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Ocean biodiversity at risk in a warming world

‘Gravel parking lots instead of coral reef gardens’

Coral Gardens: A school of surgeonfish cruise coral reefs near Palmyra Atoll.

Coral Gardens: A school of surgeonfish cruise coral reefs near Palmyra Atoll. Photo courtesy UC San Diego.

By Summit Voice

FRISCO — Global warming is likely to drastically reduce ocean diversity, without a food web that’s able to support an abundance of large sharks and whales. A new study shows that oceans in an ancient greenhouse world had few large reefs,poorly oxygenated water and tropical surface waters warm as a hot tub.

The research by the Scripps Institution of Oceanography, UC San Diego, paleobiologist Richard Norris and colleagues suggests that aspects of this greenhouse ocean could reappear in the future if greenhouse gases continue to rise at current accelerating rates. Continue reading

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Climate: Atmospheric CO2 reaches 400 ppm

Concentration will wane from seasonal high point, but long-term trend is up

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Mauna Loa. Photo courtesy USGS.

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Carbon dioxide in the atmosphere this week reached a level last recorded 2 to 5 million years ago.

By Summit Voice

FRISCO — Climate scientists have been closely tracking atmospheric carbon dioxide levels for a long time, but this week, the colorless, odorless gas made big headlines.

An atmospheric observatory on Mauna Loa for the first time measured daily concentrations of CO2 at slightly above 400 parts per million, a dubious milestone which, better than any other number, captures the extent to which we are changing the world. Continue reading

Newly discovered magma layer may help answer some long-standing questions about plate tectonics

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Research off the coast of Nicaragua led researchers to discover a previously unknown layer of magma that may help explain tectonic movements in the Earth’s crust and mantle.

Findings could lead to better understanding of earthquake dynamics

By Summit Voice

SUMMIT COUNTY — While the observation-based scientific understanding of plate tectonics is well advanced, researchers have long debated the exact mechanics that drive the movement of the Earth’s crust.

New findings based on research conducted off the Nicaragua coastline may help answer some of those questions, as scientists say they’ve discovered a layer of liquified molten rock in Earth’s mantle that may be responsible for the sliding motions of the planet’s massive tectonic plates. Continue reading

New coral data traces 7,000 years of El Niño history

20th century oscillations show intensification that may be linked with global warming

El Nino graphic

A NOAA graphic showing early January 2012 ocean surface temperature anomalies.

By Summit Voice

SUMMIT COUNTY — Atmospheric scientists say they’ve used coral records to trace the history of El Niño cycles going back about 7.000 years, showing that 20th century oscillations  are much stronger than those captured in the fossil record.

But the study also showed large natural variations in past ENSO strength, making it difficult to attribute the 20th century intensification of ENSO to rising carbon dioxide levels. Such large natural fluctuations in ENSO activity are also apparent in multi-century climate model simulations, but the 20th century intensification stands out as statistically significant and could be linked with global warming.

The new information will help assess the accuracy of climate model projections for 21st century climate change in the tropical Pacific. Continue reading

Study confirms ancient California megadroughts

100 to 200 year dry spells not uncommon

Fallen Leaf Lake, California.

By Summit Voice

SUMMIT COUNTY — With the central Sierra Nevada in drought conditions, researchers with the University of Nevada, Reno and their partners at Scripps Institution of Oceanography in San Diego are warning that the region is no stranger to megadroughts, often lasting several hundred years.

The best-known of those is the Medieval megadrought, between 800 to 1250 A.D. when annual precipitation was less than 60 percent of normal. The Reno-Tahoe region is now about 65 percent of annual normal precipitation for the year, which doesn’t seem like much, but imagine if this were the “norm” each and every year for the next 200 years. Continue reading

Environment: Plastic trash alters ocean ecosystems

Floating plastic garbage in the Pacific has created vast new habitat for aquatic insects.

Study shows human garbage is altering marine ecosystems on a large scale

By Summit Voice

SUMMIT COUNTY — Scientists have known for years that a significant portion of society’s plastic debris ends up in the oceans, including the so-called great Pacific garbage patch about 1,000 miles west of California.

Most of the plastic is broken down into tiny fingernail-sized pieces, and the amount of plastic garbage has increased 100-fold in just the past 40 years.

Now, in the first empirical sign that the plastic is changing ocean habitats on a large scale, researchers from the Scripps Institution of Oceanography at UC San Diego documented an increase in sea skater populations, a pelagic marine insect that normally lays its eggs on naturally occurring flotsam including seashells, seabird feathers, tar lumps and pumice. Continue reading

Coral reefs in Caribbean damaged by development and deforestation long before feeling heat of global warming

Coral reefs in the Caribbean were hit hard by runoff from land areas long before they started feeling the impacts of climate change.

Scientists say controlling local stressors is critical to preserving reef ecosystems

By Summit Voice

SUMMIT COUNTY — Coral reefs in the Caribbean have been hit hard by increasing ocean temperatures, but new research shows that a long-term decline in coral health began well before the ocean warming trend.

Scientists with the Scripps Institution of Oceanography at UC San Diego recently excavated coral reefs on the Caribbean side of Panama, determining that damage from land clearing and overfishing pre-dates damage caused by human-caused climate change by at least decades.

“This study is the first to quantitatively show that the cumulative effects of deforestation and possibly overfishing were degrading Caribbean coral and molluscan communities long before climate change impacts began to really devastate reefs,” said lead author and Scripps alumna Katie Cramer, currently based at the Global Coral Reef Monitoring Network at the International Union for Conservation of Nature. Continue reading

Coral reefs: Too hot, too cold …

Scripps researchers find corals can adapt to cooler oceans temps, but heat kills in the long run

Sponge diversity is high on coral reefs. PHOTO COURTESY NATIONAL PARK SERVICE/A. BOURQE.

Feeding coral polyps. PHOTO COURTESY NATIONAL PARK SERVICE/A. BOURQUE.

By Summit Voice

SUMMIT COUNTY — Along with steady warming of the world’s oceans, temperature extremes have become more common. In 2010, for example, coral reefs in some areas had to survive one of the hottest summers on record, along with record-breaking cold winter temperatures.

To help guide future coral reef conservation efforts, scientists with the Scripps Institution of Oceanography at UC San Diego compared damage to corals exposed to heat as well as cold stress, finding that cool temperatures can inflict more damage in the short term, but heat is more destructive in the long run. Continue reading

New surveys up estimates of coral reef biodiversity

Since the early days of marine exploration, biologists have been recording the stunning diversity of coral reefs.

Scientists use DNA barcodes to track ‘staggering diversity’ of world’s oceans

By Summit Voice

SUMMIT COUNTY — Cataloging species with DNA barcodes helped scientists with the Smithsonian National Museum of Natural History determine that the biodiversity in the world’s coral reefs has been seriously underestimated.

Coral reefs are some of the most endangered habitats on Earth. Given coral’s rapid decline and global range, DNA barcoding offered the scientists a quick and efficient method for their survey. Present estimates of species diversity in reefs are 600,000 to more than 9 million species worldwide.

“We cannot give a new estimate today, but we may be able to in a few years,”said Laetitia Plaisance, of the Smithsonian’s National Museum of Natural History and the Scripps Institution of Oceanography, and lead author of the survey. “Given the complexity and extent of the world’s coral reefs, the survey covered only a very limited depth and habitat range,” said Plaisance. “And yet we have so many more species than we ever expected.” Continue reading

Sea bass fisheries collapsing in Southern California

Over-fishing, changing ocean temps blamed for plummeting numbers as Scripps researchers unveil ‘illusion of plenty

Kelp bass numbers have dropped by 90 percent in the past 30 years. IMAGE COURTESY SCRIPPS INSTITUTION OF OCEANOGRAPHY.

By Summit Voice

SUMMIT COUNTY — Over-fishing and climate-driven changes in water temperature have combined to cause the collapse of two important recreational fisheries off the southern California coast in the past few decades.

Barred sand bass and kelp bass populations have declined by as much as 90 percent, but the drop has been masked because fishermen are still able to catch the fish in areas where they congregate to spawn, according to Scripps Institution of Oceanography postdoctoral researcher Brad Erisman and his colleagues, who examined the health of regional populations of the two species by combining information from fishing records and other data on regional fish populations.

Their findings were published in the most recent edition of the Canadian Journal of Fisheries and Aquatic Sciences. The researchers said the total amount, or biomass, of each bass species decreased 90 percent since 1980. Continue reading

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