Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

Keep me logged in
New? Register here
Forgot your password?

Latest Posts


Climate Hustle

Greenhouse Gas Concentrations in Atmosphere Reach New Record

Posted on 9 November 2013 by John Hartz

This article is a reprint of apress release posted by the World Meteorological Organization (WMO) on Nov 6, 2013.

The amount of greenhouse gases in the atmosphere reached a new record high in 2012, continuing an upward and accelerating trend which is driving climate change and will shape the future of our planet for hundreds and thousands of years.

Cover of WMO GHG BulletinThe World Meteorological Organization’s annual Greenhouse Gas Bulletin shows that between 1990 and 2012 there was a 32% increase in radiative forcing – the warming effect on our climate – because of carbon dioxide (CO2) and other heat-trapping long-lived gases such as methane and nitrous oxide.

Carbon dioxide, mainly from fossil fuel-related emissions, accounted for 80% of this increase. The atmospheric increase of CO2 from 2011 to 2012 was higher than its average growth rate over the past ten years, according to the Greenhouse Gas Bulletin.

Since the start of the industrial era in 1750, the global average concentration of CO2 in the atmosphere has increased by 41%, methane by 160% and nitrous oxide by 20%.

What is happening in the atmosphere is one part of a much wider picture. Only about half of the CO2 emitted by human activities remains in the atmosphere, with the rest being absorbed in the biosphere and in the oceans.

“The observations from WMO’s extensive Global Atmosphere Watch network highlight yet again how heat-trapping gases from human activities have upset the natural balance of our atmosphere and are a major contribution to climate change,” said WMO Secretary-General Michel Jarraud. 

The Intergovernmental Panel on Climate Change (IPCC) in its recent 5th Assessment Report stressed that atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years,” he said.

“As a result of this, our climate is changing, our weather is more extreme, ice sheets and glaciers are melting and sea levels are rising,” said Mr Jarraud.

“According to the IPCC, if we continue with ‘business as usual,’ global average temperatures may be 4.6 degrees higher by the end of the century than pre-industrial levels – and even higher in some parts of the world. This would have devastating consequences,” he said. 

“Limiting climate change will require large and sustained reductions of greenhouse gas emissions. We need to act now, otherwise we will jeopardize the future of our children, grandchildren and many future generations,” said Mr Jarraud. “Time is not on our side,” he added.

The WMO Greenhouse Gas Bulletin reports on atmospheric concentrations – and not emissions - of greenhouse gases. Emissions represent what goes into the atmosphere. Concentrations represent what remains in the atmosphere after the complex system of interactions between the atmosphere, biosphere and the oceans.

Carbon dioxide (CO2)

Carbon dioxide is the single most important greenhouse gas emitted by human activities such as fossil fuel burning and deforestation. According to WMO’s Greenhouse Gas Bulletin, on the global scale, the amount of CO2 in the atmosphere reached 393.1 parts per million in 2012, or 141% of the pre-industrial level of 278 parts per million.
The amount of CO2 in the atmosphere increased 2.2 parts per million from 2011 to 2012, which is above the average 2.02 parts per million per year for the past 10 years, showing an accelerating trend.

Monthly observed concentrations of CO2 in the atmosphere exceeded the symbolic 400 parts per million threshhold at several Global Atmosphere Watch stations in the Arctic during 2012.  During 2013 hourly and daily concentrations passed this threshold in other parts of the world, including at Mauna Loa, Hawaii, the oldest continuous atmospheric measurement station in the world which is widely regarded as a benchmark site in the Global Atmosphere Watch. Concentrations of CO2 are subject to seasonal and regional fluctuations. At  the current rate of increase, the global annual average CO2  concentration is set to cross the 400 parts per million threshold in 2015 or 2016.

CO2 lingers in the atmosphere for hundreds if not thousands of years and so will determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for centuries even if emissions of CO2 are stopped immediately.

Methane (CH4)

Methane is the second most important long-lived greenhouse gas. Approximately 40% of methane is emitted into the atmosphere by natural sources (e.g., wetlands and termites), and about 60 % comes from human activities like cattle breeding, rice agriculture, fossil fuel exploitation, landfills and biomass burning.  

Atmospheric methane reached a new high of about 1819 parts per billion (ppb) in 2012, or 260% of the pre-industrial level, due to increased emissions from anthropogenic sources. Since 2007, atmospheric methane has been increasing again after a temporary period of levelling-off. 
In a special section on methane, the bulletin said that there has not yet been a measurable increase in Arctic methane due to melting of the permafrost and hydrates. It said that the increase in global average methane levels was rather associated with increased emissions in the tropical and mid-latitude Northern Hemisphere. Attribution of this increase to anthropogenic (human-influenced) or natural sources requires better coverage and more sophisticated observations in the atmosphere which are currently not available.

Nitrous oxide (N2O)

Nitrous oxide is emitted into the atmosphere from both natural (about 60%) and anthropogenic sources (approximately 40%), including oceans, soil, biomass burning, fertilizer use, and various industrial processes. Its atmospheric concentration in 2012 was about 325.1 parts per billion, which is 0.9 parts per billion above the previous year and 120% of the pre-industrial level.  Its impact on climate, over a 100-year period, is 298 times greater than equal emissions of carbon dioxide. It also plays an important role in the destruction of the stratospheric ozone layer which protects us from the harmful ultraviolet rays of the sun.

Other greenhouse gases

WMO Graphs of GHGs

The total radiative forcing by all long-lived greenhouse gases in 2012 corresponds to equivalent CO2 concentration of 475.6 parts per million, compared to 473.0 parts per million in 2011. Other long-lived greenhouse gases include ozone-depleting chlorofluorocarbons (CFCs), as well as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) which are increasing at relatively rapid rates.


The WMO Global Atmosphere Watch Programme ( coordinates systematic observations and analysis of greenhouse gases and other trace species. Fifty countries contributed data for the Greenhouse Gas Bulletin. Measurement data are reported by participating countries and archived and distributed by the World Data Centre for Greenhouse Gases (WDCGG) at the Japan Meteorological Agency.

Additional resources: Intergovernmental Panel for Climate Change 5th Assessment Report (The Physical Science Basis)

WMO: The Global Climate 2001-2010: A Decade of Climate Extremes

0 0

Bookmark and Share Printable Version  |  Link to this page


Comments 1 to 8:

  1. Good article and good to know that methane from Actic permafrost isn't rapidly increasing (current growth rate still quite a bit lower than in the 80s).  I'd speculate that methane from northern mid-latitudes is mainly from increased fracking.  Can this not be determined isotopically?

    0 0
  2. I am not as comforted as you, Steve. Levels of methane in the Arctic remain among the highest in the world, sometimes over vast areas. In general, there is a clear overall increase in CH4 concentrations as you go from the equator to the pole.

    Why should this continue to be the case if there aren't high emissions coming from that region?

    Your question about isotopic identification is a good one. I'll have to look at the report to see if they have addressed it. Of course, if a main source in the Arctic is from deep deposits of fossil methane that have come free due to slope failures from permafrost melt, the signatures may not be much different than from fracked fossil methane.

    Fo all of our sakes, though, let's hope the conclusions are right on the origin of this methane, since the sources proposed are at least in theory controlable.

    0 0
    Moderator Response:

    [JH] Unnecessary white space eliminated.

  3. To clarrify a point of potential confusion, the 32% increase between 1990 and 2012 is an increase in the change in the Top Of Atmosphere (TOA) energy imbalance due to Well Mixed GreenHouse Gases (WMGHG) relative to 1750 (the "radiative forcing").  That is, of the total change in radiative forcing since 1750, approximately 25% has occurred in the last 20 years.

    The change in radiative forcing should not be mistaken with the total greenhouse effect of well mixed greenhouse gases.  The total greenhouse effect of CO2, for example, is about 30 W/m^2.  Relative to the total greenhouse effect of CO2, radiative forcing of greenhouse gases has only caused a 2.2% increase over the last 22 years.

    A confusion between "radiative forcing" and "total greenhouse effect" is invited in the article by describing the "radiative forcing" as "... the warming effect on our climate" whereas it is the change in warming effect on our climate.  As I can easilly imagine AGW "skeptics" arguing for the small total effect of CO2 based on this confusion - ie, arguing that the total greenhouse effect of CO2 is at most 2.2 W/m^2 because the 0.7 W/m^2 increase since 1990 is 32% of the warming effect - I thought the clarrification may be usefull.

    As another point of clarrification, that increase is the increase from WMGHGs alone, and does not include the negative effect of aerosols.

    Finally, for anybody interested in exploring the data in more detail can find it here

    0 0
  4. I too sigh with relief that the permafrost is not belching yet. The article repeats the common assertion that CO2 will remain high even if we stop CO2 augmentation immediately: It seems that natural consumption could increase substantially, especially with the help of civilization. Perhaps it is foolish, but our book, Pluvinergy … proposes that if we eliminate CO2 augmentation and increase uptake we can adjust the concentration back down within the century. Our hypothesis proposes working at the scale of the atmosphere to both eliminate CO2 augmenting fuels as well as directly cooling the planet. Thus, the theory proposes that we can have a chance of fixing the mess. Is our work that far off? I hope not.

    0 0
  5. I read many of the scientific arguments both pro and con for Co2 being a heat trapping gas. I don't understand most of the arguments because I am not a scientist. It seems to me that a way to settle this argument would be to get two containers fill one with Co2 and the other with regular atmosphere, place a thermometer in the bottom of both and let them sit side by side for a day and then observe the temperature variation in both containers over a 24 hour period to find the truth. This might be an Occam's Razor type of experiment.

    0 0
  6. Romulan01,

    Here is a youtube video of the experiment that you describe.  This was done with a lamp but it works in the sun also.  This experiment is commonly done in High School or lower classes.  Google is your friend.

    The issue is not that simple experiments have not proven beyond any reasonable doubt that the greenhouse effect exists, the problem is that nothing will ever convince the deniers.

    0 0
  7. Romulan01 @5, Jolan tru.

    The experiment has already been done several time by several different people.  Perhaps the most famous attempt is that by the mythbusters:

    Such attempts have problems, however.  In the Mythbusters experiment, for example, the central container would recieve more light than the adjacent containers due to spill over from the adjacent lights, thereby contaminating the experiment.  The controll (the ordinary air sample) was not in the central container, so some or all of their measured greenhouse effect may have been simply poor experiment design.  Other factors contaminating the various youtube recorded similar experiments include possible heat from the method of producing CO2, high humidity resulting in little or not difference in greenhouse effect between the CO2 enriched and controll sample, and significant wind velocity resulting in large loss of heat by conduction.  I have seen no youtube recorded experiment which could be considered sound.

    To perform the experiment properly you would need to have a control consisting of pure nitrogen and oxygen in an approximate 7:3 mix (so as to have no greenhouse gases in the control), you would need to ensure not heat loss by conduction or convection (ideally by conducting the experiment in a vacum), and you would have to use the same light with identical placement for the various experimental runs (which would need to be run sequentially).

    However, all that might be interesting, but it is uncessary.  Here is an observed and predicted IR spectrum from the Mexican Gulf near Texas:

    The area under the grapp reprsents total energy per second per unit area radiated to space.  Because of that, the large notch in the middle represents a large reduction in energy radiated to space (per second per unit area).  For the Earth to be in energy balance, that reduction must be made up for by increased radiation elsewhere, which prima facie must be accomplished by increased temperature.  The large notch was caused by CO2 in the atmosphere, a fact known by its location, and by the successful prediction by the model (dotted lines).

    Ever since these observations were published in 1970, there has been no scientific doubt of the existence of a greenhouse effect.  There has merely been the attempt to manufacture doubt by pseudoscientists.

    Since 1970, similar observations with similar accuracy have been made hundreds of thousands of times.  What is more, the pseudoscientists who doubt the existence of the greenhouse effect generally (and falsely) claim that the satellite temperature record is more accurate than the surface temperature record, but the satellite temperature record is determined using radiation models of exactly the same kind that show conclusively that there is a greenhouse effect, and which have been confirmed so precisely so many thousands of times.

    Finally, if you want a simple explanation of how the greenhouse effect works, I recommend that you start here.

    0 0
  8. Romulan01 @6, I just had a closer look at the video linked to by Michael Sweet.  I noticed that:

    1) The CO2 was produced by an endothermic reaction, ie, one which cools the products and hence the surrounding environment;

    2) The bottle with enhanced CO2 was open when the CO2 was fed in, thereby preventing pressure build up and a resulting increase in temperature.  This is possible because CO2 is heavier than air so the CO2 fed in would displace normal air out of the bottle; and

    3) The experiment was conducted indoors (avoiding high convective heat loss), and with only two lamps (providing symmetry in overlap heating).

    In short, it avoids all of the problems mentioned in my prior post, and is in fact a very good experiment.

    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Get It Here or via iBooks.

The Consensus Project Website



(free to republish)



The Scientific Guide to
Global Warming Skepticism

Smartphone Apps


© Copyright 2017 John Cook
Home | Links | Translations | About Us | Contact Us