The Fourth Assessment Report of the Intergovernmental Panel on Climate Change released in 2007 significantly increased our confidence about the role of humans on climate change. There is now a high degree of confidence that the (a) observed increases in atmospheric concentrations of CO₂, CH₄ and N₂O far exceed those of the pre-industrial era, (b) global increases in CO2 arise mainly from fossil fuel use and land use change while those of CH₄ and N₂O originate primarily from agricultural activities, and (c) net effect of human activities since 1750 has been one of warming, with a radiative forcing of 1.6 W m^-2. Depending on the scenario of human development, global temperatures are expected to rise between 1.8 and 4.0 °C by the end of the 21st century.

The agricultural sector is anticipated to be highly affected by regional changes in temperature and precipitation. Changes in crop productivity and global food production may be positive in the lower range of temperature increases but would turn negative if the upper range in temperature increases were to occur. While crops may benefit from the so-called CO₂-fertilization effect, yield losses may be expected if crops were to operate under high temperature, drought, and / or environmental stress (e.g., O₃) conditions. Thus, our challenge is to develop cultivars and production systems that are adapted to the climatic conditions to prevail during this century and productive enough to satisfy the dietary needs of increasing populations. There will be also challenges and opportunities for the development and application of agricultural technologies capable of (a) mitigating greenhouse-gas emissions and (b) producing bioenergy crops in a sustainable manner.