Study behind Reno “desert” warning used now-retracted worst-case climate model

• Warnings about the desertification of Reno relied on a discredited emissions scenario the IPCC officially declared implausible.
• The study’s most dramatic projections depend on RCP8.5, which requires a five-fold increase in coal consumption by 2100.
• Over 99 percent of Earth’s land surface will remain within the same biome classification under realistic projections.
• The study excluded the well-established CO? fertilization effect that helps plants resist desertification.
• Bad science from PeerJ led to bad journalism from the Reno Gazette Journal.

A Reno Gazette Journal article warning that climate change could turn the Reno-Sparks area into desert by century’s end relies on a scientific study built from a now-retracted “worst-case” emissions scenario that the Intergovernmental Panel on Climate Change officially declared implausible in April, critics charge.

The newspaper’s alarming report drew from a PeerJ study projecting future vegetation shifts using climate models — including the discredited RCP 8.5 pathway, which the international committee responsible for IPCC climate scenarios eliminated from its new CMIP7 framework after acknowledging high-end emissions levels “have become implausible.”

Discredited scenario undercuts the study’s scariest projections

The PeerJ study modeled “potential vegetation” — what climate conditions alone might support — under several emissions scenarios. But its most dramatic projections depended on RCP 8.5, a pathway that assumed global coal use would roughly quintuple by century’s end and that world population would swell to as much as 14.5 billion by 2100 — both figures well outside what demographers and energy analysts consider plausible.

The scenario’s collapse is no small technicality. The committee that builds scenarios for the IPCC now projects that even its new highest-emissions pathway would produce roughly 1.4 degrees Celsius less warming by 2100 than RCP 8.5 predicted — a “fundamental reduction in the projected upper bound of climate risk,” according to analysis published by Climate Depot.

Roger Pielke Jr., writing in The Honest Broker, called the development “absolutely huge” for climate science. “Tens of thousands of research papers have been — and continue to be — published using these scenarios, a similar number of media headlines have amplified their findings, and governments and international organizations have built these implausible scenarios into policy and regulation,” Pielke wrote. “We now know that all of this is built on a foundation of sand.”

Study’s own caveats never made it into the newspaper

The newspaper’s coverage omitted a crucial detail: the study’s own authors concluded that more than 99 percent of Earth’s land surface would remain within the same broad biome classification under their projections, with major shifts confined to limited areas.

The researchers also left out something scientists have documented for decades: rising atmospheric carbon dioxide tends to help plants grow and use water more efficiently, an effect known as CO? fertilization. That omission cuts against the study’s alarming tone, since deserts have been shrinking, not spreading, as elevated CO? makes vegetation more resilient.

“Real forests, as opposed to those in climate models, respond to far more than temperature, rainfall, or greenhouse gas concentrations,” noted analysis published by Anthony Watts on Watts Up With That. The authors “explicitly state that they ‘acknowledge our inability to predict the future’ with certainty.”

A peer-review and press failure, not just a bad headline

Critics say the failure extends beyond the newspaper to the scientific peer-review process itself. Reviewers at PeerJ, they argue, should have pressed the authors on why they still leaned on RCP 8.5 after the IPCC itself had walked away from it.

“If RGJ had done a little independent fact checking, its reporters would have noticed that Reno’s long-term climatic temperature trend is based on one highly biased weather station located in the middle of Reno International Airport,” Watts wrote. “A recent experiment conducted at the airport proved that station reads abnormally warm, reducing Reno’s chances of becoming a desert in the future.”

Watts argued good science and good journalism share the same basic obligation: testing claims against reality before presenting them as fact. “In both cases, readers were misled. Bad science bred bad journalism,” he wrote.

The episode is a reminder that “settled science” headlines often rest on assumptions few readers ever see — and that a newsroom’s job is to check those assumptions before running with them, not after.

Sources for this article include:

WattsUpWithThat.com

AEI.org

ClimateDepot.com