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Global warming: At current CO2 concentrations, sea level set to rise about 30 feet during the next few centuries

Concentrations of atmospheric carbon dioxide at Mauna Loa, Hawaii.

Average carbon dioxide levels will probably start to stay above 400 ppm sometime in 2013.

Analysis of 40-million year record calibrates CO2 concentrations with historic sea levels

By Summit Voice

SUMMIT COUNTY — Even if  atmospheric carbon dioxide concentrations were to be stabilzed at today’s levels of about 400 parts per million, sea levels would gradually increase by about 30 during the next few centuries, according to researchers who calibrated CO2 levels against sea level for the past 40 million years.

The study sought to pinpoint the ‘natural equilibrium’ sea level for CO2 concentrations ranging between ice-age values of 180 parts per million and ice-free values of more than 1,000 parts per million. Continue reading

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Study eyes global jellyfish populations

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Are jellyfish numbers increasing globally? One recent study suggests decadal fluctuations. Photo courtesy NOAA.

More long-term and widespread monitoring needed to pinpoint trends

By Summit Voice

FRISCO —Global jellyfish populations appear to fluctuate on a decadal basis, including an increase in the 1990s and early 2000s that has led to the current perception of an overall global increase in jellyfish abundance.

But reports that jellyfish are steadily increasing may be unfounded, according to a recent study led by researchers from the Dauphin Island Sea Lab in Alabama and the National Oceanography Centre, Southampton, UK, who concluded there is no robust evidence for a global increase in jellyfish over the past two centuries.

The researchers did find a hint of a slight increase in jellyfish since 1970, although this trend was countered by the observation that there was no difference in the proportion of increasing vs. decreasing jellyfish populations over time. Continue reading

Global warming could lead to runaway ice cap meltdown

New study shows very fast response between global temperature and ice volume and sea level

“when significant ice-volume adjustments happen, they are rarely slow.”

By Summit Voice

FRISCO — A new study confirms the strong links between global temperatures, melting ice and sea level and suggests that sea level responds more quickly that previously believed, probably because of the feedback warming effect of open water.

Ice volume changes during ancient times can be reconstructed from sea-level records, but detailed assessments of the role of ice volume in climate change is hindered by inadequacies in sea-level records and/or their timescales.

Now, a research team led by Eelco Rohling, Professor of Ocean and Climate Change at the University of Southampton, has developed a new way to date sea level rise and accurately link it with changes in ice volume. The scientists were able to apply the new dating method throughout the entire last glacial cycle (150,000 years), which resulted in an unprecedented continuous sea-level record with excellent independent age control. Continue reading

Global warming: New study tries to pin down the effects of ocean acidification on shellfish

New study tries to pinpoint impacts of ocean acidification on shellfish.

Cold-water species hit hardest by increased levels of carbon dioxide

By Summit Voice

SUMMIT COUNTY — The effects of ocean acidification on shellfish are widespread around the globe and may be the most pronounced at high latitudes with low water temperatures, according to new research that examined a wide range of species from the tropics to the Arctic.

But there is some evidence that, with enough time, shellfish and other marine organisms may be able to adapt to the changes caused by global warming, according to the study published this week in the journal Global Change Biology.

“In areas of the world’s oceans where it is hardest for marine creatures to make their limestone shell or skeleton, shellfish and other animals have adapted to natural environments where seawater chemistry makes shell-building materials difficult to obtain,” said Dr .Sue-Ann Watson, formerly of the University of Southampton and British Antarctic Survey (now at James Cook University) said. “Evolution has allowed shellfish to exist in these areas and, given enough time and a slow enough rate of change, evolution may again help these animals survive in our acidifying oceans.” Continue reading

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