Tag Archives: Arctic

Deep Ancient Water Is Stopping The Antarctic Ocean From Warming

Deep Ancient Water Is Stopping The Antarctic Ocean From Warming

The waters around the Antarctic may be one of the last places on Earth to feel the effects of man-made climate change. According to researchers at the University of Washington (UW) and the Massachusetts Institute of Technology (MIT), ancient seawater upwelling from the depths explainwhy the sea surface has remained roughly the same temperature while most of the planet has experienced temperature rises.

Using a combination of observations from floating ocean current trackers and cutting-edge computer simulations, the new Nature Geoscience study shows that this centuries-old seawater hasnt been to the surface since the dawn of the Industrial Revolution. Although the cooler waters around the Antarctic were previously blamed on ocean currents drawing sea surface heat down to the depths, it appears that cold water yet to experience the newly-warmed atmosphere is currently rising up to the surface.

With rising carbon dioxide you would expect more warming at both poles, but we only see it at one of the poles, so something else must be going on, the studys lead author Kyle Armour, a UW assistant professor of oceanography and of atmospheric sciences, said in a statement. We show that it’s for really simple reasons, andocean currentsare the hero here.

Observed warming over the past 50 years, as measured in degrees Celsius per decade. Its clear that the Southern Ocean has warmed by only a fraction, and it appears ocean currents are to blame for this unusual refrigeration mechanism. Kyle Armour/UW

Seawater from the deepest depths of the worlds oceans upwell at different times, and they do so when they become less dense than the water above them. This can happen for many reasons, including a reduction in salt concentrationor an influx of heat at depth, both of which make them more buoyant. On occasion, there can be a mechanical driver of seawater upwelling, such as persistent winds.

This is whats happening in the Southern Ocean, where extremely powerful westerly winds keep pushing warming surface water northwards; this gives the deeper, older water space to upwell into. The novel aspect of the waters here is that they have to upwell from depths of several thousand meters, far beyond the depths that most other oceanic currents reach. This means that it takes them an incredibly long time to reach the surface and interact with the atmosphere.

According to the models run by the team, the water only just beginning to reach the surface off the coast of Antarctica last experienced the Earths atmosphere centuries ago in the North Atlantic, before any serious man-made climate change had the chance to significantly heat it up. In fact, their simulations show that the oceanic currents that have experienced the most warming appear to be gathering at the North Pole, which also partly explains why Arctic sea ice is disintegrating so rapidly.

When we hear the term ‘global warming,’ we think of warming everywhere at the same rate, Armour added. We are moving away from this idea and more toward the idea of regional patterns of warming, which are strongly shaped by ocean currents.

The fact that Antarctic sea ice has been growing just as the Arctics has been disintegrating has baffled scientists for some time; irritatingly, this discrepancy is often cited by climate change deniers as proof that climatologists dont know what theyre talking about. It was only a matter of time before several explanations emerged, and this new study represents one of two corroborating theories helping to explain why the sea ice around Antarctica has been unexpectedly growing.

Photo Gallery

Read more: http://www.iflscience.com/environment/deep-ancient-water-stopping-antarctic-ocean-warming

Wreckage Of Sunken Whaling Ships Discovered Off Alaskan Coast

Wreckage Of Sunken Whaling Ships Discovered Off Alaskan Coast

The sunken remains of two ill-fated whaling ships have been found off the coast of Alaska, 144 years after they became crushed by pack ice, forcing all crew members to abandon their vessels. Though all were later rescued, the event marks one of the greatest catastrophes in the history of U.S whaling, and resulted in the loss of an entire fleet of 33 ships.

Back in the 18th and 19th centuries, whale oil was used around the world for heating, candle wax, soap, and a number of other purposes. As such, whaling was pretty big business, and attracted fleets from across the world to the Arctic each summer, when the ice relented and several species of whales migrated northwards.

However, the conditions at the top of the world can be unpredictable, as this particular fleet discovered to their peril in September 1871, when their ships became trapped in ice before they had a chance to manoeuvre away. Since the disaster, various artefacts from the sunken vessels have been discovered floating in the sea or washed up on the shore. Andresearchers have now located two of the ships for the first time.

Using sonar and other submarine-sensing equipment, a team of archaeologists from the National Oceanic and Atmospheric Association (NOAA) surveyed the waters along a 48-kilometer (30-mile) stretch of coastline near Wainwright, Alaska. In doing so, they were able to plot the outline of two flattened hulls, along with other items such as anchors, ballast and blubber-boiling equipment.

The researchers found anchors, rigging equipment, and other structural features of the sunken ships. NOAA

Until now, attempts to uncover the downed fleet had been thwarted by the thick layer of pack ice that covers much of the Arctic for large periods of the year, although a steady decrease in the amount of ice present during the height of summer over the past four decades has opened up new opportunities for conducting the search. As a consequence, the team was finally able to locate the ships last September, when the Arctic sea ice reaches its yearly minimum.

Reacting to the exciting discovery, project co-director Bad Barr said in a statement: This exploration provides an opportunity to write the last chapter of this important story of American maritime heritage and also bear witness to some of the impacts of a warming climate on the regions environmental and cultural landscape, including diminishing sea ice and melting permafrost.

Photo Gallery

Read more: http://www.iflscience.com/editors-blog/wreckage-sunken-whaling-ships-discovered-alaskan-coast

Scientists Think Rivers Of Liquid Nitrogen Once Flowed On Pluto

Scientists Think Rivers Of Liquid Nitrogen Once Flowed On Pluto

There are tropics on Pluto. While this may sound counterintuitive, its climate means that there are warmer parts of the world relative to its colder, arctic regions. As new research presented at the 2016 Lunar and Planetary Science Conferencethis week reveals, this diverse climate means that rivers and lakes of liquid nitrogen are likely to form at the surface.

Even with less than half of New Horizons data, scientists are unravelling more and more secrets about the dwarf planet by the day. The latest comes by way of researchers at NASAwho confirm that Pluto despite being on average 5.9 billion kilometers (3.7 billion miles) away from the Sun has seasons.

The central tropical region of Pluto, from 60 north to 60 south, experiences the Sun passing directly overhead. Its arctic region above 30 north experiences prolonged sunlight in the summer months, whilst the arctic region beneath 30 south is utterly frigid in a simultaneous winter.

Pluto is tipped over on its rotational axis at 120, rather wonky compared to Earths 23 tilt. As a result of this, during a northern arctic summer, the region receiving the most heat is its north pole.

Go home Pluto, youre drunk: The extreme axial tilt of the dwarf planet. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The dwarf planet wobbles and shakes on its axis as it orbits the Sun just like Earth does, meaning that these arctic regions advance and retreat over cycles of hundreds of thousands of years. One region, however, never experiences arctic climates.

This band, between 13 N and 13 S, appears to have been gouged out, in that theres a dark, deep stripe compared to the rest of the planet. The researchers think that the constant warm band here means that ice and volatiles compounds that evaporate at low temperatures couldnt accumulate here under the Suns constant bombardment.

The dark equatorial band. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Incidentally, the icy worlds elliptical orbit means that it moves between 50 Earth-Sun distances at its furthest point from the Sun and 30 Earth-Sun distances at its nearest point. Consequently, the temperature difference between a distant summer and a closer summer are more extreme than almost anywhere else.

This is all still relative, mind you: a summertime peak temperature is still around -200C (-330F). As Pluto takes 248 Earth years to rotate around the Sun, these summers and winters last for more than a century.

A second paper presented at the conference reveals that Plutos atmospheric pressure has varied wildly over its history, driven by these long-term orbital and rotational changes. It has ranged from about one-ten-thousandth right up to up to one-fifth of Earths.

These enormous changes in atmospheric pressure would have a distinct effect on the surface of the world; at higher pressures, the abundant nitrogen at the surface would remain a liquid instead of a gas. This means rivers, floods and lakes of liquid nitrogen may haved existed on Pluto.

Researchers noted that these features would be relatively common around 800,000 years ago, when temperatures were hot enough to lead to widespread melting. There may be some still around today near the equatorial region, although they have yet to be spotted. Frozen lakes, however, have been seen, and these ice reservoirs were almost certainly once liquid.

An enhanced color image of Pluto highlighting its wildly varying geological features. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Pluto is the gift that just keeps on giving, it seems. A plethora of papers have recently revealed that Plutos atmosphere isnt disintegrating as much as we previously thought, and most significantly, the surface is active essentially meaning that mountain building and perhaps cryovolcanism is still happening on this distant, icy sphere.

Above is a video of the research presented from the LPSC.

Photo Gallery

Read more: http://www.iflscience.com/space/pluto-has-rivers-liquid-nitrogen-extreme-seasons-and-chaotic-atmosphere

Why Arctic Melting Will Be Erratic In The Short Term

Why Arctic Melting Will Be Erratic In The Short Term

 

rctic sea ice melts each summer, reaching its minimum extent sometime in September, before refreezing through the winter. Over the past 35 years, the September sea ice extent has reduced by about 35% overall and this decline is projected to continue as global temperatures increase.

In 2007 and 2012 the summer ice extent was dramatically lower, causing some some media speculation that we would soon see a summer which was “ice-free” (meaning a year with less than 1 million km2 of sea-ice).

Most climate scientists were more cautious. The weather in 2007 and 2012 was warmer than usual and the winds were particularly favourable for melting sea ice. Although human influence on Arctic sea ice has been detected, there was no evidence that these weather patterns would continue each year.

In contrast, 2013 and 2014 had more sea ice than 2012, causing other speculation that a recovery was underway. Is this claim warranted?

The figure below shows Arctic sea ice extent (the black line) has undergone a long-term decrease, with the dashed line representing a linear trend. But there have also been shorter periods of rapid melt, no change, and apparent increases in extent during this decline – represented below by coloured trend lines for some deliberately chosen eight year periods.

 

Satellite observations of September Arctic sea ice extent. Ed Hawkins/University of Reading

The most recent eight-year period, starting from the extreme low of 2007, shows an upward trend. This does not mean that the Arctic sea ice is recovering. As with global temperature, these erratic changes are what we expect to see.

Bouncing Towards An Ice-Free Summer

Imagine a ball bouncing down a bumpy hill. Gravity will ensure that the ball will move downwards. But if the ball hits a bump at a certain angle it might move horizontally or even upwards for a time, before resuming its inevitable downward trajectory. This bouncing ball is an analogy for the changing Arctic sea ice.

The hill represents the long-term downward trend in Arctic sea ice due to increasing global temperatures and the bumps introduce changes from this smooth trajectory. These erratic bounces could be in either direction, causing an apparent acceleration or temporary reduction in melt rate. By only examining a small part of the trajectory you might conclude that the ball was moving against gravity. A longer term view would see it as a bounce.

There is no expectation that sea ice, or any other aspect of the climate, will change smoothly over time. The climate system simply does not work that way. Previous studies have suggested that natural climate variations (or “bounces”) play a key role in how sea ice evolves, and suggested that some of the rapid melt in the early 2000s was a temporary acceleration.

 

September minimum, 1984 and 2012. NASA

A new study I co-authored with a team of Canadian and American scientists, published in Nature Climate Change, highlights that the recent slower melt is a temporary, but not unexpected, deceleration. The complex climate models used to make projections of future climate also exhibit similar periods of little change and more rapid change in Arctic sea ice. The recent trends are well within the range of these expectations. We might even see a decade or more with little apparent change in sea ice.

The causes of these fluctuations in melt rate are still being explored. One suggestion is that slow variations in Atlantic sea surface temperatures are involved. More observations of the Arctic ocean, atmosphere and sea ice would help answer this question.

An Ice-Free Future?

When will the Arctic be ice-free – or equivalently, when will the ball reach the bottom of the hill? The IPCC concluded it was likely that the Arctic would be reliably ice-free in September by 2050, assuming high future greenhouse gas emissions (where “reliably ice-free” means five consecutive years with less than 1 million km2 of sea ice).

We expect the long-term decline in Arctic sea ice to continue as global temperatures rise. There will also be further bounces, both up and down. Individual years will be ice-free sometime in the 2020s, 2030s or 2040s, depending on both future greenhouse gas emissions and these natural fluctuations.

Even when it reaches the bottom of the hill the ball will continue to bounce. Similarly, not every future year will be ice-free in summer. But if global temperatures continue to increase the bounces will become smaller and the ice-free periods will spread from late summer into autumn and early summer.

Commercial Arctic shipping is already increasing to exploit shorter journey times from Europe to Asia, while oil, gas & mineral extraction possibilities are being explored and Arctic tourism is growing. Decisions about such activities need to assess both the risks and opportunities. The important role of natural sea ice fluctuations needs to be considered in such assessments.

The Conversation

Read more: http://www.iflscience.com/environment/why-arctic-melting-will-be-erratic-short-term

Polar Bears Face Starvation And Cub Loss Due To Sea Ice Loss

Polar Bears Face Starvation And Cub Loss Due To Sea Ice Loss

The future is not looking bright for polar bears living in Canada’s Arctic islands. If the current climate trend continues to the end of the century, sea ice decline will mean that many areas are no longer able to support polar bears, a depressing new study has found. With an absence of ice for several months a year, polar bears may face losing their cubs and starvation, leaving a rather bleak outlook for this population. The work has been published in the open access journal PLOS ONE.

The world is warming up, and it’s having devastating impacts on ecosystems. Among those areas feeling the heat is the Arctic, which has lost an average of 54,000 square kilometers (20,800 square miles) of ice every year since the late 1970s. This year, the sea ice extent in this region was the sixth lowest on record.

These losses dramatically change Arctic marine ecosystems, making marine mammals particularly susceptible to the effects of rising temperatures. Polar bears, in particular, are very sensitive to losses in sea ice because it serves as a platform for hunting seals and mating. If they can’t get enough food in their bellies, they won’t have sufficient energy reserves to survive the lean months. Furthermore, climate change may mean that some seal habitats are no longer viable, further reducing the availability of food.

To gain a better understanding of how climate change may affect polar bear populations, researchers from the University of Alberta used a regionally focused climate model to project sea ice changes in the Canadian Arctic Archipelago. This area is home to a quarter of the world’s polar bears, despite only covering 9% of the global polar bear range. Currently, sea ice is constantly present throughout the year.

They predict that towards the end of the century, the vast majority of the archipelago could experience early ice break up, which would leave regions ice-free for two to five months every year. This would force pregnant females to retreat to land early, which could interfere with births. By 2010, females may lose between 55 to 100% of their cubs.

Furthermore, because long ice-free periods mean that polar bears likely will not be able to eat sufficient amounts of food, up to 1 in 5 adult bears and even more young and old bears could starve each year.

Although it’s difficult to say whether these predictions are reliable, areas are already experiencing sharp declines in polar bear numbers. The southern Beaufort Sea, for example, experienced a 25 to 50% decline in abundance between 2001 and 2010. However, extinction is not necessarily looming as efforts to reduce greenhouse gas emissions could mean that sea ice loss could begin to slow down. 

[Via PLOS ONE, New Scientist, The Star and WWF]

Read more: http://www.iflscience.com/plants-and-animals/polar-bears-face-starvation-and-cub-loss-due-sea-ice-loss