Reuters, Paris
The UN climate panel report released Monday on the physical science of climate change uses five possible scenarios for the future.
The scenarios are the result of complex calculations that depend on how quickly humans curb greenhouse gas emissions. But the calculations are also meant to capture socioeconomic changes in areas such as population, urban density, education, land use and wealth.
For example, a rise in population is assumed to lead to higher demand for fossil fuels and water. Education can affect the rate of technology developments. Emissions increase when land is converted from forest to agricultural land.
Each scenario is labeled to identify both the emissions level and the so-called Shared Socioeconomic Pathway, or SSP, used in those calculations.
SSP1-1.9: The IPCC's most optimistic scenario, this describes a world where global CO2 emissions are cut to net zero around 2050. Societies switch to more sustainable practices, with focus shifting from economic growth to overall well-being. Investments in education and health go up. Inequality falls. Extreme weather is more common, but the world has dodged the worst impacts of climate change.
This first scenario is the only one that meets the Paris Agreement's goal of keeping global warming to around 1.5 degrees Celsius above preindustrial temperatures, with warming hitting 1.5C but then dipping back down and stabilizing around 1.4C by the end of the century.
