As ocean temperatures increase, crustaceans become subjected to more immediate, microecological impacts because of their exothermically-driven growth and development. In this laboratory-based study, ovigerous American lobster (Homarus americanus) were allowed to incubate their eggs for either a normal period of time (7–9 months including time at temperatures <10°C), or were held in water >10°C to speed up the rate of egg development (4–6 months). Females that had shorter incubation times had longer periods of larval release compared with females that incubated eggs for a normal period of time. Females incubating eggs for a shorter period of time also produced more larvae, and this was explained by the daily loss of a small number of eggs. Subsequent modeling of the relationship between dates of egg extrusion and hatching using data compiled from Massachusetts Bay demonstrated that there was a critical period in the fall at which larval development would switch from a resultant hatch in the spring to a hatch in the late fall or winter. The short-term implications of global warming on egg development and hatching in lobsters is discussed, including the production of larvae at suboptimal times of the year, as well as a temporal change in the abundance of larvae during the hatching season. Either of these events can lead to an increase in larval mortality and hence a decrease in population productivity.