"[T]he next few decades offer a brief window of opportunity to minimize large-scale and potentially catastrophic climate change that will extend longer than the entire history of human civilization thus far. Policy decisions made during this window are likely to result in changes to Earth’s climate system measured in millennia rather than human lifespans, with associated socioeconomic and ecological impacts that will exacerbate the risks and damages to society and ecosystems that are projected for the twenty-first century and propagate into the future for many thousands of years. . . . [T]o avoid severe and persistent impacts from long-term climate change, there is a need for policies that lead to complete decarbonization of the world’s energy systems" (360-361).
Clark, Peter U., et al. “Consequences of Twenty-First-Century Policy for Multi-Millennial Climate and Sea-Level Change.” Nature Climate Change, vol. 6, no. 4, 8 Feb. 2016, pp. 360-369, doi:10.1038/nclimate2923.
"[T]he Earth System may be approaching a planetary threshold that could lock in a continuing rapid pathway toward much hotter conditions—Hothouse Earth. . . . Where such a threshold might be is uncertain, but it could be only decades ahead at a temperature rise of ∼2.0 °C above preindustrial, and thus, it could be within the range of the Paris Accord temperature targets. . . . Humanity is now facing the need for critical decisions and actions that could influence our future for centuries, if not millennia. . . . [A] deep transformation based on a fundamental reorientation of human values, equity, behavior, institutions, economies, and technologies is required" (8257-8258).
Steffen, Will, et al. "Trajectories of the Earth System in the Anthropocene." Proceedings of the National Academy of Sciences of the United States of America, vol. 115, no. 33, Aug. 2018, pp. 8252-8259, doi:10.1073/pnas.1810141115.