Luckily, on Thursday, Paris mayor and chair of the C40 network of cities committed to climate action Anne Hidalgo announced that 27 major cities, representing 54 million people, had already passed this milestone, according to a GCAS press release.
Brown and former New York Mayor Michael Bloomberg released a report this week showing that the voluntary promises made by more than 3,000 cities, states, business and non-profit organizations as part America's Pledge will get the U.S. less than half the way to the pollution cuts it promised in the Paris agreement.
Tokyo, Seoul and Rotterdam, meanwhile, joined Paris, London, Barcelona and Mexico City in vowing to run only electric buses by 2025.
"Who would have thought that the heads of major auto companies would all be agreeing that the era of the internal combustion engine is coming to an end", he told AFP.
Specifically, some studies suggest that by 2030, global greenhouse gas emissions could be lowered by as much as 1.5 to 2.2 gigatons (CO2e) every year if the commitments from almost 6,000 cities, states, regions and over 2,000 companies are fully implemented.
Why? Because of the difference between the words "electricity" and "energy".
A few days prior to the launch of GCAS, Brown signed a historic bill that would ensure carbon-free electricity for the whole state of California by 2045. While other sectors have declined over time, especially emissions from power plants, the California Air Resources Board said transportation emissions rose 4 percent between 2014 and 2016.
Bloomberg and Brown, a Democrat, said they calculate the country is within striking distance of the reduction in greenhouse gases previously promised by the U.S.
"Liar, criminal, fool - take your choice", he added when asked what Trump's environmental legacy would be. Nuttall, who served as the spokesperson of the United Nations Framework Convention on Climate Change said that he doesn't think that anyone ever thought that the achieving the Paris Agreement would be "some kind of calm sailing".
"Would it be easier if the Federal government and Congress were our partner?"
"This is part of our "Road to Zero" initiative to eliminate our environmental footprint", said Sony President and CEO Kenichiro Yoshida.
This spirit of collaboration is in keeping with the history of San Francisco, which witnessed the signing of the UN Charter in 1945, first establishing a rules-based worldwide order that championed multilateralism over self-interest, and endorsed progress not through conflict, but through all people working together.
"The transition to a net-zero economy is the growth story of the century", Stern said.
Barbados Prime Minister Mia Mottley speaks during the opening plenary of the Global Action Climate Summit Thursday, Sept. 13, 2018, in San Francisco.
Espinosa's speech at the closing ceremony underscored the need for all actors to embrace "inclusive multilateralism", strongly mirroring the UN Secretary-General's remarks on Monday in NY, where he called on leaders to adopt a sense of urgency to deliver a decisive response to climate change.