Scientific evidence strongly indicates that human activities are playing a significant role in bringing about major changes in our climate system, particularly in the last four decades. Significant changes in climate as a result of these human activities are projected for the rest of the 21^st Century and beyond. The scientific analyses also strongly indicate that the globally-averaged temperature charges are being largely driven by changing atmospheric concentration of radiatively important gases and particles, lending credence to concerns about much larger changes in climate being predicted for the coming decades. Analyses of the complex physical, chemical, and biological processes affecting the climate system, backed by direct observations of these processes, have implicated human activities, especially the burning of fossil fuels along with land use changes, as major factors in the increasing concentrations of the heat-trapping gases and particles. Analyses of the climate system also indicate that, without major policy or technology changes, the climate will continue to grow warmer and have effects on precipitation patterns over most of our planet. It is also important to recognize that while climate change is a global problem, its impacts occur at the local and regional scale. Regional integrated climate assessments are critical for informing sound climate mitigation and adaptation considerations. This presentation provides a discussion of the current understanding of the science of climate change and the role being played by human activities, with a special emphasis on the implications for the agriculture community.