The New York Times discusses How Much the Planet will Warm if Carbon Dioxide Levels Double. For more than 40 years, scientists have expressed the answer as a range of possible temperature increases, between 1.5 and 4.5 degrees Celsius, that will result from carbon dioxide levels doubling from preindustrial times. Now, a team of researchers has sharply narrowed the range of temperatures, tightening it to between 2.6 and 4.1 degrees Celsius. The new paper, published on Wednesday in the journal Reviews of Geophysics, narrowed the range of temperatures considerably and shifted it toward warmer outcomes. The researchers determined that there was less than a 5 percent chance of a temperature shift below two degrees, but a 6 to 18 percent chance of a higher temperature change than 4.5 degrees Celsius, or 8.1 degrees Fahrenheit.
The Washington Post discusses how that climate study rules out less severe global warming scenarios. The current pace of human-caused carbon emissions is increasingly likely to trigger irreversible damage to the planet, according to a comprehensive international study released Wednesday. Researchers studying one of the most important and vexing topics in climate science — how sensitive the Earth’s climate is to a doubling of the amount of carbon dioxide in the atmosphere — found that warming is extremely unlikely to be on the low end of estimates.
Science Magazine discusses how, after 40 years, this study’s researchers finally see Earth’s climate destiny more clearly. It seems like such a simple question: How hot is Earth going to get? Yet for 40 years, climate scientists have repeated the same unsatisfying answer: If humans double atmospheric carbon dioxide (CO2) from preindustrial levels, the planet will eventually warm between 1.5°C and 4.5°C—a temperature range that encompasses everything from a merely troubling rise to a catastrophic one.
The Guardian discusses that study’s conclusions, that the best and worst case scenarios are less likely than thought. Uncertainty over climate outcomes reduced but experts warn urgent reduction in CO2 levels is essential. Doomsayers and hopemongers alike may need to revise their climate predictions after a study that almost rules out the most optimistic forecasts for global heating while downplaying the likelihood of worst-case scenarios. The international team of scientists involved in the research say they have narrowed the range of probable climate outcomes, which reduces the uncertainty that has long plagued public debate about this field.
The Atlantic discusses A New Solution to Climate Science’s Biggest Mystery. For the first time in 41 years, researchers have provided a new answer to one of the thorniest—and most fundamental—questions in Earth science. This week, a team of 25 researchers—drawn from across the earth sciences and descended from the Bavaria effort—published the first new answer in 41 years. Their estimate of this value, called “climate sensitivity,” significantly reduces the amount of uncertainty involved in forecasting climate change. “It helps us answer this fundamental question, which is: How warm is it gonna get?” Kate Marvel, a climate scientist at NASA and an author of the paper, told me.