A few climate models are now predicting an unprecedented and alarming spike in temperatures — perhaps as much as 5 degrees Celsius

New projections suggest the doubling of CO₂ in the earth's atmosphere could lead to an increase in global temperatures around 5°C. Gian-Reto Tarnutzer/Unsplash

A handful of climate projections are predicting much higher rise in global temperatures than scientists have seen in the models before.
While there's concern over the number, some scientists hope the latest projections are outliers. 

A 2-degree rise in temperature could lead sea level to jump, coral reefs to die, and water to become dangerously scarce in some parts of the world. Some models right now predict a 5-degree rise.

Several recent climate models have suggested the Earth's climate could warm to a far higher temperature than scientists previously predicted, according to a report from Bloomberg.

The startling anomaly first appeared in models from the National Center for Atmospheric Research (NCAR), which suggested that if Earth's atmospheric carbon-dioxide concentration doubles (as it's expected to do by the end of the century), the planet could wind up 5.3 degrees hotter. That's 33% higher than the group's previous estimate.

About a fifth of new climate-model results published in the past year have indicated similarly stark global temperature spikes, according to Bloomberg. The UK-based Met Office Hadley Center predicted a 5.5 degrees of warming, the US Department of Energy calculated a 5.3°-degree jump, French scientists estimated a 4.9-degree increase, and a model from Canadian scientists predicted the largest rise: 5.6 degrees

Scientists hope the models are an "overshot," Bloomberg reported. It will take scientists a significant amount time – at least months – to figure out how to interpret the results.

The climate models estimate "climate sensitivity," which tells scientists how much warmer the planet will get as a result of rising CO₂ concentrations. For four decades, the expected temperature rise if CO2 levels double has been about 3 degrees.


These models have a proven track record of accurately forecasting climate change. A recent study from the American Geophysical Union found that climate projections over the past five decades have largely been accurate — actual climate observations aligned with the models' predictions.

Still, there's a hope among climate scientists that the new projections are outliers. About a dozen other models are still due to be released, Bloomberg reported, and they could help paint a clearer picture.

"We hope it's not the right answer," Klaus Wyser, a senior researcher at the Swedish Meteorological and Hydrological Institute told Bloomberg.

In the 2015 Paris climate agreement — from which President Donald Trump has started to withdraw the US —countries pledged to reduce carbon emissions in order to keep global temperatures from rising more than 2 degrees. It also established a more ambitious goal of limiting warming to 1.5 degrees, but that's likely now out of reach given that the planet has already warmed by about 1 degree.

If global temperatures rise by 2 degrees, models predict, sea levels would get 1.6 feet higher, global heatwaves would become far more common, and subtropical areas could lose a third of their supply of fresh water. Nearly all aquatic life in oceans worldwide would be impacted; 99% of coral reefs could die.

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