Arctic Environmental Change of the Last Four Centuries

Overpeck, Jonathan T.; Hughen, Konrad A; Hardy, Douglas R.; Bradley, Raymond S.; Case, Roslyn A.; Douglas, Marianne S. V.; Finney, Bruce P.; Gajewski, Konrad; Jacoby, Gordon C.; Jennings, Anne E.; Lamoureux, Scott F.; Lasca, A.; MacDonald, Glen M.; Moore, J.; Retelle, Michael J.; Smith, S.; Wolfe, Alexander P.; Zielinski, Gregory A.

doi:10.1126/science.278.5341.1251

Cited by 945 publications

(734 citation statements)

References 71 publications

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“…The pattern of warming/freshening in the tropical surface ocean indicated by the coral O records is consistent with recent mid-latitude and high-latitude temperature reconstructions suggesting that the 20th century could be the warmest of the millenium (Overpeck et al, 1997;Mann et al, 1998Mann et al, , 1999. The growing number of coral records showing a signi"cant warming/freshening trend points to the involvement of the tropical oceans in enhancing the hydrological cycle and the warming of higher latitudes, as suggested by Graham (1995) from theoretical constraints.…”

Section: Punctuated Long-term Trendssupporting

confidence: 63%

New views of tropical paleoclimates from corals

Gagan

Ayliffe

Beck

et al. 2000

Quaternary Science Reviews

455

287

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Corals o!er a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi-decadal climate sensitivity is incomplete. In the eastern equatorial Paci"c, coral isotopic records track variations in ENSO-related changes in sea-surface temperature; further west, corals record variability in sea-surface temperature and rainfall that accompanies zonal displacement of the Indonesian Low during ENSO events. These multi-century records reveal previously unrecognised ENSO variability on time scales of decades to centuries. Outside the ENSO-sensitive equatorial Paci"c, long-term trends towards recent warmer/wetter conditions suggest the tropics respond to global forcings. New coral paleothermometers indicate that surface-ocean temperatures in the tropical southwestern Paci"c were depressed by 4}63C during the Younger Dryas climatic event and rose episodically during the next 4000 yr. High temporal-resolution measurements of Sr/Ca and O in corals provide information about the surface-ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation. Radiocarbon measurements in corals, coupled with ocean circulation models, may be used to reconstruct near-surface ocean circulation, past mixing rates, and the distribution of fossil fuel CO in the upper ocean. Most recently, seasonal to interannual variations in the radiocarbon of corals from the equatorial Paci"c have been linked to the redistribution of surface waters associated with the ENSO.

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Section: Punctuated Long-term Trendssupporting

confidence: 63%

New views of tropical paleoclimates from corals

Gagan

Ayliffe

Beck

et al. 2000

Quaternary Science Reviews

455

287

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“…The impact of isoprene emissions on Arctic atmospheric chemistry was investigated with the RACM2 model (Regional Atmospheric Chemistry Mechanism, version 2, Stockwell and Goliff, 2004;Papiez et al, 2009). By running RACM with and without isoprene emissions and observing how the predicted concentrations of reactive species varied with time, we could assess how isoprene emissions influence atmospheric chemistry.…”

Section: Atmospheric Chemistry Modelmentioning

confidence: 99%

“…First, the climate of the Arctic is disproportionately affected by global climate change. For example, CO 2 concentration measurements have revealed increases in growing-season length (Myneni et al, 1997), and temperature records (including paleoclimate proxies) have revealed a strong warming trend at high latitudes (Overpeck et al, 1997;Serreze et al, 2000). Precipitation amounts also have increased during the last 50 years (Rawlins et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Isoprene emissions from a tundra ecosystem

et al. 2013

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Whole-system fluxes of isoprene from a moist acidic tundra ecosystem and leaf-level emission rates of isoprene from a common species (Salix pulchra) in that same ecosystem were measured during three separate field campaigns. The field campaigns were conducted during the summers of 2005, 2010 and 2011 and took place at the Toolik Field Station (68.6° N, 149.6° W) on the north slope of the Brooks Range in Alaska, USA. The maximum rate of whole-system isoprene flux measured was over 1.2 mg C m−2 h−1 with an air temperature of 22 °C and a PAR level over 1500 μmol m−2 s−1. Leaf-level isoprene emission rates for S. pulchra averaged 12.4 nmol m−2 s−1 (27.4 μg C gdw−1 h−1) extrapolated to standard conditions (PAR = 1000 μmol m−2 s−1 and leaf temperature = 30 °C). Leaf-level isoprene emission rates were well characterized by the Guenther algorithm for temperature with published coefficients, but less so for light. Chamber measurements from a nearby moist acidic tundra ecosystem with little S. pulchra emitted significant amounts of isoprene, but at lower rates (0.45 mg C m−2 h−1) suggesting other significant isoprene emitters. Comparison of our results to predictions from a global model found broad agreement, but a detailed analysis revealed some significant discrepancies. An atmospheric chemistry box model predicts that the observed isoprene emissions have a significant impact on Arctic atmospheric chemistry, including a reduction of hydroxyl radical (OH) concentrations. Our results support the prediction that isoprene emissions from Arctic ecosystems will increase with global climate change

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“…Arctic climate is naturally variable (Overpeck et al, 1997) and is sensitive to humaninduced changes . Although the Arctic is widely recognized as being a critical region for global climate change, the specific mechanisms by which climate change affects arctic landscapes are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

Mann

Peteet

Reanier³

et al. 2002

Quaternary Science Reviews

117

132

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Many of the physical and biological processes that characterize arctic ecosystems are unique to high latitudes, and their sensitivities to climate change are poorly understood. Stratigraphic records of land-surface processes and vegetation change in the Arctic Foothills of northern Alaska reveal how tundra landscapes responded to climatic changes between 13,000 and 8000 14 C yr BP. Peat deposition began and shrub vegetation became widespread ca. 12,500 14 C yr BP, probably in response to the advent of warmer and wetter climate. Increased slope erosion caused rapid alluviation in valleys, and Populus trees spread northward along braided floodplains before 11,000 14 C yr BP. Lake levels fell and streams incised their floodplains during the Younger Dryas (YD) (11,000-10,000 14 C yr BP). A hiatus in records of Populus suggest that its geographic range contracted, and pollen records of other species suggest a cooler and drier climate during this interval. Basal peats dating to the YD are rare, suggesting that rates of paludification slowed. Immediately after 10,000 14 C yr BP, lake levels rose, streams aggraded rapidly again, intense solifluction occurred, and Populus re-invaded the area. Moist acidic tundra vegetation was widespread by 8500 14 C yr BP along with wet, organic-rich soils. Most of these landscape-scale effects of climatic change involved changes in moisture. Although low temperature is the most conspicuous feature of arctic climate, shifts in effective moisture may be the proximate cause for many of the impacts that climate change has in arctic regions. r

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Arctic Environmental Change of the Last Four Centuries

Cited by 945 publications

References 71 publications

New views of tropical paleoclimates from corals

New views of tropical paleoclimates from corals

Isoprene emissions from a tundra ecosystem

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

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