Showing posts with label currents. Show all posts
Showing posts with label currents. Show all posts

Tuesday, September 1, 2015

Arctic Sea Ice Collapse Threatens - Update 7

The image below shows Arctic sea ice extent, with the blue dot indicating that extent for August 30, 2015, was 4.804 million square kilometers. Satellite records shows that, at this time of the year, extent was only lower in 2007, 2011 and 2012.


There are a number of reasons why sea ice looks set to decrease dramatically over the next few weeks. On above image, extent for 2015 looks set to soon cross the lines for the years 2007 and 2011, while the sea ice today is in an even worse condition than one might conclude when looking at extent alone.

Thick sea ice is virtually absent compared to the situation in the year 2012 around this time of year, as illustrated by the image below that compares sea ice thickness on August 30, 2012 (left) with August 30, 2015 (right).


Furthermore, sea surface temperatures are very high. The North Pacific, on August 31, 2015, was about 1°C (1.8°F) warmer than it was compared to the period from 1971 to 2000, as illustrated by the Climate Reanalyzer image on the right.

As the image below shows, sea surface temperature anomalies are very high around North America, both in the Pacific Ocean and in the Atlantic Ocean.

The image below shows sea surface temperatures on August 30, 2015, indicating that a huge amount of ocean heat has accumulated in the Atlantic Ocean off the coast of North America.


The Gulf Stream is carrying much of this warm water toward the Arctic Ocean. Additionally, warm water from the Pacific Ocean is entering the Arctic Ocean through the Bering Strait.


Above image below shows sea surface temperature anomalies in the Arctic as at August 31, 2015.




There still are a few weeks to go before sea ice can be expected to reach its minimum, at around half September 2015, while sea currents will continue to carry warmer water into the Arctic Ocean for months to come.

There is a strengthening El Niño, while more open water increases the chance that storms will develop that will push the last remnants of the sea ice out of the Arctic Ocean, as discussed in earlier posts such as this one. Storms can also mix warm surface waters all the way down to the seafloor, as discussed in this earlier post. Typhoons increase this danger. The above image show three typhoons in the Pacific Ocean on 30 August, 2015, and the Climate Reanalyzer image on the right shows them on September 1, 2015.

These typhoons are headed in the direction of the Arctic. The Climate Reanalyzer forecast for September 8, 2015, below shows typhoons in the Pacific Ocean close to the Arctic Ocean, as well as strong wind over the Arctic Ocean.


The situation is dire and calls for comprehensive and effective action, as discussed in the Climate Plan.

Thick sea ice is virtually absent compared to the situation in the year 2012 around this time of year....
Posted by Sam Carana on Tuesday, September 1, 2015

Tuesday, August 18, 2015

Disappearance Of Thick Arctic Sea Ice

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Arctic sea ice is in a horrible state. On August 16, 2015, Arctic sea ice extent was 5.786 million square km, the smallest extent on record for this time of year except for the years 2007, 2011 and 2012, as illustrated by the image on the right.

The situation today is even worse than one might conclude when looking at sea ice extent alone. Thick sea ice is virtually absent compared to the situation in the year 2012 around this time of year, as illustrated by the image below comparing sea ice thickness on August 16, 2012 (left) with August 16, 2015 (right).


The ice used to be over 4 m thick, or over 13 ft thick, north of Greenland and the Canadian Archipelago. This thick multi-year ice has been a feature of the Arctic sea ice for over 100,000 years. It used to be there all year long, unlike the thinner ice that could melt away entirely during the melting season.

The disappearance of this thick multi-year ice is a major development. Why? Until now, the thicker multi-year sea ice used to survive the melting season, giving the sea ice strength for the next year, by acting as a buffer to absorb heat that would otherwise melt away the thinner ice. Without multi-year sea ice, the Arctic will be in a bad shape in coming years, and huge amounts of heat that would otherwise go into melting the ice will instead be warming up the Arctic Ocean, further accelerating warming of its waters.

Absence of thick sea ice makes it more prone to collapse, and this raises the question whether the sea ice could collapse soon, even this year. Sea ice works like a mirror. Without sea ice, sunlight that was previously reflected back into space, will instead be absorbed by the Arctic. Albedo changes in the Arctic alone could more than double the net radiative forcing resulting from the emissions caused by all people of the world, as calculated by Prof. Peter Wadhams back in 2012.

Furthermore, there is a danger that loss of the sea ice will weaken the currents that currently cool the bottom of the sea, where huge amounts of methane may be present in the form of free gas or hydrates in sediments. This danger is illustrated by the image below by Reg Morrison, from an earlier post.


Absence of sea ice also goes hand in hand with opportunities for storms to develop over the Arctic Ocean. Such storms could push the remaining sea ice out of the Arctic Ocean. Such storms could also mix surface heat all the way down to the seafloor, where methane could be contained in sediments.

As described in an earlier post, sea surface anomalies of over 5 degrees Celsius were recorded in August 2007 (NOAA image right). Strong polynya activity caused more summertime open water in the Laptev Sea, in turn causing more vertical mixing of the water column during storms in late 2007, as described in this study, and bottom water temperatures on the mid-shelf increased by more than 3 degrees Celsius compared to the long-term mean.

Indeed, the danger is that heat will warm up sediments under the sea, containing methane in hydrates and as free gas, causing large amounts of this methane to escape rather abruptly into the atmosphere.

The image on the right, from a study by Hovland et al., shows that hydrates can exist at the end of conduits in the sediment, formed when methane did escape from such hydrates in the past.

Heat can travel down such conduits relatively fast, warming up the hydrates and destabilizing them in the process, which can result in huge abrupt releases of methane.

Since waters can be very shallow in the Arctic, much of the methane can then rise up through these waters without getting oxidized. As the methane causes further warming in the atmosphere, this will contribute to the danger of even further methane escaping, further accelerating local warming, in a vicious cycle that can lead to catastrophic conditions well beyond the Arctic. For additional feedbacks in the Arctic, see the feedbacks page

At the same time, ocean heat is at a record high and there's an El Niño that's still gaining strength. This ocean heat is likely to reach the Arctic Ocean in full strength by October 2015, at a time when sea ice may still be at its minimum. The image below shows sea surface temperatures on August 16, 2015 (left) and anomalies (right).


How warm is the water entering the Arctic Ocean? Merely looking at sea surface temperatures could make one overlook the full extent of the predicament we are in. Ocean heat traveling underneath the sea surface can be even warmer than temperatures showing up at the surface. This is illustrated by the image below indicating that on August 16, 2015, warm water emerged at the sea surface near Svalbard with temperatures as high as 14.9°C or 58.7°F, a 9.5°C or 17.1°F anomaly.


There still is about a month to go before sea ice can be expected to reach its minimum, at around half September 2015, while sea currents will continue to carry warmer water into the Arctic Ocean for months to come.

The situation is dire and calls for comprehensive and effective action, as discussed in the Climate Plan


Thick sea ice is virtually absent compared to the situation in the year 2012 around this time of year, as illustrated by...
Posted by Sam Carana on Tuesday, August 18, 2015

Sunday, February 22, 2015

Multiple Benefits Of Ocean Tunnels

By Sam Carana and Patrick McNulty

Comprehensive climate action will do more than just cutting emissions, it will also take further action, as pictured in the image below.

Comprehensive and effective action is discussed at the Climate Plan blog
Taking a broad perspective makes it easier for proposed projects to be assessed on their benefits in a multitude of areas.

Ocean tunnels can capture vast amounts of energy from ocean currents, such as the Gulf Stream and the Kuroshio Current. These locations are close to areas with high energy demand, such as the North American East Coast and the coast of East Asia, which can reduce the need for long distance transmission lines.

Ocean tunnels provide clean energy continuously, i.e. 24 hours a day, all year long. This makes that they can satisfy demand for electricity both at peak and off-peak usage times.

  • Their ability to supply large amounts of electricity at times of peak demand will benefit the necessary transition from polluting to clean ways of generating electricity.
  • Their ability to also supply large amounts of electricity at off-peak usage times will help to reduce the price of electricity at such times, thus opening up opportunities for a number of activities that can take place at off-peak hours and that require large amounts of energy.

    Such activities include large-scale grinding of olivine rock and transport of the resulting olivine sand, and large-scale production of hydrogen through electrolysis to power transport (box right). Electrolysis can also create oxygen-enriched water that can improve the quality of waters that are oxygen-depleted.  
Hydrogen to power Shipping

Ocean tunnels can make electricity cheap at off-peak times. This will reduce the cost of recharging batteries of electric vehicles at night.

It will also reduce the cost of producing hydrogen at off-peak hours. To power ships crossing the oceans, hydrogen looks more cost-effective, as such ships cannot return to base for a nighly battery recharge. Such ships have plenty of cargo space to carry hydrogen, even when the hydrogen is not highly compressed. Some of the world's largest ports are close to strong ocean currents.



Ocean tunnels can generate electricity in two ways, i.e. by capturing the kinetic energy contained in the flow of ocean currents, and by means of Ocean Thermal Energy Conversion (OTEC) using temperature differences between cooler deeper parts of the ocean and warmer surface waters to run a heat engine to produce energy.

Besides generating energy, ocean tunnels can assist with further activities, which will increase the value of ocean tunnels in the fight against climate change. Such activities include the following:
  • By reaching deeper parts of the ocean, OTEC can pull up sunken nutrients and put them out at surface level to fertilize the waters there, while the colder water that is the output of OTEC will float down, taking along newly-grown plankton to the ocean depths before it can revert to CO2, as described in the earlier post Using the Oceans to Remove CO2 from the Atmosphere.
  • Ocean tunnels can be used to distribute olivine sand in the water. The force of the currents and the turbines will help the process of transforming olivine into bicarbonate. This can reduce carbon dioxide levels in the water by sequestering carbon, while also reducing ocean acidification. Olivine sand contains silicate and small amounts of iron, allowing diatoms to grow that will capture additional carbon dioxide, while also raising levels of free oxygen in the water. The latter will stimulate growth of microbes that break down methane in the water before it reaches the atmosphere. Further nutrients can be added, as also discussed in this earlier post
  • Ocean tunnels can also assist with albedo changes. Ocean tunnels can act as the infrastructure to create water microbubbles along their track. Increasing water albedo in this way can reduce solar energy absorption by as much as 100 W m − 2, potentially reducing equilibrium temperatures of standing water bodies by several Kelvins, as Russel Seitz wrote back in 2010. There may also be potential for ocean tunnels to be used to spray water vapor into the air with the aim of brightening clouds over areas where it counts most.
  • The turbines in tunnels will also reduce the flow of ocean currents somewhat, thus reducing the flow of warm water into the Arctic. Furthermore, tunnels can be shaped in ways to guide the flow of warm water away from the Arctic Ocean down a southwards course along the Canary Current along the coast of West Africa. thus diverting warm water that would otherwise end up in the Arctic Ocean. This could also reduce the chance of hurricanes hitting the east coast of North America, as Sandy did in 2012.
The Gulf Stream, carrying warm water all the way into the Arctic Ocean

The video below is narrated by Dave Borlace and describes Ocean Mechanical Thermal Energy Conversion, the method conceived and developed by Patrick McNulty to generate electricity while cooling the ocean surface in the path of ocean currents such as the Gulf Stream.