1,500 year quantitative reconstruction of winter precipitation in the Pacific Northwest

Steinman, Byron A.; Abbott, Mark B.; Mann, Michael; Stansell, Nathan D.; Finney, Bruce P.

doi:10.1073/pnas.1201083109

Cited by 76 publications

(55 citation statements)

References 31 publications

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“…That pattern is believed to be associated with the settlement era. However, prior to 1500 there was also a region-wide period of extensive fire, probably driven by drier and possibly warmer conditions (Steinman et al 2012;Weisberg and Swanson 2003). Our projected rate of 0.6 to 1.8 % per year over the 2010 to 2100 period from the two warmer scenarios is comparable to the observed relatively high rate prior to 1500.…”

Section: Firesupporting

confidence: 84%

Projected climate change impacts on forest land cover and land use over the Willamette River Basin, Oregon, USA

2015

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Upland forests in the Pacific Northwest currently provide a host of ecosystem services. However, the regional climate is expected to warm significantly over the course of the 21st century and this factor must be accounted for in planning efforts to maintain those services. Here we couple a dynamic global vegetation model (MC2) with a landscape simulation model (Envision) to evaluate potential impacts of climate change on the vegetation cover and the disturbance regime in the Willamette River Basin, Oregon. Three CMIP5 climate model scenarios, downscaled to a 4 km spatial resolution, were employed. In our simulations, the dominant potential vegetation cover type remained forest throughout the basin, but forest type transitioned from primarily evergreen needleleaf to a mixture of broadleaf and needleleaf growth forms adapted to a warmer climate. By 2100, there was a difference (i.e., climate/vegetation disequilibrium) between potential and actual forest type for 20-50 % of the forested area. In the moderate to high climate change scenarios, the average area burned per year increased three to nine fold from the present day. Forest harvest on private land is projected to be affected late in the century because of fire altering the availability of rotation-age stands. A generally more disturbed and open forest landscape is expected, which may significantly alter the hydrologic cycle.Climatic Change

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Section: Firesupporting

confidence: 84%

Projected climate change impacts on forest land cover and land use over the Willamette River Basin, Oregon, USA

2015

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“…Lengths of significant periods are indicated in the graph Vries or Suess (~1/200 year −1 ) and Geisberg (1/83 year −1 ) cycles found in cosmogenic ( 14 C and 10 Be) records (e.g., Emile-Geay et al 2007;Neftel et al 1981;Ogurtsov et al 2002;Suess 1980). Similar cycles are also found in records of the PDO (Benson et al 2003) and of the Pacific-North American teleconnection pattern (PNA) (Liu et al 2014;Steinman et al 2012). This similarity of the variability points to an influence of solar radiation on the ENSO.…”

Section: A Coccolithophore Markers Of Ensosupporting

confidence: 49%

A 2700-year record of ENSO and PDO variability from the Californian margin based on coccolithophore assemblages and calcification

Beaufort

Grelaud

2017

Prog. in Earth and Planet. Sci.

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The El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) account for a large part of modern climate variability. Over the last decades, understanding of these modes of climate variability has increased but prediction in the context of global warming has proven difficult because of the lack of pertinent and reproducible paleodata. Here, we infer the dynamics of these oscillations from fossil assemblage and calcification state of coccolithophore in the Californian margin because El Niño has a strong impact on phytoplankton ecology and PDO on the upwelling intensity and hence on the ocean chemistry. Intense Californian upwelling brings water rich in CO 2 and poor in carbonate ions and coccolithophores secrete lower calcified coccoliths. Seasonally laminated sediments of the Santa Barbara Basin are used to document ENSO variability and PDO index for the last 2700 years at a temporal resolution of 3 years. The records present the same characteristics as other PDO or ENSO records from the same area spanning the last centuries. We are therefore confident on the value produced here for the last 2.7 millennia. The records show important centennial variability that is equivalent to solar cycles.

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“…However, the issue remains that there is no easy way to determine the real noise spectrum of the proxies. With the advent of more isotope-enabled GCM simulations, further improvement could come from the use of more proxy system models to more accurately estimate the proxy-climate relationships for all types of proxies (see Conroy et al, 2008;Evans et al, 2013;Russon et al, 2013;Stansell et al, 2013;Steinman et al, 2012;Sturm et al, 2010;Thompson et al, 2011;Tierney et al, 2011;Dee et al, 2015).…”

Section: Reflections On the Methodsmentioning

confidence: 99%

Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data

2017

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Abstract. The El Niño-Southern Oscillation (ENSO) is the most important source of global climate variability on interannual timescales and has substantial environmental and socio-economic consequences. However, it is unclear how it interacts with large-scale climate states over longer (decadal to centennial) timescales. The instrumental ENSO record is too short for analysing long-term trends and variability and climate models are unable to accurately simulate past ENSO states. Proxy data are used to extend the record, but different proxy sources have produced dissimilar reconstructions of long-term ENSO-like climate change, with some evidence for a temperature-precipitation divergence in ENSO-like climate over the past millennium, in particular during the Medieval Climate Anomaly (MCA; AD ∼ 800-1300) and the Little Ice Age (LIA; AD ∼ 1400-1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using weighting based on empirical orthogonal function (EOF) to create two new large-scale reconstructions of ENSOlike climate change derived independently from precipitation proxies and temperature proxies. The method is developed and validated using model-derived pseudo-proxy experiments that address the effects of proxy dating error, resolution, and noise to improve uncertainty estimations. We find no evidence that temperature and precipitation disagree over the ENSO-like state over the past millennium, but neither do they agree strongly. There is no statistically significant difference between the MCA and the LIA in either reconstruction. However, the temperature reconstruction suffers from a lack of high-quality proxy records located in ENSO-sensitive regions, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite, and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records and establish the long-term stability of this important mode of climatic variability.

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1,500 year quantitative reconstruction of winter precipitation in the Pacific Northwest

Cited by 76 publications

References 31 publications

Projected climate change impacts on forest land cover and land use over the Willamette River Basin, Oregon, USA

Projected climate change impacts on forest land cover and land use over the Willamette River Basin, Oregon, USA

A 2700-year record of ENSO and PDO variability from the Californian margin based on coccolithophore assemblages and calcification

Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data

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