Amazon aims to become a "net zero" emitter of greenhouse gases by 2040. Besides cutting emissions with electric vehicles and other operational initiatives, Amazon plans to buy credits linked to projects that remove carbon from the atmosphere. The net-zero pledge presents a huge challenge for a company that seeks to grow like a startup and operates a cargo airline, a sprawling retail and logistics business, grocery stores and data centers. Amazon's accounting of its carbon footprint includes emissions generated by its own offices and data centers, purchased electricity, tailpipe emissions from delivery partners and the manufacturing of Amazon-branded products, among other things. In contrast to some retailers, the Seattle company doesn't attempt to account for the emissions that go into the manufacture of products it sells, with the exception of private-label merchandise. "The challenges we collectively face on the path to net-zero carbon are considerable," Amazon said in its report.