SCIENCE CHINA PRESS
Climate change is causing rapid warming in the arctic and tropical regions where natural wetland store large pools of carbon and emit methane. As climate continues to warm, there is widespread concern that wetland methane emissions will increase and contribute even more to atmospheric greenhouse gases and climate change. Since 2007, atmospheric methane concentrations have increased at rapid rates, with 2020 having the largest observed methane increase since systematic measurements began. The precise causes are difficult to quantify because methane is emitted from a diverse number of natural and human-activities, and the removal of methane is from complex chemical processes. Here, using new data on methane stable isotopes, combined with thousands of potential emissions scenarios, a new study confirms that emissions from anthropogenic sources, including agriculture, landfill/waste, and fossil fuel industry, are clearly the driver for the renewed rise of the potent greenhouse gas since 2007, while global wetlands play a minor role with a contribution of less than 20%.
Methane is a powerful greenhouse gas with 80 times more warming potential than carbon dioxide over a 20-year period and responsible for almost half of the global warming since the industrial revolution. Methane is also a precursor to ground-level ozone pollution and thus tackling methane emissions would bring short-term climate benefits as well as improve air quality. Since 2007, atmospheric methane concentrations have been increasing rapidly, and even more so since 2014, and the causes for the increase have been debated in terms of the contribution from natural processes versus human activities.
According to the Global Carbon Project’s Global Methane Budget, roughly one-third of global methane emissions come from microbes in natural wetlands that produce methane when decomposing organic material where no oxygen is available. Human activities are known account for about 60 percent of global methane emissions, which include agriculture, landfills and waste, and oil and gas activities, each accounting for 20–25% of global methane emissions. This means that any changes in natural wetlands to the rising temperature could potentially have a significant influence on atmospheric methane levels.
The scientists tested a comprehensive set of emission scenarios using data from different greenhouse gas inventories and wetland models. They found that the emissions scenarios assuming large wetland methane increases did not match the observed atmospheric isotopic record. In contrast, the methane emission sources linked to human activities better matched the observed atmospheric isotopes. The work provides a detailed attribution of methane growth to agricultural emissions that increased by almost 20% from 2000 to 2017 driven by rising livestock populations, landfills and waste emissions rising by 10 million metric tonnes, largely attributing to an over 40% increase in the world urban populations from 2000 to 2017. The emissions from oil and natural gas industry have increased by 5 million metric tonnes with large uncertainty, and coal production increased by 40% globally from the same period.
“Increased human activities clearly emerge as the main cause of rising atmospheric methane concentrations. No evidence for strong natural feedback of climate on wetland methane emissions exists for now despite its potential dominant role in the future as the temperature goes higher”. says Zhen Zhang, an Earth-systems researcher at University of Maryland College Park who led this study.
“This study shows the value of observing methane isotope signatures as a technique to isolate and better understand methane sources. Sustained and strategic observations of methane over wetland regions are needed to detect climate change feedbacks, which become more likely each year as climate warms.” said Benjamin Poulter, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The recent 26th Conference of Parties to the United Nations Framework Convention on Climate Change also highlighted methane mitigation as an essential component to addressing climate change. This study demonstrates that mitigation in sectors dominated by human activities would have a significant impact on the growth of atmospheric methane.
“Good news is the natural feedback is still not that strong. But without substantial mitigation actions, we will lose the opportunity to control methane as we will have no solution with the natural feedback once it’s there”. said Zhen Zhang.
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See the article:
Anthropogenic emissions are the main contribution to the rise of atmospheric methane (1993-2017)
https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwab200/6425695
JOURNAL
National Science Review
DOI
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We must be winning the CO2 debate. Now Methane is the big culprit weather control knob
that they claim to want to control. Methane has a short residence time in the atmosphere due to its volatility.
Vegans.
Well …
Vegetarian is an old Indian word. It means “bad hunter”.
Throw it all against the wall and see what sticks.
It is not helpful to find problems and invent solutions to a problem that has not been proven to exist. And attacking the food and energy supply can only bring pain.
From the actual paper regarding CH4 measurements from wetlands in the tropics :
It isn’t quite “models all the way down”, but it’s close.
– – – – –
GISS provide annual “zonal” data for the GISTEMP dataset (graphed below from 1960).
An argument can be made that the warming over the last 50 years or so in the Arctic can be qualified as “rapid”, but not so much for “the tropics”.
One can draw at least two conclusions from looking at the graph of GISS’s interpretation of global temperature changes: 1) The tropics (and Southern Hemisphere) determine overall global temperature changes (the Arctic can warm rapidly without affecting average global temperatures significantly), and 2) Over the 60-year period shown (during an upswing in cyclic temperature changes) global temperatures only increased an estimated approximately 1 C (1.7 C/century) during a period of rapid atmospheric CO2 increases.
Color me unconvinced that mankind’s emission of GHGs is an existential threat.
Methane is a low weight gas, so a ton of is a lot more molecules compared to a ton of CO2. Ton to ton methane is 80 time more active as greenhouse gas than CO2, but per molecule (ppm) it is only 30 times.
Hmmm . . . just wondering if the authors of the “peer-reviewed” National Science Review article cited above accounted for the likelihood of methane being released from decomposing methane hydrates currently existing at certain ocean depths, as the world’s oceans gradually heat up from the last global glacial interval, which only started happening some 12,500 years ago.
I can image it is extremely difficult to measure the amount of methane coming out of methane hydrates over all of the world’s oceans. I am not aware of any large scale scientific effort to do such.
“Huge amounts of methane are stored around the world in the sea floor in the form of solid methane hydrates. These hydrates represent a large energy reserve for humanity. Climate warming, however, could cause the hydrates to destabilize. The methane, a potent greenhouse gas, would escape unused into the atmosphere and could even accelerate climate change . . . In the open ocean, where the average bottom-water temperatures are around 2 to 4 degrees Celsius, methane hydrates occur starting at depths of around 500 meters . . . In very cold regions like the Arctic, methane hydrates even occur on the shallow continental shelf (less than 200 metres of water depth) or on the land in permafrost, the deep-frozen Arctic soil that does not even thaw in the summer . . . It is estimated that there could be more potential fossil fuel contained in the methane hydrates than in the classic coal, oil and natural gas reserves. Depending on the mathematical model employed, present calculations of their abundance range between 100 and 530,000 gigatons of carbon. Values between 1000 and 5000 gigatons are most likely. That is around 100 to 500 times as much carbon as is released into the atmosphere annually by the burning of coal, oil and gas.“ — source: https://worldoceanreview.com/en/wor-1/ocean-chemistry/climate-change-and-methane-hydrates/ , my underlining emphasis added.
Since the above article make no mention whatsoever of methane hydrates in the oceans being a possible source of increasing atmosphere methane, I assert the claimed “new study confirms that emissions from anthropogenic sources, including agriculture, landfill/waste, and fossil fuel industry, are clearly the driver for the renewed rise of the potent greenhouse gas since 2007” lacks scientific credibility.
The relevant absorption band for CH4 is at wavenumbers where earth radiation is way low, the CH4 population is less than 2 ppmv and any energy absorbed by CH4 molecules is thermalized and redirected to water vapor molecules from which much of the outward directed radiation around an altitude of 4 km makes it all the way to space. There won’t be any significant effect on climate from methane.
The Methane (CH4 @ur momisugly 2ppmv) climate change mantra doesn’t do a thing for me.
Just (2) parts per million is so small looks like the proverbial piss in the ocean to me.
And what do we know of methane levels in the past, could they have been much lower ?
I don’t care about their chemistry, their physics nor their graphs, just feeble attempts to frighten.
Its just a load of bullshit and squashed tomatoes in my opinion . .
CH4 we now is 2ppmv !! That’s good enough for me just a piss in the ocean . .
I am confused about methane being 80 times more potent than CO2. Climate models use a doubling of CO2 to generate 4 degrees of warming. Is doubling methane 80 times worse?
Methane goes from 700 ppb to 1800 bbp from 1750 to 2010.
https://www.eea.europa.eu/data-and-maps/figures/atmospheric-concentration-of-ch4-ppb-1
Something smells and I am not sure that it is the methane.
It’s based on adding a tonne of methane versus a tonne of CO2. Since there are already a lot of tonnes of CO2, adding another doesn’t change much, while adding a tonne of methane causes a higher fractional increase. It’s just a playing with numbers scare tactic. If they thought about the way a calorimeter works, heat input is by photons, of course, and the limit is simply the ratio of specific heats of the two gases….CO2 .846 kJ/kg-K, CH4 2.254 kJ/kg-K, but both about 30 J/mol-K The CH4 can absorb more heat instantaneously due to more available molecular vibration modes, but it also radiates more away since it’s not going to get warmer than its surroundings….but the photons had to come from somewhere else before they were absorbed (and reradiated), so actual effect of a few ppb of CH4 increase compared to CO2 at 400 ppm is irrelevant.
They do sophisticated line by line IR spectrums to come up with this stuff…..but in the end……(CO2 ppm/ CH4 ppm) x (M.Wt. CH4/ M.Wt. CO2) = 400/1.8x 16/44 = 80 for “global warming potential”, making the relationship of GWP to Bullshit hopefully clearer.
In a post about Gore … er … uh … Kerry bringing up methane at COP(whatever) was signaling that after fossil fuels, the next target of the Greens would be our food.
(Same BS. Different gas.)
Speaking of methane, didn’t I hear that President Joe Biden asked Camilla, the Duchess of Cornwall and wife of Britain’s Prince Charles, to “pull his finger” at a meeting during COP26?
I may not have the details of that exactly right. 🙂
Positive feedbacks, which supposedly would greatly increase methane (CH4) emissions from natural sources, are mostly hypothetical, and at the scales needed to have much effect they are frankly implausible.
The fact that a study run by climate alarmists has verified that those hypothetical positive feedbacks aren’t happening to a significant extent is encouraging. Yet, despite confirmation from their own work that natural processes are not producing methane at a significantly accelerated rate, they still fret about it, and still believe that “without substantial mitigation actions, we will lose the opportunity to control methane.” It is a discouraging confirmation that groupthink is generally more influential than evidence, even among those who fancy themselves “scientific.”
The dominant methane feedback is negative, not positive. It is the simple fact that the atmospheric lifetime of methane is only about a decade, and higher atmospheric methane levels accelerate the natural oxidative processes which remove it.
Most climate alarmists assume that as long as mankind continues to produce GHGs and release them into the atmosphere, the concentrations of those gases in the atmosphere will continue to rise. But that is untrue, except for gases, like carbon tetrafluoride (CF4), which have extremely long atmospheric lifetimes.
As is the case for CO2 (but even more quickly), the rise in atmospheric methane level must plateau unless human emissions of the gas continue to increase, simply because the processes which remove CO4 (and CO2) accelerate as the atmospheric concentration rises.
Assuming the Pranther et al CH4 atmospheric lifetime estimate of 9.1±0.9 years (which the AMS uses), we can calculate that the rate of increase in CH4 level (which averages about 0.01 ppmv/year) is only about 1/60-th of the rate of the CH4 removal processes, and only about 1/35-th the rate of anthropogenic CH4 emissions. That means atmospheric CH4 level responds very quickly to changes in CH4 emission rate, and if the CH4 emission rate were to cease increasing then the level of CH4 in the atmosphere would rise at most only a few percent before plateauing.
Clarification: “a few percent” means percentage of the current CH4 level, not percentage of the atmosphere.
If anthropogenic CH4 emissions were to plateau at the current level then the atmospheric CH4 concentration would soon cease rising; if anthropogenic CH4 emissions were to decrease by just 3% then the atmospheric CH4 level would immediately plateau (as happened from 1999 to 2006); and if anthropogenic CH4 emissions were to decrease by substantially more than that then the CH4 level would decline instead of continuing to rise.
But it was much warmer in the MWP when the tundra thawed and forests were much farther north and no runaway warming then.
This will be great for sales of my patented cow fart stoppers! Im going to sell a gazillion of them.
If we stop sending agricultural and industrial products to urban parasites, that would help in several ways.
Where to start… “Methane … [is] responsible for almost half of the global warming since the industrial revolution.” From 1850 to the present, that would be half of 1.1C, or 0.55C. The credibility of the press release is thus destroyed.