Amazon, which ships millions of packages a year to shoppers' doorsteps, says it wants to be greener. The online retailing giant announced plans Monday to make half of all its shipments carbon neutral by 2030.

To reach that goal, the online retail giant says it will use more renewable energy like solar power; have more packages delivered in electric vans; and push suppliers to remake their packaging. It's calling the initiative "Shipment Zero."

Amazon also said it would make its carbon footprint public for the first time later this year. The initiative "follows an extensive project over the past two years to develop an advanced scientific model to carefully map our carbon footprint to provide our business teams with detailed information helping them identify ways to reduce carbon use in their businesses," Dave Clark, senior vice president of worldwide operations at Amazon, in a post on company's blog.

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Amazon has faced criticism for not doing more to combat climate change. Although the retailer says it has a "long-term goal" of being powered entirely by renewable energy, the company hasn't detailed when it expects to reach that objective.

But mitigating the effects of global warming requires taking drastic measures to curb human-made carbon emissions within the next 12 years, scientists say. That makes it urgent for companies like Amazon to act immediately, environmentalists say.

A group of Amazon shareholders and employees filed a resolution late last year that would require it to share its plan for going green.

"I think an effective plan will include dates and milestones," Emily Cunningham, one of the employees, told CBS News at the time. "To me, climate change is the issue of our lifetime. And we want to make sure they understand it's that important."

-- The Associated Press contributed reporting