Global sea-level rise measurements are currently meeting or exceeding the high end of the 2007 IPCC projected rises and new research by a University of Colorado geologist has a likely explanation, according to a story by The Geological Society of America.
"What's missing from the models used to forecast sea-level rise are critical feedbacks that speed everything up," says Bill Hay.
One surprising feedback is Arctic sea ice. Melting sea ice in itself does not raise the sea-level, similar to ice in a drink. However, the reduction of sea ice in the Arctic is playing a key role in the warming of the Arctic, which in turn leads to ice losses in nearby Greenland and over the land areas of northern Canada. Also, when the sea ice melts it reduces the amount of fresh water in the Arctic as more brinier, warmer water mixes in from the south. This process is not in any of the models, according to Hay.
The record low sea ice extent in the Arctic this year.
Then there are those gigantic stores of ice in Greenland and Antarctica. During the last interglacial period, sea level rose 10 meters due to the melting of all that ice -- without any help from humans. New data suggests that the sea-level rise in the oceans took place over a few centuries, not thousands of years, according to Hay. (via The Geological Society of America)
Greenland had a record-setting melt this past summer.
Another positive feedback is the amount of groundwater being mined across the world in order to ease drought. That water eventually gets added to the oceans as shown by a recent visualization by NASA's Earth Observatory.
In closing from The Geological Society of America article.....
"You would expect negative feedbacks to creep in at some point," says Hay. "But in climate change, every feedback seems to go positive." The reason is that Earth's climate seems to have certain stable states. Between those states things are unstable and can change quickly. "Under human prodding, the system wants to go into a new climate state."
Arctic sea ice clearly getting younger and thinner.
Hard to believe if you live in North America, but November 2013 was the warmest November on record globally.
Frequent logging and deforestation in high latitude regions where snowfall is common and timber activity is low may actually provide better climatic benefits...
A particular climate geoengineering effort to reduce the amount of sunlight might not work out.....
Understanding the climate model.
A look at the model projected long-term changes in global temperatures and precipitation based on a combination of four greenhouse gas emission scenarios.