The limiting factor concept has often been used to describe plant growth responses to altered availability of resources. However, even preliminary experiments, where atmospheric CO2 concentrations and solution mineral concentrations were varied, demonstrated that a more complex concept was required to interpret the potential effects of climate change and mineral availability on plant growth. It is proposed that these resources for plant growth may be better viewed as simultaneously limiting. Further, in considering the limitation in plant growth to mineral nutrition it is important to consider both the solution concentration and the total amount of the individual minerals available to the plant. Sustaining a positive response to increased CO2 concentration, for example, requires an increase in plant uptake of the total amount of minerals. Consequently, it is very difficult to predict the plant growth response to climate change because of the large uncertainty about mineral availability. On the one hand, increased CO2 concentrations should stimulate nitrogen fixation by both free-living organisms and symbiotic systems, and improve soil properties for mineral availability as a result of increased organic matter deposition in the soil. On the other hand, increased temperature and altered rainfall patterns may result in increased losses of soil minerals. Even the direction in the net change in available soil minerals is unclear. Realistic evaluations of the effects of climate change on plant growth will be challenged to contend with the large uncertainty and complexities in understanding mineral availability and plant mineral nutrition.