Early rice farming and anomalous methane trends

Ruddiman, William F.; Guo, Zhengtang; Zhou, Xin; Wu, Hanbin; Yu, Yanyan

doi:10.1016/j.quascirev.2008.03.007

Cited by 110 publications

(77 citation statements)

References 23 publications

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“…It has been estimated that more than 75 % of the Earth's ice-free area has been modified by human activities; these regions can be considered as 'anthropogenic biomes' (Ellis and Ramankutty 2008). Research in recent years has shown that human impacts are not only driving current and future environmental changes, but have also played significant roles in environmental changes in the Holocene (Edwards and MacDonald 1991;Ruddiman et al 2008;Kuneš et al 2008). Understanding climate-human-environmental interactions at local and regional scales is the foundation for fully understanding environmental changes at a global scale; moreover, resolving our past is an essential element in predicting the future (Dearing 2006).…”

Section: Introductionmentioning

confidence: 99%

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Wei

Zhao

2015

Veget Hist Archaeobot

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A dataset consisting of 70 surface pollen samples from forest, alpine meadow, alpine steppe, temperate steppe, desert steppe, shrub/semi-shrub steppe and desert sites in the Tianshan Mountains, northwestern China provides an opportunity to study the relationships between surface pollen assemblages and modern vegetation and climate in this region. Redundancy analysis (RDA), the human influence index (HII) and pollen ratios were used to facilitate analysis of the pollen data. The modern pollen assemblages are primarily composed of Picea, Artemisia, Chenopodiaceae, Poaceae, Asteraceae, Nitraria and Ephedra. The results suggest that the surface pollen assemblages of different vegetation types largely represent the modern vegetation in terms of the primary taxa and dominant types. The RDA indicates that the mean annual precipitation (MAP) and the July temperature (T July ) are the major climate variables that control the modern pollen assemblages. Picea, Artemisia, Poaceae, Cyperaceae, Fabaceae, Asteraceae, Polygonaceae and Apiaceae pollen assemblages are positively correlated with MAP and negatively correlated with T July , while the pollen ratios for certain other types, such as Chenopodiaceae, Ephedra and Nitraria, are negatively correlated with MAP and positively correlated with T July . The arboreal/non-arboreal ratios are notably high in the forest samples, indicating a sensitive response to forest vegetation. Moreover, the Artemisia/Chenopodiaceae pollen ratios are generally correlated with the vegetation type and annual precipitation change, suggesting that these factors could be useful indicators of moisture variability in arid regions. However, it is difficult to distinguish between steppe and steppe desert based on this ratio, due partly to human disturbance. The HII is significantly correlated with certain pollen taxa, including Poaceae, Plantago, Polygonaceae and Elaeagnaceae, particularly in the alpine meadow and steppe samples. Our results have implications for interpreting the available fossil pollen data in the study region and other arid and semi-arid regions.

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Section: Introductionmentioning

confidence: 99%

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Wei

Zhao

2015

Veget Hist Archaeobot

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“…South America is of particular interest because it is connected to water masses coming from the Atlantic and Pacific sectors. We will also propose a possible explanation for methane evolution during the Holocene, which is still under debate (Ruddiman et al, 2008) and of particular interest with regard to global warming.…”

Section: Introductionmentioning

confidence: 99%

Evidence from wavelet analysis for a mid-Holocene transition in global climate forcing

Debret

Sebag

Crosta

et al. 2009

Quaternary Science Reviews

133

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A strong mid-Holocene transition has been identified by wavelet analyses in several sea ice cover records from the circum-Antarctic area, ice core records (Taylor dome, Byrd) and tropical marine records. The results are compared with those previously published in a synthesis of North Atlantic records and with 4 new records from the Norwegian and Icelandic seas and from a coastal site in Ireland. These new records confirm the previous

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“…As for the possible contribution from river deltas, Ruddiman (2007) suggested that this may also reflect anthropogenic influences, with forest clearance leading to erosion and increased sediment loads in rivers, and contributing to an expansion of river delta systems. In addition, a compilation of archaeological sites in rice-growing areas of China, suggests a ten-fold increase in new sites between 6 and 5 kyr BP (Ruddiman et al, 2008). Further refinement of the anthropogenic hypothesis for the Holocene CH 4 increase, now recognizes that in addition to early rice farming and irrigation, biomass burning, releases from livestock and human waste, and climate feedbacks also contributed to the CH 4 anomaly (Ruddiman, 2007).…”

Section: Introductionmentioning

confidence: 99%

The MIS 11 – MIS 1 analogy, southern European vegetation, atmospheric methane and the "early anthropogenic hypothesis"

Tzedakis

2010

Clim. Past

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Abstract. Marine Isotope Stage (MIS) 11 has been considered a potential analogue for the Holocene and its future evolution. However, a dichotomy has emerged over the precise chronological alignment of the two intervals, with one solution favouring a synchronization of the precession signal and another of the obliquity signal. The two schemes lead to different implications over the natural length of the current interglacial and the underlying causes of the evolution of greenhouse gas concentrations. Here, the close coupling observed between changes in southern European tree populations and atmospheric methane concentrations in previous interglacials is used to evaluate the natural vs. anthropogenic contribution to Holocene methane emissions and assess the two alignment schemes. Comparison of the vegetation trends in MIS 1 and MIS 11 favours a precessional alignment, which would suggest that the Holocene is nearing the end of its natural course. This, combined with the divergence between methane concentrations and temperate tree populations after 5 kyr BP, provides some support for the notion that the Holocene methane trend may be anomalous compared to previous interglacials. In contrast, comparison of MIS 1 with MIS 19, which may represent a closer astronomical analogue than MIS 11, leads to substantially different conclusions on the projected natural duration of the current interglacial and the extent of the anthropogenic contribution to the Holocene methane budget. As answers vary with the choice of analogue, resolution of these issues using past interglacials remains elusive.

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Early rice farming and anomalous methane trends

Cited by 110 publications

References 23 publications

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Evidence from wavelet analysis for a mid-Holocene transition in global climate forcing

The MIS 11 – MIS 1 analogy, southern European vegetation, atmospheric methane and the "early anthropogenic hypothesis"

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Early rice farming and anomalous methane trends

Cited by 110 publications

References 23 publications

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Evidence from wavelet analysis for a mid-Holocene transition in global climate forcing

The MIS 11 – MIS 1 analogy, southern European vegetation, atmospheric methane and the &quot;early anthropogenic hypothesis&quot;

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The MIS 11 – MIS 1 analogy, southern European vegetation, atmospheric methane and the "early anthropogenic hypothesis"