There's Only 5 Percent Chance Earth Can Stay Below 'Tipping Point' by 2100, Researchers Say

Pam Wright
Published: August 1, 2017

By the turn of the century, the earth is very likely to exceed the 2 degrees Celsius threshold viewed by many scientists as the "tipping point" that should be avoided at all costs and was set by the landmark Paris Climate Accord, a pair of studies says.

According to research published Monday in Nature Climate Change, the Earth is already headed on a trajectory that will likely surpass the goals set by the Paris Agreement, which calls for a reduction in greenhouse gas emissions to keep rising global temperatures below the 2 degree Celsius threshold.

Some researchers now say it's a little too late to do much about it, even with the good intentions of all but three countries committed to reducing CO2. In fact, researchers say there is only a 5 percent chance that we will avoid going over the 2C threshold and only a 1 percent chance temperatures could be kept below a 1.5-degree Celsius increase by 2100.

“Our analysis shows that the goal of 2 degrees is very much a best-case scenario,” said lead author Adrian Raftery, a University of Washington professor of statistics and sociology. “It is achievable, but only with major, sustained effort on all fronts over the next 80 years.”

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The 2 degree Celsius (3.6 degrees Fahrenheit) threshold, first conceived by Yale economist William Nordhouse in 1977, is considered the point when the planet as we know it will no longer exist as rising seas, weather anomalies, strengthened hurricanes, fewer crops and extended droughts become the norm. 

Using statistical analysis, the team of researchers determined that the rise will most likely be between 2.0 and 4.9 degrees Celcius by the turn of the century.

"Our median forecast is 3.2 C,"  Raftery said. "Our model is based on data which already show the effect of existing emission mitigation policies. Achieving the goal of less than 1.5 C warming will require carbon intensity to decline much faster than in the recent past."

Like other studies, the researchers took data from the Intergovernmental Panel on Climate Change and used model scenarios based on economics, population and carbon emissions to project what might happen in the future. 

Surprisingly, Raftery and his fellow researchers determined that population is not relevant to the outcome of the study's findings. 

"This is due to the fact that much of the expected future population growth will be in Africa, in countries whose carbon emissions are currently very low," Raftery said.

A Similar Conculsion

Researchers for a separate study published Monday in Nature came to a similar conclusion.

The scientists for this study analyzed past emissions of greenhouse gasses in conjunction with the burning of fossil fuels and determined that even if humans stopped burning fossil fuels, Earth would still reach and even surpass the 2C threshold by 2100. They also found that should emissions continue another 15 years, the rise in global temperature could rise to as much as 3 degrees above pre-industrial levels.

"Even if we would stop burning fossil fuels today, then the Earth would continue to warm slowly," Thorsten Mauritsen, author of the second study, told CNN. "It is this committed warming that we estimate."

Scientists notee that if emissions were to cease, human-caused aerosols would be washed out of the atmosphere in a matter of weeks, but human-caused CO2 would persist and not decrease for centuries or even millennia. 

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