The authors of the article, themselves women geoscience academics, give some reasons for the leaky pipeline. But I've been thinking about all the reasons that people might choose to get a science PhD and then not end up in academia - and only some of them are specific to women.
Here's my list of reasons that ANYONE might leak out of the pipeline. I've italicized the items that I am guessing are more prevalent among women.
- Failure to get an academic job. (We can't all be academics if there aren't enough jobs to go around. And there don't seem to be.)
- No desire to be an academic. (People start grad school intending to be other things? Gasp!)
- Desire to do the sort of science that can be easier to do in private industry (more funding, better facilities, and whatnot).
- Desire for greater income provided by industry jobs.
- Desire for more reasonable work hours provided by some industry and government jobs.
- Desire to balance family and career. Feel that such balance is hard to attain in academia.
- Desire to work in an industry where your 30s are not chewed up by trying to ensure that you still have a job in your 40s.
- Fear of failure. Imposter syndrome.
- Overt discrimination against women, minorities, disabled persons, homosexuals.
- Unconscious bias against women, minorities, disabled persons, homosexuals.
- Lack of role models for women, minorities, disabled persons, homosexuals.
- Lack of good mentorship in how to attain an academic job.
- Lack of good advising during the PhD process (or in a post-doc) that results in fewer publications, etc. making you less competitive for academic jobs.
- Poor recommendations because you have bad letter writers.
- Poor recommendations because you have personality problems to which your letter writers must confess.
- Lack of desire to move away from a specific location.
- Spouse or significant other that is unable/unwilling to move to/away from a specific geographic region.
- Care for an elderly or disabled family member that ties you to a specific location.
- Discrimination based on child-bearing status.
- Fear that they will be unable to reproduce or have as many children as desired once they reach tenure.
- Fear that they will be unable to adequately care for their pre-existing children while trying to reach tenure.
It seems to me, from making this list, that while there are some barriers that apply on to those of us with no Y chromosome, there are lots of barriers to anyone who is: (1) not a white, able-bodied, heterosexual male or (2) looking for a career where work does not totally subsume the rest of their life.
To fix (1) we need to keep strengthening recruitment and mentorship at all levels while continuing to educate and supervise those responsible for hiring decisions. With time (1) should be fixable. I remain hopeful that I will live to see the day that (1) is no longer on the list. To fix (2) we need to overhaul the structure of academia - starting with tenure. On this front, I am much more pessimistic.