Climate study suggests more severe temperature scenario

The average global temperature will likely increase between 4.1 and 8.1 degrees Fahrenheit (or between 2.3 and 4.5 degrees Celsius) if current rates of fossil fuel use and deforestation continue, The Washington Post reported Wednesday, citing a new study.

The projection in a paper published in the journal Reviews of Geophysics is narrower than that of a 1979 report, which estimated a range of between 2.7 and 8.1 degrees Fahrenheit (or 1.5 and 4.5 Celsius). The new study suggests the planet will likely not warm at the lower end of estimates.

The research indicates a 95 percent chance that if carbon dioxide output doubles, which is projected over the next 50 years, the earth would warm more than 3.6 degrees compared to preindustrial temperatures, past the point at which climatologists say effects such as major sea level rises and heat waves will occur.

Researchers noted that steep cuts to emissions in the near future could avert such a scenario, but that if carbon dioxide levels do double, the earth stands a 6 percent to 18 percent chance of increasing beyond the study’s 8.1-degree upper limit, the Post reported.

Twenty-five researchers on the four-year study analyzed data including instrument records, paleoclimate records used to assess prehistoric temperatures and satellite data.

“[I]t now appears extremely unlikely that the climate sensitivity could be low enough to avoid substantial climate change (well in excess of 2°C warming) under a high‐emissions future scenario. We remain unable to rule out that the sensitivity could be above 4.5°C per doubling of carbon dioxide levels, although this is not likely,” the study abstract states. “Continued research is needed to further reduce the uncertainty and we identify some of the more promising possibilities in this regard.”

Co-author Kate Marvel, a physicist at NASA’s Goddard Institute of Space Studies and Columbia University, told the Post “basically what we’re saying here is that there is really no evidence for any sort of natural response, any sort of big, stabilizing feedback, that in the absence of human actions, is going to save us from climate change.”

“The primary determinant of future climate is human actions,” she added.