Landmark Climate Report Promises Massive Effects for Western U.S., Seattle

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A new report on global climate change published early Monday morning provides a blunt assessment of a world under stress and changing at a hastening pace.

The report, which says it's "unequivocal" that humans are warming the world at a rate not seen in the last 2,000 years, blames climate change for shrinking glaciers, fueling heat waves and making droughts more frequent.

Many of the stark take-aways in this report — the sixth time researchers have assessed the physical science of climate change for the United Nations Intergovernmental Panel on Climate Change — are now familiar.

But the numbers are more specific, the scientists are more confident and the warnings are even more direct.

"Climate change is really widespread and intensifying and many of the changes are unprecedented in thousands of years," said Kyle Armour, an associate professor and climate scientist at the University of Washington, who served as a lead author on the report. Armour added that climate change was affecting every region on Earth.

"Humans are responsible for all the warming we've seen in the last 100 years," he said.

Some of climate change's impacts can be reduced or avoided if humanity cuts its greenhouse gas emissions, the report says, but others — such as rising sea levels — will continue for centuries even if we draw net greenhouse gas emissions down to zero, the report says.

The report's implications for the Pacific Northwest are myriad, and they foretell a landscape and ecology forever shifted.

The world already has warmed by more than a degree Celsius since the 19th century. In each of the emissions scenarios the scientists considered, global temperatures reached at least 1.5 degrees Celsius higher than preindustrial times, with some projections sending them far higher.

Karin Bumbaco, the assistant state climatologist for Washington, said it was "sobering" to read that heat waves once expected every 50 years were projected to be 14 times more likely if the world warms by 2 degrees Celsius over preindustrial times.

At least 129 Washingtonians suffered heat-related deaths this summer, most of them in the wake of a record-breaking heat wave in late June.

"Heat is still on my mind," said Bumbaco, who was not part of the IPCC report process.



Bumbaco noted also that the IPCC report authors — with high confidence — projected that marine heat waves, such as the 2015 "blob" that upended marine ecosystems and killed millions of marine animals, would become more frequent.

Even if emissions are rapidly reduced, Washington's shrinking glaciers will show climate change's effects for decades.

"Even though we could potentially stabilize global climate by reducing emissions rapidly, there are some things in the climate system that are particularly slow to respond," Armour said. "The glaciers would continue to melt for decades."

Global seas are projected to rise for centuries, giving coastal communities, including those in Washington, headaches.

"Regardless of how quickly we get our emissions down, we're likely looking at ... about 6 to 12 inches of global average sea level rise through the middle of the century," said Bob Kopp, a lead author of the report and a climate scientist at Rutgers University. "But beyond 2050, sea level projections become increasingly sensitive to the emission choices we are making today."

With aggressive action, surface temperatures could rebound faster, though the science suggests it could take decades.

"If we could magically turn off greenhouse gas emissions tomorrow, we wouldn't see temperatures fall the next day," said Guillaume Mauger, of UW's Climate Impacts Group, adding that the report is clear about saying it could take 20 to 30 years to see temperatures fall. "We're going to have to plan for changes."

Some good news: Scientists still consider tipping point events that would upend the system and cause massive impacts — such as ice sheet collapse or an abrupt change to ocean circulation — unlikely. But they also can't rule out those events entirely, and the higher temperatures rise, the more possible these low-likelihood, high-consequence events become.

Armour said the world should understand by now what must be done. Emissions of heat-trapping gases must drop — rapidly, he said.

"Every fraction of a degree matters. There's no threshold or cliff edge that will take us from everything from being fine to disastrous," Armour said. "Our future is up to us."