If someone leaves the faucet running in your bathroom and the house floods, it’s easy to assign responsibility for the damage. But for other disasters – bigger, costlier and more complicated ones – the link between cause and effect isn’t as clear.
In recent years, scientists have improved methods for connecting extreme weather events, sometimes called climate disasters, to climate change. Advancements in attribution science clarify how burning fossil fuels has increased the likelihood of extreme weather occurring. These findings form the backbone of a growing list of lawsuits attempting to hold major emitters responsible for deaths and damages incurred during climate disasters.
A new University of Washington study takes this work a step further by showing that past emissions from carbon majors – the top 178 oil, gas, coal and cement producers – will continue impacting our environment for decades to come.
The results were published Sept. 23 in PLOS Climate.
“We know that fossil fuel emissions have caused a lot of warming, and we’re seeing the impacts of that, but the question is: How long does that warming last into the future?” said Dargan Frierson, a UW associate professor of atmospheric and climate science.
If greenhouse gas emissions were to plummet tomorrow, the environment would not revert to its old self. Carbon majors have emitted more than a trillion tons of carbon dioxide, a substantial portion of which will remain in the air, trapping heat, for millennia.
Even if we stop emitting, Earth will remain approximately 1.5 degrees Celsius above preindustrial temperatures.
“We expect continued warming of the climate until we stop fossil fuel emissions,” Frierson said. “The only stable future is one with no fossil fuels burned at all.”
To arrive at this conclusion, researchers simulated global climate through 2500 using the Finite Amplitude Impulse Response, or FaIR, model in both low and higher emissions scenarios, with and without emissions from carbon majors through 2024.
In a future where greenhouse gas emissions are limited, carbon majors are responsible for a larger percent of warming above preindustrial levels.
In higher emissions scenarios, where fossil fuel burning continues unabated, Earth becomes much warmer as emissions rise. In the most extreme scenario tested, future emissions cause a much larger percentage of warming than carbon majors. But the total temperature change from carbon majors is about the same.
“The amount of warming is calculable and relatively independent of future emissions,” Frierson said. “If there are legal decisions about accountability, the responsibility is not just now, it will continue for many many years into the future.”
The relationship between greenhouse gases and global warming is not new. In fact, scientists understood the risks many decades ago. Efforts to hold emitters accountable hinge on allegations that companies knew about those risks and concealed that information from the public, sometimes employing deceptive tactics to spread disinformation.
This new study shows that the gasses released by leading emitters, from both extracting and burning fossil fuels, may also be responsible for events that have not happened yet. Emissions from the past can increase the odds of a future disaster through persistent warming.
“This is important for current decisions about fossil fuels,” Frierson said. “Future fossil fuel production will exacerbate climate disasters for many decades to come, so new legal battles about who is accountable should be expected for many years.”
Lauren Henrie, a former student of Environmental Science and Resource Management at the UW, is a co-author.
