scholarly journals Decadal-Scale SST and Salinity Variations in the Central Tropical Pacific: Signatures of Natural and Anthropogenic Climate Change

2011 ◽  
Vol 24 (13) ◽  
pp. 3294-3308 ◽  
Author(s):  
Intan S. Nurhati ◽  
Kim M. Cobb ◽  
Emanuele Di Lorenzo
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
Time Scales ◽  
Tropical Pacific ◽  
Anthropogenic Climate Change ◽  
Central Pacific ◽  
Proxy Record ◽  
Decadal Scale ◽  
Central Pacific Warming ◽  
Salinity Variations

Abstract Accurate projections of future temperature and precipitation patterns in many regions of the world depend on quantifying anthropogenic signatures in tropical Pacific climate against its rich background of natural variability. However, the detection of anthropogenic signatures in the region is hampered by the lack of continuous, century-long instrumental climate records. This study presents coral-based sea surface temperature (SST) and salinity proxy records from Palmyra Island in the central tropical Pacific over the twentieth century, based on coral strontium/calcium and the oxygen isotopic composition of seawater (δ18OSW), respectively. On interannual time scales, the Sr/Ca-based SST record captures both eastern and central Pacific warming “flavors” of El Niño–Southern Oscillation (ENSO) variability (R = 0.65 and 0.67, respectively). On decadal time scales, the SST proxy record is highly correlated to the North Pacific gyre oscillation (NPGO) (R = −0.85), reflecting strong dynamical links between the central Pacific warming mode and extratropical decadal climate variability. Decadal-scale salinity variations implied by the coral-based δ18OSW record are significantly correlated with the Pacific decadal oscillation (PDO) (R = 0.54). The salinity proxy record is dominated by an unprecedented trend toward lighter δ18OSW values since the mid–twentieth century, implying that a significant freshening has taken place in the region, in line with climate model projections showing enhanced hydrological patterns under greenhouse forcing. Taken together, the new coral records suggest that low-frequency SST and salinity variations in the central tropical Pacific are controlled by different sets of dynamics and that recent hydrological trends in this region may be related to anthropogenic climate change.

scholarly journals Response of ENSO and the Mean State of the Tropical Pacific to Extratropical Cooling and Warming: A Study Using the IAP Coupled Model

2009 ◽  
Vol 22 (22) ◽  
pp. 5902-5917 ◽  
Author(s):  
Y. Yu ◽  
D-Z. Sun
Keyword(s):  
Climate Change ◽  
Climate Modeling ◽  
Coupled Model ◽  
Tropical Pacific ◽  
Equatorial Region ◽  
Upper Ocean ◽  
Central Pacific ◽  
Intergovernmental Panel ◽  
Ocean Atmosphere ◽  
The Tropical Pacific

Abstract The coupled model of the Institute of Atmospheric Physics (IAP) is used to investigate the effects of extratropical cooling and warming on the tropical Pacific climate. The IAP coupled model is a fully coupled GCM without any flux correction. The model has been used in many aspects of climate modeling, including the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) climate change and paleoclimate simulations. In this study, the IAP coupled model is subjected to cooling or heating over the extratropical Pacific. As in an earlier study, the cooling and heating is imposed over the extratropical region poleward of 10°N–10°S. Consistent with earlier findings, an elevated (reduced) level of ENSO activity in response to an increase (decrease) in the cooling over the extratropical region is found. The changes in the time-mean structure of the equatorial upper ocean are also found to be very different between the case in which ocean–atmosphere is coupled over the equatorial region and the case in which the ocean–atmosphere over the equatorial region is decoupled. For example, in the uncoupled run, the thermocline water across the entire equatorial Pacific is cooled in response to an increase in the extratropical cooling. In the corresponding coupled run, the changes in the equatorial upper-ocean temperature in the extratropical cooling resemble a La Niña situation—a deeper thermocline in the western and central Pacific accompanied by a shallower thermocline in the eastern Pacific. Conversely, with coupling, the response of the equatorial upper ocean to extratropical cooling resembles an El Niño situation. These results ascertain the role of extratropical ocean in determining the amplitude of ENSO. The results also underscore the importance of ocean–atmosphere coupling in the interaction between the tropical Pacific and the extratropical Pacific.

scholarly journals Tropical Pacific Surface Wind Energy Spectra and Coherence: Basinwide Observations and Their Observing System Implications

2020 ◽  
Vol 33 (16) ◽  
pp. 7141-7154
Author(s):  
Andrew M. Chiodi ◽  
D. E. Harrison
Keyword(s):  
Surface Wind ◽  
Tropical Pacific ◽  
Central Pacific ◽  
Eastern Equatorial Pacific ◽  
Term Change ◽  
Decadal Scale ◽  
Optimal Spacing ◽  
Minimal Redundancy ◽  
Original Array ◽  
The Tropical Pacific

AbstractThe tropical Pacific moored-buoy array spacing was based on wind coherence scales observed from low-lying islands in the western-central tropical Pacific. Since the array was deployed across the full basin in the mid-1990s, winds from the array have proven critical to accurately monitoring for decadal-scale changes in tropical Pacific winds and identifying spurious trends in wind analysis products used to monitor for long-term change. The array observations have also greatly advanced our ability to diagnostically model (hindcast) and thereby better understand the observed development of central Pacific sea surface temperature anomaly development associated with El Niño and La Niña events, although the eastern equatorial Pacific is not yet accurately hindcast. The original array-design assumptions that the statistics calculated from the western-central Pacific island records are representative of open-ocean conditions and other regions of the tropical Pacific have not been thoroughly reexamined. We revisit these assumptions using the basinwide wind observations provided by the array and find that key wind statistics change across the tropical Pacific basin in ways that could not be determined from the original island wind study. The island results provided a best-case answer for mooring zonal spacing with minimally redundant coherence between adjacent buoys. Buoy-observed meridional coherence scales are longer than determined from the islands. Enhanced zonal sampling east of 140°W and west of 180° is needed to obtain minimal redundancy (optimal spacing). Reduced meridional sampling could still yield minimal redundancy for wind and wind stress fields over the ocean waveguide.

Great Plains Drought in Simulations of the Twentieth Century

2010 ◽  
Vol 23 (8) ◽  
pp. 2178-2196 ◽  
Author(s):  
Rachel R. McCrary ◽  
David A. Randall
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
Great Plains ◽  
Low Frequency ◽  
Tropical Pacific ◽  
Future Climate Change ◽  
Climate System Model ◽  
Model Version ◽  
Frequency Variations

Abstract Coupled global circulation models (CGCMs) have been widely used to explore potential future climate change. Before these climate projections can be trusted, the ability of the models to simulate present-day climate must be assessed. This study evaluates the ability of three CGCMs that participated in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change to simulate long-term drought over the Great Plains region with the same frequency and intensity as was observed during the twentieth century. The three models evaluated in this study are the Geophysical Fluid Dynamics Laboratory Coupled Model, version 2.0 (CM2.0); the National Centers for Atmospheric Research Community Climate System Model, version 3 (CCSM3); and third climate configuration of the Met Office Unified Model (HadCM3). The models are shown to capture the broad features of the climatology of the Great Plains, with maximum precipitation occurring in early summer, as observed. However, all of the models overestimate annual precipitation rates. Also, in CCSM3, precipitation and evapotranspiration experience unrealistic decreases between the months of June and August. Long-term droughts are found in each simulation of the twentieth century that are comparable in duration, severity, and spatial extent as has been observed. However, the processes found to be associated with simulated long-term droughts vary among the models. In both CM2.0 and HadCM3, low-frequency variations in Great Plains precipitation are found to correspond with low-frequency variations in tropical Pacific SSTs. In CCSM3, on the other hand, there appears to be no significant correlation between tropical Pacific SST variability and Great Plains precipitation. Strong land–atmosphere coupling in CCSM3 may explain the persistence of long-term droughts in this model.

scholarly journals High-Resolution Water Stable Isotope Ice-Core Record: Roosevelt Island, Antarctica

2021 ◽  
Author(s):  
◽  
Daniel Emanuelsson
Keyword(s):  
El Niño ◽  
El Nino ◽  
Ice Core ◽  
Tropical Pacific ◽  
Central Pacific ◽  
Amundsen Sea ◽  
Enso Variability ◽  
The Pacific ◽  
Decadal Scale ◽  
Isotope Record

<p>This thesis presents a water-isotope (δD) record from 1900 to 2009 for the Roosevelt Island Climate Evolution (RICE) ice core, Antarctica. Examination of the RICE isotope record with observation data (using global reanalysis and SST datasets) revealed details of the climate signal that is preserved within the full 763 m isotope record. RICE δD provides a proxy record, which captures the central tropical Pacific ENSO variability, the significant (p < 0.01) central Pacific δD-SST correlation pattern contain the Niño-4 SST region. Central tropical Pacific ENSO variability projects upon the Amundsen Sea region via a Pacific–South American pattern (PSA)-like teleconnection. RICE δD is primarily influenced by Amundsen Sea circulation, which coincides with the leading PSA pattern’s (PSA1) circulation focal point in the Amundsen Sea. Additionally, RICE regional physical setting (sheltered from direct impact from Amundsen Sea cyclones by WA orography) offers a unique setting, where enriched isotopes only are associated with one PSA1 polarity (El Niño, PSA1+, Amundsen Sea anticyclones). In contrast, during La Niña and Amundsen Sea cyclones, δD is depleted. Combined these settings, provides a compelling explanation to why RICE δD preserves PSA1 and ENSO variability. On interannual and seasonal time scales, the RICE δD variability is well-explained by the PSA teleconnections and their interactions over the Pacific sector. The influence from PSA2 on δD is strong during the beginning of the year (December–February, DJF). In contrast, the PSA1 influence is strong during the latter part of the year, peaking in spring (September–November, SON). The isotope record appears to preserve tropical Pacific El Niño-like interdecadal variability, particularly a decadal-signal from the central-Pacific (Niño-4 SST region) and from the Pacific-wide Interdecadal Pacific Oscillation (IPO). On decadal-scales RICE δD is modulated by ENSO and Southern Annular Mode (SAM); when the correlation with SAM is active (during IPO+) δD appears to be in a depleted state and when the correlation with SAM breaks down (during IPO−) δD appears to be in a relatively enriched state. A RICE δD SST proxy reconstruction can potentially provide a record longer than the currently available observational datasets, allowing for examination of intrinsic decadal-scale tropical Pacific climate variability and its extratropical impact.</p>

scholarly journals High-Resolution Water Stable Isotope Ice-Core Record: Roosevelt Island, Antarctica

2021 ◽  
Author(s):  
◽  
Daniel Emanuelsson
Keyword(s):  
El Niño ◽  
El Nino ◽  
Ice Core ◽  
Tropical Pacific ◽  
Central Pacific ◽  
Amundsen Sea ◽  
Enso Variability ◽  
The Pacific ◽  
Decadal Scale ◽  
Isotope Record

<p>This thesis presents a water-isotope (δD) record from 1900 to 2009 for the Roosevelt Island Climate Evolution (RICE) ice core, Antarctica. Examination of the RICE isotope record with observation data (using global reanalysis and SST datasets) revealed details of the climate signal that is preserved within the full 763 m isotope record. RICE δD provides a proxy record, which captures the central tropical Pacific ENSO variability, the significant (p < 0.01) central Pacific δD-SST correlation pattern contain the Niño-4 SST region. Central tropical Pacific ENSO variability projects upon the Amundsen Sea region via a Pacific–South American pattern (PSA)-like teleconnection. RICE δD is primarily influenced by Amundsen Sea circulation, which coincides with the leading PSA pattern’s (PSA1) circulation focal point in the Amundsen Sea. Additionally, RICE regional physical setting (sheltered from direct impact from Amundsen Sea cyclones by WA orography) offers a unique setting, where enriched isotopes only are associated with one PSA1 polarity (El Niño, PSA1+, Amundsen Sea anticyclones). In contrast, during La Niña and Amundsen Sea cyclones, δD is depleted. Combined these settings, provides a compelling explanation to why RICE δD preserves PSA1 and ENSO variability. On interannual and seasonal time scales, the RICE δD variability is well-explained by the PSA teleconnections and their interactions over the Pacific sector. The influence from PSA2 on δD is strong during the beginning of the year (December–February, DJF). In contrast, the PSA1 influence is strong during the latter part of the year, peaking in spring (September–November, SON). The isotope record appears to preserve tropical Pacific El Niño-like interdecadal variability, particularly a decadal-signal from the central-Pacific (Niño-4 SST region) and from the Pacific-wide Interdecadal Pacific Oscillation (IPO). On decadal-scales RICE δD is modulated by ENSO and Southern Annular Mode (SAM); when the correlation with SAM is active (during IPO+) δD appears to be in a depleted state and when the correlation with SAM breaks down (during IPO−) δD appears to be in a relatively enriched state. A RICE δD SST proxy reconstruction can potentially provide a record longer than the currently available observational datasets, allowing for examination of intrinsic decadal-scale tropical Pacific climate variability and its extratropical impact.</p>

scholarly journals Rectification of El Niño–Southern Oscillation into Climate Anomalies of Decadal and Longer Time Scales: Results from Forced Ocean GCM Experiments

2014 ◽  
Vol 27 (7) ◽  
pp. 2545-2561 ◽  
Author(s):  
De-Zheng Sun ◽  
Tao Zhang ◽  
Yan Sun ◽  
Yongqiang Yu
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Wind Stress ◽  
Surface Wind ◽  
Tropical Pacific ◽  
Surface Wind Stress ◽  
Interannual Fluctuations ◽  
Mean State ◽  
The Tropical Pacific

Abstract To better understand the causes of climate change in the tropical Pacific on the decadal and longer time scales, the rectification effect of ENSO events is delineated by contrasting the time-mean state of two forced ocean GCM experiments. In one of them, the long-term mean surface wind stress of 1950–2011 is applied, while in the other, the surface wind stress used is the long-term mean surface wind stress of 1950–2011 plus the interannual monthly anomalies over the period. Thus, the long-term means of the surface wind stress in the two runs are identical. The two experiments also use the same relaxation boundary conditions, that is, the SST is restored to the same prescribed values. The two runs, however, are found to yield significantly different mean climate for the tropical Pacific. The mean state of the run with interannual fluctuations in the surface winds is found to have a cooler warm pool, warmer thermocline water, and warmer eastern surface Pacific than the run without interannual fluctuations in the surface winds. The warming of the eastern Pacific has a pattern that resembles the observed decadal warming. In particular, the pattern features an off-equator maximum as the observed decadal warming. The spatial pattern of the time-mean upper-ocean temperature differences between the two experiments is shown to resemble that of the differences in the nonlinear dynamic heating, underscoring the role of the nonlinear ocean dynamics in the rectification. The study strengthens the suggestion that rectification of ENSO can be a viable mechanism for climate change of decadal and longer time scales.

Lifetime of anthropogenic climate change: Time-scales of CO2and temperature perturbations

2009 ◽  
Vol 6 (4) ◽  
pp. 042015
Author(s):  
Michael Ebv ◽  
K Zickfeld ◽  
A Montenegro ◽  
D Archer ◽  
K J Meissner ◽  
...  
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Anthropogenic Climate Change

Political Preferences, Personality Traits, and Environmentalism

2020 ◽  
Author(s):  
Alistair Soutter ◽  
René Mõttus
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Personality Traits ◽  
Public Discourse ◽  
Environmental Attitudes ◽  
Scientific Evidence ◽  
Political Orientation ◽  
Anthropogenic Climate Change ◽  
Political Preferences ◽  
Party Voting

Although the scientific evidence of anthropogenic climate change continues to grow, public discourse still reflects a high level of scepticism and political polarisation towards anthropogenic climate change. In this study (N = 499) we attempted to replicate and expand upon an earlier finding that environmental terminology (“climate change” versus “global warming”) could partly explain political polarisation in environmental scepticism (Schuldt, Konrath, &amp; Schwarz, 2011). Participants completed a series of online questionnaires assessing personality traits, political preferences, belief in environmental phenomenon, and various pro-environmental attitudes and behaviours. Those with a Conservative political orientation and/or party voting believed less in both climate change and global warming compared to those with a Liberal orientation and/or party voting. Furthermore, there was an interaction between continuously measured political orientation, but not party voting, and question wording on beliefs in environmental phenomena. Personality traits did not confound these effects. Furthermore, continuously measured political orientation was associated with pro-environmental attitudes, after controlling for personality traits, age, gender, area lived in, income, and education. The personality domains of Openness, and Conscientiousness, were consistently associated with pro-environmental attitudes and behaviours, whereas Agreeableness was associated with pro-environmental attitudes but not with behaviours. This study highlights the importance of examining personality traits and political preferences together and suggests ways in which policy interventions can best be optimised to account for these individual differences.

6600–6000 cal BC Abrupt Climate Change and Neolithic Dispersal from West Asia

2017 ◽  
Author(s):  
Bernhard Weninger ◽  
Lee Clare
Keyword(s):  
Climate Change ◽  
Abrupt Climate Change ◽  
Western Anatolia ◽  
Southeast Europe ◽  
The Balkans ◽  
Farming Communities ◽  
Anatolian Plateau ◽  
Decadal Scale ◽  
Early Farming ◽  
New Hypothesis

Recent advances in palaeoclimatological and meteorological research, combined with new radiocarbon data from western Anatolia and southeast Europe, lead us to formulate a new hypothesis for the temporal and spatial dispersal of Neolithic lifeways from their core areas of genesis. The new hypothesis, which we term the Abrupt Climate Change (ACC) Neolithization Model, incorporates a number of insights from modern vulnerability theory. We focus here on the Late Neolithic (Anatolian terminology), which is followed in the Balkans by the Early Neolithic (European terminology). From high-resolution 14C-case studies, we infer an initial (very rapid) west-directed movement of early farming communities out of the Central Anatolian Plateau towards the Turkish Aegean littoral. This move is exactly in phase (decadal scale) with the onset of ACC conditions (~6600 cal BC). Upon reaching the Aegean coastline, Neolithic dispersal comes to a halt. It is not until some 500 years later—that is, at the close of cumulative ACC and 8.2 ka cal BP Hudson Bay cold conditions—that there occurs a second abrupt movement of farming communities into Southeast Europe, as far as the Pannonian Basin. The spread of early farming from Anatolia into eastern Central Europe is best explained as Neolithic communities’ mitigation of biophysical and social vulnerability to natural (climate-induced) hazards.

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