They noted that concerns over job losses and lower standards due to worldwide trade - which have prompted US President Donald Trump to take a protectionist stance - should be tackled by "bolstering an open and fair rules-based multilateral trading system". But having the first meeting in California, she said, sends a strong message to the Trump administration.
"After Trump resigned from the Paris agreement, and began dismantling important national climate policies like the Clean Power Plan, experts now give the USA much lower ratings for policy performance", report co-author, Jan Burck, said.
"The best way for the remaining "G19" to defend the Paris Agreement is to enact promises within it. Trump has made his choice: it's time for the other leaders to get down to business".
"We don't want a parallel discussion on climate".
"The withdrawal of the United States from this important and groundbreaking climate change agreement is inconsistent with the environmental, collaborative, and forward-thinking principles and values of San Mateo County's vision and leadership", the adopted resolution says.
And LA Mayor Gil Garcetti has been in the forefront of a movement that has pulled together more than 300 major cities in committing to Paris.
State Senate leader Kevin De León said California looks forward to taking the global stage at the summit in San Francisco.
But let's not kid ourselves about Putin. The Russian economy is fuelled by oil and gas and his political leverage comes in part by supply large parts of Europe with that gas. Trump has advocated more protectionist measures.
Reports claim that Polish President Andrzej Duda earlier on Thursday met with President Trump where both of them discussed that all nations must confront the threat from North Korea.
Brown, a longtime climate advocate, has also taken global diplomacy on emissions into his own hands, visiting China last month to meet with leaders there on how to cap emissions levels at 2 degrees Celsius above pre-industrial levels. Merkel's husband is a Professor of physical and theoretical chemistry. In Paris all world leaders acknowledged that when it came to cutting emissions to reduce the risk of unsafe climate change, they all had to do much, much more. Additionally, a petition been created on Change.org urging the G20 to take action on climate change and has already obtained over 40,000 signatures from people across the globe.
Make a date in your diary.