Global warming may be more severe than expected by 2100

OSLO (Reuters) - World temperatures could rise 15 percent more than expected this century, obliging governments to make deeper cuts in greenhouse gas emissions to limit global warming, scientists said on Wednesday.

Average surface temperatures could increase up to 0.5 degree Celsius (0.9 Fahrenheit) more than previously projected by 2100 in the most gloomy scenarios for warming, according to a study based on a review of scientific models of how the climate system works.

The extra heat would make it harder to achieve targets set by almost 200 nations in 2015 to limit a rise in temperatures to "well below" 2C (3.6F) above pre-industrial times to restrict droughts, heat waves and more powerful storms.

RELATED: Foods that could go extinct due to climate change

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Foods that could go extinct due to climate change
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Foods that could go extinct due to climate change

Avocados

There are many reasons why avocados are more expensive now than ever before, including a farmers' strike. But the biggest threats to avocados are rooted in environmental issues linked to climate change: hot weather and droughts have caused problems everywhere from California to Australia. Avocados are weather-sensitive and slow growing — making them especially susceptible to the effects of climate change. 

(Photo credit should read RONALDO SCHEMIDT/AFP/Getty Images)

Coffee

In September, a report from the nonprofit Climate Institute concluded that the area around the world fit for coffee production would decrease by 50% due to climate change. In addition to dealing with drought, climate change has made coffee crops more vulnerable to diseases like coffee rust, which have wiped out more than a billion dollars in crops. 

(Photo by Taylor Weidman/Bloomberg via Getty Images)

Beer

Warmer and more extreme weather is hurting hops production in the US, reports ClimateWatch Magazine. 

And droughts could mean less tasty drinks. Some brewers fear that a shortage of river water may force them to brew with groundwater — a change that the head brewer at Lagunitas said "would be like brewing with Alka-Seltzer," according to NPR. 

(Photo via Getty Images)

Oysters

Right now, climate change is actually helping oysters, as they grow faster in warmer waters. However, warmer waters also make oysters more susceptible to oyster drills, reports Seeker, citing a recent study in Functional Ecology

Drills are snails that attack and eat oysters. They're already a multi-million dollar problem for the oyster industry that could get worse thanks to warming water temperatures.

(Photo via Getty Images)

Maple syrup

Climate change is already shifting maple syrup tapping season and impacting the quality of syrup, according to Climate Central. Southern producers fear that eventually, areas like Virginia won't get cold enough for maple syrup production, even during the chilliest time of the year. 

(Photo via Getty Images)

Chocolate

Indonesia and Ghana, which have historically had ideal climates for growing cocoa beans, are already seeing decreased yields of cocoa. Chocolate companies, like Mars, have hired meteorologists to study the impact of changing weather patterns and attempt to reduce damage. 

"If climate conditions in these growing areas begin to change over time, it may influence both the supply and quality available of an ingredient that we use in our products," Katie Johnson, a senior manager on the commercial applied research team, told Business Insider in September. "Anticipating what the climate will be like 10, 20, or even 100 years from now is difficult, though the better we can understand what the different climate scenarios and risks to our supply chain are, the more prepared we can be in the future."

(Photo by Charlotte Lake / Alamy)

Lobsters

If ocean waters increase more than five degrees, baby lobsters may not be able to survive, according to research by the University of Maine Darling Marine Center and Bigelow Laboratory for Ocean Sciences, the Guardian reported. 

The United Nations’ Intergovernmental Panel on Climate Change has said that the Gulf of Maine will reach that temperature by 2100. In other words, Maine's lobsters could go from a more than $330 million business to extinct in 84 years. 

(Photo via Getty Images)

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"Our results suggest that achieving any given global temperature stabilization target will require steeper greenhouse gas emissions reductions than previously calculated," authors Patrick Brown and Ken Caldeira of the Carnegie Institution for Science wrote in the journal Nature.

The United Nations says that current government pledges to limit emissions are already far too weak to achieve the goals set by the 2015 Paris Agreement and put the world on track for a warming of more than 3C (5.4C).

William Collins, a professor of meteorology at the University of Reading who was not involved in Wednesday's study, called it a "step-change advance".

"We are now more certain about the future climate, but the bad news is that it will be warmer than we thought," he wrote in a comment.

The report examined existing scientific models of how the sun's energy reaches the Earth and how some bounces back into space from clouds and the planet's surface.

Such simulations, based on ever more years of satellite observations, help to understand the climate and make temperature predictions.

The models that best represent the recent climate "tend to be the models that project the most global warming over the remainder of the twenty-first century," the scientists wrote.

RELATED: A look at global warming's glacial impact

12 PHOTOS
Global warming, climate change impacting Patagonia's massive glaciers
See Gallery
Global warming, climate change impacting Patagonia's massive glaciers
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 29: Ice calves from the Northern wall of the Perito Moreno glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, on November 29, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a bluish hue due to light refraction. The Southern Patagonian Ice Field is the third largest ice field in the world. The majority of the almost 50 large glaciers in Los Glaciares National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 28: Runoff cascades from the edge of Heim glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 28, 2015 in Santa Cruz Province, Argentina. The majority of the almost fifty large glaciers in the park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 27: The Perito Moreno glacier stands in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 27, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a blueish hue due to light refraction. The majority of the almost fifty large glaciers in the park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 28: Runoff cascades from the edge of Heim glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 28, 2015 in Santa Cruz Province, Argentina. The majority of the almost fifty large glaciers in the park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 27: The Perito Moreno glacier stands in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 27, 2015 in Santa Cruz Province, Argentina. The majority of the almost fifty large glaciers in the park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 29: The Perito Moreno glacier stands in Los Glaciares National Park, part of the Southern Patagonian Ice Field, on November 29, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a bluish hue due to light refraction. The Southern Patagonian Ice Field is the third largest ice field in the world. The majority of the almost 50 large glaciers in Los Glaciares National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 28: An iceberg broken off from a melting glacier floats in Lake Argentino, which holds runoff water from the Southern Patagonian Ice Field, the third largest ice field in the world, on November 28, 2015 in Santa Cruz Province, Argentina. The majority of the almost fifty large glaciers in the surrounding Los Glaciares National Park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 29: Melting glacial ice floats in Los Glaciares National Park, part of the Southern Patagonian Ice Field, on November 29, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a bluish hue due to light refraction. The Southern Patagonian Ice Field is the third largest ice field in the world. The majority of the almost 50 large glaciers in Los Glaciares National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 28: An iceberg broken off from a melting glacier floats in Lake Argentino, which holds runoff water from the Southern Patagonian Ice Field, the third largest ice field in the world, on November 28, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a blueish hue due to light refraction. The majority of the almost fifty large glaciers in the surrounding Los Glaciares National Park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 29: Melted glacial ice floats in Los Glaciares National Park, part of the Southern Patagonian Ice Field, on November 29, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a bluish hue due to light refraction. The Southern Patagonian Ice Field is the third largest ice field in the world. The majority of the almost 50 large glaciers in Los Glaciares National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 29: The Perito Moreno glacier stands in Los Glaciares National Park, part of the Southern Patagonian Ice Field, on November 29, 2015 in Santa Cruz Province, Argentina. Certain areas of glacial ice take on a bluish hue due to light refraction. The Southern Patagonian Ice Field is the third largest ice field in the world. The majority of the almost 50 large glaciers in Los Glaciares National Park have been retreating during the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey (USGS) reports that over 68 percent of the world's freshwater supplies are locked in ice caps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
SANTA CRUZ PROVINCE, ARGENTINA - NOVEMBER 28: Runoff cascades from the edge of Heim glacier in Los Glaciares National Park, part of the Southern Patagonian Ice Field, the third largest ice field in the world, on November 28, 2015 in Santa Cruz Province, Argentina. The majority of the almost fifty large glaciers in the park have been retreating over the past fifty years due to warming temperatures, according to the European Space Agency (ESA). The United States Geological Survey reports that over 68 percent of the world's freshwater supplies are locked in icecaps and glaciers. The United Nations climate change conference begins November 30 in Paris. (Photo by Mario Tama/Getty Images)
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In one pessimistic scenario, under which greenhouse gas emissions continue to rise until 2100, temperatures could rise by 4.8C (8.6F) against 4.3C (7.7F) estimated by a U.N. panel of experts in 2014, they said.

Models are a lynchpin of the Paris accord, which seeks to re-direct trillions of dollars of investment to cleaner energy such as solar and wind power from fossil fuels.

U.S. President Donald Trump dealt a blow to the pact by saying he will withdraw and instead promote the U.S. fossil fuel industry. He doubts mainstream scientific findings that man-made emissions are the prime cause of warming.

In September, another scientific report suggested that humankind might be able to emit more greenhouse gases than expected before breaching the Paris temperature goals.

Piers Forster, a professor of climate change at the University of Leeds who was an author of that study, welcomed Wednesday's findings as a piece in a wider puzzle.

"It's important to take account of all lines of evidence," he told Reuters.

(Reporting by Alister Doyle; Editing by Hugh Lawson; Study available at: https://www.nature.com/articles/doi:10.1038/nature24672)

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