Arctic Sea Ice Collapse Threatens - Update 9

The image below shows that Arctic sea ice had reached a level of 4.45 million square kilometers on September 16, 2015 (end of dark blue line at center of image).

NSIDC has meanwhile called the 2015 minimum, but the first sentence of their post hastens to add that on September 11, Arctic sea ice reached its likely minimum for 2015,  at 4.41 million square kilometers (1.70 million square miles), putting 2015 in the fourth lowest place since satellite records began. Arctic sea ice minimum was lower only in 2012 (dotted line), 2007 (light blue line) and 2011 (orange line). Sea ice extent was 4.413 million square kilometers both on September 9, 2015, as well as on September 10 and 11, 2015.

September 9 would be early for the sea ice to reach its minimum, as a comparison with earlier years on above image illustrates. The dark blue line on above image shows that sea ice extent fell slightly on September 16, compared to the day before, and is now below the 2011 extent (orange line) for this time of the year. Over the next few days, sea ice extent may well fall somewhat further, and reach a level below the 2011 minimum, thus reaching the third lowest minimum extent since record began. This could eventuate due to winds compacting the sea ice.

More importantly, sea ice thickness is still falling, as illustrated by the image below showing the sea ice thickness on September 9 in the left panel and a forecast for thickness on September 24 in the right panel.

The image below compares sea ice thickness between September 24, 2012 (left panel) with that forecast for September 24, 2015 (right panel).

Above image illustrates why the situation in 2015 is even more threatening than it was in 2012. Only the ice that is colored light green, yellow and red is more than 3 meters thick. In 2015, ocean heat has been melting the sea ice from underneath. So, even while the currently lower temperatures of the air may have resulted in a slight increase in extent over the past week, the added ice is very thin. Ocean heat first of all goes into melting the thickest sea ice, i.e. the parts that are meters below the surface. This because the water at surface level is colder than the water underneath the surface. This explains why much of the water surface will remain covered by (very thin) ice as air temperatures are now falling (compared to air temperatures over the past few months).

The image below shows sea surface temperatures as at September 17, 2015.

In conclusion, while the sea ice appears to have survived the 2015 melting season without collapsing, the threat that this will occur in the coming years is ominous. Lack of multi-year sea ice makes that sea ice is in a very vulnerable situation. Total collapse of sea ice is therefore more likely to happen in the coming years. Every time ocean heat will arrive in the Arctic Ocean at its fullest strength in future, this heat will no longer be able to be fully absorbed by the process of melting thick sea ice, so what's left of the sea ice will melt very quickly.

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. Cyclones that emerge with greater force due to high sea surface temperatures further increase this danger.

The big danger is that ocean heat will cause methane contained in sediments on the Arctic Ocean seafloor to be released abruptly in large quantities, triggering further methane releases spiraling into runaway warming.

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

Below is a text-only version of this post for radio.

Sea ice thickness on September 24, 2012 (left panel) compared to a forecast for September 24, 2015 (right panel). This...
Posted by Sam Carana on Friday, September 18, 2015

3.27°C warmer by 2030?

Will it be 3.27°C warmer by the year 2030?

In December 2015, world delegates will descend on Paris to ensure that global warming will not cross the guardrail of 2°C above pre-industrial levels.

[ click on images to enlarge them ]

In a way, we have already crossed this guardrail. NOAA data show that the year-to-date land surface temperature was 1.47°C above the 20^th century average on the Northern Hemisphere in 2015, as illustrated by the image on the right.

Granted, there was less warming on the Southern Hemisphere, so the globally-averaged land surface temperature was a little bit lower, i.e. 1.34°C above the 20^th century average. For reference, the image below on the right gives an overview of mean 1901-2000 temperatures. Anyway, the difference between hemispheres is small and not very relevant since most people live on the Northern Hemisphere.

[ click on image to enlarge ]

More importantly, this 1.47°C rise is a rise compared to the 20^th century average. The 20^th century average was some 0.60°C higher than temperatures were at the start of the NOAA record in 1880. In other words, temperatures for most people on Earth are already 2.07°C higher than they were in 1880.

Furthermore, between 1750 and 1880 the global average temperature had already increased by some 0.20°C.

Sure, 2015 is an El Niño year, but this El Niño is still strengthening, so 2016 could well be even warmer. Moreover, recent temperatures are in line with expectations of a polynomial trendline that is based on these NOAA data and that points at yet another degree Celsius rise by 2030, on top of the current level, as illustrated by the top image. Altogether, this would make it 3.27°C warmer than in 1750 for most people on Earth by the year 2030.

So, instead of acting as if dangerous global warming could possibly eventuate beyond the year 2100, delegates in Paris should commit to lowering temperatures, starting now.

To lower temperatures, cutting emissions alone will not be enough.

Stopping all emissions by people would make that the aerosols that are currently sent up in the air by burning fuel and that are currently masking the full impact of global warming, will fall out of the air in a matter of weeks. Until now, about half of the global temperature rise is suppressed by such aerosols. Stopping aerosols release overnight could make temperatures rise abruptly by 1.20°C in a matter of weeks.

Furthermore, carbon dioxide that is emitted now will take ten years to reach its peak impact, so we're still awaiting the full wrath of carbon dioxide emitted over the past decade.

A recent study calculates that global mean surface temperature may increase by 0.50°C after carbon emissions are stopped, and they will decrease only minimally from that level for the next 10,000 years.

Removing carbon dioxide from the atmosphere would not work fast enough to avoid further warming and acidification of the oceans. In fact, temperatures look set to rise even faster as feedbacks start to kick in more fully, such as albedo changes due to decline of the snow and ice cover in the Arctic and methane releases from the Arctic Ocean seafloor. Furthermore, water vapor will increase by 7% for every 1°C warming. Water vapor is one of the strongest greenhouse gases, so increasing water vapor will further contribute to a non-linear temperature rise.

In conclusion, the world needs to commit to comprehensive and effective action that includes both emission cuts and removal of greenhouse gases from the atmosphere and oceans, as well as further action to deal with the dire situation in the Arctic, as discussed at the Arctic-news Blog.

In December 2015, world delegates will descend on Paris to ensure that global warming will not cross the guardrail of 2°...
Posted by Sam Carana on Thursday, September 10, 2015

Arctic Sea Ice Collapse Threatens - Update 8

The image below, from Arctic-roos.org, shows Arctic sea ice extent up to September 6, 2015.

Editorial note: The dramatic drop in sea ice extent shown on the image below turns out to be an error. The website at Arctic-roos.org is being updated and will show the correct extent soon.

The image shows a recent drop in sea ice extent that is so dramatic (red line, i.e. extent for the year 2015) that some think that it must be a glitch in the system. Even so, it should act as a warning about deterioration of the sea ice in the Arctic.

As discussed in earlier posts, the sea ice today is in a terrible condition. 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 September 5, 2012 (left panel) with September 5, 2015 (right panel).

Furthermore, sea surface temperatures are very high. The North Pacific, on September 3, 2015, was more than 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.

Sea surface temperature are very high around North America, both in the Pacific Ocean and in the Atlantic Ocean. The image below shows sea surface temperatures on September 4, 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 pushing 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 September 6, 2015. 

As the Arctic warms up faster than the rest of the world, the jet stream becomes ever more destabilized, as illustrated by the image below. 

The image on the right, from the Naval Research Laboratory, shows sea ice speed and drift as forecast on September 5, 2015, for September 6, 2015. 

The situation looks set to get worse. Warm oceans increase the chance that strong winds will emerge that can have a devastating impact on the remaining sea ice in the Arctic.

As the September 7, 2015, image below right shows, cyclones are lining up in the Pacific Ocean, with their strongest impact yet to hit the Arctic Ocean. 

There still is some time 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. Cyclones increase this danger.

These cyclones are headed in the direction of the Arctic. The Climate Reanalyzer forecast for September 14, 2015, below shows strong winds over the Pacific Ocean close to the Arctic Ocean, as well as over the Arctic Ocean and the North Atlantic.

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

Sea surface temperature anomalies in the Arctic as at September 6, 2015. From 'Arctic Sea Ice Collapse Threatens -...
Posted by Sam Carana on Monday, September 7, 2015

Methane Monster II ~ Demise of the Arctic

Presentation by Jennifer Hynes on runaway feedbacks in the Arctic and the resulting threat of near-term human extinction. At https://www.youtube.com/watch?v=7zUUZAomj6E

There are links to the transcript and to the complete set of slides of the presentation at Jennifer Hynes' blog.

In case you are looking for the earlier presentation by Jennifer Hynes, called 'The Arctic Methane Monster's Rapid Rise', it's at youtube.com/watch?v=a9PshoYtoxo and is also displayed below.