Two prominent climate scientists who adhere to United Nations climate assessments are scolding the media and alarmist scientists for claiming worst-case scenarios are the most likely climate outcome. In a January 29 commentary ( published in the peer-reviewed science journal Nature, Zeke Hausfather of Berkeley Earth and Glen Peters of the Center for International Climate Research explained that worst-case scenarios, typically presented as the default likely future climate, are extremely unlikely.

“Happily — and that’s a word we climatologists rarely get to use — the world imagined in RCP8.5 [the “business as usual” scenario of substantially increasing emissions and negative impacts] is one that, in our view, becomes increasingly implausible with every passing year,” the scientists wrote.

“A sizeable portion of the literature on climate impacts refers to RCP8.5 as business as usual, implying that it is probable in the absence of stringent climate mitigation,” the scientists explained. “The media then often amplifies this message, sometimes without communicating the nuances. This results in further confusion regarding probable emissions outcomes, because many climate researchers are not familiar with the details of these scenarios in the energy-modelling literature.”

The scientists emphasized that the United Nations Intergovernmental Panel on Climate Change (IPCC) scenarios of weak or modest emissions mitigation – rather than no emissions mitigation or strong mitigation – are most likely. The scientists noted the weak or modest mitigation scenarios project a temperature increase of 2.5-to-3.0 degrees above pre-industrial levels in 2100, versus the worst-case 5.0-degree increase frequently presented by activists and the media.

“We must all — from physical scientists and climate-impact modelers to communicators and policymakers — stop presenting the worst-case scenario as the most likely one,” the scientists wrote. “Overstating the likelihood of extreme climate impacts can make mitigation seem harder than it actually is.”

With a general belief existing that temperatures are currently about 1 degree Celsius warmer than was the case during the depths of the Little Ice Age prior to the Industrial Revolution, the two scientists believe the Earth is on pace for approximately 1.5 to 2.0 degrees Celsius warming during the next 80 years. Temperature measurements from NASA satellites ( show warming of merely at a pace of 0.13 degrees Celsius per decade during the past 40 years, suggesting that unless something changes, we can expect merely 1.0 degrees warming as the most likely scenario during the next 80 years.

Interestingly, Scientific American published an article about the two scientists’ findings and titled it, “The Worst Climate Scenarios May No Longer Be the Most Likely.” As if the worst climate scenario ever was the most likely….


  • CFACT Ed

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