Dramatic Ocean Circulation Changes Caused a Colder Europe in the Past

 

ScienceDaily (Jan. 15, 2011) — The unusually cold weather this winter has been caused by a change in the winds. Instead of the typical westerly winds warmed by Atlantic surface ocean currents, cold northerly Arctic winds are influencing much of Europe.

 

However, scientists have long suspected that far more severe and longer-lasting cold intervals have been caused by changes to the circulation of the warm Atlantic ocean currents themselves.

Now new research led by Cardiff University, with scientists in the UK and US, reveals that these ocean circulation changes may have been more dramatic than previously thought.

The findings, published January 14, 2011 in the journal Science, show that as the last Ice Age came to an end (10,000 -- 20,000 years ago) the formation of deep water in the North-East Atlantic repeatedly switched on and off. This caused the climate to warm and cool for centuries at a time.

The circulation of the world's ocean helps to regulate the global climate. One way it does this is through the transport of heat carried by vast ocean currents, which together form the 'Great ocean conveyor'. Key to this conveyor is the sinking of water in the North-East Atlantic, a process that causes warm tropical waters to flow northwards in order to replace the sinking water. Europe is kept warmer by this circulation, so that a strong reduction in the rate at which deep water forms can cause widespread cooling of up to 10 degrees Celsius.

Lead author Dr David Thornalley, Cardiff School of Earth and Ocean Sciences, explains how the scientists studied changes in ocean circulation: "We retrieved ocean sediment cores from the seafloor of the Northeast Atlantic which contained the shells of small organisms. We used these shells to examine the past distribution of radiocarbon in the ocean. Radiocarbon is a radioactive form of carbon that acts like a natural stopwatch, timing how long it has been since water was last at the sea surface. This allows us to determine how quickly deep water was forming in the Northeast Atlantic at different times in the past."

The team of scientists found that each time deep water formation switched off, the Northeast Atlantic did not fill with water that sank locally. Instead it became inundated with water that had originally formed near Antarctica and then spread rapidly northwards. The new results suggest that the Atlantic ocean is capable of radical changes in how it circulates on timescales as short as a few decades.

Dr Thornalley said: "These insights highlight just how dynamic and sensitive ocean circulation can be. Whilst the circulation of the modern ocean is probably much more stable than it was at the end of the last Ice Age, and therefore much less likely to undergo such dramatic changes, it is important that we keep developing our understanding of the climate system and how it responds when given a push."

The research is funded through the Natural Environment Research Council's Rapid Climate Change programme and the National Science Foundation (USA). The Science paper The Deglacial Evolution of North Atlantic Deep

Climate change and the Antarctic: Ocean acidification

Ocean acidification is a consequence of rising global carbon dioxide levels that is predicted to have serious consequences for cold-water ecosystems, including cold-water corals. Rising CO2 levels upset the balance of carbonate ions in seawater, making it difficult for some organisms, which have shells composed of the mineral calcium carbonate, to form their shells. Many of the organisms that are affected, and are predicted to be affected, are critical for ecosystem health. The Southern Ocean will be impacted early by acidification due to its unique chemistry.

Background

The process of ocean acidification involves several steps. CO2 in the air above the sea surface constantly dissolves in seawater and forms carbonic acid. Carbonic acid can break up into hydrogen ions and bicarbonate ions. The hydrogen ions react with carbonate ions and create more bicarbonate ions, while concentrations of carbonate ions decreases. Decreased carbonate ion concentration means that less carbonate is available for the formation of calcium carbonate, a mineral that forms the shells of many organisms. The decreased concentration also can result in existing shells dissolving. Under normal circumstances the amount of carbon dioxide dissolving in seawater occurs at a level that is not detrimental to shell-forming organisms. However, as CO2 increases, the balance is tipped towards decreased carbonate availability and mineral dissolution. The increased concentration of hydrogen ions under the process described above tends to drive down ocean pH, making the water more acidic – hence the term ocean acidification.


Impact on the Southern Ocean

Colder water is naturally lower in calcium carbonate concentration. Furthermore, scientists believe that ocean acidification will affect the Southern Ocean food webs first because the Southern Ocean is closer to undersaturation levels with respect to calcium carbonate than other oceans. Numerous experiments have reported that calcium carbonate-dependent organisms (also called calcifying organisms or calcifiers) experience significant problems when exposed to lower pH environments. Current atmospheric CO2 concentrations have resulted in a drop of about 0.1 pH units (a 30% increase in acidity), and if current trends continue, ocean pH could drop by an average of 0.5 units to about 7.8 around the year 2100 under the IS92a “business as usual” emissions scenario. The latter represents an ocean that is 320% more acidic than it was in pre-industrial times. Despite that change, the ocean will still be in a slightly alkaline state, the boundary between acid and alkali lying at a pH of 7. Calcifying organisms play critical roles in marine ecosystems, such as the Southern Ocean, and declining populations will have serious consequences for the food web.

The impact on cold-water corals could also be severe. Cold-water corals are particularly vulnerable to ocean acidification, since cold water makes it more difficult for corals to survive. Corals, like calcifying organisms, rely on calcium carbonate to form their skeletons. These cold-water corals found in the Southern Ocean are believed to be several hundred years old and provide valuable information on the history of the ocean and past climate.

ASOC believes it is critical that global leaders act now to minimize sources of carbon dioxide emissions to mitigate the impact of climate change and ocean acidification on the world’s oceans. Scientists are still learning about Southern Ocean ecosystems and species – who knows what we could lose if we upset ocean chemistry.

Read more about ocean acidification in our recent paper.

Antarctic and Southern Ocean Coalition, Web site.

NASA Satellites Capture a Stronger La Nina

New NASA satellite data indicate the current La Niña event in the eastern Pacific has remained strong during November and December 2010.

A new Ocean Surface Topography Mission (OSTM)/Jason-2 satellite image of the Pacific Ocean that averaged 10 days of data was just released from NASA. The image, centered on Dec. 26, 2010, was created at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.

"The solid record of La Niña strength only goes back about 50 years and this latest event appears to be one of the strongest ones over this time period," said Climatologist Bill Patzert of JPL. "It is already impacting weather and climate all around the planet." 

 

The La Niña is evident by the large pool cooler than normal (blue and purple) water stretching from the eastern to the central Pacific Ocean, reflecting lower than normal sea surface heights. "This La Niña has strengthened for the past seven months, and is one of the most intense events of the past half century," said Climatologist Bill Patzert of NASA JPL. Credit: NASA JPL/Bill Patzert



This Ocean Surface Topography Mission (OSTM)/Jason-2 satellite image of the Pacific Ocean is based on the average of 10 days of data centered on Dec. 26, 2010. The new image depicts places where the Pacific sea surface height is higher (warmer) than normal as yellow and red, with places where the sea surface height is lower (cooler) than normal as blue and purple. Green indicates near-normal conditions. Sea surface height is an indicator of how much of the sun's heat is stored in the upper ocean. Credit: NASA JPL/Bill Patzert


"Although exacerbated by precipitation from a tropical cyclone, rainfalls of historic proportion in eastern Queensland, Australia have led to levels of flooding usually only seen once in a century," said David Adamec, Oceanographer at NASA's Goddard Space Flight Center, Greenbelt, Md. "The copious rainfall is a direct result of La Niña’s effect on the Pacific trade winds and has made tropical Australia particularly rainy this year."

The new image depicts places where the Pacific sea surface height is near-normal, higher (warmer) than normal and lower (cooler) than normal. The cooler-than normal pool of water that stretches from the eastern to the central Pacific Ocean is a hallmark of a La Niña event.

Earth's ocean is the greatest influence on global climate. Only from space can we observe our vast ocean on a global scale and monitor critical changes in ocean currents and heat storage. Continuous data from satellites like OSTM/Jason-2 help us understand and foresee the effects of ocean changes on our climate and on climate events such as La Niña and El Niño.

The latest report from NOAA's Climate Prediction Center (CPC) noted that "A moderate-to-strong La Niña continued during December 2010 as reflected by well below-average sea surface temperatures (SSTs) across the equatorial Pacific Ocean." The CPC report said that La Niña is expected to continue well into the Northern Hemisphere spring 2011.

Unchanging Wind

by Hadel Samir Ma’ayeh

The wind hurls among the Olive trees
unchanging its path through the brittle leaves.
Murky waters unsettled by the sands
and red lobsters do their usual dance.
The lonely wind makes a wave
as it passes the hallowed cave.
Untouched by time and
no sound or chime.
The reddish sun hides in the distance
like the unchanging wind without resistance.

Global Warming Causes and Effects

By Derek Markham

One of the biggest issues facing us right now is global warming. Its effects on animals and on agriculture are indeed frightening, and the effects on the human population are even scarier. The facts about global warming are often debated, but unfortunately, even if we disagree about the causes, global warming effects are real, global, and measurable. The causes are mainly from us, the human race, and the effects on us will be severe.

Global Warming Effects and Causes: A Top 10 List

 

1. Global Warming Cause: Carbon dioxide emissions from fossil fuel burning power plants
Our ever increasing addiction to electricity from coal burning power plants releases enormous amounts of carbon dioxide into the atmosphere. 40% of U.S. CO2 emissions come from electricity production, and burning coal accounts for 93% of emissions from the electric utility industry [EPA, pg. 10]. Every day, more electric gadgets flood the market, and without widespread alternative energy sources, we are highly dependent on burning coal for our personal and commercial electrical supply.



2. Global Warming Cause: Carbon dioxide emissions from burning gasoline for transportation
Our modern car culture and appetite for globally sourced goods is responsible for about 33% of emissions in the U.S. [EPA pg. 8] With our population growing at an alarming rate, the demand for more cars and consumer goods means that we are increasing the use of fossil fuels for transportation and manufacturing. Our consumption is outpacing our discoveries of ways to mitigate the effects, with no end in sight to our massive consumer culture.



3. Global Warming Cause: Methane emissions from animals, agriculture such as rice paddies, and from Arctic seabeds

Methane is another extremely potent greenhouse gas, ranking right behind CO2. When organic matter is broken down by bacteria under oxygen-starved conditions (anaerobic decomposition) as in rice paddies, methane is produced. The process also takes place in the intestines of herbivorous animals, and with the increase in the amount of concentrated livestock production, the levels of methane released into the atmosphere is increasing. Another source of methane is methane clathrate, a compound containing large amounts of methane trapped in the crystal structure of ice. As methane escapes from the Arctic seabed, the rate of global warming will increase significantly.



4. Global Warming Cause: Deforestation, especially tropical forests for wood, pulp, and farmland
The use of forests for fuel (both wood and for charcoal) is one cause of deforestation, but in the first world, our appetite for wood and paper products, our consumption of livestock grazed on former forest land, and the use of tropical forest lands for commodities like palm oil plantations contributes to the mass deforestation of our world. Forests remove and store carbon dioxide from the atmosphere, and this deforestation releases large amounts of carbon, as well as reducing the amount of carbon capture on the planet.



5. Global Warming Cause: Increase in usage of chemical fertilizers on croplands

In the last half of the 20th century, the use of chemical fertilizers (as opposed to the historical use of animal manure) has risen dramatically. The high rate of application of nitrogen-rich fertilizers has effects on the heat storage of cropland (nitrogen oxides have 300 times more heat-trapping capacity per unit of volume than carbon dioxide) and the run-off of excess fertilizers creates ‘dead-zones’ in our oceans. In addition to these effects, high nitrate levels in groundwater due to over-fertilization are cause for concern for human health.



6. Global Warming Effect: Rise in sea levels worldwide 

Scientists predict an increase in sea levels worldwide due to the melting of two massive ice sheets in Antarctica and Greenland, especially on the East coast of the U.S. However, many nations around the world will experience the effects of rising sea levels, which could displace millions of people. One nation, the Maldives, is already looking for a new home, thanks to rising sea levels.




7. Global Warming Effect: More killer storms

The severity of storms such as hurricanes and cyclones is increasing, and research published in Nature found:

“Scientists have come up with the firmest evidence so far that global warming will significantly increase the intensity of the most extreme storms worldwide. The maximum wind speeds of the strongest tropical cyclones have increased significantly since 1981, according to research published in Nature this week. And the upward trend, thought to be driven by rising ocean temperatures, is unlikely to stop at any time soon.”

8. Global Warming Effect: Massive crop failures

According to recent research, there is a 90% chance that 3 billion people worldwide will have to choose between moving their families to milder climes and going hungry due to climate change within 100 years.

“Climate change is expected to have the most severe impact on water supplies. “Shortages in future are likely to threaten food production, reduce sanitation, hinder economic development and damage ecosystems. It causes more violent swings between floods and droughts.”" – Guardian: Global warming causes 300,000 deaths a year

9. Global Warming Effect: Widespread extinction of species

According to research published in Nature, by 2050, rising temperatures could lead to the extinction of more than a million species. And because we can’t exist without a diverse population of species on Earth, this is scary news for humans.

“Climate change now represents at least as great a threat to the number of species surviving on Earth as habitat-destruction and modification.” Chris Thomas, conservation biologist at the University of Leeds

10. Global Warming Effect: Disappearance of coral reefs

A report on coral reefs from WWF says that in a worst case scenario, coral populations will collapse by 2100 due to increased temperatures and ocean acidification. The ‘bleaching’ of corals from small but prolonged rises in sea temperature is a severe danger for ocean ecosystems, and many other species in the oceans rely on coral reefs for their survival.

“Despite the oceans’s immensity — 71 per cent of the Earth’s surface with an average depth of almost 4km (2½m) — there are indications that it is approaching its tipping point. For reefs, warming waters and acidification are closing in like a pair of jaws that threaten to make them the first global ecosystem to disappear.” – Times Online: 21st-century Noah’s Ark needed to save coral reefs from extinction

New scheme launched for 'bleached and dying' coral life

 

By Neil Bowdler Science reporter, BBC News

 

Conservationists led by scientists from the Zoological Society of London have launched a new drive to save some of the world's most endangered corals. 

The new EDGE Coral Reefs programme lists the most endangered corals and has enlisted scientists around the world to educate local communities on their importance.

The most dire predictions suggest that tropical coral reefs will be all but extinct within the next half a century, with rising sea temperatures posing the greatest threat.

Coral bleaching

Coral reefs are not just beautiful explosions of colour and sea life - they protect coastal communities from storms and the fish and shrimp they sustain feed people the world over.

But the reefs are in immediate danger from a host of sources.

Top of the list is the threat from rising sea temperatures, which results in "coral bleaching". This involves the loss of algae cells called zooxanthellae, which renders the coral unable to photosynthesise.

While the coral can survive temporary spikes in ocean temperature and the resulting bleaching, longer-term temperature rises kill the marine organisms.

Other threats include ocean acidification, as the seas absorb increased levels of carbon dioxide from the atmosphere.

 

Rising sea temperatures result in "bleached" coral which prevents the organism from photosynthesising.
 

"Corals are hugely threatened by climate change, by things like rising sea temperature which leads to coral bleaching, ocean acidification, increased storm intensity and frequency and then there's also the local pressures which affect the reef," says Catherine Head, who is co-ordinating the EDGE Coral Reefs project from London.

"Things like overfishing, pollution, sedimentation, coastal development. All those things exacerbate the effects of climate change."

Addressing such local pressures, she says, can buy the reefs some time until governments move to address rising atmospheric and air temperatures.
   
Local interests

As part of the new project, a list of the most endangered corals has been compiled, including a "top 10" of threatened coral species.

Unlike the IUCN Red List of Threatened Species, the EDGE list, say its creators, ranks species in both in terms of the threat they face of extinction and in terms of their evolutionary uniqueness.

Such species, they argue, could play a key role in the adaptation of coral populations to climate change.
The project has also enlisted scientists around the globe to research threatened species and to educate local communities on their importance.

According to Rachel Jones, Senior Aquarium Keeper at the Zoological Society of London (London Zoo), the challenge is to convince those who live close to reefs that protecting them is in their interests.

"Tropical reefs are found in places where often population pressures are really really high and where people are poor they rely on the reef for their food.

"So we need to create an environment where it's worth more to the people who live on reefs to keep the reef alive than it is to dynamite fish it or to trawl it for shrimp or whatever."

Most Endangered

• Elegance coral or Catalaphyllia jardinae has large tubular tentacles which are green with pink tips and a 'zebra' striped oral disk
• Crisp pillow coral or Anomastraea irregularis has an overall blue-grey or cream colour and its individual polyps are small, numerous and a shade of brown
• Horastrea coral or Horastrea indica is a hemispherical, colonial species and is pale-brown in colour with blue-grey oral discs
• Pillar coral or Dendrogyra cylindrus grows in tall cylindrical columns of heights up to 2m giving it a distinctive pillar-like appearance
• Elliptical star coral or Dichocoenia stokesii is spherical in shape with irregularly shaped corallites
• Mushroom coral or Heliofungia actiniformis has a flat shape with large, lobed teeth
• Elkhorn coral or Acropora palmata forms branching 'antler' type colonies which are yellowy-tan in colour with white tips to the branches
• Parasimplastrea coral or Parasimplastrea sheppardi is a small, encrusting coral which is colourful in appearance
• Pearl bubble coral or Physogyra lichtensteini is a colonial species that can form 'massive' colonies with a bubble-like appearance
• Ctenella coral or Ctenella chagius is a brain coral that is endemic to the Chagos Archipelago

Source: ZSL

 Corals Reefs see Second Worst Year Ever in 2010

by Zachary Shahan

 

"Forecast stress on coral due to warm ocean temperatures for Australia, Jan - Apr 2011. The northern 2/3 of the Great Barrier Reef are under the highest alert level for coral bleaching. Waters are cooler along the southern portion of the reef, due, in part, to the storms that have brought record flooding to portions of Queensland, Australia."

We’ve covered coral bleaching, the devastation of coral reefs and their relationship to global warming here on Planetsave numerous times over the past few years. For clear reasons: this is a true global environmental catastrophe with numerous harmful ramifications. Dr Jeff Masters of WunderBlog delves into the harsh coral reef collapse of 2010 and future projections in a recent post. Here’s the intro:

Record warm ocean temperatures across much of Earth’s tropical oceans during the summer of 2010 created the second worst year globally for coral-killing bleaching episodes. The warm waters, fueled in part by the El Niño phenomena, caused the most coral bleaching since 1998, when 16 percent of the world’s reefs were killed off. “Clearly, we are on track for this to be the second worst (bleaching) on record,” NOAA coral expert Mark Eakin in an interview last month. “All we’re waiting on now is the body count.” The summer 2010 bleaching episodes were worst in Southeast Asia, where El Niño warming of the tropical ocean waters during the first half of the year was significant. In Indonesia’s Aceh province, 80% of the bleached corals died, and Malaysia closed several popular dive sites after nearly all the coral were damaged by bleaching. However, in the Caribbean’s Virgin Islands, coral bleaching was not as severe as experienced in 2005, according to National Park Service fisheries biologist Jeff Miller. I’ll discuss the reasons for this in a future blog post. In other portions of the Caribbean, such as Venezuela and Panama, coral bleaching was worse than that experienced in 2005.

"Departure of sea surface temperature in the Australian region over the past one hundred years, year-by-year (red line), and decade-by-decade (grey bars.) The 2010 value is preliminary and does not include data for December 2010. If ocean temperatures and ocean acidity continue to rise in Australian waters at the same pace as has occurred over the past 100 years, the Great Barrier Reef will be in significant danger by 2050."

And here’s the future outlook portion of the piece:

Long term outlook for world’s coral reefs: grim
The large amount of carbon dioxide humans have put into the air in recent decades has done more than just raise Earth’s global temperature–it has also increased the acidity of the oceans, since carbon dioxide dissolves in sea water to form carbonic acid. Corals have trouble growing in acidic sea water, and the combined effects of increasing ocean temperatures, increasing acidity, pollution, and overfishing have reduced coral reefs globally by 19 percent since 1950. Another 35 percent could disappear in the next 40 years, even without the impact of climate change, according to a report released in October 2010 by the World Meteorological Organization and the Convention on Biological Diversity. Coral loss has been the most severe in Earth’s hottest ocean, the Indian Ocean. Up to 90% of coral cover has been lost in the Maldives, Sri Lanka, Kenya and Tanzania and in the Seychelles. Global warming has heated up most of the tropical ocean surface waters by about 0.5°C (0.9°F) over the past 50 years, and the remarkable bleaching episodes of 1998 and 2010 both occurred when strong (natural) El Niño episodes heated up Pacific tropical waters to record levels. If the Earth continues to heat up this century as expected, coral bleaching episodes will grow more frequent and intense, particularly during strong El Niño episodes. The twin stresses of ocean acidification and increasing ocean temperatures will probably mean that by 2050, it will be difficult for any coral reefs to recover when subject to additional stresses posed by pollution or major storms, according to a talk presented by Stanford climate scientist Ken Caldeira at last month’s American Geophysical Union (AGU) meeting.

Read more here: Globe’s coral reefs take second worst beating on record during 2010