The 16-year-old from Sweden tweeted a picture of herself on Thursday to mark the holiday, saying that while she doesn’t usually celebrate in her home country, this year she “thought I might give it a try.”
“Apparently when it comes to scaring a bunch of angry climate crisis deniers – I don’t even have to dress up!! #trickortreat,” she wrote.
Thunberg is currently in Los Angeles, where she will be the keynote speaker at Friday’s youth climate strike.
Thunberg has garnered worldwide fame for the fierce determination she has demonstrated in her fight against climate change, which has prompted a global movement of climate strikers.
She has previously mocked haters ― including President Donald Trump and Russian President Vladimir Putin ― for speaking out against her and repeatedly laughed off adults who would “spend their time mocking and threatening teenagers and children for promoting science.”
“I guess they must simply feel so threatened by us,” she wrote in a tweet earlier this year.