real, he just doesn't care. For deniers, ignoring these worries is more profitable. Why worry when you're 70?"
Then there was: "Can't wait for President Trump to call us FAKE NEWS. You can take our official twitter, but you'll never take our free time!"
The writers didn't immediately respond to a request for comment. However, in another tweet they claim to work at Mt. Rainer National Park in Washington.
They have, though, inspired a movement of what appear to be employees of other government agencies who are using Twitter to continue spreading science.
Welcome, for example, to @RogueNASA. It also describes itself as a member of the "Resistance." Sample tweet: "Rogue Twitter accounts are fun, but gov't employees and scientists are very afraid of being fired if they speak out & share facts #resist."
Here's the @AltHHS account offering its version of a healthy human service: "The Blackout will not make us Backout from our duty as scientists. #FactsMatter #FactsNotFear."
And just in case you think there's anyone who claims they are a White House staffer who's leaking away, here you go.
There's no way of proving that the people behind these Twitter feeds work for government agencies. If you're fond of resistance movements, their anonymity is a good thing. Many, though, will worry that surveillance methods will be employed to root them out and punish them in covert or overt ways.
Still, the AltUSNatParkService account has already garnered more than 678,000 followers. Perhaps, then, it takes censorship for people to really be interested in scientific truths.
And Twitter does have its own peculiar power to make people pay attention.