Hundreds of scientists and supporters have gathered in New Zealand cities to kick off the worldwide March for Science, a movement defending the role of science in society and calling for evidence-based politics.

"Climate change has been ground zero for alternative facts for many years now," climate science professor James Renwick said at the march in Wellington on Saturday.

Marching for science in Auckland NZ #ScienceMarch #ScienceMarchNZ pic.twitter.com/LaGuADIzjW

— Bart Janssen (@bjjanssen) April 22, 2017

Understanding the way the climate was changing was a science problem but working out how to deal with it was a social and a political problem, he said.
"We must have good science informing good policy," he said.

#ScienceMarchNZ with the crew! Great messages! pic.twitter.com/kuf9Q812rT

— Heather Hendrickson (@DrHHNZ) April 22, 2017

The Paris Agreement, from which US President Donald Trump has threatened to withdraw, was a great achievement in policy terms but action was necessary, he said.

More than 600 pro-science satellite marches were planned around the world on Saturday, with the main event in the US capital Washington expected to draw large crowds.

Protesters gathered in Wellington, Dunedin, Queenstown, Christchurch, Palmerston North and Auckland to show their solidarity with colleagues in the US protesting against the policies of the Trump administration.

#ScienceMarchNZ Wellington pic.twitter.com/tnQMbxTMeD

— Mike Dickison (@adzebill) April 22, 2017