"After Zero" is a science fiction short story by Australian writer Greg Egan, first published in the anthology Phase Change: New SF Energies edited by Matthew Chrulew in 2022.
In 2060, Latifa (also the protagonist from "Zero for Conduct") is pursuing a project to launch a plasma powered scattering device to the first Lagrange point between Earth and Sun.
It is supposed reduce the amount of sunlight reaching Earth in an attempt to cool down its record-breaking temperatures caused by climate change.
Her project competes for funding against another known as Time Portal, which aims to send four humans into the past to change history by using a rotating ring dragging spacetime with it (as described by the Kerr metric).
Furthermore, the story is "a kind of The Man Who Sold the Moon scenario, extending over decades" and features a "dire" problem.