Not all of the companies report all of this information. Dell, for example, only reports business air travel for scope 3 emissions.
HP does break down its emissions into a number of categories; it reported that it produced 1,865,200 tons in 2010 just from its own operations, with additional emissions coming from business travel, product manufacture, transport, use, and recycling--all totalled, that would equal about 26,953,200 tonnes of greenhouse gases emissions, more on par with Apple's reported figures. The company's 2011 figures were not available at the time of writing, though a company spokesperson told Macworld that they should be published in late April.
According to its 2010 report, Samsung only accounts for scope 3 product use on eight globally sold products and for most, but not all of its partners (the most recent data on those partners was from 2009). Several of its figures are broken down between Korea and overseas emissions as well, but the company says it produced 10,655,000 tons of greenhouse gases in scopes 1 and 2, with an additional 45,706,000 tons produced in scope 3--that's a total of more than 55 million tons. Samsung says that globally it produced 6.41 tons of greenhouse gases per 100 million Korean won in sales, which--as of currency conversions at the time of writing--works out to a rather hefty 72.1 tons per $1 million.
Apple doesn't say if it uses the GHG Protocol to measure its emissions, but its report does cover manufacturing and suppliers, which seems to suggest it provides a comprehensive overall picture. The company also says that its calculations adhere to the International Standards Organization's ISO 14040 and ISO 14044 specifications for reporting the information.
To the same end, Apple touts the fact that many of its products, for which it produces detailed individual impact reports, have vastly reduced carbon emissions over their predecessors. On the top of that list is the Apple TV, whose current incarnation is responsible for 90 percent less carbon emissions than the version that appeared in 2007. Likewise, the 2011 iMac's carbon emissions have been reduced 50 percent over the original model released way back in 1998, and the 2011 Mac mini has dropped 52 percent since the 2007 iteration. Even the iPad 2 has been reduced 5 percent over its predecessor.
While some of that has to do with the manufacture of the products--Apple estimates 61 percent of its overall greenhouse gas emissions are related to that portion of the product life cycle--much of it has to do with ancillary factors, such as transporting those devices to stores and customers. Because the company has reduced the size of packaging in many of its devices, it can fit more boxes in the same capacity, thus reducing the number of planes and flights needed. For example, Apple says that it's reduced iPhone packaging 42 percent between 2007 and 2011, meaning that one fewer 747 flight is needed for ever 371,250 units shipped.
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