Tag "Atlantic Ocean"
Cold water currently slowing fastest Greenland glacier
NASA research shows that Jakobshavn Glacier, which has been Greenland’s fastest-flowing and fastest-thinning glacier for the last 20 years, has made an unexpected about-face.
The researchers suspect the cold water was set in motion by a climate pattern called the North Atlantic Oscillation (NAO), which causes the northern Atlantic Ocean to switch slowly between warm and cold every five to 20 years.
Water Temperature and Weather Jakobshavn, located on Greenland’s west coast, drains about 7 percent of the island’s ice sheet.
Because of its size and importance to sea level rise, scientists from NASA and other institutions have been observing it for many years.
Researchers hypothesized that the rapid retreat of the glacier began with the early 2000s loss of the glacier’s ice shelf — a floating extension of the glacier that slows its flow.
Jakobshavn has been accelerating each year since losing its ice shelf, and its front (where the ice reaches the ocean) has been retreating.
The team suspects that both the widespread Atlantic cooling and the dramatic cooling of the waters that reached the glacier were driven by the shift in the NAO.
If so, the cooling is temporary and warm waters will return when the NAO shifts to a warm phase once again.
We’ve shown that ocean temperatures can be just as important.”
The paper on the new research in Nature Geoscience is titled “Jakobshavn’s 20 Years of Acceleration and Thinning Interrupted by Regional Ocean Cooling.”
Cold water currently slowing fastest Greenland glacier
NASA research shows that Jakobshavn Glacier, which has been Greenland’s fastest-flowing and fastest-thinning glacier for the last 20 years, has made an unexpected about-face.
The researchers suspect the cold water was set in motion by a climate pattern called the North Atlantic Oscillation (NAO), which causes the northern Atlantic Ocean to switch slowly between warm and cold every five to 20 years.
Water Temperature and Weather Jakobshavn, located on Greenland’s west coast, drains about 7 percent of the island’s ice sheet.
Because of its size and importance to sea level rise, scientists from NASA and other institutions have been observing it for many years.
Researchers hypothesized that the rapid retreat of the glacier began with the early 2000s loss of the glacier’s ice shelf — a floating extension of the glacier that slows its flow.
Jakobshavn has been accelerating each year since losing its ice shelf, and its front (where the ice reaches the ocean) has been retreating.
The team suspects that both the widespread Atlantic cooling and the dramatic cooling of the waters that reached the glacier were driven by the shift in the NAO.
If so, the cooling is temporary and warm waters will return when the NAO shifts to a warm phase once again.
We’ve shown that ocean temperatures can be just as important.”
The paper on the new research in Nature Geoscience is titled “Jakobshavn’s 20 Years of Acceleration and Thinning Interrupted by Regional Ocean Cooling.”
Poor diet may have caused nosedive in major Atlantic seabird nesting colony
The findings provide fresh evidence of the fragility of marine ecosystems and lend weight to the scientific case for creating the Ascension Island Ocean Sanctuary (AIOS), set to be one of the largest fully protected reserves in the Atlantic Ocean.
The most numerous seabird of tropical waters, sooty terns breed on Ascension Island where the colony is the largest in the entire Atlantic Ocean.
A team based in the University’s School of Biosciences believes the birds’ plight is closely linked to changes in populations of predatory fish such as tuna.
However, while many seabird species subsequently began to thrive, the tern population did not recover as expected and the Birmingham team, together with researchers from the University of Exeter, the Ascension Island Government Conservation Department (AIGCD) and the Army Ornithological Society (AOS), set out to find out why. “We believe that a number of factors might influence the size of the breeding population of sooty terns on the island but we wanted to understand such factors in greater detail, resulting in causal explanations of the tern population decline over the past 60 years,” says Dr Jim Reynolds, lead author on the paper.
The team started to look at the birds’ diet after noticing that some of the food naturally regurgitated by the terns contained lots of prey low in nutrients, such as squid, marine snails and even locusts.
Feathers from more than 180 specimens, dating from 1890 to the present day, were collected and analysed by collaborators at the University of Coimbra in Portugal.
The results clearly showed that a change in the terns’ diets from eating mainly fish to eating lower quality food was coincidental with their population decline.
As oceans warm, the movements of top predators and the fish on which they forage are changing, possibly making it more difficult for the terns to follow them in search of food.”
Marine protected areas such as that planned for Ascension Island may well help to alleviate pressure on species like sooty terns.
The North Atlantic Seesaw
Now, people often discuss procedures like “removing the effects of the El Nino from the global temperature record”.
This is to note that although there are areas of the surface which show a good positive correlation to global temperatures, there are also areas that show a good negative correlation to global temperatures.
It displays how well the temperatures in each gridcell agree or disagree with the global average temperature variations shown in Figure 1.
Setting those questions aside, the overall pattern in the Pacific is clearly related to the heat which is moved by the El Nino / La Nina pump.
The results of this pumping action can be seen in Figure 2 as the green areas in the western Pacific heading towards the north and south polar regions.
Note that both the Western Pacific and the North Atlantic move in opposition to the NINO3.4 area.
When enough heat has accumulated in the eastern Pacific, the El Nino / La Nina pump pushes warm water first westward, then poleward.
Note that the North Atlantic is included among the areas with a strong negative correlation to the NINO3.4 area.
Trump was 100% right (not just 97%) to show real leadership and walk away from Paris President Trump has rejected and exited the Paris climate treaty – walked America away from the Mad Hatter tea party that was the entire multi-decade, often hysterical and always computer model-driven UN climate process.
Our resident cartoonist, Josh, noticed and replied: inspiring, now all bad weather can be blamed on @realDonaldTrump pic.twitter.com/ZlKZj56mUS — Josh (@Cartoonsbyjosh) June 2, 2017 Hi, Justthefacts…… ….. for the Earth’s orbit section and all astronomical background…..some time is needed to understand the real Earth’s trajectory….. Any questions to me always welcome…… Following background: There is good data and analysis done at NASA JPL Pasadena… I can quote literature….. but the IPCC/AGW “hijacked” the orbit topic by not using American data….and the IPCC orbit analysis went to Belgium, to the University of Louvain, a center of entrenched AGW-proponents….
Tipping points are real: Gradual changes in CO2 levels can induce abrupt climate changes
Their study is the first to confirm that there have been situations in our planet’s history in which gradually rising CO2 concentrations have set off abrupt changes in ocean circulation and climate at “tipping points.”
These sudden changes, referred to as Dansgaard-Oeschger events, have been observed in ice cores collected in Greenland.
The results of the study have just been released in the journal Nature Geoscience.
Previous glacial periods were characterised by several abrupt climate changes in the high latitudes of the Northern Hemisphere.
This temperature rise is the result of interactions between ocean currents and the atmosphere, which the scientists used the climate model to explore.
According to their findings, the increased CO2 intensifies the trade winds over Central America, as the eastern Pacific is warmed more than the western Atlantic.
This is turn produces increased moisture transport from the Atlantic, and with it, an increase in the salinity and density of the surface water.
Finally, these changes lead to an abrupt amplification of the large-scale overturning circulation in the Atlantic.
Further, the study’s authors reveal that rising CO2 levels are the dominant cause of changed ocean currents during the transitions between glacial and interglacial periods.
That being said, we’ve now confirmed that there have definitely been abrupt climate changes in the Earth’s past that were the result of continually rising CO2 concentrations.”
First Step Toward Atlantic Drilling Could Decimate Key Species In Ocean Food Chain
One of the first steps toward offshore drilling development in the Atlantic Ocean could decimate a key species in the marine food chain, a new study finds.
Seismic surveying, the process of blasting airguns underwater to locate oil and gas deposits, could have devastating effects on zooplankton, a food source relied upon by many marine animals, according to a study published Thursday in the journal Nature.
Researchers at Australia’s Curtin University and University Tasmania reported that blasts from a single seismic airgun caused a two-to-threefold increase in dead adult and larval zooplankton within 24 hours of exposure as compared to control groups.
The process could pose a “significant and unacknowledged potential” threat to ocean ecosystems, including the fish, whales and marine animals that feed on zooplankton, the researchers said.
pilipenkoD via Getty Images The study was released just two weeks after the National Marine Fisheries Service drafted permits that would allow companies to engage in seismic surveying along the East Coast ― a major step forward in the Trump administration’s pledge to expand offshore oil and gas drilling.
Francine Kershaw, a marine mammal and oceans scientist for the Natural Resources Defense Council, warned that the seismic blasting “effectively decimates” zooplankton.
“To permit this devastating activity ― in the face of strong evidence of its impact ― is to sacrifice our oceans and coastal communities for the profits of the oil and gas industry.” The Morning Email Wake up to the day’s most important news.
“Sound and hearing are of transcendent importance to many ocean life forms, including marine mammals and fish,” Dr. Dr. Doug Nowacek, a marine scientist at Duke University, told reporters on a press call this month.
Authorization of the permits faces a 30-day public comment period.
If approved, five companies could begin seismic surveying as early as this fall.
How the Arctic Ocean became saline
The results of the study have now been published in the journal Nature Communications.
Every year, ca.
Only once the land bridge between Greenland and Scotland disappeared did the first ocean passages emerge, connecting the Arctic with the North Atlantic and making water exchange possible.
Using a climate model, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now successfully simulated the effect of this geological transformation on the climate.
In their simulations, they gradually submerged the land bridge to a depth of 200 metres. “In reality, this tectonic submersion process lasted several million years,” says Climate Scientist Michael Stärz, first author of the study.
This threshold depth corresponds to the depth of the surface mixed layer, and determines where the relatively light Arctic surface water ends and the underlying layer of inflowing North Atlantic water begins. “Only when the oceanic ridge lies below the surface mixed layer can the heavier saline water of the North Atlantic flow into the Arctic with relatively little hindrance,” explains Stärz. “Once the ocean passage between Greenland and Scotland had reached this critical depth, the saline Arctic Ocean as we know it today was created.”
ScienceDaily, 6 June 2017.
Study finds a natural cause for early 20th century Arctic warming – but kowtows to CO2 in the present
Study finds a natural cause for early 20th century Arctic warming – but kowtows to CO2 in the present.
From the universities of Kyoto & San Diego comes this old tired catchphrase, along with a polar bear picture to go with the press release.
“We found that early 20th century sea surface temperatures in the tropical Pacific and North Atlantic had warmed much more than previously thought,” explains lead author Hiroki Tokinaga of Kyoto.
“Using observations and model simulations, we’ve demonstrated that rising Pacific-Atlantic temperatures were the major driver of rapid Arctic warming in the early 20th century.” Previous explanations for early Arctic warming have including decreased volcanic aerosols and increased solar radiation, but none of these have been able to simulate observed conditions from the period.
“It is likely that temperatures in the Arctic will continue to rise due to anthropogenic global warming,” concludes Tokinaga.
Careful monitoring is essential, given the enormous impact on the Arctic climate.” ### The paper “Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability” appeared 30 May 2017 in the Proceedings of the National Academy of Sciences of the United States of America, with doi: 10.1073/pnas.1615880114 Pacific North American circulation pattern links external forcing and North American hydroclimatic change over the past millennium Significance We have developed a new reconstruction of changes in the wintertime atmospheric circulation over North America based on data distributed across the region.
Our reconstruction shows that PNA has been strongly and consistently correlated with sea surface temperature variation, solar irradiance, and volcanic forcing over the period of record, and played a significant role in translating these forcings into decadal-to-multidecadal hydroclimate variability over North America.
Climate model ensembles show limited power to predict multidecadal variation in PNA over the period of our record, raising questions about their potential to project future hydroclimatic change modulated by this circulation pattern.
If the early 20th century Arctic warming was caused by ” this phenomenon occurred when the warming phase — ‘interdecadal variability mode’ — of both the Pacific and Atlantic Oceans coincided” but in the present you claim “It is likely that temperatures in the Arctic will continue to rise due to anthropogenic global warming,” concludes Tokinaga.
Why couldn’t “‘interdecadal variability mode’ — of both the Pacific and Atlantic Oceans” be the cause now?
Hot Seismic Testing to Begin in Atlantic Ocean in Push for Offshore Drilling
Source: EcoWatch The Interior Department announced it is moving forward with seismic surveys in the Atlantic Ocean, following President Donald
