March 2014 Arctic Sea Ice Volume 2nd lowest on Record

The March 2014 Arctic sea ice volume, as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center, was the 2nd lowest on record at 21.818 km³. Only March 2011 had a lower volume, at 21.421 km³, as illustrated by the graph below, by Wipneus.

Another way of depicting the continued fall of the sea ice volume is the Arctic Death Spiral below, by Andy Lee Robinson.

This puts the sea ice in a very weak position. This month, the sea ice will reach its highest volume, which may well be the lowest volume on record for April. The Naval Reserach Laboratory 30-day animation below shows recent sea ice thickness.

The lowest sea ice volume for 2014 is expected to be reached in September, and - given the shape the ice is in now - will likely be one of the lowest minima on record. In fact, there is a chance that there will be no ice left whatsoever later this year. As illustrated by the image below, again by Wipneus, an exponential curve based on annual minima from 1979 points at zero ice volume end 2016, with the lower limit of the 95% confidence interval pointing at zero ice end of 2014.

Absence of sea ice will mean that a lot of more heat will be absorbed by the Arctic Ocean.

As NSIDC.org describes, sea ice reflects 50% to 70% of the incoming energy, but thick sea ice covered with snow reflects as much as 90% of the incoming solar radiation. After the snow begins to melt, and because shallow melt ponds have an albedo of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15. The ocean reflects only 6% of the incoming solar radiation and absorbs the rest. Furthermore, all the heat that during the melt went into transforming ice into water will - in the absence of ice - be absorbed by the ocean as well.

Such feedbacks are causing warming to accelerate in the Arctic Ocean, much of which is very shallow and thus vulnerable to warming. The Gulf Stream can be expected to keep carrying warmer water into the Arctic Ocean. Extreme weather events such as heatwaves and cyclones could make the situation a lot worse.

Warming of the Arctic Ocean threatens to destabilize huge amounts of methane held in sediments at the seafloor, in the form of free gas and hydrates. The danger is that release of methane from the seafloor of the Arctic Ocean will warm up the Arctic even further, triggering even more methane releases, as well as heatwaves, wildfires and further feedbacks, in a spiral of runaway warming that will lead to starvation, destruction and extintion at massive scale across the globe.

In conclusion, the situation is dire and calls for comprehensive and effective action, as discussed at the climate plan blog.

Permafrost thawing could accelerate global warming

"If the permafrost melts entirely, there would be 5x the amount of carbon in the atmosphere than there is now" - Jeff Chanton

Jeff Chanton, the John Widmer
Winchester Professor of
Oceanography at Florida State.

A team of researchers lead by Florida State University have found new evidence that permafrost thawing is releasing large quantities of greenhouse gases into the atmosphere via plants, which could accelerate warming trends.

The research is featured in the newest edition of the Proceedings of the National Academy of Sciences.

“We’ve known for a while now that permafrost is thawing,” said Suzanne Hodgkins, the lead author on the paper and a doctoral student in chemical oceanography at Florida State. “But what we’ve found is that the associated changes in plant community composition in the polar regions could lead to way more carbon being released into the atmosphere as methane.”

Permafrost is soil that is frozen year round and is typically located in polar regions. As the world has gotten slightly warmer, that permafrost is thawing and decomposing, which is producing increased amounts of methane.

Relative to carbon dioxide, methane has a disproportionately large global warming potential. Methane is 33 times more effective at warming the Earth on a mass basis and a century time scale relative to carbon dioxide.

Changes in plant community composition in the polar regions could lead to way more carbon being released into the atmosphere as methane

As the plants break down, they are releasing carbon into the atmosphere. And if the permafrost melts entirely, there would be five times the amount of carbon in the atmosphere than there is now, said Jeff Chanton, the John Widmer Winchester Professor of Oceanography at Florida State.

“The world is getting warmer, and the additional release of gas would only add to our problems,” he said.

Chanton and Hodgkins’ work, “Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production,” was funded by a three-year, $400,000 Department of Energy grant. They traveled to Sweden multiple times to collect soil samples for the study.

The research is a multicontinent effort with researchers from North America, Europe and Australia all contributing to the work.

River ice reveals new twist on Arctic melt

A new study led by Lance Lesack, a Simon Fraser University geographer and Faculty of Environment professor, has discovered unexpected climate-driven changes in the mighty Mackenzie River’s ice breakup. This discovery may help resolve the complex puzzle underlying why Arctic ice is disappearing more rapidly than expected.

Lance Lesack,
photo by Simon Fraser University

Lesack is the lead author on Local spring warming drives earlier river-ice breakup in a large Arctic delta. Published recently in Geophysical Research Letters, the study has co-authors at Wilfrid Laurier University, the University of Alberta and Memorial University.

Its goal was to understand how warming global temperatures and the intensifying Arctic hydrological cycle associated with them may be driving increasing water discharges and more rapid ice breakup in the Arctic’s great rivers.

But the researchers stumbled upon an unexpected phenomenon while trying to figure out why the Mackenzie River’s annual ice breakup has been shortening even though its water discharge isn’t increasing, as in Russian rivers.

Just slightly warmer springs with unexpected snowfall declines — rather than warmer winters or increasing river discharge, as previously suspected — can drive earlier-than-expected ice breakup in great Arctic rivers.

The Mackenzie exemplifies this unexpected phenomenon. The researchers discovered this by accessing records dating back to 1958 of the river’s water levels, snow depths, air temperatures and times of ice breakup.

This finding is significant, as Arctic snow and ice systems are important climate-system components that affect the Earth’s ability to reflect solar radiation.

Mackenzie delta river, before (top) and after
(bottom, one day later) onset of dynamic ice
breakup in the central Mackenzie's delta middle
channel. Photos by Simon Fraser University.

“Our surprising finding was that spring temperatures, the period when river-ice melt occurs, had warmed by only 3.2 degrees Celsius. Yet this small change was responsible for more than 80 per cent of the variation in the earlier ice breakups, whereas winter temperatures had warmed by 5.3 degrees but explained little of this variation,” says Lesack.

“This is a strong response in ice breakup for a relatively modest degree of warming, but further investigation showed that by winter’s end snow depths had also declined by one third over this period. The lesser snow depths mean less solar energy is needed to drive ice breakup.”

Lesack says this is the first field-based study to uncover an important effect of reduced winter snowfall and warmer springs in the Arctic — earlier-than-expected, climate-change-related ice breakup.

“The polar regions have a disproportionate effect on planetary reflectivity because so much of these regions consist of ice and snow,” says Lesack. “Most of the planetary sea ice is in the Arctic and the Arctic landmass is also seasonally covered by extensive snow. If such ice and snow change significantly, this will affect the global climate system and would be something to worry about.”

Lesack hopes this study’s findings motivate Canadian government agencies to reconsider their moves towards reducing or eliminating ground-based monitoring programs that measure important environmental variables.

There are few long-term, ground-based snow depth records from the Arctic. This study’s findings were based on such records at Inuvik dating back to 1958. They significantly pre-dated remote sensing records that extend back only to 1980. Without this longer view into the past, this study’s co-authors would still be in the dark about the more rapid than expected Arctic melt and planetary heat-up happening.

Like a giant elevator to the stratosphere

Recent research results show that an atmospheric hole over the tropical West Pacific is reinforcing ozone depletion in the polar regions and could have a significant influence on the climate of the Earth.

Potsdam, 3 April 2014. An international team of researchers headed by Potsdam scientist Dr. Markus Rex from the Alfred Wegener Institute has discovered a previously unknown atmospheric phenomenon over the South Seas. Over the tropical West Pacific there is a natural, invisible hole extending over several thousand kilometres in a layer that prevents transport of most of the natural and manmade substances into the stratosphere by virtue of its chemical composition. Like in a giant elevator, many chemical compounds emitted at the ground pass thus unfiltered through this so-called “detergent layer” of the atmosphere. Scientists call it the “OH shield”. The newly discovered phenomenon over the South Seas boosts ozone depletion in the polar regions and could have a significant influence on the future climate of the Earth – also because of rising air pollution in South East Asia.

In tropical thunderstorms over the West Pacific air masses and
the chemical substances they contain are quickly hurled upward
to the edge of the stratosphere. If there are sufficient OH
molecules in the atmosphere, the air is extensively cleaned by
chemical transformation processes. Where OH concentrations are
low, such as those now found in large sections of the tropical
West Pacific, the cleaning capacity of the atmosphere is reduced.
Photo: Markus Rex, Alfred Wegener Institute

At first Dr. Markus Rex suspected a series of flawed measurements. In October 2009 the atmospheric physicist from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) was on board the German research vessel “Sonne” to measure trace substances in the atmosphere in the tropical West Pacific.

Tried and tested a thousand times over, the ozone probes he sent up into the tropical sky with a research balloon every 400 kilometres reported – nothing.

Or to be more accurate: almost nothing. The ozone concentrations in his measurements remained nearly constantly below the detection limit of approx. 10 ppbv* in the entire vertical range from the surface of the Earth to an altitude of around 15 kilometres. Normally ozone concentrations in this part of the atmosphere are three to ten times higher.

Although low values at an altitude of around 15 kilometres were known from earlier measurements in the peripheral area of the tropical West Pacific, the complete absence of ozone at all heights was surprising. However, after a short period of doubt and various tests of the instruments it dawned on the worldwide recognised ozone specialist that he might be onto a phenomenon yet unknown to science. A few research years later and after the involvement of other colleagues came confirmation: Markus Rex and his team on board the “Sonne” had tracked down a giant natural hole over the tropical South Seas, situated in a special layer of the lower atmosphere known as the “OH shield”. The research results on the newly discovered OH minimum will be published soon in the journal “Atmospheric Chemistry and Physics”, with the Institute of Environmental Physics of the University of Bremen and other international research institutions as partners.

Nearly all chemical substances produced by people, animals,
plants, algae or microorganisms on the ground or in the oceans
react quickly with OH and break down in this process. During this
chemical self-cleaning process substances that are not easily
water-soluble are transformed into water-soluble products and
then washed out by precipitation. Through this mechanism OH
molecules remove most substances from the atmosphere.
The OH molecule is therefore also called the detergent of the
atmosphere. Only extremely long-lived chemical compounds,
such as methane or CFCs, also known as "ozone killers", can
rise through the OH shield into the stratosphere.
Graphics: Markus Rex, Alfred Wegener Institute

“Even though the sky appears to be an extensively uniform space for most people, it is composed of chemically and physically very different layers,” Markus Rex explains the complex makeup of the atmosphere.

The air layers near the ground contain hundreds or even thousands of chemical compounds. This is why winter and spring, mountains and sea, city and forests all have a distinct smell. The great majority of these substances are broken down into water-soluble compounds in the lower kilometres of the atmosphere and are subsequently washed out by rain.

Since these processes require the presence of a certain chemical substance, the so called hydroxyl (=OH) radical, this part of the atmosphere is called the “OH shield”. It acts like a huge atmospheric washing machine in which OH is the detergent.

The OH shield is part of the troposphere, as the lower part of the atmosphere is called. “Only a few, extremely long-lived compounds manage to make their way through the OH shield,” says Rex, “then they also get through the tropopause and enter the stratosphere.” Tropopause refers to the boundary layer between the troposphere and the next atmospheric layer above it, the stratosphere. Particularly substances that enter the stratosphere unfold a global impact. The reason for this is that once they have reached the stratosphere, their degradation products remain up there for many years and spread over the entire globe.

Extremely long-lived chemical compounds find their way to the stratosphere, even where the OH shield is intact. These include methane, nitrous oxide (“laughing gas”), halons, methyl bromide and chlorofluorocarbons (CFCs), which are notorious as “ozone killers” because they play a major role in ozone depletion in the polar regions.

Location and extent of low ozone concentrations and thus
of the OH hole over the West Pacific. Fig. (a) shows the
region of origin of the air in the stratosphere, Fig. (b) ozone
sonde measurements (dots) and satellite measurements
(coloured map) of the total amount of ozone in the
tropospheric column of air and Fig. (c) the total amount of
OH in the tropospheric column of air calculated with a model.
Graphics: Markus Rex, Alfred Wegener Institute.

After many years of research scientists now understand the complicated process of stratospheric ozone depletion very well.

“Nevertheless measured ozone depletion rates were often quite a bit larger than theoretically calculated in our models,” Markus Rex points out a long unsolved problem of atmospheric research.

“Through the discovery of the OH hole over the tropical West Pacific we have now presumably made a contribution to solving this puzzle.”

And at the same time discovered a phenomenon that raises a number of new questions for climate policy.

Researchers are now tackling these questions in a new research project funded by the EU with around 9 million euros, i.e. “StratoClim”, which is coordinated by the Alfred Wegener Institute. Within this project a new monitoring station will be established in the tropical Westpacific, together with the Institute of Environmental Physics at the University of Bremen.

“We have to realise,” reminds the Potsdam atmospheric physicist, “that chemical compounds which enter the stratosphere always have a global impact.” Thanks to the OH hole that the researchers discovered over the tropical Pacific, greater amounts of brominated hydrocarbons can reach the stratosphere than in other parts of the world. Although their ascent takes place over the tropical West Pacific, these compounds amplify ozone depletion in the polar regions. Since scientists identified this phenomenon and took it into account in the modelling of stratospheric ozone depletion, their models have corresponded excellently with the actually measured data.

However, it is not only brominated hydrocarbons that enter the stratosphere over the tropical West Pacific. “You can imagine this region as a giant elevator to the stratosphere,” states Markus Rex using an apt comparison. Other substances, too, rise here to a yet unknown extent while they are intercepted to a larger extent in the OH shield elsewhere on the globe. One example is sulphur dioxide, which has a significant impact on the climate.

Sulphur particles in the stratosphere reflect sunlight and therefore act antagonistically to atmospheric greenhouse gases like CO2, which capture the heat of the sun on the Earth. To put it simply, whereas greenhouse gases in the atmosphere heat the globe, sulphur particles in the stratosphere have a cooling effect. “South East Asia is developing rapidly in economic terms,” Markus Rex explains a problem given little attention to date. “Contrary to most industrial nations, however, little has been invested in filter technology up to now. That is why sulphur dioxide emissions are increasing substantially in this region at present.”

This is how air reaches the stratosphere. Through the rapid
upward transport in tropical thunderstorms they reach an area
of slow large-scale ascent and rise from there through the
tropopause into the stratosphere over the course of weeks.
This process is most pronounced during northern hemispheric
winter. Model calculations show that, during this season, this
process mainly takes place over the tropical West Pacific. Due
to the formation of cirrus (= ice) clouds in the extremely cold
tropical tropopause, a large portion of the water-soluble
chemical substances is removed from the air and cannot reach
the stratosphere. OH molecules transform water-insoluble into
water-soluble compounds. Hence, if the concentration of OH
molecules along the dotted transport pathways shown above
is high only few chemical compounds make it into the
stratosphere. Conversely, the lower the OH concentration is
along the transport pathways, the more chemical
compounds enter the stratosphere.
Graphics: Yves Nowak, Alfred Wegener Institute.

If one takes into account that sulphur dioxide may also reach the stratosphere via the OH hole over the tropical West Pacific, it quickly becomes obvious that the atmospheric elevator over the South Seas not only boosts ozone depletion, but may influence the climate of the entire Earth. In fact, the aerosol layer in the stratosphere, which is also composed of sulphur particles, seems to have become thicker in recent years. Researchers do not know yet whether there is a connection here.

But wouldn’t it be a stroke of luck if air pollutants from South East Asia were able to mitigate climate warming? “By no means,” Markus Rex vigorously shakes his head. “The OH hole over the South Seas is above all further evidence of how complex climate processes are. And we are still a long way off from being in a position to assess the consequences of increased sulphur input into the stratosphere. Therefore, we should make every effort to understand the processes in the atmosphere as best we can and avoid any form of conscious or unconscious manipulation that would have an unknown outcome.”

Background:

Why is there an OH hole over the West Pacific?
The air in the tropical West Pacific is extremely clean. Air masses in this area were transported across the expanse of the huge Pacific with the trade winds and for a long time no longer had contact with forests or other land ecosystems that produce innumerable short-lived hydrocarbons and release them into the air. Under these clean air conditions OH is formed from ozone through chemical transformation to a great degree. If there is hardly any ozone in the lower atmosphere (= troposphere), as is the case in the West Pacific, only little OH can be formed. The result is an OH hole.

The graph shows ozone profiles measured in three different
marine regions: the tropical Atlantic, the tropical West Pacific
and the West Pacific outside the tropics. The red curve clearly
shows that ozone is consistently very low up to an altitude of
15 kilometres over the tropical West Pacific. In the other
regions the ozone concentrations are in a range typical
for the troposphere.
Graphics: Markus Rex, Alfred Wegener Institute

Ozone, in turn, forms in the lower atmosphere only if there are sufficient nitrogen oxides there. Large amounts of nitrogen oxide compounds are produced in particular by intensive lightning over land.

However, the air masses in the tropical West Pacific were not exposed to any continental tropical storms for a very long time during their transport across the giant ocean. And the lightning activity in storms over the ocean is relatively small. At the same time the lifetime of atmospheric ozone is short due to the exceptionally warm and moist conditions in the tropical West Pacific. In this South Sea region the surface temperatures of the ocean are higher than anywhere else on our planet, which makes the air not only quite warm, but also quite moist.

The ozone is thus quickly lost, especially directly above the water. And due to the lack of nitrogen oxide compounds little ozone is subsequently formed. Rapid vertical mixing in the convection areas that exist everywhere over the warm ocean and in which the warm air rises takes care of the rest. Finally, there is no more ozone in the entire column of air in the troposphere. And without ozone (see above) the formation of OH is suppressed.

What impact does the OH hole over the West Pacific have?

The illustration shows the average lifetime of sulphur dioxide
and some brominated hydrocarbons for normal conditions
over the tropical Atlantic and for conditions of reduced
OH-concentrations over the tropical West Pacific.
Graphics: Markus Rex, Alfred Wegener Institute

The OH molecule is also called the detergent of the atmosphere. Nearly all of the thousands of different chemical substances produced by people, animals, plants, fungi, algae or microorganisms on the ground or in the oceans react quickly with OH and break down in this process. Therefore, virtually none of these substances rises into the stratosphere. In the area of the OH hole, however, a larger portion of this varied chemical mix can enter the stratosphere.

And local emissions may unfold a global impact, especially if they make it to the stratosphere. There they spread globally and can influence the composition of the air for many years – with far-reaching consequences for ozone chemistry, aerosol formation and climate.

Why wasn’t the OH hole discovered earlier?
The tropical West Pacific is one of the most remote regions on our planet. That is why extensive measurements of the air composition have yet to take place in this area. There is also a considerable gap in the otherwise dense network of global ozone measurement stations here. Even in the past measurements from the peripheral sections of the now investigated region showed minimal ozone values in the area of the upper troposphere, but not the consistently low values that have now been found across the entire depth of the troposphere. The newly discovered phenomenon reveals itself in its full scope only through the measurements that were conducted to such an extensive degree for the first time and was thus not able to be grasped at all previously.

*One part of ozone per billion by volume (ppbv) means there is one ozone molecule for every billion air molecules.