Changes in climate, mainly changes in temperature, precipitation, and carbon dioxide concentration are predicted to occur. These changes in climate will affect weather conditions that are vitally important in the growth and development of crops. Historically, yield increases have been observed in many crops, including Glycine max (soybean). This yield increase has been associated with deliberate breeding objectives designed to optimize plant performance for the contemporary climate. This deliberate breeding initiative has modified plant physiologic parameters. This study looks at how changes in soybean physiological parameters, through different cultivars, have attributed to observed yield increases and how future climate changes will impact soybean yields with changing plant physiological parameters. Simulations using an integrated biosphere model, Agro-IBIS, were conducted to model soybean yields. The model was run with data representing a contemporary climate time period, 1983-2013, and a future time period, 2041-2071. Future weather data includes higher temperatures, spring and winters with increased precipitation, and summers with decreased precipitation. Soybean yields increased with newer cultivars, described by specific changes in plant physiological parameters including initial and final carbon allocation to the roots. Yields in future climate scenarios were found to increase with less variability in more recent cultivars. This study also found that certain combinations of plant physiological traits exhibit more variability in future climates, information which plant breeders can use to make selections for less variable, high yielding soybeans.