Saturday, August 5, 2017

Duck and cover. Climate catastrophe now probably inevitable

The climate chickens are coming home to roost, and the news for farmers, coastal cities, wildlife, people who don’t live in high-elevation bunkers and humans who drink water—they are now likely to be disastrous.

And that’s the best case scenario, according to a new study in Nature Climate Change.

The scary thing about changing climate is how intertwined it is with everything in our lives. As the Hawai`i Climate Adaptation logo suggest, Pili na mea a pau: All things are related.

The only way to avoid it being even worse is with herculean effort. Far more effort than is now being engaged. And nobody’s likely to be putting out that kind of effort—especially not our country, which just walked away from the Paris climate accords.

The latest predictions of climate warming suggest that by the end of this century, there’s a 90 percent chance the earth will be significantly hotter than the disastrous 2 degree rise that folks have been predicting.

There’s a small chance that it will stay as low as 2-degree rise, and a small chance of as much as a 5-degree rise. The median rise is now estimated to be 3.2 degrees, according to authors of a new paper in Nature Climate Change.

We are already so far down the climate change turnpike that even really strong measures would only keep the warming to 2 degrees, said the paper’s lead author, Adrian Raftery, a University of Washington statistician.

"Our analysis shows that the goal of 2 degrees is very much a best-case scenario. It is achievable, but only with major, sustained effort on all fronts over the next 80 years," he said in a Eurekalert article.

Scientists have long known it could be that bad, but the International Panel on Climate Change and others have downplayed the worst case scenarios, in part because they are so horrific as to be easily rejected. Imagine cities under water. Farmlands poisoned by saltwater intrusion. Coastal resorts washed away. Flooding in dry areas and drought in our breadbaskets. Storms. Massive wildlife losses.

“Damages from heat extremes, drought, extreme weather and sea level rise will be much more severe if 2 degrees C or higher temperature rise is allowed. Our results show that an abrupt change of course is needed to achieve these goals." said one of the paper’s co-authors, Dargan Frierson, a University of Washington associate professor of atmospheric sciences.

The study was a detailed review of climate data, country by country.

"This is a high-tech statistical model that looks at what has happened to per-capita output in each country, to carbon intensity in each country, and to population in each country. What we find is that there is a wide range of what could happen, but unfortunately the bottom end of the range is still fairly bad, and the top end of the range is catastrophic," said another of the paper’s co-authors, University of California at Santa Barbara economist Dick Startz.

"Our predictions assume that carbon intensity is going to continue to trend downward, as it has been. That still leaves us in a mess. The only thing that is going to get us out of it is finding a way to make carbon intensity fall much more quickly than it has been," Startz said.

He said it is difficult but possible to envision a global initiative that could keep the temperature rise within some limits, using major advances in energy technology, but he’s not hopeful. Carbon intensity as been declining, but not nearly fast enough to make a significant impact.

"We can hope for some magic breakthrough or we can do the unpleasant task of charging more when we're polluting. But even that might not be enough," Startz said.

California already has a sense of how bad it could be in terms of sea level rise, as the state earlier this year released a major report on the subject. It’s available here.

California, as Hawai`i is, is already seeing some of the early effects, the report said: 

“Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding, and increased coastal erosion.”

Much of the sea level change in recent decades has been from thermal expansion of ocean water, glacier melting and ice cap melting. But the planet is moving into a new phase in which there is melting of the massive ice sheets of Greenland and Antarctica.

California’s take on the most likely sea level rise by 2100 without significant mitigation? That would be 1.6 to 3.4 feet.

Worst case? Ten feet.

Hawai`i's efforts to understand the local impacts of climate and related changes are being overseen by the state's Interagency Climate Adaptation Committee, which has a website here

© Jan TenBruggencate 2017

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