The 2021 Global Change Outlook presents the MIT Joint Program’s latest projections for the future of the Earth’s energy, managed resources (including water, agriculture and land), and climate, as well as prospects for achieving the Paris Agreement’s short-term targets (as defined by Nationally Determined Contributions, or NDCs) and long-term goals of keeping the increase in the average global temperature below 2°C or even 1.5°C.
The massive impact of the Covid-19 pandemic on lives and economies underscores that our collective survival and well-being hinges on our willingness to confront environmental threats that have global consequences. Key to protecting lives and making communities more resilient to such threats will be an emphasis on proactive, science-based decision-making at all levels of society. And among the most serious risks that science can help illuminate and alleviate are those resulting from human-induced climate change.
To minimize those risks, the Paris Agreement(Global Change Outlook)aims to commit nearly 200 nations to implement greenhouse gas emissions-reduction policies consistent with keeping the increase in the global average temperature since preindustrial times to well below 2 degrees Celsius — and pursue efforts to further limit that increase to 1.5 C. Recognizing that the first set of submitted near-term Paris pledges, known as Nationally Determined Contributions (NDCs), are inadequate by themselves to put the globe on track to meet those long-term targets and thus avoid the worst consequences of climate change, the accord calls for participating nations to strengthen their NDCs over time. To that end, the United States and a few other nations announced more stringent emissions-reduction goals for 2030 at the virtual climate summit convened by President Joe Biden in April.
To support decision-makers now engaged in or impacted by this ongoing, international effort to stabilize the climate, the MIT Joint Program on the Science and Policy of Global Change has released its 2021 Global Change Outlook. Based on a rigorous, integrated analysis of population and economic growth, technological change, NDCs, Covid-19 impacts, and other factors, the report presents the Joint Program’s latest projections for the future of the Earth’s energy, food, water and climate systems, as well as prospects for achieving the Paris Agreement’s short and long-term climate goals.
Global Change Outlook Projections are provided for a baseline “Paris Forever” scenario, in which current (as of March 2021) NDCs are maintained in perpetuity; a Paris 2 C scenario that caps global warming at 2 C by 2100; and two scenarios — “Accelerated Actions” (which includes the newly announced U.S. goal for 2030) and Paris 1.5 C — which limit warming to 1.5 C by 2100. Uncertainty is quantified using 400-member ensembles of projections for each scenario. This year’s outlook introduces a visualization tool that enables a higher-resolution exploration of the first three scenarios.
2021 Global Change Outlook,The Paris Agreement established more precise long-term temperature targets than previous climate pacts by specifying the need to keep “aggregate emissions pathways consistent with holding the increase in global average temperature well below 2°C above pre-industrial levels” and further adding the goal of “pursuing efforts to limit the temperature increase to 1.5°C.”
“Our outlook shows that we could dramatically reduce overall climate risk through more ambitious and accelerated policy measures and investments aligned with meeting the Paris Agreement’s long-term 1.5 C or 2 C climate targets,” says MIT Joint Program Director of Global Change Outlook, Ronald Prinn. “Decision-makers in government, industry, and financial institutions can play a key role in moving us further along this path.
Full Document(PDF): 2021 Global Change Outloo