In this Wednesday, Sept. 12, 2012 photo, Apple CEO Tim Cook speaks following an introduction of the new iPhone 5 in San Francisco. (AP Photo/Eric Risberg)

Apple, the world’s largest public company by market capitalization, announced late Wednesday a suite of new renewable energy investments and partnerships in China — the world’s largest nation by greenhouse gas emissions.

The iPhone and Apple Watch maker, which already powers its electricity hungry data centers and U.S. operations generally with 100 percent renewable energy, will now also seek to green its supply chain in the vast country, chief executive Tim Cook announced in China Wednesday.

“Climate change is one of the great challenges of our time, and the time for action is now,” said Cook in a statement released to press.

Apple’s 19 offices and 24 stores in China are now carbon neutral, the company announced, thanks to the completion of 40 megawatts worth of solar capacity  in Sichuan Province.

But that’s just the start — the company also said that it plans to build 200 additional megawatts worth of solar projects across country, so as to begin to offset the greenhouse gas emissions of the companies in its supply chain. A megawatt is equivalent to a million watts, and the company calculates that this is enough electricity to power 265,000 Chinese homes for a year.

Most ambitious of all, the company is also joining with its business and manufacturing partners in China to install still more solar and other renewables — a total of 2 gigawatts worth of planned capacity. That will be led by 400 megawatts of solar installations by Foxconn, whose factory in Zhengzhou manufactures iPhones.

The investments, said the company, will prevent 20 million metric tons of greenhouse gas emissions between now and the year 2020.

The announcements come shortly before the intensely anticipated United Nations meeting in Paris, where nations of the globe will seek to forge a first-ever binding global agreement to reduce emissions. In advance of the meeting, many major companies have also pledged emissions reductions and clean energy investments, but Apple and some other tech firms, like Google, have been among the most ambitious of very large corporations.

Google just announced that it would invest in the largest planned wind farm in Africa, at Kenya’s Lake Turkana.

“To see Apple really putting commitments that are at scale to their energy demand in China, it’s a significant signal to the sector, and a signal that we hope other companies will follow,” said Gary Cook, a senior information technology analyst with Greenpeace who has been analyzing energy use in the sector, and how renewable it is.

Cook says that while IT companies like Apple have done a great deal of late to use clean energy to power data centers, to also make this happen in the manufacturing space and supply chain is an added step.

Earlier this year, Apple also announced that it is buying $ 848 million worth of solar energy from a nearly 3,000 acre solar farm that First Solar is installing in Monterey County, California. First Solar at the time called it “the largest agreement in the industry to provide clean energy to a commercial end user.”

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