Projecting Energy and Climate for the 21st Century

The growing evidence of severe climate change impacts on human life and the global economy has created the increasing need for an assessment of low-carbon pathways. While the ultimate goal of zero- or near-zero global emissions is clear, the timing and trajectory to achieve low-carbon economic system is not. Projecting energy and climate is getting more challenging because the current energy and emission policies diverge further and further from the stated long-term policy goals. We provide a discussion of descriptive and prescriptive approaches to energy and climate forecasts. While the fundamental uncertainties are unavoidable, a group of scenarios that project the entire range of plausible developments provides better guidance for decision-making than any (or several) individual scenario(s). We offer an example of an integrated approach from the MIT Joint Program Outlook that can be used for a quantitative analysis of decision-making risks associated with different energy pathways. Despite the broad variety of scenarios, the article finds some robust findings for the energy system.