From the Foundation for Earth Science Bylaws - Section 4:
4.3.1. Plenary Directors shall be elected at each annual members' business meeting to terms of one year.
4.3.2. At Large Directors shall be elected to terms of office of two years; provided, however, that at the first annual members' business meeting following adoption of these Amended and Restated Bylaws, one At Large Director shall be elected to an initial term of one year and two shall be elected to an initial term of two years. Following the expiration of these initial terms, the terms of office of At Large Directors subsequently elected shall be two years. At all times, the number of At Large Directors designated for each term shall be equal to two or as equal as possible to two if the number of authorized directors is not evenly divisible by two.
4.3.3. All terms of office of directors shall run from the date of the annual members' business meeting at which the Director was elected until the date of the annual members' business coinciding with the conclusion of their respective term of office. Directors shall be elected at each annual meeting to fill those terms that expire at that annual meeting. If the directors are not elected at an annual meeting at which elections are to be held per these bylaws, they may be elected at any other regular meeting or at any special meeting held for that purpose (which need not be the exclusive purpose of that meeting).
4.3.4. Each director, including a director elected to fill a vacancy or elected at a special meeting, shall hold office until expiration of the term for which elected and until a successor has been elected and qualified.