California Governor Jerry Brown signed the historic policy and officially introduced the legislation into the law in an effort meet the guidelines and proposals set out in the Paris Climate Agreement. The signing ceremony took place in the state capital of Sacramento.

The 80 year-old Governor expressed his delight at the executive order and new bill, adding that embracing the challenges we face in terms of our climate is one of the biggest challenges facing the entire world.

Governor Brown said, “This bill and the executive order put California on a path to meet the goals of Paris and beyond. It will not be easy. It will not be immediate. But it must be done."

Over 20 countries across the world have made similar pledges in their fight against climate change, but California which has the fifth largest economy in the world, is by far the biggest jurisdiction to do so to date.

The electric industry is responsible for 16% of the state’s greenhouse gas emissions. California has established ambitious goals in its plans to slash greenhouse gas emissions by almost 40% by 2030.

California has emerged a s prominent leader on climate action and was critical of the decision by incumbent US President Donald Trump to opt out of the landmark 2015 Paris climate treaty, which was seen as an aggressive and vindictive move to dismantle the policies established during the Obama administration.

Executive Director of the Sierra Club, Michael Brune said it was difficult to put into words just hoew significant this new legislation is for California.

He said, “It's impossible to overstate how significant it is for a state as large and influential as California to commit to 100 percent clean energy. California is showing the world that a transition to 100 percent clean energy is within reach."

But Brown cautioned that reducing emissions enough to meet the Paris goal of capping global warming below two degrees Celsius (3.6 degrees Fahrenheit) remains a daunting task.

"Have no illusions," Brown said. "California and the rest of the world have miles to go before we achieve zero-carbon emissions."

Scientist estimate that the global economy will have to become "carbon neutral" removing any additional CO2 put into the atmosphere by mid-century or shortly thereafter to keep under the 2 degree Celsius cap.

Brown first proposed renewable legislation 40 decades ago during his inaugural stint as California chief executive, earning him the nickname "Governor Moonbeam."

"Brown really launched the modern renewable energy industry when he was governor the first time," said Jim Williams, a professor of Energy Systems Management at the University of San Francisco and author of a seminal 2012 study that mapped the decarbonization of California's economy by mid-century.

Brown, 80 years old, will leave office in November.