Methane buildup in the atmosphere

Levels of carbon dioxide (CO2) in the atmosphere are now firmly above the 400 parts per million (ppm) level, as illustrated by the graph below, from keelingcurve.ucsd.edu.

As above graph shows, levels of CO2 go up and down with the seasons. Even higher levels are expected to be reached in May 2014. Importantly, 400 ppm is 143% its pre-industrial peak levels of 280 ppm.

Levels of methane (CH4) in the atmosphere are rising even faster. According to IPCC AR5, methane levels were 1798 ppb in 2010 and 1803 ppb for 2011. A graph included in an earlier post shows historic levels of CH4, CO2 and N2O levels, highlighting methane's steep rise (now some 250% its pre-industrial level). The graph below, based on a plot by NOAA, shows the rise of methane over the past few decades and also shows that methane levels similarly go up and down with the seasons.

Globally, IPCC/NOAA figures suggest that abundance of methane in the atmosphere did reach 1814 ppb in 2013 and is rising with some 5 to 6 ppb annually. IASI data show that - at the hight of the northern summer, in August 2013 - mean methane levels rose strongly, to levels well above 1800 ppb, as also discussed in posts such as this one.

Next to seasonal variations, methane levels also differ depending on altitude. Often, when mean methane values are given, readings at 14,383 feet altitude are used, as methane typically reaches its highest levels at this altitude.

The image on the right compares methane levels for 2013 and 2014 at this altitude over six recent days, with a.m readings and p.m. readings for each day.

Around this time of year in 2013, as the graph shows, methane levels went through the 1800 ppb mark. The same thing occurred this year, while levels have meanwhile increased with a few ppb, so at first glance methane's rise appears to continue as anticipated by the IPCC.

While the above is very worrying, the situation may be even more dire than this. The graph below compares methane levels in 2013 and in 2014, averaged over the same six-day period (April 5 through to April 10) and at six different altitudes.

Above image indicates that, while the difference between 2013 and 2014 at lower altitudes (8,367 feet and 14,383 feet) may seem relatively small, increases at higher altitudes may be much stronger. In other words, rather than rising in a similar way across all altitudes, methane may in fact be building up much more strongly at higher altitudes.

This frightening possibility was raised a few times at this blog, such as in the altitude analysis in January 2014 and in the post Quantifying Arctic Methane, which noted that IPCC-estimates of global methane levels may rely too much on low-altitude data collected over the past few decades. Indeed, the total methane burden may already be rising much more rapidly than the IPCC is anticipating, also because methane is rising in the atmosphere, increasing the burden especially at higher altitudes, as evidenced by increasing occurence of noctilucent clouds.

The above analysis uses a limited dataset, just like the previous one, but if verified by further analysis, it could be that a dramatic rise in the presence of methane in the atmosphere is occuring without showing up at lower altitudes. This could also explain how earlier releases of methane from hydrates could have been ignored by many, i.e. relatively small increases in methane levels at relatively low altitudes may have given a false reassurance that such releases were not adding much methane to the atmosphere. Further analysis, comparing satellite data at different altitudes over the years, could give more clarity on these points.

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.