July 09, 2019 by Julia Conley, staff writer, Common Dreams
“Once we’re over the threshold…you’re dealing with how the Earth works, and it goes on its own ride.”
The Atlantic coast near Galicia, Spain. A study by an MIT researcher warns that humans are pumping carbon into the world’s oceans at a rate that could trigger a mass extinction event. (Photo: Paulo Brandao/flickr/cc)
The continuous accumulation of carbon dioxide in the planet’s oceans—which shows no sign of stopping due to humanity’s relentless consumption of fossil fuels—is likely to trigger a chemical reaction in Earth’s carbon cycle similar to those which happened just before mass extinction events, according to a new study.
MIT geophysics professor Daniel Rothman released new data on Monday showing that carbon levels today could be fast approaching a tipping point threshold that could trigger extreme ocean acidification similar to the kind that contributed to the Permian–Triassic mass extinction that occurred about 250 million years ago.
Rothman’s new research comes two years after he predicted that a mass extinction event could take place at the end of this century. Since 2017, he has been working to understand how life on Earth might be wiped out due to increased carbon in the oceans.
“If we push the Earth system too far, then it takes over and determines its own response—past that point there will be little we can do about it.”
—Timothy Lenton, University of Exeter
Rothman created a model in which he simulated adding carbon dioxide to oceans, finding that when the gas was added to an already-stable marine environment, only temporary acidification occurred.
When he continuously pumped carbon into the oceans, however, as humans have been doing at greater and greater levels since the late 18th century, the ocean model eventually reached a threshold which triggered what MIT called “a cascade of chemical feedbacks,” or “excitation,” causing extreme acidification and worsening the warming effects of the originally-added carbon.
Over the past 540 million years, these chemical feedbacks have occurred at various times, Rothman noted. But the most significant occurances took place around the time of four out of the five mass extinction events—and today’s oceans are absorbing carbon far more quickly than they did before the Permian–Triassic extinction, in which 90 percent of life on Earth died out.
The planet may now be “at the precipice of excitation,” Rothman told MIT News.On social media, one critic called the study’s implications about life on Earth “completely terrifying.”
The study, which was completed with support from NASA and the National Science Foundation, also notes that even though humans have only been pumping carbon into the oceans for hundreds of years rather than the thousands of years it took for volcanic eruptions and other events to bring about other extinctions, the result will likely be the same.
“Once we’re over the threshold, how we got there may not matter,” Rothman told MIT News. “Once you get over it, you’re dealing with how the Earth works, and it goes on its own ride.”
Other scientists said the study, which will be published this week in the Proceedings of the National Academy of Sciences, represents a clear call for immediate action to drastically reduce the amount of carbon that is being pumped into the world’s oceans. Climate action groups and grassroots movements have long called on governments to impose a moratorium on fossil fuel drilling, which pumps about a billion metric tons of carbon into the atmosphere every year.
“We already know that our CO2-emitting actions will have consequences for many millennia,” says Timothy Lenton, a professor of climate change and earth systems science at the University of Exeter. “This study suggests those consequences could be much more dramatic than previously expected.”
“If we push the Earth system too far,” Lenton added, “then it takes over and determines its own response—past that point there will be little we can do about it.”
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July 09, 2019 byJessica Corbett, Common Dreams
West Antarctica’s massive Thwaites Glacier is often called “one of the world’s most dangerous glaciers” because of its potential contributions to sea level rise. (Photo: James Yungel/NASA)
New NASA-funded research warns that because of human-caused global heating, West Antarctica’s massive Thwaites Glacier is at risk of reaching a tipping point that could raise the global sea level by about 20 inches.
“After reaching the tipping point, Thwaites Glacier could lose all of its ice in a period of 150 years. That would make for a sea level rise of about half a meter (1.64 feet).”—Hélène Seroussi, NASA
The study, published Monday in the journal the Proceedings of the National Academy of Sciences, was conducted by researchers at the Georgia Institute of Technology, NASA Jet Propulsion Laboratory, and the University of Washington.
Though this team focused on the Thwaites Glacier—which is about the size of Florida or Britain—the report follows several others that have raised alarm about how rapidly ice is disappearing in Antarctica, including one study from May which found that the continent’s ice sheets are thinning five times faster than they were in the 1990s.
In a statement Monday, Georgia Tech explained that researchers found “instability hidden within Antarctic ice is likely to accelerate its flow into the ocean and push sea level up at a more rapid pace than previously expected.”
In the last six years, five closely observed Antarctic glaciers have doubled their rate of ice loss, according to the National Science Foundation. At least one, Thwaites Glacier, modeled for the new study, may be in danger of succumbing to this instability, a volatile process that pushes ice into the ocean fast.
The Thwaites Glacier is often called “one of the world’s most dangerous glaciers” because of its potential contributions to sea level rise. As Common Dreams reported in January, NASA scientists recently discovered a 1,000-foot deep cavity in the glacier large enough to have held about 14 billion tons of ice before it melted, which heightened concerns about the glacier’s future.
Researchers behind the new study weren’t able to project exactly how much ice the Thwaites Glacier will lose in the next 50 to 800 years, “due to unpredictable fluctuations in climate and the need for more data,” but they factored the instability into 500 ice flow simulations for the glacier, which “together pointed to the eventual triggering of the instability,” according to the Georgia Tech statement.
“If you trigger this instability, you don’t need to continue to force the ice sheet by cranking up temperatures. It will keep going by itself, and that’s the worry,” said lead author Alex Robel, an assistant professor in Georgia Tech’s School of Earth and Atmospheric Sciences. However, he added, “climate variations will still be important after that tipping point because they will determine how fast the ice will move.”
The simulations spanned several centuries, as is common for studies on sea level rise. The models suggested that the glacier could reach the tipping point “in the next 200 to 600 years,” said co-author and NASA scientist Hélène Seroussi. “It depends on the bedrock topography under the ice, and we don’t know it in great detail yet.”
“There’s almost eight times as much ice in the Antarctic ice sheet as there is in the Greenland ice sheet and 50 times as much as in all the mountain glaciers in the world.”
—Alex Robel, Georgia Tech
“After reaching the tipping point, Thwaites Glacier could lose all of its ice in a period of 150 years,” Seroussi said. “That would make for a sea level rise of about half a meter (1.64 feet).”
Experts have also raised alarm about how quickly ice is melting in Greenland and the Arctic, but Antarctica is of particular concern because, as Robel pointed, “there’s almost eight times as much ice in the Antarctic ice sheet as there is in the Greenland ice sheet and 50 times as much as in all the mountain glaciers in the world.”
While the researchers acknowledged the need for further study, they also emphasized the importance of preparing for rising seas—which increasingly endanger island nations and coastal communities.
“You want to engineer critical infrastructure to be resistant against the upper bound of potential sea level scenarios a hundred years from now,” said Robel. “It can mean building your water treatment plants and nuclear reactors for the absolute worst-case scenario, which could be two or three feet of sea level rise from Thwaites Glacier alone, so it’s a huge difference.”
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EIA – How much of U.S. carbon dioxide emissions are associated with electricity generation?
In 2018, emissions of carbon dioxide (CO2) by the U.S. electric power sector were 1,763 million metric tons (MMmt), or about 33% of total U.S. energy-related CO2 emissions of 5,268 (MMmt).1
CO2 emissions by U.S. electric power sector by source, 2018
| Source | Million metric tons | Share of sector total |
| Coal | 1,150 | 65% |
| Natural gas | 581 | 33% |
| Petroleum | 21 | 1% |
| Other2 | 11 | <1% |
| Total | 1,763 |
1 Preliminary data.
2 Includes CO2 emissions from the combustion of miscellaneous waste materials made from fossil fuels and by some types of geothermal power generation.
Learn more:
Monthly Energy Review, Tables 12.1 and 12.6 contain the most recent estimates of monthly and annual U.S. energy-related CO2 emissions, total and by the electric power sector.
Energy Explained: Energy and the Environment–Greenhouse gases
Energy Explained: Where Greenhouse Gases Come From
- Does EIA have projections for energy production, consumption, and prices for individual states?
- How do I convert between short tons and metric tons?
- How does the hole in the ozone layer affect global warming?
- How much carbon dioxide is produced from U.S. gasoline and diesel fuel consumption?
- How much carbon dioxide is produced per kilowatthour of U.S. electricity generation?
- How much carbon dioxide is produced when different fuels are burned?
- Why do carbon dioxide emissions weigh more than the original fuel?
- How much of U.S. carbon dioxide emissions are associated with electricity generation?
- What are U.S. energy-related carbon dioxide emissions by source and sector?
- What are greenhouse gases and how do they affect the climate?
- What are the energy-related carbon dioxide emissions from fossil fuels for the United States and the world?
- What are the greenhouse gas and air pollutant emissions factors for fuels and electricity?
