Arctic News

Thursday, August 8, 2019

July 2019 Hottest Month On Record

The July 2019 temperature was on a par with, and possibly marginally higher than, that of July 2016, according to a World Meteorological Organization (WMO) news release pointing an image by the Copernicus Climate Change Programme that is used as the background for above image.

Previously, July 2016 was the hottest July on record with a global land and ocean temperature of 16.67°C (62.01°F), or 3.25°C above the pre-industrial temperature of 13.42°C (56.16°F) and surpassing the record set before that, in July 2015.

The July 2019 Surface Temperature was 16.7°C in real temperatures (as opposed to anomalies), as illustrated by the image on the right, supplied by James Hansen and constructed using Dr. Phil Jones climatology and GISS 250 km smoothing of anomalies.

The image also shows, James Hansen adds, that the monthly mean of the daily mean (not daily maximum) exceeded 35°C (95°F) in parts of North Africa and the Middle East.

The month July typically is the hottest month of the year. July 2019 was 2.34°C (or 4.21°F) hotter than the 1980-2015 annual global mean, and July 2019 was the hottest July on record, making it the hottest month on record to date.

According to NASA data, July 2016 was 2.26°C hotter than the 1980-2015 annual global mean, and August 2016 was actually the previously hottest month on record with 2.31°C above the 1980-2015 annual mean, so August 2019 could be even hotter, which is quite remarkable given that we're currently in an El Niño-neutral period.

There's a spread of more than 3°C between the coldest and hottest monthly temperatures, in line with the seasonal cycle. Since the land/sea ratio is larger on the Northern Hemisphere and land heats up faster than oceans, July typically is the hottest month of the year, so the annual mean temperature for the year 2019 will be somewhat lower than the temperature for July 2019.

Above image takes another perspective, showing NASA Land and Ocean Temperature Index (LOTI) data that are adjusted 0.78° to reflect a 1750 baseline (as opposed to NASA's default 1951-1980 baseline), to reflect ocean air temperatures (as opposed to sea surface temperatures) and higher polar anomaly (to better reflect absent data).

Two trends are added, based on the adjusted data, as described in an earlier analysis. The blue long-term trend is based on 1880-July 2019 data and points at a 3°C (or 5.4°F) rise by 2026. The red short-term trend is based on 2012-July 2019 data, to better illustrate El Niño/La Niña variability and the danger that large methane eruptions from the seafloor of the Arctic Ocean could result in near-term human extinction.

NASA's LOTI anomaly of 0.93°C above 1951-1980 for July 2019 becomes 1.71°C above pre-industrial when adjusted as described above. The trends also show that it could be 1.85°C above pre-industrial, in line with the earlier analysis that already pointed at a potential mean temperature for 2019 of 15.27°C, or 1.85°C above pre-industrial. Depending on what will happen in the Arctic and on further variables such as the strength of El Niño over the remainder of the year, 2019 could even cross the 2°C guardrail that politicians at the Paris Agreement pledged would not be crossed.

Above image shows the worrying rise of Northern Hemisphere sea surface temperature anomalies from the 20th century average, with the added trend illustrating the danger that this rise will lead to Arctic sea ice collapse and large methane eruptions from the seafloor of the Arctic Ocean, further accelerating the temperature rise.

Unbearable heat

As temperatures keep rising, there are places on the northern hemisphere where the July heat is becoming ever harder to bear.

The image on the right shows that on July 29, 2019, it felt like it was as hot as 57.2°C or 135°F in China (in the area marked by the green circle).

How could it get this hot? As the image underneath on the right shows, the temperature in that area was 35.1°C or 95.1°F (at the right circle), while it was much hotter at some places elsewhere in China, e.g. it was 41.5°C or 106.6°F at the left circle on July 29, 2019.

What made the weather so hard to bear was a combination of high temperature and high relative humidity, which was 81% in the area at the circle on the right at the time.

The jet stream is becoming ever more deformed as the Arctic heats up faster than the rest of the world. On July 29, 2019, the jet stream was all over the place, with a strong presence north of the circle, which made warm, moist air from the south move over China.

Since the Arctic continues to heat up faster than the rest of the world, such situations are likely to become more common. As noted in an earlier post, cyclones can increase humidity, making conditions worse. New research has meanwhile emerged pointing at the increasing risk associated with the combination of cyclones and heatwaves.

Wet Bulb Temperature

The temperature in that area of 35.1°C, at 81% relative humidity and a pressure level of 1004 hPa, translates into a wet bulb temperature of 32.11°C.

Had the temperature remained at 35.1°C, but had relative humidity kept rising to 100%, i.e. rainfall, the wet bulb temperature threshold of 35°C would have been exceeded (35.01°C). Alternatively, had relative humidity remained at 81%, but had the temperature kept rising to 38.2°C, the wet bulb temperature threshold of 35°C would equally have been exceeded (35.07°C), showing how dangerous the situation is. A wet bulb temperature of 35°C can be lethal, as the human body will be unable to lose heat, even when the wind is strong and no matter how much one drinks or sweats.

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

Links

• Another exceptional month for global average temperatures, Copernicus Climate Change Service, ECMWF
https://climate.copernicus.eu/another-exceptional-month-global-average-temperatures

• July matched, and maybe broke, the record for the hottest month since analysis began
https://public.wmo.int/en/media/news/july-matched-and-maybe-broke-record-hottest-month-analysis-began

• NOAA Global Climate Report - July 2016
https://www.ncdc.noaa.gov/sotc/global/201607

• July 2019 Global Temperature Update, by James Hansen
http://www.columbia.edu/~mhs119/Temperature/Emails/July2019.pdf

• An emerging tropical cyclone–deadly heat compound hazard, by Tom Matthews et al. (2019)
https://www.nature.com/articles/s41558-019-0525-6

• Most Important Message Ever
https://arctic-news.blogspot.com/2019/07/most-important-message-ever.html

• Temperature
https://arctic-news.blogspot.com/p/temperature.html

• How Much Warming Have Humans Caused?
https://arctic-news.blogspot.com/2016/05/how-much-warming-have-humans-caused.html

• It could be unbearably hot in many places within a few years time
https://arctic-news.blogspot.com/2016/07/it-could-be-unbearably-hot-in-many-places-within-a-few-years-time.html

• Peaks Matter
https://arctic-news.blogspot.com/2018/08/peaks-matter.html

• Extinction Alert
https://arctic-news.blogspot.com/2019/02/extinction-alert.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

Tuesday, July 30, 2019

Arctic Sea Ice Gone By September 2019?

Record low Arctic sea ice extent for the time of year

Arctic sea ice minimum extent typically occurs about half September. In 2012, minimum extent was reached on September 17, 2012, when extent was 3.387 million km².

On July 28, 2019, Arctic sea ice extent was 6.576 million km². How much extent do you think there will be by September 17, 2019? From July 28, 2019, to September 17, 2019, that's a period of 52 days during which a lot of melting can occur. Could there be a Blue Ocean Event in 2019, with virtually all sea ice disappearing in the Arctic?

Consider this. Extent was 6.926 million km² on September 17, 1989. Extent was 3.387 million km² on September 17, 2012, so 3.539 million km² had disappeared in 23 years. Over those years, more ice extent disappeared than what was left on September 17, 2012.

The question is how much sea ice extent will be left when it will reach its minimum this year, i.e. in September 2019. The red dashed line on the image at the top continues the path of the recent fall in sea ice extent, pointing at zero Arctic sea ice extent in September 2019. Progress is followed at this post.

Zero Arctic sea ice in 2019

Zero Arctic sea ice in 2019 sounds alarming, and there is good reason to be alarmed.

Above map shows temperatures on Greenland on July 31, 2019, with temperatures at one location as high as 23.2°C or 73.8°F and at another location - in the north - as high as 14.2°C or 57.6°F.

The map on the right shows sea surface temperature anomalies compared to 1961-1990 as on July 29, 2019. Note the high anomalies in the areas where the sea ice did disappear during the past few months. The reason for these high anomalies is that the buffer has disappeared that previously had kept consuming heat in the process of melting.

Where that buffer is gone, the heat has to go somewhere else, so it will be absorbed by the water and it will also speed up heating of the atmosphere over the Arctic.

Sea ice melting is accelerating for a number of reasons:

Ocean Heat - Much of the melting of the sea ice occurs from below and is caused by heat arriving in the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean.
Direct Sunlight - Hot air will melt the ice from above and this kind of melting can increase strongly due to changing wind patterns.
Rivers - Heatwaves over land can extend over the Arctic Ocean and they also heat up river water flowing into the Arctic Ocean.
Fires - Changing wind patterns can also increase the intensity and duration of such heatwaves that can also come with fires resulting in huge amounts of greenhouse gas emissions, thus further speeding up the temperature rise, and also resulting in huge emissions of soot that, when settling on sea ice, speeds up melting (see images below).
Numerous feedbacks will further speed up melting. Heating is changing the texture of the sea ice at the top and is making melt pools appear, both of which cause darkening of the surface. Some further feedbacks, i.e. storms and clouds are discussed below in more detail.

Above combination image shows smoke from fires in Siberia getting pushed over the Laptev Sea on August 11, 2019, due to cyclonic winds over the Arctic Ocean. This was also discussed in an earlier post. The image below shows the situation on August 12, 2019.

The image below shows the situation on August 14, 2019.

In the video below, Paul Beckwith discusses the situation.

In the video below, Paul Beckwith discusses the heating impact of albedo loss due to Arctic sea ice loss, including the calculations in a recent paper.

As the Arctic is heating up faster than the rest of the world, it is also more strongly affected by the resulting extreme weather events, such as heatwaves, fires, strong winds, rain and hail storms, and such events can strongly speed up the melting of the sea ice.

All around Greenland, sea ice has now virtually disappeared. This is the more alarming considering that the thickest sea ice was once located north of Greenland. This indicates that the buffer is almost gone.

Why is disappearance of Arctic sea ice so important? Hand in hand with albedo loss as the sea ice disappears, there is loss of the buffer (feedbacks #1, #14 and more). As long as there is sea ice in the water, this sea ice will keep absorbing heat as it melts, so the temperature will not rise at the sea surface. The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.

Once the sea ice is gone, further heat must go elsewhere. This heat will raise the temperature of the water and will also make the atmosphere heat up faster.

Storms and Clouds

Storms: As temperatures in the Arctic are rising faster than at the Equator, the Jet Stream is changing, making it easier for warm air to enter the Arctic and for cold air to descend over continents that can thus become much colder than the oceans, and this stronger temperature difference fuels storms.

Clouds: More evaporation will occur as the sea ice disappears, thus further heating up the atmosphere (technically know as latent heat of vaporization).

In the video below, Paul Beckwith further discusses Arctic albedo change and clouds.

Disappearance of the sea ice causes more clouds to form over the Arctic. This on the one hand makes that more sunlight gets reflected back into space. On the other hand, this also make that less outward infrared radiation can escape into space. The net effect of more clouds is that they are likely cause further heating of the air over the Arctic Ocean (feedbacks #23 and #25).

More low-altitude clouds will reflect more sunlight back into space, and this occurs most during Summer when there is most sunshine over the Arctic. The image below, a forecast for August 17, 2019, shows rain over the Arctic. Indeed, more clouds in Summer can also mean rain, which can devastate sea ice, as discussed in an earlier post.

Regarding less outward radiation, the IPCC has long warned, e.g. in TAR, about a reduction in outgoing longwave radiation (OLR): "An increase in water vapour reduces the OLR only if it occurs at an altitude where the temperature is lower than the ground temperature, and the impact grows sharply as the temperature difference increases."

While reduction in OLR due to water vapor is occurring all year long, the impact is particularly felt in the Arctic in Winter when the air is much colder than the surface. In other words, less OLR makes Arctic sea ice thinner, especially in Winter.

The inflow of ocean heat into the Arctic Ocean can increase strongly as winds increase in intensity. Storms can push huge amounts of hot, salty water into the Arctic Ocean, as discussed earlier, such as in this post and this post. As also described at the extreme weather page, stronger storms in Winter will push more ocean heat from the Atlantic toward the Arctic Ocean, further contributing to Arctic sea ice thinning in Winter.

Seafloor Methane

[ The Buffer has gone, feedbacks #14 and #16 ]

As the buffer disappears that until now has consumed huge amounts of heat, the temperature of the water of the Arctic Ocean will rise even more rapidly, with the danger that further heat will reach methane hydrates at the seafloor of the Arctic Ocean, causing them to get destabilized and release huge amounts of methane (feedback #16).

Ominously, high methane levels were recorded at Barrow, Alaska, at the end of July 2019, as above image shows.

[ from an earlier post ]

And ominously, a mean global methane level as high as 1902 ppb was recorded by the MetOp-1 satellite in the afternoon of July 31, 2019, as above image shows.

As the image on the right shows, mean global levels of methane (CH₄) have risen much faster than carbon dioxide (CO₂) and nitrous oxide (N₂O), in 2017 reaching, respectively, 257%, 146% and 122% their 1750 levels.

Temperature Rise

Huge releases of seafloor methane alone could make marine stratus clouds disappear, as described in an earlier post, and this clouds feedback could cause a further 8°C global temperature rise.

Indeed, a rapid temperature rise of as much as 18°C could result by the year 2026 due to a combination of elements, including albedo changes, loss of sulfate cooling, and methane released from destabilizing hydrates contained in sediments at the seafloor of oceans.

[ from an earlier post ]

Below is Malcolm Light's updated Extinction Diagram.

[ click on images to enlarge ]

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

Link

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Smoke Covers Much Of Siberia
https://arctic-news.blogspot.com/2019/07/smoke-covers-much-of-siberia.html

• Extreme Weather
https://arctic-news.blogspot.com/p/extreme-weather.html

• Albedo and more
https://arctic-news.blogspot.com/p/albedo.html

• Radiative Heating of an Ice‐Free Arctic Ocean, by Kristina Pistone et al. (2019)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082914

• High cloud coverage over melted areas dominates the impact of clouds on the albedo feedback in the Arctic, by Min He et al. (2019)
https://www.nature.com/articles/s41598-019-44155-w

• ESD Reviews: Climate feedbacks in the Earth system and prospects for their evaluation, by Christoph Heinze et al. (2019)
https://www.earth-syst-dynam.net/10/379/2019/esd-10-379-2019-discussion.html

• Contribution of sea ice albedo and insulation effects to Arctic amplification in the EC-Earth Pliocene simulation, by Jianqiu Zheng et al. (2019)
https://www.clim-past.net/15/291/2019

• Far-infrared surface emissivity and climate, by Daniel Feldman et al. (2014)
https://www.pnas.org/content/111/46/16297.abstract

• Extreme Weather
https://arctic-news.blogspot.com/p/extreme-weather.html

• Feedbacks in the Arctic
https://arctic-news.blogspot.com/p/feedbacks.html

• Rain Storms Devastate Arctic Ice And Glaciers
https://arctic-news.blogspot.com/2015/01/rain-storms-devastate-arctic-ice-and-glaciers.html

• A rise of 18°C or 32.4°F by 2026?
https://arctic-news.blogspot.com/2019/02/a-rise-of-18c-or-324f-by-2026.html

• As El Niño sets in, will global biodiversity collapse in 2019?
https://arctic-news.blogspot.com/2018/11/as-el-nino-sets-in-will-global-biodiversity-collapse-in-2019.html

• Dangerous situation in Arctic
https://arctic-news.blogspot.com/2018/11/dangerous-situation-in-arctic.html

• Warning of mass extinction of species, including humans, within one decade
https://arctic-news.blogspot.com/2017/02/warning-of-mass-extinction-of-species-including-humans-within-one-decade.html

Thursday, July 25, 2019

Smoke Covers Much Of Siberia

Smoke covers much of Siberia, as shown by the NASA Worldview image dated July 25, 2019.

The enormous intensity of the fires is illustrated by the image below, showing carbon monoxide (CO) levels as high as 80,665 ppb on July 25, 2019.

The image below shows that, at that same spot on July 25, 2019, carbon dioxide (CO₂) levels were as high as 1205 ppm.

The image below shows that aerosols from biomass burning were at the top end of the scale.

When soot from fires settles on snow and ice, it darkens the surface, resulting in more sunlight getting absorbed (instead of reflected back into space, as was previously the case), thus further speeding up the melting.

The loss of sea ice north of Greenland is particularly worrying, since this is the area where once the thickest sea ice was present. The image below shows the situation on July 24, 2019.

The image below shows the sea ice disappearing north of Greenland and Ellesmere Island on July 25, 2019.

The huge recent fall in sea ice volume is illustrated by the graph below, by Wipneus.

The naval.mil animation below illustrates the rapid fall in sea ice thickness, showing 30-day period including seven forecasts up to August 1, 2019.

The combination image below shows sea ice thickness forecasts for July 25, 2019, and for August 1, 2019.

The video below, by Robin Westenra, further illustrates our predicament.

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

Links

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

Tuesday, July 16, 2019

Most Important Message Ever

This is the most important message ever posted.
Please share it widely and add your comments!
(click on share in the box underneath this post)

A catastrophe of unimaginable proportions is unfolding. Life is disappearing from Earth and runaway heating could destroy all life. At 5°C heating, most life on Earth will have disappeared. When looking only at near-term human extinction, 3°C will likely suffice. Study after study is showing the severity of the threat, yet too many keep ignoring or denying it, at the peril of the world at large. Have a look at the following:

Crossing the 2°C guardrail

The image below shows two trends, a long-term trend (blue) and a short-term trend (red) that better reflects El Niño peaks.

The image confirms an earlier analysis that it could be 1.85°C (or 3.33°F) hotter in 2019 than in 1750.

June 2019 was the hottest June on record, it was 2.08°C (or 3.74°F) hotter than the annual global mean 1980-2015, which was partly due to seasonal variations, as the image below shows.

This gives an idea of how hot it will be mid 2019. July 2019 is on course to be hottest month on record, further highlighting the danger that a strengthening El Niño could cause a steep temperature rise soon.

Remember the 2015 Paris Agreement, when politicians pledged to act on the threat of climate change, including by “Holding the increase in the global average temperature to well below 2°C above pre-industrial levels . . . ”

The image at the top highlights the danger of a rapid temperature rise occurring soon and of the 2°C (or 3.6°F) guardrail getting crossed soon, i.e. in 2020 (the blue long-term trend, based on 1880-June2019 data), or in 2019 (red trend, based on 2011-June 2019 data). Moreover, the danger is that temperatures will not come down after crossing 2°C, but instead will continue in a steep rise toward 3°C.

We are already at about 2°C above pre-industrial

In the image at the top, NASA data are adjusted, as discussed in an earlier post. Such adjustment is appropriate for a number of reasons.

Firstly, NASA uses the period 1951-1980 as their default baseline. Most of the adjustment is due to the use of a 1750 baseline, which better reflects pre-industrial.

Furthermore, air temperatures over oceans and higher polar anomalies are more appropriate, as confirmed by a recent study that concludes that missing data have been responsible for an underestimation of global warming by 0.1°C, and as illustrated by the image on the right, from a recent study, which shows the difference between using surface air temperature globally (black line), versus when sea surface temperature are used for oceans (dark blue line) and in case of incomplete coverage (light blue line).

At a 3°C rise, humans will likely go extinct

The image at the top shows two trends, a long-term trend in blue and a short-term trend in red which follows variations such as El Niño more closely. The blue trend points at a 3°C (or 5.4°F) rise by 2026, while the red trends shows that a 3°C rise could eventuate as early as in 2020 in case of a persistently strengthening El Niño.

At a 3°C rise, humans will likely go extinct, as habitat for humans (and many other species) will disappear. Such a rise will cause a rapid decline of the snow and ice cover around the globe, in turn making that less sunlight gets reflected back into space. Associated changes are discussed in more detail at this page and this page, and include that the jet stream will further get out of shape, resulting in more extreme weather events such as droughts, heatwaves and firestorms. Changes to the jet stream will also contribute to a further strengthening of storms, which threatens to push large amounts of hot, salty water into the Arctic Ocean, triggering eruptions of more and more seafloor methane.

From a 4°C rise, Earth will have a moist-greenhouse scenario

As the temperature rise gains further momentum, runaway heating may well turn Earth into a lifeless planet. This danger was discussed in a 2013 post, warning that, at 4°C rise, Earth will enter a moist-greenhouse scenario and without anything stopping the rise, it will continue to eventually destroy the ozone layer and the ice caps, while the oceans would be evaporating into the atmosphere's upper stratosphere and eventually disappear into space.

[ from an earlier post ]

At 5°C rise, most life on Earth will be extinct

At 5°C rise, most life on Earth will be extinct. A 2018 study by Strona & Bradshaw indicates that most life on Earth will disappear with a 5°C rise (see box on the right).

As the temperature keeps rising, chances are that all life on Earth will go extinct, as Earth would be left with no ozone layer to protect life from deadly UV-radiation. Furthermore, Earth would no longer have water, an essential building block of life. Soil moisture, ground water and water in oceans would evaporate and eventually disappear into space, as discussed in an earlier post.

There are several reasons why the temperature will keep rising well beyond a 5°C rise, as discussed below.

Could Earth go the same way as Venus?

At first glace, such a lifeless planet scenario may seem unlikely, as Earth did experience high temperatures before, but each time it did cool down again. While many species went extinct as a result of steep temperature rises, each time some species did survive the mass extinction events in the past.

This time, however, the situation is much more dire than during previous mass extinctions, and temperatures could keep rising, due to:

Brighter Sun - The sun is now much brighter than it was in the past;
No sequestration - The rapidity of the rise in greenhouse gases and of the associated temperature rise leaves species little or no time to adapt or move, and leaving no time for sequestration of carbon dioxide by plants and by deposits from other species, nor for formation of methane hydrates at the seafloor of oceans;
No weathering - The rapidity of the rise also means that weathering doesn't have a chance to make a difference. Rapid heating is also dwarfing what weathering (and vegetation) can do to reduce carbon dioxide levels; and
Methane - Due to the rapid temperature rise, there is also little or no time for methane to get decomposed. Methane levels will skyrocket, due to fires, due to decomposition of dying vegetation and due to releases from melting terrestrial permafrost and from the seafloor (see more on methane further below).

The methane threat

Our predicament

The predicament of this geological time is that methane in hydrates has been accumulating for a long time, especially in the Arctic, where there is little or no hydroxyl present in the atmosphere in the first place, while some 75% of the East Siberian Arctic Shelf (ESAS) is shallower than 50 m, as also discussed in this earlier post and this earlier post.

As more methane rises abruptly from the seafloor in plumes, the chance reduces that it will get decomposed in the water, and especially so in the Arctic where long uni-directional sea currents prevent microbes to return to the location of such plumes.

Shallow seas (light blue areas on the image on the right) make waters prone to warm up quickly during summer peaks, allowing heat to penetrate the seabed.

Methane rising through shallow waters will also enter the atmosphere more quickly. Elsewhere in the world, releases from hydrates underneath the seafloor will largely be oxidized by methanotroph bacteria in the water. In shallow waters, however, methane released from the seabed will quickly pass through the water column.

Large abrupt releases will also quickly deplete the oxygen in the water, making it harder for bacteria to break down the methane.

[ from an earlier post ]

The image on the right highlights methane's accelerating rise, showing levels of methane (CH₄), carbon dioxide (CO₂) and nitrous oxide (N₂O) in the atmosphere that are, respectively, 257%, 146% and 122% their 1750 levels.

Hydroxyl depletion extending methane's lifetime

The graph on the right also shows that methane levels in the atmosphere remained almost unchanged during the period 2000-2007. One explanation for this is that, as the world heated up due to the rising levels of greenhouse gases in the atmosphere, the amount of water vapor in the atmosphere rose accordingly (at a rate of 7% for each degree Celsius rise), which translated into more hydroxyl getting produced that resulted in more methane getting decomposed. So, while methane emissions kept rising, the amount of methane in the atmosphere remained relatively stable, as more methane got decomposed. Eventually, in 2007, the continued rise in methane emissions started to overwhelm the capacity of hydroxyl to decompose methane.

The danger is that, as huge amounts of methane get released rapidly, hydroxyl depletion will extend its lifetime, in turn further accelerating heating and resulting in further releases of seafloor methane.

Methane's GWP

Measured over a few years, methane's global warming potential (GWP) is very high. The image on the right, from IPCC AR5, shows that over a 10-year timescale, the current global release of methane from all anthropogenic sources exceeds all anthropogenic carbon dioxide emissions as agents of global warming; that is, methane emissions are more important than carbon dioxide emissions for driving the current rate of global warming.

The values for methane's GWP that are used in the image on the right are also used in the image below, which shows that over the first few years, methane's GWP is more than 150 times higher than carbon dioxide.

Above image is actually conservative, as the IPCC also gives higher values for methane's GWP in AR5, i.e. for fossil methane and when including climate change feedbacks, while there also is additional warming due to the carbon dioxide that results from methane's oxidation. Furthermore, research published in 2016 and 2018 found methane to be more potent than IPCC's GWP for methane in AR5, so it seems appropriate to use 150 as methane's GWP for periods of a few years.

Self-reinforcing feedback loops further accelerate heating in the Arctic and just one of them, seafloor methane, could suffice to cause runaway heating.

from an earlier post (2014)

As the image below shows, in which a GWP of 150 for methane is used, just the existing carbon dioxide and methane, plus seafloor methane releases, would suffice to trigger the clouds feedback tipping point to be crossed that by itself could push up global temperatures by 8°C, within a few years.

As described on above image and in an earlier post, a rapid temperature rise could result from a combination of elements, including albedo changes, loss of sulfate cooling, and methane released from destabilizing hydrates contained in sediments at the seafloor of oceans.

[ from an earlier post ]

In the video below, Professor Peter Wadhams and Stuart Scott discuss the threat of large methane releases (recorded March 2019, published July 2019).

Seafloor methane releases could be triggered soon by strong winds causing an influx of warm, salty water into the Arctic ocean, as described in an earlier post and discussed in the 2017 video below. In the above images, methane is responsible for a temperature rise of as much as 1.1°C in a matter of years, but the rise won't stop there. A study published in 2012 calculates that 1000-fold methane increase could occur resulting in a rise of as much as 6°C within 80 years, with more to follow after that.