Tricia just posted some new environmental treaty data from UNEP, in STATA format. It doesn’t cover as many treaties as David Frank’s dataset, but it covers 12 important ones and is updated through 2009. Here’s her description:
Time Series from 1960-2009
Data Downloaded from the UNEP GEO Data Portal at: http://geodata.grid.unep.ch/
For treaties, includes all 12 treaties listed on the UNEP GEO data portal, except the UN Framework. Treaty data is listed as missing “.” for years before the treaty existed, coded as “0” before a country joined, and “1” for all years after joining. Variable name is official treaty name, original source and years of treaty in dataset.