The Late Quaternary History of Atmospheric Trace Gases and Aerosols: Interactions Between Climate and Biogeochemical Cycles

Blunier, Thomas; Ono, Yuichi; Delmas, Robert J.

doi:10.1007/978-3-642-55828-3_2

Cited by 34 publications

(17 citation statements)

References 140 publications

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“…The LGM, ca 21,000 cal yr BP, represents the global (though not regional) maximum of the extent of the ice sheets (Peltier 2004) and a time when sea level was ca 120m lower than at present and tropical land areas were more extensive than today. Greenhouse gas concentrations (compared to pre-industrial) were low (Raynaud et al 2003) and atmospheric aerosol loadings were high (Kohfeld and Harrison 2001). Ocean temperatures were, in general, lower than today with the largest changes occurring in high northern latitudes (Schäfer-Neth and Paul 2003).…”

Section: Discussion: the Climatic Control Of Observed Changes In Firementioning

confidence: 96%

Changes in fire regimes since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data

Power

Marlon²,

Ortiz³

et al. 2007

Clim Dyn

609

453

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Knowledge of historical fire activity tends to be focused at local to landscape scales with few attempts to examine how local patterns of fire activity scale to global patterns. Generally, fire activity varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesised sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In eastern and western North America and western Europe and southern South America, charcoal records indicate less-than-present fire activity from 21,000 to ~11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greaterthan-present fire activity from ~19,000 to ~17,000 cal yr BP whereas most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ~13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8000 to ~2000 cal yr BP, Indonesia from 11,000 to 4000 cal yr BP, and southern South America from 6000 to 3000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the postglacial period. These complex patterns can be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.

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Section: Discussion: the Climatic Control Of Observed Changes In Firementioning

confidence: 96%

Changes in fire regimes since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data

Power

Marlon²,

Ortiz³

et al. 2007

Clim Dyn

609

453

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“…Carbon dioxide, methane, and nitrous oxide varied little over the past 2,000 years prior to the industrial era (Figure 10-1). Ice core measurements indicate that carbon dioxide and nitrous oxide remained within a few ppm and ppb, respectively, of their mean concentrations and within the uncertainties of the data (Raynaud et al 2003, Gerber et al 2003. Methane fluctuated between 600 and 750 ppb, changing with the climate and likely resulting from fluctuations in natural and early anthropo-FIGURE 10-1 Evolution of atmospheric carbon dioxide and methane over the last 22,000 years.…”

Section: Greenhouse Gasesmentioning

confidence: 84%

“…SOURCE: Joos (2005). Reprinted with permission; copyright 2005. genic sources (Blunier et al 1993, Ruddiman and Thomson 2001, Raynaud et al 2003, Keppler et al 2006. Since the beginning of the Industrial Revolution (ca.…”

Section: Greenhouse Gasesmentioning

confidence: 99%

Surface Temperature Reconstructions for the Last 2,000 Years

North¹

2006

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Our understanding of climate and how it has varied over time is advancing rapidly as new data are acquired and new investigative instruments and methods are employed. Thus in 2005, I suggested to the U.S. Congress that the National Research Council (NRC) could help answer questions about the data and methods that have been used in constructing records of Earth's surface temperatures from times when there were no scientific instruments, using proxy indicators. How has temperature varied over the last 2,000 years? How certain is the answer to this question? Subsequently, this study was requested by Representative Sherwood Boehlert, chairman of the Committee on Science, U.S. House of Representatives. Chairman Boehlert asked for a clear and concise report in a relatively short period of time, and the NRC agreed to undertake the study quickly. An ad hoc committee was formed, with the group carefully composed to include the breadth and depth of expertise and perspectives needed to analyze all aspects of how surface temperatures are estimated and interpreted and to comment generally on climate science. The NRC asked the committee to summarize current scientific information on the temperature record for the past two millennia, describe the main areas of uncertainty and how significant they are, describe the principal methodologies used and any problems with these approaches, and explain how central is the debate over the paleoclimate temperature record to the state of scientific knowledge on global climate change.The committee has prepared a report that, in my view, provides policy makers and the scientific community with a critical view of surface temperature reconstructions and how they are evolving over time, as well as a good sense of how important our understanding of the paleoclimate temperature record is within the overall state of scientific knowledge on global climate change. The report does not make policy recommendations.I thank the members of the committee, who worked intensely to produce this careful report in a short period of time and contributed much personal time, insight, and energy. ForewordCopyright © National Academy of Sciences. All rights reserved.Surface Temperature Reconstructions for the Last 2,000 Years http://www.nap.edu/catalog/11676.htmlThe NRC staff and all those who contributed papers, data, graphics, and other information, as well as the independent experts who participated in the rigorous review process, were essential participants. Surface Temperature Reconstructions for the Last 2,000 Years http://www.nap.edu/catalog/11676.html ix This committee was asked to describe and assess the state of scientific efforts to reconstruct surface temperature records for the Earth over approximately the last 2,000 years. (The full Statement of Task appears in Appendix A.) Normally, a technical issue such as surface temperature reconstructions might not generate widespread attention, but this case brings interesting lessons about how science works and how science, especially climate science, is commun...

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“…It is in the context of demonstrable self-regulation, involving maximum global atmospheric concentrations over almost half a million years of about 280 ppmv for CO 2 and 750 ppbv for methane, that any evaluation of contemporary values rising beyond 360 and 1 700, respectively, must be placed. These contemporary values are already significantly in excess of the peaks recorded in the Vostok series even when they are smoothed to replicate the processes affecting the trace gas record in the Vostok ice (Raynaud et al 2003) (Box 2.1).…”

Section: The Long-term Envelope Of Natural Self-regulationmentioning

confidence: 99%

“…A critical question in global change science is the establishment of the extent to which anthropogenic atmospheric changes over the last few centuries have been unprecedented Raynaud et al 2003). The ice core measurements overlap with direct atmospheric measurements in the contemporary period (solid lines) required.…”

Section: Millennial-scale Oscillations and Abrupt Changesmentioning

confidence: 99%

Planetary Machinery: The Dynamics of the Earth System Prior to Significant Human Influence

2005

Global Change and the Earth System

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The Late Quaternary History of Atmospheric Trace Gases and Aerosols: Interactions Between Climate and Biogeochemical Cycles

Cited by 34 publications

References 140 publications

Changes in fire regimes since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data

Changes in fire regimes since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data

Surface Temperature Reconstructions for the Last 2,000 Years

Planetary Machinery: The Dynamics of the Earth System Prior to Significant Human Influence

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