Photo: Contributed Photo, Contributed
Melting ice floes in Antarctica.
Melting ice floes in Antarctica.
Photo: Contributed Photo, Contributed
PHOTOS: Before and after climate change
For thirty years, NASA has used satellite-based imagery and temperature data to study climate change.
Click through to see before and after images of climate change.
PHOTOS: Before and after climate change
For thirty years, NASA has used satellite-based imagery and temperature data to study climate change.
Click through to see before and after images of climate change.
Before: Exceptionally early ice melt, Greenland
Date: June 10, 2014
Source: NASA
Before: Exceptionally early ice melt, Greenland
Date: June 10, 2014
Source: NASA
Photo: NASA
After: Exceptionally early ice melt, Greenland
Date: June 15, 2016
Source: NASA
After: Exceptionally early ice melt, Greenland
Date: June 15, 2016
Source: NASA
Photo: NASA
Before: Arctic ice
Date: September 1984
Before: Arctic ice
Date: September 1984
Photo: NASA
After: Arctic ice
Date: September 2016
After: Arctic ice
Date: September 2016
Photo: NASA
Before: Early sea-ice breakup in Beaufort Sea, Arctic
Date: April 13, 2015
Source: NASA
Before: Early sea-ice breakup in Beaufort Sea, Arctic
Date: April 13, 2015
Source: NASA
Photo: NASA
After: Early sea-ice breakup in Beaufort Sea, Arctic
Date: April 15, 2016
Source: NASA
After: Early sea-ice breakup in Beaufort Sea, Arctic
Date: April 15, 2016
Source: NASA
Photo: NASA
Before: Lake Mead at record low
Date: May 15, 1984
Source: NASA
Before: Lake Mead at record low
Date: May 15, 1984
Source: NASA
Photo: NASA
After: Lake Mead at record low
Date: May 23, 2016
Source: NASA
After: Lake Mead at record low
Date: May 23, 2016
Source: NASA
Photo: NASA
Before: Flooding in Brazos River, Texas
Date: May 4, 2013
Source: NASA
Before: Flooding in Brazos River, Texas
Date: May 4, 2013
Source: NASA
Photo: NASA
After: Flooding in Brazos River, Texas
Date: May 28, 2016
Source: NASA
After: Flooding in Brazos River, Texas
Date: May 28, 2016
Source: NASA
Photo: NASA
Before: Shrinking glaciers along western Antarctica
Date: February 18, 1975
Source: NASA
Before: Shrinking glaciers along western Antarctica
Date: February 18, 1975
Source: NASA
Photo: NASA
After: Shrinking glaciers along western Antarctica
Date: March 2, 2015
Source: NASA
After: Shrinking glaciers along western Antarctica
Date: March 2, 2015
Source: NASA
Photo: NASA
Before: Vanishing glaciers in Glacier National Park, Montana
Date: August 17, 1984
Source: NASA
Before: Vanishing glaciers in Glacier National Park, Montana
Date: August 17, 1984
Source: NASA
Photo: NASA
After: Vanishing glaciers in Glacier National Park, Montana
Date: August 23, 2015
Source: NASA
After: Vanishing glaciers in Glacier National Park, Montana
Date: August 23, 2015
Source: NASA
Photo: NASA
Before: Imja Glacier melt, Himalayas
Date: Autumn, circa 1956
Source: NASA
Before: Imja Glacier melt, Himalayas
Date: Autumn, circa 1956
Source: NASA
Photo: NASA
After: Imja Glacier melt, Himalayas
Date: October 18, 2007
Source: NASA
After: Imja Glacier melt, Himalayas
Date: October 18, 2007
Source: NASA
Photo: NASA
Before: Shrinking Great Salt Lake, Utah
Date: November 2, 2011
Source: NASA
Before: Shrinking Great Salt Lake, Utah
Date: November 2, 2011
Source: NASA
Photo: NASA
After: Shrinking Great Salt Lake, Utah
Date: November 13, 2015
Source: NASA
After: Shrinking Great Salt Lake, Utah
Date: November 13, 2015
Source: NASA
Photo: NASA
Before: Shrinking Ellesmere Island ice caps, Canada
Date: July 12, 2004
Source: NASA
Before: Shrinking Ellesmere Island ice caps, Canada
Date: July 12, 2004
Source: NASA
Photo: NASA
After: Shrinking Ellesmere Island ice caps, Canada
Date: August 4, 2015
Source: NASA
After: Shrinking Ellesmere Island ice caps, Canada
Date: August 4, 2015
Source: NASA
Photo: NASA
Before: Pine Island Glacier calving, Antarctica
Date: October 28, 2013
Source: NASA
Before: Pine Island Glacier calving, Antarctica
Date: October 28, 2013
Source: NASA
Photo: NASA
After: Pine Island Glacier calving, Antarctica
Date: November 13, 2013
After: Pine Island Glacier calving, Antarctica
Date: November 13, 2013
Photo: NASA
Before: Shrinking Mýrdalsjökull ice cap, Iceland
Date: September 16, 1986
Source: NASA
Before: Shrinking Mýrdalsjökull ice cap, Iceland
Date: September 16, 1986
Source: NASA
Photo: NASA
After: Shrinking Mýrdalsjökull ice cap, Iceland
Date: September 20, 2014
Source: NASA
After: Shrinking Mýrdalsjökull ice cap, Iceland
Date: September 20, 2014
Source: NASA
Photo: NASA
Before: Helheim Glacier melt, Greenland
Date: May 12, 2001
Source: NASA
Before: Helheim Glacier melt, Greenland
Date: May 12, 2001
Source: NASA
Photo: NASA
After: Helheim Glacier melt, Greenland
Date: June 19, 2005
Source: NASA
After: Helheim Glacier melt, Greenland
Date: June 19, 2005
Source: NASA
Photo: NASA
Sea-level rise in California could be catastrophic, study says
A state-commissioned report on climate change released Wednesday raises the stakes for fighting global warming, offering a clearer and, in some cases, more catastrophic picture of how much sea levels will rise in California.
The Bay Area will see the ocean swell as much as 3.4 feet by 2100 if significant action isn’t taken, the report says. The scientists who produced the study pegged the prospect of that outcome at 67 percent. Tougher action on greenhouse gases would mean a lesser rise of up to 2.4 feet, the study says.
The scope of the likely rise is largely in line with earlier estimates, but not completely. One worst-case scenario says ocean levels could rise 10 feet by century’s end, which would swamp countless homes, roads, harbors and even airports along the coast.
“We have learned that the potential for a higher sea level is greater than we thought,” said Gary Griggs, a professor of Earth sciences at UC Santa Cruz and one of seven climate experts who prepared the report.
The 71-page document was requested by the California Natural Resources Agency and the California Ocean Protection Council, in collaboration with the governor’s office, to help state and local officials plan for rising seas.
The report, an update of a 2013 state analysis, lays out expected ocean levels through 2150 for a number of locations and scenarios varying with the amount of greenhouse gas emissions globally.
Last year, nearly 200 nations committed in Paris to curb greenhouse gases enough so that the Earth’s temperature wouldn’t rise more than 2 degrees Celsius. The emission targets are not binding, however, and many scientists predict that President Trump’s executive order aimed at repealing Obama administration limits on coal-fired power plant pollution will prevent the U.S. from reaching its target.
The new analysis for California is based largely on recent, better information on ice melt at the Earth’s poles.
The main drivers of rising seas to date have been melting glaciers and the expansion of water that naturally occurs as temperatures warm. However, thawing ice sheets will soon become the primary contributor, according to the state-commissioned study.
The report indicates that Greenland has enough ice to raise global sea level by 24 feet while Antarctica has enough to lift oceans 187 feet. Glaciers, meanwhile, contain only enough ice to raise seas 1.5 feet.
While these continent-size masses of ice are not expected to completely melt, even a small amount of liquefaction could have big effects, particularly for California.
Because the ocean at the poles is lifted by strong gravitational forces, when that ice thaws and water is released toward the tropics, the liquid relaxes and spreads out, according to Griggs.
“It turns out for Antarctica, the biggest impact is along the California coast,” he said.
For every foot of global sea-level rise caused by melting ice in the western Antarctic, California will see the the ocean rise about 1.25 feet, according to the report.
The report emphasizes the importance of preparing for the spike.
“California leads the way in both addressing climate change and protecting our coastal and ocean communities and resources,” Jenn Eckerle, deputy director of the Ocean Protection Council, said in a statement. “Our statewide policy on sea-level rise is another example of that leadership. We provide guidance to state agencies and local governments for incorporating sea-level rise projections into planning, permitting, investment, and other decisions.”
Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander
Rising Reality series
Read Chronicle urban design critic John King’s stories on the challenges posed by sea-level rise in the Bay Area: http://projects.sfchronicle.com/2016/sea-level-rise/