Research Explainer

by Dennis Meredith, author, The Climate Pandemic: How Climate Disruption Threatens Human Survival

A multitude of headlines proclaimed the UN’s conclusion that the world is exceeding the 1.5-degree Celsius global temperature limit above preindustrial levels. Beyond that limit, global warming’s impacts will supposedly worsen considerably. However in reality, this limit is more a matter of faith than science and should be discounted as a distraction from accurate coverage of climate change.

Scientists have long preached the gospel of the One True Number; and the congregation of journalists has embraced the validity of the 1.5-degree limit. One reason for that acceptance, of course, is the supposed authority of climate scientists. But journalists may have also readily embraced it because it offers a ready news peg, a pithy headline, and a convenient shorthand to depict climate change’s impacts, albeit a misleading one. The gospel of global temperature limits implies a simple, binary climate future. That is, if we limit its rise to X degrees, we’ll be okay; if not, we’re done for.

But global temperature limits are scientifically meaningless and entirely artificial on several levels. First of all, no single number could possibly reflect the enormously complex reality of climate change. How could it possibly accurately encompass the state of ocean warming, polar ice melting, heat waves, drought, ecological disruption, or other consequences of a hotter planet?

Another telltale indicator of the faith-based nature of the 1.5-degree temperature limit is the fact that scientists chose the conveniently memorable 1.5 degrees, rather than 1.4 degrees, or 1.6 degrees, or some other number that might indicate scientific rigor.

The history of the goals of limiting global temperature rise to 2 degrees and 1.5 degrees also reveals them to be clearly faith-based, not scientific. The initial 2-degree limit did not originate from an analysis of scientific data on global temperatures, historical records, glacial melting, or ecological impacts. Rather, it was merely the global temperature rise believed to occur if atmospheric carbon dioxide level doubled.

Economist William Nordhaus proposed the 2-degree limit in the 1970s in two informal, non-peer-reviewed discussion papers. Even Nordhaus himself called such standards “extremely tentative,” “deeply unsatisfactory,” and “rough guesses.”

The Stockholm Environmental Institute recommended the 2-degree limit in a 1990 report, even while acknowledging that a temperature rise beyond 1 degree “may elicit rapid, unpredictable, and nonlinear responses that could lead to extensive ecosystem damage.” But since it was too late for society to limit the temperature rise to 1 degree, the authors of the report focused on a 2-degree upper limit.

However, as climatologist Reto Knutti and colleagues wrote in a 2015 critique, “no scientific assessment has clearly justified or defended the 2 °C target as a safe level of warming.”

The lower 1.5-degree limit, by the same token, was not chosen because it represented some safe level, but because scientists believed that the 1.5-degree limit was attainable and that the damage from global warming would be less than for a 2-degree increase. Both faith-based numbers ultimately became political numbers when they were enshrined as climate gospel in the 2015 United Nations Paris Agreement.

But responsible journalism requires not blindly accepting authorities’ pronouncements, but investigating and revealing their basis and their validity. Journalists should accept—and explain to their audiences—that the 1.5-degree measure, or any single target, is meaningless; that accuracy requires reporting the perilous, even potentially apocalyptic , reality that the impacts of climate change are relentlessly increasing. Driving this increase is the unabated production of fossil fuels, and the resulting continued rise in carbon dioxide levels. The reality is also that fossil fuels will remain indispensable because they produce the vast majority of the energy that underpins the global economy, providing food, shelter, transportation, and other necessities. Only a small percentage of energy comes from renewable sources.

Simplistically citing the breaching of some arbitrary limit should give way to in-depth reporting what scientists’ really know about the dire future of climate change. Their data and models reveal that, absent an unprecedented revolution in energy production, the current, profoundly dangerous climate trends will continue.