How much increase in GHG emissions is caused by Amazon Prime?

Question

From Wikipedia:

Amazon Prime is a paid subscription service offered by Amazon that gives users access to free two-day delivery (one-day in some areas) [...] and other benefits for a monthly or yearly fee. In April 2018, Amazon reported Prime had more than 100 million subscribers.

It's my understanding that express shipping like this involves shipping multiple smaller packages from various locations (instead of combining shipments), and sending things by airplane and small trucks or cars instead of slower ships, large trucks, or trains. It seems clear that all of these changes result in increased greenhouse gas (GHG) emissions compared to standard shipping.

Is there any research or analysis on how much increase in GHG emissions is caused by Amazon Prime? Obviously some assumption must be made about how often Prime users would opt for express shipping were Prime not available.

Answer 1

I looked into a similar question 2 years ago and came to the conclusion that it's impossible to answer this. The problem is that Amazon doesn't disclose any information about their carbon footprint. In fact in 2011 when an investor proposed that Amazon would participate in the Carbon Disclosure Project, the Amazon Board of Directors actively encouraged their shareholders to vote against this proposal and said that they:

do not believe that preparing an ad hoc climate change report is an efficient use of time and resources (source: Amazon shareholder meeting PDF)

However it has been suggested that the real reason behind this is that Amazon uses the services of many 3rd party vendors and suppliers, which means that it's rather difficult to come to a complete carbon footprint calculation.

Even though Amazon does now disclose some information on renewable energy usage (e.g. see their Sustainability webpage) they still do not provide carbon footprint information, at least not to the CDP or on their own website.

So best we can do is take a wild guess. Most likely Amazon Prime's rush delivery will cause some extra inefficiency in transportation thus causing extra transport. However given the 140 Amazon warehouses spread out over the US and the large amount of items that need to be transported every day anyway, I suspect that the difference will actually be small. My guess is that the larger part of the extra carbon footprint caused by Amazon Prime comes from the extra stuff people buy (and don't really need) since Amazon Prime subscribers will think less before ordering something.