How to add a citation to a sentence that has parentheses at the end? How can I add a author-date citation to a sentence that ends with parentheses? That can occur when using parenthetical remarks or when an abbreviation is introduced:

However, methane has a higher Global Warming Potential (GWP)(IPCC 2013).
Most environmental impacts were due to methane emissions (which has higher GWP factors)(IPCC 2013).

Having two parentheses next to one another sure looks awkward. Is there a &quot;workaround&quot; or should I work harder and restructure the sentences.
Update: I am writing my thesis and the university does not recommend any citation style.
This depends on the writing and citation style you are using. In APA you should use a semicolon to separate the citation from the acronym:

However, methane has a higher Global Warming Potential (GWP; IPCC, 2013).
Most environmental impacts were due to methane emissions (which has higher GWP factors; IPCC, 2013).

Source: http://blog.apastyle.org/apastyle/2013/05/punctuation-junction-parentheses-and-brackets.html