11 million protesters are expected to gather near landmarks, government buildings demanding climate action on war footing.
School Strike for Climate today: When, where and how to join this Friday's strike for climate action
The protests on 27 September aim at inaction in addressing the ongoing climate crisis.
Schools, colleges and universities have suspended classes for the day, government has encouraged staff to take the day off.
The global strike was called by climate activist Greta Thunberg and by her organization Fridays for Future.
Millions of students, adults take to streets demanding change in vast global climate strike on 20 September
Recent years have brought historic droughts, more intense bushfires, devastating floods and the blanching of the Great Barrier Reef.
Teen activists from all over the world will convene for the first-ever Youth Climate Summit at the UN headquarters.
Campaigners are also staging protests most European countries, Australia, Japan, India, South Africa, Canada among others.