Antarctic ocean heating up – caused by greenhouse gas emissions and ozone depletion

September 26, 2018 Posted by Christina MacPherson | ANTARCTICA, climate change | Leave a comment

Sea levels could rise by up to 30 feet, due to Antarctic melting

At this rate, Earth risks sea level rise of 20 to 30 feet, historical analysis shows  New research finds that a vast area of Antarctica retreated when Earth’s temperatures weren’t much warmer than they are now, WP  Chris Mooney, September 20  2018

Temperatures not much warmer than the planet is experiencing now were sufficient to melt a major part of the East Antarctic ice sheet in Earth’s past, scientists reported Wednesday, including during one era about 125,000 years ago when sea levels were as much as 20 to 30 feet higher than they are now.

“It doesn’t need to be a very big warming, as long as it stays 2 degrees warmer for a sufficient time, this is the end game,” said David Wilson, a geologist at Imperial College London and one of the authors of the new research, which was published in Nature. Scientists at institutions in Australia, New Zealand, Japan and Spain also contributed to the work.

The research concerns a little-studied region called the Wilkes Subglacial Basin, which is roughly the size of California and Texas combined and contains more than 10 feet of potential sea-level rise. Fronted by three enormous glaciers named Cook, Mertz and Ninnis, the Wilkes is known to be vulnerable to fast retreat because the ice here is not standing on land and instead is rising up from a deep depression in the ocean floor.

Moreover, that depression grows deeper as you move from the current icy coastline of the Wilkes farther inland toward the South Pole, a downhill slope that could facilitate rapid ice loss.

What the new science adds is that during past warm periods in Earth’s history, some or all of the ice in the Wilkes Subglacial Basin seems to have gone away. That’s an inference researchers made by studying the record of sediments in the seafloor just off the coast of the current ice front……..

Humans have caused about 1 degree Celsius (1.8 degrees Fahrenheit) of warming above the preindustrial planetary temperatures experienced before the year 1880 or so. The world has pledged to avoid a warming above 2 degrees Celsius, and even hopes to hold the warming to 1.5 degrees, but current promises made by countries are not nearly enough to prevent these outcomes.

n other words, we are already on a course that could heat the planet enough to melt some or all of the Wilkes Basin.

“We say 2 degrees beyond preindustrial, and we’re already beyond preindustrial,” Wilson said. “So this is potentially the kinds of temperatures we could see this century.”

The study cannot reveal, however, just how quickly ice emptied out of the Wilkes Basin. The past warm periods in question are thought to have been driven by slight variations in Earth’s orbit as it rotates around the sun, leading to stronger summer heat. That warmth was maintained for thousands of years.

…….. The new research “contributes to the mounting pile of evidence that East Antarctica is not as stable as we thought,” Isabella Velicogna, a glaciologist at the University of California at Irvine, said by email. Velicogna was not directly involved in the paper…….https://www.washingtonpost.com/energy-environment/2018/09/20/antarctica-warming-could-fuel-disastrous-sea-level-rise-study-finds/?utm_term=.7c426ea2a985

September 21, 2018 Posted by Christina MacPherson | ANTARCTICA, climate change | Leave a comment

Antarctica – so remote, but so significant in climate science

Why remote Antarctica is so important in a warming world  The Conversation.December 4, 2017 Chris Fogwill, Professor of Glaciology and Palaeoclimatology, Keele University, Chris Turney, Professor of Earth Sciences and Climate Change, UNSW, Zoe Robinson, Reader in Physical Geography and Sustainability/Director of Education for Sustainability, Keele University

“……..What was once thought to be a largely unchanging mass of snow and ice is anything but. Antarctica holds a staggering amount of water. The three ice sheets that cover the continent contain around 70% of our planet’s fresh water, all of which we now know to be vulnerable to warming air and oceans. If all the ice sheets were to melt, Antarctica would raise global sea levels by at least 56m.

Where, when, and how quickly they might melt is a major focus of research. No one is suggesting all the ice sheets will melt over the next century but, given their size, even small losses could have global repercussions. Possible scenarios are deeply concerning: in addition to rising sea levels, meltwater would slow down the world’s ocean circulation, while shifting wind belts may affect the climate in the southern hemisphere.

1. In 2014, NASA reported that several major Antarctic ice streams, which hold enough water to trigger the equivalent of a one-and-a-half metre sea level rise, are now irreversibly in retreat. With more than 150m people exposed to the threat of sea level rise and sea levels now rising at a faster rate globally than any time in the past 3,000 years, these are sobering statistics for island nations and coastal cities worldwide.
   

   An immediate and acute threat

   Recent storm surges following hurricanes have demonstrated that rising sea levels are a future threat for densely populated regions such as Florida and New York. Meanwhile the threat for low-lying islands in areas such as the Pacific is immediate and acute.

2. Multiple factors mean that the vulnerability to global sea level rise is geographically variable and unequal, while there are also regional differences in the extremity of sea level rise itself. At present, the consensus of the IPPC 2013 report suggests a rise of between 40 and 80cm over the next century, with Antarctica only contributing around 5cm of this. Recent projections, however, suggest that Antarctic contributions may be up to ten times higher.Studies also suggest that in a world 1.5-2°C warmer than today we will be locked into millennia of irreversible sea level rise, due to the slow response time of the Antarctic ice sheets to atmospheric and ocean warming.

   We may already be living in such a world. Recent evidence shows global temperatures are close to 1.5°C warmer than pre-industrial times and, after the COP23 meeting in Bonn in November, it is apparent that keeping temperature rise within 2°C is unlikely.

3. So we now need to reconsider future sea level projections given the potential global impact from Antarctica. Given that 93% of the heat from anthropogenic global warming has gone into the ocean, and these warming ocean waters are now meeting the floating margins of the Antarctic ice sheet, the potential for rapid ice sheet melt in a 2°C world is high.In polar regions, surface temperatures are projected to rise twice as fast as the global average, due to a phenomenon known as polar amplification. However, there is still hope to avoid this sword of Damocles, as studies suggest that a major reduction in greenhouse gases over the next decade would mean that irreversible sea level rise could be avoided. It is therefore crucial to reduce CO₂ levels now for the benefit of future generations, or adapt to a world in which more of our shorelines are significantly redrawn.

   This is both a scientific and societal issue. We have choices: technological innovations are providing new ways to reduce CO₂ emissions, and offer the reality of a low-carbon future. This may help minimise sea level rise from Antarctica and make mitigation a viable possibility.

   Given what rising sea levels could mean for human societies across the world, we must maintain our longstanding view of Antarctica as the most remote and isolated continent. https://theconversation.com/why-remote-antarctica-is-so-important-in-a-warming-world-88197

December 6, 2017 Posted by Christina MacPherson | ANTARCTICA, climate change | Leave a comment

An immense glacier is melting, in Antarctica

UNFROZEN IN TIME, Huffington Post, Video and Pictures: Tom Compagnoni | Words: Josh Butler, 1 December 17 There’s a glacier in Antarctica so immense that, if it melted, would raise sea levels globally by 3.5 metres.

It’s melting. Right now.

“The facts around climate change are undeniable. It’s happening,” Australian glaciologist Ben Galton-Fenzi told The Huffington Post Australia. “The research we do now isn’t about trying to convince ourselves it’s real, because it’s irrefutable. What we’re trying to do is understand what the response time of the system is going to be into the future, so we can adapt to it.”

The Totten glacier is the biggest in east Antarctica. The glacier itself is around 120 kilometres long, 30 kilometres wide and drains some 538,000 square kilometres of the continent. That’s an area bigger than California. The ice is kilometres thick, but it’s melting at 70 metres a year in some spots. A study released in December reported warmer water was melting the Totten ice from below.

Galton-Fenzi and his small team will spend the next few months trying to work out exactly how fast the glacier is melting, gathering data to build better models to predict melt rates and how that will affect sea levels.

“The majority of the heat that has gone into the global climate system has gone into the ocean, about 90 percent over the last few decades of measurements,” he said. “The hypothesis is ocean temperatures around Antarctica will keep warming and drive the melting of the glaciers. If the glaciers flow faster, sea levels will rise, and that has profound implications for global civilisation.”……..“Climate change is a reality. There’s the whole debate around how we deal with it, and the work we do in Antarctica is influencing our ability to look forward and genuinely understand how much things are going to change,” Australian Antarctic Division director, Dr Nick Gales told HuffPost Australia from Hobart, the base of operations for the AAD.

“It is alarming. There is huge change going on there. The more we learn, the more we see change happening at rates faster than we predicted. It’s fundamentally important to support the science, communicate the science really well, and make sure the policy makers are aware of the science so they can take account of that in forming mitigation and adaptation strategies around the world.”
The AAD is the government body that administers Australian operations in Antarctica, from delivering workers and equipment to the continent, to selecting the research applications to be undertaken each season, to making sure the kitchen at Casey is well stocked with chocolate.

“When we started doing science in Antarctica, it was important and interesting because we were learning about things we simply didn’t know about.”

“Nowadays, the science is really critically important to what we do in the future.”

It’s critical to our wellbeing and our ability to understand what’s coming, and adapt and mitigate the effects. What about the droughts? Are they going to become more regular? What will happen to our low-lying areas and Pacific islands in relation to sea level rise? The science we do is critical for informing that.”This season, the AAD will support almost 100 projects in Antarctica and the Southern Ocean. More than 500 expeditioners will make their way down each year for major “season-defining” projects such as Galton-Fenzi’s Totten glacier work, and smaller-scale operations. Gales said around two-thirds of the Australian-led research in Antarctica is related to climate science.

It is a continent almost entirely covered by ice, the largest ice sheet in the world and the planet’s largest single reserve of fresh water. It’s almost entirely untouched by humans, uninhabited but for the research teams (and a whole lot of amazing animal life, as we soon discovered); a continent literally devoted to science.

The 1959 Antarctic treaty, signed by the 12 countries which had been active in Antarctica — Argentina, Australia, Belgium, Chile, France, Japan, New Zealand, Norway, Russia, South Africa, the United Kingdom and United States — agreed to set aside territorial claims and enshrine the continent as a place for peace, science and international collaboration. Scientists work together, sharing resources, manpower and findings, for the good of humanity under this treaty, which states:

– Antarctica shall be used for peaceful purposes only (Art. I)
– Freedom of scientific investigation in Antarctica and cooperation toward that end … shall continue (Art. II).
– Scientific observations and results from Antarctica shall be exchanged and made freely available (Art. III).

“It’s unique. It’s extraordinary that, in a place like that, the world can agree to set aside differences and focus on those really important issues,” Gales said………
Johnstone and Black are cutting through the frozen sea ice for experiments on ocean acidification. As the Earth continues to emit carbon dioxide, the oceans soak up a large percentage of that extra CO2; around 30 percent, Black said.

Rob King, an AAD biologist based in Hobart, said around eight billion tonnes of CO2 is going into oceans each year.

“It increases the acidity of the ocean and lowers the pH. The global ocean average is about 8.2pH, and we’re expecting by the year 2100 with the current emissions scenarios we have, the pH will drop to 7.8,” Black said.
That’s a massive change for the ocean, with the water becoming far more acidic. That’s bad news for many tiny organisms and plankton that make up the bottom of the oceanic food chain, upon which larger creatures like penguins, fish, dolphins, seals, sharks and whales depend. Black and Johnstone have planted tiny chambers on the ocean floor to simulate how the water and the organisms will react to more acidic waters. They will also collect water and loads of these tiny organisms for experiments in the lab.

“As we acidify the water, anything with a calcium carbonate structure in its shell, like shellfish, pteropods and other organisms, will actually have trouble forming that shell and maintaining it,” Black said.

“When we look at the relative biomass of different organisms, we get about 600 million tonnes of phytoplankton down here. That’s the most biomass of any organism in the Southern Ocean. While they seem small and insignificant, they are the most important part of the ecosystem. Any change in that under climate change conditions will have flow on effects up the food chain.”……….
“Under the sea ice you’ve got a really stable environment. It’s always the same temperature, even though it’s a really harsh temperature of minus 1.85C all year, but it doesn’t vary much so they only have to adapt to one temperature,” the marine biologist said.’

“There’s very little current under here, because for 10 months of the year, there’s a covering of sea ice. They don’t have to deal with big tidal currents or waves or storms or wind action, or temperature changes. The conditions are relatively stable through the year.”

The word ‘frozen’ is often used to denote something which has stopped; static, not moving. It is synonymous with lifelessness, death, a barren wasteland. Antarctica is a frozen continent, but it is by no means dead. It grows and shrinks like a living organism. With the yearly melt and refreeze, as the continent effectively doubles in size during the winter as sea water becomes ice, it is arguably the most alive continent on Earth. The life that exists down here — human, animal and plant alike — is some of the hardiest, most resilient on the planet. It’s an entire continent devoted to peace and science, to work for the betterment of the entire planet.

It’s alive with purpose………. http://stories.huffingtonpost.com.au/antarctica/

December 2, 2017 Posted by Christina MacPherson | ANTARCTICA, climate change | Leave a comment