Drush bootstrap level error
Your problem is that Drush is running the PHP version that you have installed for your hosting environment (and Drush's own php.ini). You need to get Drush to run its own PHP that it installs with. 

What host are you running on? If it is Windows then open a console and type set. That will show you the environment variables that you are using for your account. If there is a PHP variable in there, note it's contents and delete it by issuing the following command in the command windows: set PHP=

If that doesn't work set it back to what is was before. Any other platform I cannot help you with.

Also check this post: Modifying the PHP or PHP configuration that drush runs under