Monday, October 1, 2012

Sea Level Rise

Throughout the contentious debates regarding climate change, one effect of these changes is sea level rise.  The article below is the most recent in a series of sobering assessments of earth's climate and sea level changes.  Of course, no one knows, really, what the future holds.  I find it hard to ignore, however, the melting of ice sheets, the disintegration of ice shelves, and the shrinking Arctic ice coverage.  It's difficult to know who to trust on this one.

 Read on for more info...


Irreversible Warming Will Cause Sea Levels to Rise for Thousands of Years to Come, New Research Shows

ScienceDaily (Oct. 2, 2012) — Greenhouse gas emissions up to now have triggered an irreversible warming of Earth that will cause sea levels to rise for thousands of years to come, new research has shown.
The results come from a study, published today (Oct. 2) in IOP Publishing's journal Environmental Research Letters, which sought to model sea-level changes over millennial timescales, taking into account all of Earth's land ice and the warming of the oceans -- something which has not been done before.
The research showed that we have already committed ourselves to a sea-level rise of 1.1 metres by the year 3000 as a result of our greenhouse gas emissions up to now. This irreversible damage could be worse, depending on the route we take to mitigating our emissions.
If we were to follow the high A2 emissions scenario adopted by the Intergovernmental Panel on Climate Change (IPCC), a sea-level rise of 6.8 metres could be expected in the next thousand years. The two other IPCC scenarios analysed by the researchers, the B1 and A1B scenarios, yielded sea-level rises of 2.1 and 4.1 metres respectively.
"Ice sheets are very slow components in the climate system; they respond on time scales of thousands of years," said co-author of the study Professor Philippe Huybrechts.
"Together with the long life-time of greenhouse gases in the atmosphere, this inertia is the real poison on the climate system: anything we do now that changes the forcing in the climate system will necessarily have long consequences for the ice sheets and sea level."
In all of the scenarios that the researchers analysed, the Greenland ice sheet was responsible for more than half of the sea level rises; thermal expansion of the oceans was the second highest contributor, and the contribution of glaciers and ice was only small.
The researchers believe this is the first study to include glaciers, ice caps, the Greenland and Antarctic ice sheets and the thermal expansion of the oceans into a projection of sea-level rises. They did so by using a climate modelling system called LOVECLIM, which includes components from a number of different subsystems.
The polar ice sheets are not normally included into projections due to computational constraints, whilst researchers often find it difficult to account for the 200 000 individual glaciers that are found all over the world in very different climatic settings.
Professor Huybrechts continued: "Ultimately the current polar ice sheets store about 65 metres of equivalent sea level and if climatic warming will be severe and long-lasting all ice will eventually melt.
"Mankind should limit the concentration of greenhouse gases at the lowest possible level as soon as possible. The only realistic option is a drastic reduction of the emissions. The lower the ultimate warming will be, the less severe the ultimate consequences will be."
The researchers are from Vrije Universiteit Brussel, Manchester Metropolitan University and the Université catholique de Louvain.
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The above story is reprinted from materials provided byInstitute of Physics.
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Journal Reference:
  1. H Goelzer, P Huybrechts, S C B Raper, M-F Loutre, H Goosse, T Fichefet. Millennial total sea-level commitments projected with the Earth system model of intermediate complexity LOVECLIM. Environmental Research Letters, 2012; 7 (4): 045401 DOI: 10.1088/1748-9326/7/4/045401
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Institute of Physics (2012, October 2). Irreversible warming will cause sea levels to rise for thousands of years to come, new research shows. ScienceDaily. Retrieved October 1, 2012, from http://www.sciencedaily.com­/releases/2012/10/121001191531.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
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Saturday, September 29, 2012

Osteoporosis??


When most people think of sponges, they think of the synthetic sponges that one might buy in a supermarket.       I usually think of natural sponges.  Natural sponges are a group of some of the simplest "complex" animals on the planet.  Their simplicity certainly does not suggest any predation.

 Below is an interesting article on how certain types of sponges are seriously impacting some coral reefs.

Osteoporosis in the World's Oceans: Bioeroding Sponges Are Threatening Coral Reefs

ScienceDaily (Sep. 19, 2012) — Due to the massive production of the greenhouse gas carbon dioxide, our oceans are becoming increasingly acidic. Scientists of Senckenberg am Meer in Wilhelmshaven studied the consequences of ocean acidification on sponges that bore into calcareous materials such as coral skeletons. Results show that these sponges will profit from global changes, while coral reefs are threatened in their survival.
The study was published in the online journal PLoS ONE.
Increasing concentrations of carbon dioxide are not only changing the atmosphere, but also the oceans: Carbon dioxide reacts with water and forms carbonic acid, which acidifies the seas. The pH decreases simultaneously with this acidification, having mostly negative effects on many organisms in our oceans.
"Especially organisms that form calcareous skeletons, such as corals, will have to expend more energy in more acidic conditions," states Dr. Max Wisshak from Senckenberg am Meer in Wilhelmshaven. "In contrast -- so our hypothesis -- organisms that bioerode calcareous skeletons by biochemical etching should have an easier job in future and should thus be counted into the small circle of winners of the global change."
To test this hypothesis the team of scientists in collaboration with the Australian Institute of Marine Science and GEOMAR -- Helmholtz Centre for Oceanography in Kiel conducted elaborate experiments at the largest coral reef on earth, the Australian Great Barrier Reef, working with the bioeroding sponge Cliona orientalis. This demosponge is widely distributed, belongs to the most aggressive bioeroders, and will in future very likely contribute even more to the erosion of many coral skeletons in the Great Barrier Reef.
"We were able to confirm a clear relationship between the pH of the seawater and the bioerosion rate of these sponges," says Wisshak. "Our data predict an up to 25 percent increase of sponge bioerosion until end of this century!"
As bioeroding sponges often contribute the lion share of coral bioerosion on tropical reefs, with increasing ocean acidification the reefs will be exposed to a duplicate burden: calcification will be more difficult, and existing skeletons will be more strongly weakened by bioerosion. "This may lead to a shift from present-day positive reef growth to future negative budgets with stronger reef bioerosion. In consequence our reefs would be threatened by yet another stress factor," explains the marine geologist from Wilhelmshaven.
Testing effects of rising sea surface temperatures in the world's oceans -- another consequence of the present global change -- revealed a comparatively small influence on bioerosion rates of the sponges. What the sponges do not mind has a serious outcome for corals: Rising temperatures have a large impact on corals: Heat stress causes "bleaching" in corals, and in consequence they can die in dramatic mass mortality events.
The outcome of severe bleaching events is disastrous as reefs are home to many marine organisms and the basis of a complex food chain -- all the way up to humans.
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The above story is reprinted from materials provided bySenckenberg Research Institute and Natural History Museum.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. Max Wisshak, Christine H. L. Schönberg, Armin Form, André Freiwald. Ocean Acidification Accelerates Reef Bioerosion. PLoS ONE, 2012; 7 (9): e45124 DOI:10.1371/journal.pone.0045124
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Senckenberg Research Institute and Natural History Museum (2012, September 19). Osteoporosis in the world's oceans: Bioeroding sponges are threatening coral reefs.ScienceDaily. Retrieved September 29, 2012, from http://www.sciencedaily.com­/releases/2012/09/120919082924.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Ocean Acidification In The Caribbean Significant, Yet Variable (Nov. 28, 2008) — A new study, which confirms significant ocean acidification across much of the Caribbean and Gulf of Mexico, reports strong natural variations in ocean chemistry in some parts of the Caribbean that ...  > read more
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Wednesday, September 19, 2012

Where Has All The Ice Gone?

I used this same post for the Earth Science blog.  Sea ice coverage is certainly important for oceanography.



During the current melting season, sea ice coverage on the Arctic Ocean reached its all-time recorded low.  This year's low measured even less than the previous record, 2007.

Although many still energetically debate the causes, they cannot ignore the Arctic warmup of the past 10 or so years.

The lower ice coverage will affect marine life (including polar bears - officially a marine mammal) and will further contribute to Arctic warming.

Scientists do not know the cause(s) nor do they know what future changes are in store.

Below is a phenomenal NOAA animation of satellite still images illustrating this year's loss of ice.


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Sunday, September 16, 2012

The Last Frontier

Mission Plan: Proposed remotely operated vehicle dive sites at major features of interest in the Northeast Lau Basin
Some scientists speculate that we know more about space, our solar system, and the universe, than we do about the largest general environment on our planet - the world ocean.

There has been a lot of interest in ocean exploration the past few years - James Cameron, Bob Ballard, etc.

NOAA is helping lead an expedition looking at backarc volcanoes in the western Pacific Ocean and the organisms found there.

Click this link to the NOAA Ocean Explorer: NOAA Ocean Explorer
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Saturday, September 15, 2012

Salinity

Given our current discussions regarding seawater chemistry, I thought the following article from Woods Hole Oceanographic Institution was timely.


NASA/WHOI Voyage Set to Explore Link Between Sea Saltiness and Climate

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A NASA-sponsored expedition is set to sail to the North Atlantic's saltiest spot to get a detailed, 3-D picture of how salt content fluctuates in the ocean's upper layers and how these variations are related to shifts in rainfall patterns around the planet.
The research voyage is part of a multi-year mission, dubbed the Salinity Processes in the Upper Ocean Regional Study (SPURS), which will deploy multiple instruments in different regions of the ocean. The new data also will help calibrate the salinity measurements NASA's Aquarius instrument has been collecting from space since August 2011.
SPURS scientists aboard the research vessel Knorr leave Sept. 6 from the Woods Hole Oceanographic Institution in Woods Hole, Mass., and head toward a spot known as the Atlantic surface salinity maximum, located halfway between the Bahamas and the western coast of North Africa. The expedition also is supported by the National Oceanic and Atmospheric Administration and the National Science Foundation.
The researchers will spend about three weeks on site deploying instruments and taking salinity, temperature and other measurements, before sailing to the Azores to complete the voyage on Oct. 9.
They will return with new data to aid in understanding one of the most worrisome effects of climate change -- the acceleration of Earth's water cycle. As global temperatures go up, evaporation increases, altering the frequency, strength, and distribution of rainfall around the planet, with far-reaching implications for life on Earth.
"What if the drought in the U.S. Midwest became permanent? To understand whether that could happen we must understand the water cycle and how it will change as the climate continues to warm," said Raymond Schmitt, a physical oceanographer at Woods Hole and principal investigator for SPURS. "Getting that right is going to involve understanding the ocean, because the ocean is the source of most of the water."
Oceanographers believe the ocean retains a better record of changes in precipitation than land, and translates these changes into variations in the salt concentration of its surface waters. Scientists studying the salinity records of the past 50 years say they already see the footprint of an increase in the speed of the water cycle. The places in the ocean where evaporation has increased and rain has become scarcer have turned saltier over time, while the spots that now receive more rain have become fresher. This acceleration ultimately may exacerbate droughts and floods around the planet. Some climate models, however, predict less dramatic changes in the global water cycle.
"With SPURS we hope to find out why these climate models do not track our observations of changing salinities," said Eric Lindstrom, physical oceanography program scientist at NASA Headquarters in Washington. "We will investigate to what extent the observed salinity trends are a signature of a change in evaporation and precipitation over the ocean versus the ocean's own processes, such as the mixing of salty surface waters with deeper and fresher waters or the sideways transport of salt."
To learn more about what drives salinity, the SPURS researchers will deploy an array of instruments and platforms, including autonomous gliders, sensor-laden buoys and unmanned underwater vehicles. Some will be collected before the research vessel heads to the Azores, but others will remain in place for a year or more, providing scientists with data on seasonal variations of salinity.
Some of the devices used during SPURS to explore the Atlantic's saltiest spot will focus on the outer edges of the study area, traveling for hundreds of miles and studying the broadest salinity features. Other instruments will explore smaller areas nested inside the research site, focusing on smaller fluxes of salt in the waters. The suite of ocean instruments will complement data from NASA's salinity-sensing instrument aboard the Aquarius/SAC-D (Satelite de Aplicaciones Cientificas-D) observatory, and be integrated into real-time computer models that will help guide researchers to the most interesting phenomena in the cruise area.
"We'll be able to look at lots of different scales of salinity variability in the ocean, some of which can be seen from space, from a sensor like Aquarius," said David Fratantoni, a physical oceanographer with Woods Hole and a member of the SPURS expedition. "But we're also trying to see variations in the ocean that can't be resolved by current satellite technology."
The 2012 SPURS measurements in the North Atlantic will help scientists understand the behavior of other high-salinity regions around the world. A second SPURS expedition in 2015 will investigate low-salinity regions where there is a high input of fresh water, such as the mouth of a large river or the rainy belts near the equator.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans' role in the changing global environment.
Originally published: September 5, 2012
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