Pacific Coral Changed Rapidly After 1850
A mysterious change in the food web of the Pacific Ocean started in the mid-19th century, and the skeletons of deep-sea coral tell the tale. Continue reading →
A mysterious change in the food web of the Pacific Ocean started in the mid-19th century, and the skeletons of deep-sea coral tell the tale.
Hundreds, even thousands, of feet beneath the ocean surface, deep sea corals live for centuries. As the grow, the tiny creatures collect a chemical record of what they eat. Marine scientists recently constructed a 1,000 year-long history of North Pacific corals' cuisine by analyzing the nitrogen trapped in the coral skeletons.
The changing levels of different types of nitrogen, called isotopes, revealed information about the conditions in the ecosystem of the North Pacific subtropical gyre, a 20 million square kilometer counterclockwise circulation of the ocean's waters.
For most of the past millennium, the nitrogen in the Pacific Ocean food chain came from dissolved nitrate rising from deeper in the sea. However, abruptly 150 years ago, the coral recorded a dramatic change in the source of nitrogen entering the marine food chain. Since approximately 1850, more of the chemical has been coming from microorganisms that transform nitrogen, similarly to how beans and other legumes fix nitrogen on land. Since approximately 1850, the increase in nitrogen from microorganisms increased by 17 to 27 percent.
"In comparison to other transitions in the paleoceanographic record, it's gigantic," said lead author Owen Sherwood of the University of Colorado, Boulder, in a press release. The study was published Dec. 15 in the journal Nature.
The cause of the food chain change may have to do with an expansion and warming of the North Pacific subtropical gyre itself. Marine scientists have also observed the gyre changing again over the past few decades.
"Our new records from deep-sea corals now show that the decadal-scale changes are really only small oscillations superimposed on a dramatic long-term shift at the base of the Pacific ecosystem," study co-author Matthew McCarthy of the University of California at Santa Cruz said in a press release. "This long-term perspective may help us better predict the effects of global warming on open ocean regions."
IMAGE: A rockfish hides in a deep sea coral, Primnoa pacifica, in Juan Perez Sound in Haida Gwaii, British Columbia (Geofflos, Wikimedia Commons)
The face of the Earth changed dramatically in 2013. Natural disasters, war and other human activities left geographic scars that Landsat satellites viewed from their orbits. The Landsat program uses National Aeronautic and Space Administration satellite images to monitor the Earth from space with assistance from the U.S. Geological Survey.
On Nov. 8, 2013, Typhoon Haiyan scourged the Philippines. On the island of Leyte, 315 kilometer- (195 mile-) per-hour winds and a deadly storm surge devastated Talcoban City. NASA's False-color images show the extent of the destruction. In this image from 2004, vegetation shows up as red, urban areas are white and silver and bare ground is tan. Cloud shadows and water appear black.
The typhoon seems to have stripped the vegetation from the hills west of the Talcoban City, although some of this may have resulted from deforestation, noted
. The southeast coast lost even more vegetation, along with buildings. The area near the airport appears to have suffered intense damage. Black patch mark where water left by the storm surge formed pools. Parts of the downtown area appear smudged, which may result from the rubble and debris scattered around the city.
In Jordan, a city now appears where there was only desert in 2009. That city, the Zaatari refugee camp (shown here in a
image from July of 2013), is the the size of Fargo, North Dakota, and exemplifies the human suffering caused by the Syrian civil war. The camp opened in 2012 and grew to become Jordan's fourth largest city with approximately 115,000 people by December 2013, according to the
Back in May of 2009, the site of the Zaatari refugee camp (shown here) held only arid scrub land on the border between Jordan and Syria. The humanitarian crisis caused by the conflict in Syria continues to grow worse, Valerie Amos, under secretary general and emergency relief coordinator for the U.N. Security Council, told journalists on December 3, reported the
While a typhoon may have caused much of the vegetation loss in and around Tacloban, the loss of rainforest in the Peruvian Amazon (shown here) bore the signature of human activity. In July 2013, Clinton Jenkins, remote sensing scientist at North Carolina State University, received a tip about deforestation near Tamshiyacu in northeastern Peru, reported
. Landsat satellite imagery proved that approximately 100 hectares (247 acres) of forest had been cleared per week. The total deforestation equaled at least 1000 hectares (3.86 square miles).
Landsat images from 2012 show intact forest in the region. Jenkins estimated that approximately 300,000 tons of trees and other biomass were cut down. That loss of forest equated to the emission of 150,000 tons of carbon dioxide. "Landsat imagery is essential for environmental monitoring because it is free, easy to access, and quickly available after the satellite passes over an area," Jenkins told NASA. "Satellites are the only way to monitor these areas because they are so large and so difficult to access."
On June 11, 2013, the
started in a suburb of Colorado Springs, Colorado. The blaze torched 486 homes by the time firefighters contained the inferno nine days later, reported
. A drought that started in 2012 contributed to the intensity of the fire. A heat wave also gripped the area, which resulted in parched trees prone to burn. In this image from June 2013, the burn scar left by the inferno mars the Black Forest Reserve and nearby residential areas.
Although drought and heat contributed to the intensity of the Black Forest fire, the toll on people's homes resulted from a dramatic increase in housing development in the area. In the 60s, there were fewer than 100 homes in the area. By 2013, Colorado's Black Forest held 1,603 houses. In this image, from 1985, note the lack of squiggling suburban roads seen as tan lines in the 2013 image. "Most wildland fire policies to date have focused on reducing wildfire risk by removing trees and forest fuels, but we need a paradigm shift," Tania Schoennagel, wildfire expert at the University of Colorado-Boulder, told
. "We need to start focusing on limiting residential development in fire-prone forests and working hard to create fire-resistant communities in the wildland-urban interface to minimize future losses."
While satellite imagery shows the current chaos of war in Syria, the site of the Battle of Gettysburg now appears tranquil and pastoral. In this
image from May of 2013, fresh spring fields cut the land into a jigsaw puzzle, where 160,000 Americans once squared off to cut each other down. The battle raged from July 1-3, 1863, leaving approximately 8,000 dead and more than 27,000 wounded. This year marked the 150th anniversary, or seven score and ten years ago, of the battle that inspired President Lincoln's famous speech, the Gettysburg Address. The green patches of Little and Big Round Top Hills mark where Union forces surveyed the battlefield from a higher vantage point than the Confederates, which gave the Yankees a geographic advantage. "How soft your fields so green, can whisper tales of gore, Of how we calmed the tides of war," as Led Zeppelin said in Immigrant Song.
Pine Island Glacier
The leading edge of the Pine Island Glacier in Antarctica shattered between November 9-11 and created an iceberg 35 kilometers by 20 kilometers (21 by 12 miles), known as B-31, according to the
. Currents around Antarctica will decide the eventual fate of the newborn glacier (shown here on Nov. 13, 2013). The chunk of ice may bob around in Pine Island Bay for years, or it may drift out into the oceans surrounding Antarctica, reported
. Two major currents swirl around the frozen continent. One, the "coastal counter current" flows counterclockwise, while the larger, wider "circumpolar current" flows clockwise.
Pine Island Glacier
The Pine Island glacier moved seaward at approximately 4 kilometers per year. Icebergs break off from the glacier every five or six years, reported NASA. However, Iceberg B-31 is roughly 50 percent larger than previous icebergs that have snapped off from the Pine Island Glacier. This image shows the glacier as a rift started to form in late October that would eventually result in iceberg B-31.
As Iceberg B-31 begins its course through the ocean, ships plow though the waves far to the north. The clouds that formed in the ships' wakes distinguish the routes of the vessels as seen in this
image from Jan. 15, 2013. The particles in ships' exhaust serve as seeds for the clouds. Water vapor condenses onto the particles and creates long, thin clouds off the western coast of North America.