There's still hope to offset climate change impact, but it will be costly and formidable

There is still time to blunt the most dangerous effects of climate change, experts say.

But that time is running out.

To get a better understanding of the challenge the world faces, the Courier-Journal spoke with several climate experts. One of them was Scott Denning, a professor of atmospheric science at Colorado State University, who has dozens of peer-reviewed climate-related publications under his belt. It comes down to making a calculation after answering a basic question: How much climate change can we tolerate?

The simple answer is a temperature rise of about 3.6 degrees Fahrenheit, or 2 degrees Celsius above pre-industrial levels. To do that, carbon dioxide concentrations will likely need to stay below 450 parts per million — and we may be within about 20 years of hitting that mark, according to Denning.

Policymakers representing more than 190 nations in a 2015 agreement in Paris settled on that amount of change. We’ve already seen a 1.4 degree Fahrenheit, or a 0.8 degree Celsius, increase since about 1880.

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"It takes quite a lot of effort to reduce the coal, oil and gas we burn, particularly because China, India and Africa after that are super hungry to burn more and more," Denning said. "You have billions of people who don't have any electricity, don't have any running water, don't have toilets, don't have enough food and they want to ramp up their economies.

"That's where the sense of urgency comes from," he said.

Can we fix it?

Experts say that answer is yes, citing as a start, that 2015 Paris agreement.

What's needed to fix it?

The world needs to provide a huge amount of abundant, cleaner energy that will enable billions of people to escape dire poverty without permanently warming climate to catastrophic levels, Denning said.

"Doing this will require rapid progress on energy efficiency, phasing out all fossil fuel emissions in the next few decades, and maybe someday scrubbing the excess CO2 out of the atmosphere," he added.

A lot of research has also explored how to economically capture carbon dioxide emissions from coal-burning power plants and store it permanently deep underground.

Then-President Barack Obama took on the challenge by boosting renewable sources of energy, cutting back on emissions from coal-fired power plants under his Clean Power Plan and increasing fuel efficiency in cars and trucks. The Paris agreement was a high mark for the former president who sought to make climate change a signature issue.

"There was a lot of celebration around the Paris agreement," said David Konisky, who studies and teaches politics and policy at the Indiana University School of Public and Environmental Affairs. For the first time so many countries from around the world, including China and India, were making climate commitments, he said. "It was a real watershed moment."

But the agreement has its limits.

And one of them is that it relies on voluntary action, including "goodwill and political pressure," he said.

"The worry is if the United States formally withdraws from Paris or expresses its intent to not reach the targets, that could make other countries do the same," Konisky cautioned.

Enter President Donald Trump, who has called climate change a "hoax" and as a candidate called for "canceling" the Paris agreement.

Political leaders in Kentucky and Indiana were supportive of Trump's recent executive order to begin unraveling the Clean Power Plan, which sought to cut by nearly a third the greenhouse gas emissions from power plants — or about as much as taking 70 percent of the nation’s passenger vehicles off the roads.

"This order demonstrates a more common sense approach to the role that our abundant fossil fuel resources can play in our nation’s energy portfolio," Gov. Matt Bevin said in a written statement.

Sen. Mitch McConnell called the Clean Power Plan part of an Obama "war on coal" and Kentucky miners.

What comes next?

Trump administration could do great damage to efforts to curb greenhouse gasses but it won't be automatic, said Robert Stavins, a professor of business and government at Harvard University's John F. Kennedy School of Government.

Rolling back the Clean Power Plan "could take four years to sort out," with arduous rulemaking procedures followed by lawsuits, he said.

Greenhouse gas emissions in the United States have been falling and will likely continue to drop because of cheap, cleaner-burning natural gas that has been biting into coal demand, and technology improvements, he said. Popular tax credits on wind and solar power won't likely vanish quickly, he added.

States like California, Washington and others that voted Democratic in the last election, totaling about half the population and 40 percent of the emissions, "will become more aggressive" when it comes to fighting climate change, not less, he predicted.

"Private industry, unlike some politicians, doesn't operate on ideology" and will continue making efforts to be ready for climate change, Stavins said.

But it could be a while before Congress and a president muster the political will to put a price on carbon, he said.

Can we change the atmosphere or fiddle with the Earth in other ways?

Two years ago, a National Research Council committee determined that there is no substitute for dramatic reductions in greenhouse gas emissions to offset climate change, and that strategies to remove carbon dioxide from the atmosphere were too costly or not yet ready for deployment.

Seeding the oceans with iron to boost their ability to absorb carbon dioxide could cause risky changes in ocean ecology.

Filling the atmosphere with other kinds of particles could reflect solar radiation back into space, much like big volcanic eruptions do naturally. But that would bring an array of environmental, social, legal, economic, ethical and political risks, according to the report.

It would be so cheap, though, that Denning said one could imagine island nations facing inundation from rising seas "trying to tinker with this against the will of big countries like us."

But doing that could also severely harm the Earth's ozone layer that protects people from getting skin cancer, and it wouldn't stop all the extra carbon dioxide from getting into the ocean, making it dangerously more acidic to the peril of sea life.

A lot of people would likely object to such manipulations, said Brenda Ekwurzel, senior climate scientist with the Union of Concerned Scientists.

"You'd have to spew stuff into the atmosphere every couple of years," she said. "There could be all sorts of health problems, even mental health issues that could be attributed to what they would be doing to the atmosphere."

Others are looking into ways to vacuum carbon dioxide out of the air and inject it deep into the ground for permanent storage. But those techniques may be even more expensive than the cost of replacing high-carbon fossil fuels with low-carbon energy such as solar or wind power.

Is there any hope?

Several experts with the Global Carbon Project made up of scientists and think tanks last November published an article in The Conversation, observing that for the third year in a row, global carbon dioxide emissions from fossil fuels and industry barely grew.

"What makes the three-year trend most remarkable is the fact that the global economy grew at more than 3 percent per year during this time," they wrote, "Previously, falling emissions were driven by stagnant or shrinking economies, such as during the global financial crisis of 2008."

Will we overshoot our temperature goal?

Almost certainly, Denning said. "You just keep after it until it's under control."

It's not too big of a problem, he said. People have done "unbelievably huge things"  that cost a lot of money and effort, including constructing an interstate highway system, building the internet, electrifying rural America, and fighting and beating the Nazis in World War II.

"The magnitude of effort required to build non-carbon electricity and smart grids and (electricity) storage for all these buildings is not a whole harder than all those other things," Denning said.

"We have to do, because of we don’t do it, we will permanently turn up the thermostat on the Earth for thousands of years to a level that will melt the ice sheets eventually and flood all the coasts of the world, and in the meantime, destroy the world economy," he said. "The consequences of not doing this are so much worse."

Reach reporter James Bruggers at 502-582-4645 and at jbruggers@courier-journal.com.

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