People around the world protested Friday to call attention to the global climate crisis as part of #FridaysforFuture, a youth-driven movement that started after teenage Swedish climate activist GretaThunberg skipped school and staged sit-ins on Fridays outside the Swedish Parliament. This week, around 25,000 people from 200 countries are in Madrid for the #COP25 climate change conference, including Thunberg. This is the last gathering of the climate group before the Paris agreement goes into effect. When nations signed the deal in 2015, they agreed that global emissions of greenhouse gases must peak in 2020 at the latest, and then start coming down — or the world will face disastrous and irreversible damage. (📸: Justin Sullivan/Getty Images, Gabriel Bouys/AFP via Getty Images, Oscar Del Pozo/AFP via Getty Images and Scott Heins/Getty Images)