The "end of the world" tweet is removed by Greta Thunberg.

Swedish climate activist Greta Thunberg has deleted a 2018 tweet in which she shared a warning that climate change "will wipe out all of humanity" unless fossil fuels were abolished by 2023. The tweet was first noticed by US conservative pundit Jack Posobiec on Saturday, and a host of right-wing commentators chimed in to remind her that the world, in fact, still exists. Thunberg may not have been predicting the end of humanity in 2023, but may have been claiming that the human race faced extinction at some undetermined point in the future if fossil fuels weren't eliminated by this year. The Swedish campaigner has made similar predictions before, claiming that "irreversible chain reactions beyond human control" would take place unless carbon emissions can be reduced by more than 50% by 2030. Environmental activists have a long history of doomsday predictions, with scientists warning in the early 20th century that global cooling would render much of North America uninhabitable, while biologist Paul Ehrlich claimed in the 1970s that rising temperatures would cause mass starvation in the UK by the year 2000.