Facebook can cut down 49,000 tons of CO2 by ditching PHP for C++

The popular and addictive social networking website, Facebook, can get rid of 22,500 servers and move down to just 7,500 servers. And how is that possible? A programmer states that, by changing its coding from PHP to C++, Facebook can cut down on the use of servers on a large scale and reduce carbon dioxide emissions of a whopping 49,000 tons!

As they only say that "the bulk" is running PHP (edit: for those of you to lazy to read about the Facebook architecture [1], that is solely Apache/PHP, no database, no memcache, and to quote Jeff Rotschild of Facebook: “the need for those is a function of the runtime efficiency issues of PHP” [5]), let's assume this to be 25 000 of the 30 000 (edit: and this would be in line with other bits of info that they run around 800 dedicated memcached servers and a few thousand database servers). If C++ would have been used instead of PHP, then 22 500 servers could be powered down (assuming a conservative ratio of 10 for the efficiency of C++ versus PHP code [4]), or a reduction of 49 000 ton.