While environmental legislation may be stronger in Europe, regulation is recognized by activists on both sides of the lake to be much better in the US, even after accounting for the EPA's chronic lack of funding to achieve its broad mission. The reason is the broad central authority and data collection capabilities of the US EPA and associated agencies.  I don't know that this treaty will be able to provide an opportunity for homogenization of environmental regulations, but if it does European environmentalists stand to benefit by using the process the push for common regulatory frameworks closer to the US data-driven system (while US heavy industry pushes for a European model which notoriously allows for cheating and honor system reporting). Almost the exact opposite is the case with food and drug regulation.