It is still worth fighting climate change: but catastrophic change might be inevitable

Catastrophic climate change all but unavoidable; now what?, UW study finds little chance of keeping temperature rise within 2 degrees Celsius, Seattle PI, By Stephen Cohen, August 3, 2017
Seattle is suffering through its worst heat wave of the year, but according to a recent University of Washington study, increasingly hotter temperatures — and their deadly outcomes — are all but unavoidable.

That doesn’t mean we shouldn’t take steps to try and slow down the rising thermometer.

The UW study, co-authored by statistics and sociology professor Adrian Raftery and associate professor of atmospheric sciences Dargan Frierson, concluded there is a 90 percent chance the Earth’s average temperature will rise by more than 2 degrees Celsius (about 3.6 degrees Fahrenheit) by 2100.

Limiting a rise to less than 2 degrees was one of the goals of the 2015 Paris climate agreement due to the potentially catastrophic effects of such an increase, including heat waves, extreme storms, flooding, sea level rise, etc. But the study, published on July 31 in the journal “Nature Climate Change,” found there is a less than 5 percent chance that the goal will be met, and only a 1 percent chance the increase will be limited to 1.5 degrees.

“If we’re to keep anywhere close to the 2-degree limit, we basically need to pull out all the stops on all registers over the next 80 years,” Raftery told SeattlePI. “I don’t see any alternative.”

The study used 50 years of data on three input factors — world population, gross domestic product per person and carbon intensity — to determine a range of possible outcomes. Only one of the three (carbon intensity, or the amount of carbon needed for a constant amount of economic production) is realistically subject to policy or societal influence. Carbon intensity has been decreasing at a fairly steady rate for years, and by 2100 it may have gone down by about 90 percent, but the incremental improvement doesn’t seem to be enough.

“If we’d gotten started seriously earlier — say, back when climate change was first identified as a major issue in the 1980s — then I think we could be a bit further along than we are now,” Raftery said.

You don’t have to look too far into Washington’s past to see what even a small rise in temperature might do to the state. The winter of 2014-15 featured above-average temperatures, which led to a “temperature-driven drought,” according to Jeff Marti of the Washington Department of Ecology.

The state got a normal amount of precipitation, but warmer temperatures turned what would have been mountain snowpack into rain, which washed down rivers and out into Puget Sound instead of remaining in the mountains. When temperatures rose in the spring and summer, there was little snowpack to melt into rivers and increase the volume of water while simultaneously lowering temperatures……

One reaction would be to say, ‘Too bad, we’re going to miss the 2-degree target,’ so we kind of throw up our hands and say there’s nothing we can do,” Raftery said. “But I think that’s exactly the wrong message to take away from the study. The more warming it is, the worse the consequences, and that makes it even more urgent to to take urgent action to at least limit temperature increase to be as close to 2 degrees as possible.”

Seattlepi.com reporter Stephen Cohen can be reached at 206-448-8313or stephencohen@seattlepi.com. Follow Stephen on Twitter at @scohenPI. http://www.seattlepi.com/local/environment/article/UW-Catastrophic-effects-of-climate-change-all-11731706.php