Global environmental problems, like climate change or the depletion of the ozone layer, are due to stock pollutants (e.g. CO2). As solving them requires multilateral action, international environmental agreements (IEAs) appear as the key regulatory instrument for enabling it. Nevertheless, the uncertainty related to the consequences of their signature makes them prone to long negotiations. Therefore, understanding and quantifying the economic implications of IEAs is a challenging but still essential task to reduce the uncertainty of future IEAs. With this purpose I want to quantify the technological gains and losses of an IEA in terms of patent value. This method would overcome typical weaknesses of previous studies and takes into account anticipation and delay effects. To this end, I would like to estimate a model of patent renewal under uncertain exogenous regulation that helps me to identify the impact of a given IEA on technological change. I estimate it using a unique pollutant-specific data set combining European patent data and policy reports of an IEA.