Personally, I consider that just finishing my PhD was a rather big accomplishment because it represents four years of work, some of those spent really wondering if I had what it took to finish it. Obviously the more I work on other projects, the more it all becomes just two pieces of paper (hooray for a double diploma, two pieces of paper instead of one) that are just sat there in a folder on the shelf.
From the point of view of what’s the one thing I’ve done that has contributed most to bettering the world (that’s kind of like an accomplishment, right?) – maybe those legislative texts we wrote and did background research for. They have an influence on a very specific subset of products (different kinds products falling under a certain ISO Type I ecolabel) but all tiny bits add up to bigger bits and add up to even bigger bits. Eventually, in a couple of years, someone will rework those legislative texts to make them better but they’ll build up on the work we did.
I think that in research, especially sustainability research, it’s important to remember that most of the biggest achievements you hear about come after years and years of tiny incremental steps and are the result of work by tons of individuals. There are many stories of people inventing seemingly identical things at seemingly the same time in different parts of the world (and often only one getting the credit for it) and that’s due to the fact that radical changes and inventions are built on top of mundane work that eventually adds to something that’s thought to be radically new. So while I haven’t accomplished anything yet that’s life changing, I hope that somehow, somewhere along the line, I’ve contributed to something that one day will turn out to be important.