The lecture provides a summary of the current scientific understanding of climate science on the natural and anthropogenic drivers of changes in global climate. It presents an overview of observed changes in the climate system and their relationships with physical processes as well as an overview of projections for future climate changes. "Global warming" does not imply uniform, gradual nor possibly benign changes in global climate. As Earth is getting hotter, observed changes are non-uniform, rapid and harmful. Global climatic disruption is real without doubt; mainly human-caused; already producing significant harm; and growing more rapidly than expected. What climate change puts at risk? First the availability of water, productivity of farms, forests, fisheries, secondly damages from storms, floods, droughts, wildfires and property losses from sea-level rise, expenditures on engineered environments and distribution and abundance of species. Facing the dangers from climate change there are only three options for human society. First is mitigation, meaning measures to reduce the pace and magnitude of the changes in global climate being caused by human activities. The second is adaptation, meaning measures to reduce the adverse impacts on human well-being resulting from the changes in climate that do occur. And the third is suffering the adverse impacts that are not avoided by either mitigation or adaptation. We're already doing some of each. Minimizing the amount of suffering in that mix can only be achieved by doing a lot of mitigation and a lot of adaptation.