Earthquakes

Magnitude 5+ Earthquakes – Global

6.6 Earthquake hits east of Martinique, Windward Islands.

5.6 Earthquake hits New Ireland, Papua New Guinea.

5.5 Earthquake hits Minahas, Sulawesi, Indonesia.

5.4 Earthquake hits south of the Kermedec Islands.

5.0 Earthquake hits Unimak Island, Alaska.

5.0 Earthquake hits Tonga.

Global Warming

Warming from Arctic Sea Ice Melting More Dramatic than Thought

Melting Arctic sea ice has contributed considerably more to warming at the top of the world than previously predicted by climate models, according to a new analysis of 30 years of satellite observations.

Sea ice helps cool the Arctic by reflecting incoming solar radiation back into space. Because of its light colour, sea ice has what is known as high albedo, which is the percentage of solar radiation a surface reflects back to space. Dark ocean water left behind by melting sea ice, on the other hand, has a low albedo, usually measuring less than 20 percent, whereas bare sea ice generally measures between 50 and 70 percent, according to the National Snow and Ice Data Centre.

Since as early as the 1960s, scientists have hypothesized that melting sea ice amplifies global warming by decreasing Arctic albedo. Researchers have since devised climate models to demonstrate this phenomenon but, until now, nobody had relied entirely on satellite data to confirm this effect through time.

Now, scientists based at the University of California, San Diego have analyzed Arctic satellite data from 1979 to 2011, and have found that average Arctic albedo levels have decreased from 52 percent to 48 percent since 1979 — twice as much as previous studies based on models have suggested, the team reports today (Feb. 17) in the journal Proceedings of the National Academy of Sciences.

The amount of heat generated by this decrease in albedo is equivalent to roughly 25 percent of the average global warming currently occurring due to increased carbon dioxide levels, the team reports.

“Although more work is needed, a possible implication of this is that the amplifying feedback of Arctic sea ice retreat on global warming is larger than has been previously expected,” study co-author Ian Eisenman told Live Science.

Previous models of Arctic albedo have suggested the reflectiveness of white cloud cover could potentially mitigate a portion of albedo loss due to melting ice; but these new observations show that cloud cover has had a negligible effect on overall Arctic reflectivity, the team says.

While Arctic sea ice will not likely return to 1979 values in the near future, the ice does change from year to year and might still experience some comeback this century, though the extent to which this might happen remains unclear, Eisenman said.

“There are a lot of questions right now as to why the ice is retreating as fast as it is, and why it has the structure that it has is a little hard to say,” said Eisenman. “The cause and effects get subtle — ocean currents respond to sea ice and sea ice responds to currents.”

The team is now following up this work by studying how the deposition of black carbon — a component of soot — on Arctic ice and snow may be darkening these reflective surfaces and contributing to the decrease in albedo. If this does turn out to be a significant factor in albedo, it could explain the underestimations of previous models that didn’t account for black carbon, Eisenman said.

Melt pond 121129

Disease

Human infection with avian influenza A(H7N9) virus – update

On 14, 15 and 16 February 2014, the National Health and Family Planning Commission (NHFPC) of China notified WHO of nine additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus, including one death.

Volcanos

Roundup of Global Volcanic Activity:

Kelud (East Java): Activity has calmed down at the volcano. The new VSI webcam shows the outer crater area covered with heavy ash deposits and only a small steam plume from the crater. The SO2 aerosol plume from the eruption is still well visible in the atmosphere on satellite data.

Fuego (Guatemala): Activity has been elevated yesterday, with more frequent moderate and strong explosions accompanied by rumbling degassing sounds and shock waves that could be noticed in up to 20-25 km distance. Ash plumes rose to 500-700 m. The observatory warns that another stronger eruptive phase could occur in the next days or weeks. The current seismic signal suggests, however, that the activity has been decreasing again.

Tungurahua (Ecuador): After the major eruptions on 1 Feb, the volcano continued to produce frequent (comparably) smaller explosions of strombolian to vulcanian type, sometime causing small pyroclastic flows. Ash falls have been mainly affecting areas in Penipe, south of the volcano. During the past days, activity has been decreasing overall. IGP reports an earthquake swarm on 10 Feb, when a series of volcanic-tectonic quakes occurred under the northwestern flank of the volcano between Pondoa and Juive Grande. The earthquakes were at depths between 10 and 11 km below the crater and measured up to magnitude of 3.0 on the Richter scale. The largest were widely felt in villages around the volcano.