Slowing down of the global accumulation of atmospheric methane during the 1980s

Steele, Lloyd; Dlugokencky, E. J.; Lang, P. M.; Tans, Pieter P.; Martin, Ruth A.; Masarie, K. A.

doi:10.1038/358313a0

Cited by 290 publications

(126 citation statements)

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“…Recent studies indicate a considerable influence of atmospheric methane concentrations on Holocene climatic variations (Stauffer et al 1988;Chappellaz et al 1993). At present, tropospheric methane concentrations are increasing annually by 0.7 to 1.4% (Rasmussen & Khalil 1984;Khalil & Rasmussen 1986;Steele et al 1987Steele et al , 1992. This increase is attributed to anthropogenically mediated release and a decrease of oxidation by OH-radicals in the atmosphere (Cicerone & Oremland 1988).…”

Section: Introductionmentioning

confidence: 99%

Ethylene and methane in the upper water column of the subtropical Atlantic

et al. 1999

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Abstract. The vertical distributions of ethylene and methane in the upper water column of the subtropical Atlantic were measured along a transect from Madeira to the Caribbean and compared with temperature, salinity, oxygen, nutrients, chlorophyll-a, and dissolved organic carbon (DOC).Methane concentrations between 41.6 and 60.7 nL L −1 were found in the upper 20 m of the water column giving a calculated average flux of methane into the atmosphere of 0.82 µg m −2 h −1 . Methane profiles reveal several distinct maxima in the upper 500 m of the water column and short-time variations which are presumably partly related to the vertical migration of zooplankton.Ethylene concentrations in near surface waters varied in the range of 1.8 to 8.2 nL L −1 . Calculated flux rates for ethylene into the atmosphere were in the range of 0.41 to 1.35 µg m −2 h −1 with a mean of 0.83 µg m −2 h −1 . Maximum concentrations of up to 39.2 nL L −1 were detected directly below the pycnocline in the western Atlantic. The vertical distributions of ethylene generally showed one maximum at the pycnocline (about 100 m depth) where elevated concentrations of chlorophyll-a, dissolved oxygen, and nutrients were also found; no ethylene was detected below 270 m depth. This suggests that ethylene release is mainly related to one, probably phytoplankton associated, source, while for methane, enhanced net production occurs at various depth horizons. For surface waters, a simple correlation between ethylene and chlorophyll-a or DOC concentrations could not be observed. No considerable diurnal variation was observed for the distribution and concentration of ethylene in the upper water column.

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Section: Introductionmentioning

confidence: 99%

Ethylene and methane in the upper water column of the subtropical Atlantic

et al. 1999

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“…This increase is confirmed by glacial ice cores from the early 1800s (e.g., Dibb et al,199x), and solar spectra from 1950 (e.g., Rinsland et al, 1985). As seen in Figure 2, observations from ground-based stations show that the global level of methane has more than doubled since pre-industrial times, and continues to increase (Rasmussen & Khalil, 1981;Blake & Rowland, 1988;Steele et al, 1992;Dlugokencky et al, 1994b;Dlugokencky et al, 1995;Dlugokencky et al, 1998; scientific reviews can be found in IPCC, 1995;IPCC, 1996).…”

Section: Pre-industrial To Presentmentioning

confidence: 53%

“…examine the changing relationship between population and agricultural sources, thought to be a major contributor to CH 4 increases from pre-industrial to present times, to show that these sources may be slowing. Steele et al (1992) suggest that human sources, particularly those sources which can be reduced quickly, may be the cause of the observed rapid deceleration of the growth rate in the Northern relative to the Southern Hemisphere. Although the exact cause of this long-term decline in the global methane rate is still unresolved, Dlugokencky et al (1998) suggest that what has been observed was in fact an approach to steady state, as CH 4 net emissions and sinks were nearly constant over the past decade.…”

Section: Decadal Changes In Methane Growth Ratesmentioning

confidence: 99%

“…However, during the 70's and 80's, the rate of methane increase slowed steadily, by an average of -1 ppbv/yr (Figure 4). Continuous monitoring of methane trends in ambient air from 1979 to 1989 indicated a decreasing trend from 20 to just over 10 ppbv, with an average growth rate of 8.9 ppbv/yr from 1984 to 1996 (Dlugokencky et al, 1998(Dlugokencky et al, , 1994bSteele et al, 1992). When the data was examined for regional and seasonal effects, it was found that the slowing in the rate of increase is higher between 30-90 o N (Dlugokencky et al, 1998;Steele et al, 1992), but that the amplitude of the seasonal cycle has exhibited no significant global trends over this time, with typical amplitudes around 30 ppbv Dlugokencky et al, 1994aDlugokencky et al, , 1997.…”

Section: Decadal Changes In Methane Growth Ratesmentioning

confidence: 99%

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Atmospheric Methane: Trends and Impacts

Wuebbles

Hayhoe

2000

Non-Co2 Greenhouse Gases: Scientific Understanding, Control and Implementation

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Abstract:The concentration of methane (CH 4 ), the most abundant organic trace gas in the atmosphere, has increased dramatically over the last few centuries, more than doubling its concentration. The increasing concentrations of methane are of special concern because of its effects on climate and atmospheric chemistry. On a per molecule basis, additional methane is much more effective as a greenhouse gas than additional CO 2 . Methane is also important to both tropospheric and stratospheric chemistry. Here, we examine past trends in the concentration of methane, the sources and sinks affecting its growth rate, and the factors that could affect its growth rate in the future. This study also examines the current understanding of the effects of methane on atmospheric chemistry and climate.

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“…Continuous monitoring of CH 4 trends in ambient air from 1979 to 1989 indicates that concentrations had been increasing at an average of about 16 ppbv 5 or 1% per year. In the late 1980s, rates of increase fell to about 10 ppbv/year (Steele et al, 1992;Khalil and Rasmussen, 1993), declining even further in the early 1990s before stopping entirely at some locations in 1992 [ Fig. 9(b); Dlugokencky et al, 1998].…”

Section: Historical Concentrationsmentioning

confidence: 99%

Global change: state of the science

Wuebbles

Jain

Edmonds

et al. 1999

Environmental Pollution

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Only recently, within a few decades, have we realized that humanity signi®cantly in¯uences the global environment. In the early 1980s, atmospheric measurements con®rmed basic concepts developed a decade earlier. These basic concepts showed that human activities were a ecting the ozone layer . Later measurements and theoretical analyses have clearly connected observed changes in ozone to human-related increases of chlorine and bromine in the stratosphere. As a result of prompt international policy agreements, the combined abundances of ozone-depleting compounds peaked in 1994 and ozone is already beginning a slow path to recovery. A much more di cult problem confronting humanity is the impact of increasing levels of carbon dioxide and other greenhouse gases on global climate. The processes that connect greenhouse gas emissions to climate are very complex. This complexity has limited our ability to make a de®nitive projection of future climate change. Nevertheless, the range of projected climate change shows that global warming has the potential to severely impact human welfare and our planet as a whole. This paper evaluates the state of the scienti®c understanding of the global change issues, their potential impacts, and the relationships of scienti®c understanding to policy considerations. #

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Slowing down of the global accumulation of atmospheric methane during the 1980s

Cited by 290 publications

References 21 publications

Ethylene and methane in the upper water column of the subtropical Atlantic

Ethylene and methane in the upper water column of the subtropical Atlantic

Atmospheric Methane: Trends and Impacts

Global change: state of the science

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