Companies including Goldman Sachs, Walmart and Starbucks joined an alliance on Wednesday that aims to get 100 per cent of electricity from renewable sources to combat climate change.

The green electricity campaign, RE100, said its membership had expanded to 36 companies from 12 at a launch a year ago in New York that included IKEA Group, Swiss RE and BT Group.

The companies promise to shift to renewable energies such as wind and solar power to generate electricity to help slow climate change, blamed by a UN scientific panel for stoking more floods, downpours, heat waves and rising sea levels.

"Goldman Sachs, Johnson & Johnson, NIKE Inc, Procter & Gamble, Salesforce, Starbucks, Steelcase, Voya Financial and Walmart have today joined RE100," the campaign said.

Goals for achieving 100 per cent renewables vary widely, according to RE100, which is organised by The Climate Group and CDP, formerly known as the Carbon Disclosure Project.

Goldman Sachs aims to become 100 per cent renewable by 2020, for instance, but Johnson & Johnson's goal is by 2050. Steelcase became 100 per cent powered by renewable electricity in 2014.

"We are proud to join RE100 and announce our aspiration to power all of our facilities with renewable energy," Alex Gorsky, CEO of Johnson & Johnson, said in a statement.

Governments will meet in Paris in December, seeking to work out a UN deal to slow climate change. Many companies and investors say they are acting independently of the government negotiations. - Reuters