scholarly journals Using Pollen Records from New Zealand and Southern Chile to Reconstruct New Zealand Climate Variability over the Last 14,000 years

2021 ◽  
Author(s):  
◽  
Ignacio Alonso Jara Parra
Keyword(s):  
New Zealand ◽  
Climate Variability ◽  
Southern Hemisphere ◽  
Charcoal Analysis ◽  
Southern Chile ◽  
Climate History ◽  
Westerly Flow ◽  
Dry Conditions ◽  
Increasing Precipitation

<p>Climate variability in New Zealand (34-47°S), a long, narrow continental strip straddling the mid-latitudes of the Southern Hemisphere, results largely from the interplay between sub-tropical and sub-Antarctic atmospheric and oceanic circulation systems. Despite their importance to present-day New Zealand climate, these hemispheric-wide systems have only recently come under the spotlight of paleo-climate investigations with most attention having traditionally been centred on reconstructing climate trends. This PhD adopts a broader approach to climate reconstruction, by developing and comparing two new pollen-climate reconstructions from New Zealand (38-42°S) and one from Patagonia, Southern Chile (43°S). At each site, paleo-climate interpretations are based on the changes in climate-sensitive plant indicators. The influence of hemispheric atmospheric circulation on New Zealand climate history is assessed by: (1) comparing New Zealand climate/vegetation trends with published proxies from low- and high-latitudes, and (2) comparing New Zealand reconstructions with the Patagonian record. Finally, a multi-millennial pattern of Southern Hemisphere circulation over the last 14,000 cal yr BP (calendar years before AD 1950) is outlined. The first record presented is a 16,000-year temperature reconstruction from a small alpine lake in South Island, New Zealand (41°S), based on pollen and plant macrofossils. Climate variations are interpreted from the relative abundance of lowland and highland vegetation. The results include a lifting of the altitudinal forest limits attributed to warming pulses between 13,000-10,000 cal yr BP and between 7000-6000 cal yr BP, and a decline of lowland relative to upland forest taxa interpreted as cooling trends between 10,000-7000 cal yr BP and over the last 3000 years. The second record gives 15,000-year temperature and precipitation reconstructions from a peatbog in northern New Zealand (38°S), based on pollen and charcoal analysis. Temperature changes are assessed based on two quantitate reconstructions, whereas precipitation trends are inferred from variations in arboreal taxa with different drought tolerances. A long-term warming is inferred between 14,600-10,000 cal yr BP. Persistent dry conditions are recorded between 12,000-10,000 cal yr BP, followed by a long-term wet period between 10,000-6000 cal yr BP. The last 7000 years feature a long-term drying trend that culminates with persistent drier conditions over the last 3000 years. The third record provides a 16,000-year reconstruction from a small lake in Northwestern Patagonia (43°S), based on pollen and charcoal analysis. Climate conditions are inferred from the relative variations of pollen types with distinctive climate tolerances and complemented with changes in fire activity. These variations are in turn interpreted as resulting from changes in the position and/or strength of the Southern Westerly Winds (SWW). Cold and moist conditions attributable to stronger/northward-shifted SWW winds are observed between 16,000-13,600 cal yr BP. In contrast, warm and dry conditions suggestive of weaker/southward-shifted SWW are detected between 12,000-10,000 cal yr BP. The last 6000 years shows a trend towards colder conditions and increasing precipitation variability, suggesting a highly variable westerly flow over Patagonia. A comparison between the New Zealand and the Patagonia records suggest: (1) weakened/southward-shifted westerly flow over the southern mid-latitudes between 13,000-10,000 cal yr BP caused rapid warming and peak temperatures in New Zealand, as well as dry conditions in Northern New Zealand, (2) Enhanced/northward-shifted SWW over the southern mid-latitudes between 9000-4000 cal yr BP caused decreasing temperatures in the South Island and increasing precipitation in Northern New Zealand and (3) Overall weakened/southward-shifted SWW after 4000 cal yr BP caused a decrease in temperature in the southern New Zealand site. Drier conditions in Northern New Zealand and the overall increase in climate instability at all sites may have resulted from more frequent El Niño events along with an increase in sub-tropical climate variability.</p>

scholarly journals Using Pollen Records from New Zealand and Southern Chile to Reconstruct New Zealand Climate Variability over the Last 14,000 years

2021 ◽  
Author(s):  
◽  
Ignacio Alonso Jara Parra
Keyword(s):  
New Zealand ◽  
Climate Variability ◽  
Southern Hemisphere ◽  
Charcoal Analysis ◽  
Southern Chile ◽  
Climate History ◽  
Westerly Flow ◽  
Dry Conditions ◽  
Increasing Precipitation

<p>Climate variability in New Zealand (34-47°S), a long, narrow continental strip straddling the mid-latitudes of the Southern Hemisphere, results largely from the interplay between sub-tropical and sub-Antarctic atmospheric and oceanic circulation systems. Despite their importance to present-day New Zealand climate, these hemispheric-wide systems have only recently come under the spotlight of paleo-climate investigations with most attention having traditionally been centred on reconstructing climate trends. This PhD adopts a broader approach to climate reconstruction, by developing and comparing two new pollen-climate reconstructions from New Zealand (38-42°S) and one from Patagonia, Southern Chile (43°S). At each site, paleo-climate interpretations are based on the changes in climate-sensitive plant indicators. The influence of hemispheric atmospheric circulation on New Zealand climate history is assessed by: (1) comparing New Zealand climate/vegetation trends with published proxies from low- and high-latitudes, and (2) comparing New Zealand reconstructions with the Patagonian record. Finally, a multi-millennial pattern of Southern Hemisphere circulation over the last 14,000 cal yr BP (calendar years before AD 1950) is outlined. The first record presented is a 16,000-year temperature reconstruction from a small alpine lake in South Island, New Zealand (41°S), based on pollen and plant macrofossils. Climate variations are interpreted from the relative abundance of lowland and highland vegetation. The results include a lifting of the altitudinal forest limits attributed to warming pulses between 13,000-10,000 cal yr BP and between 7000-6000 cal yr BP, and a decline of lowland relative to upland forest taxa interpreted as cooling trends between 10,000-7000 cal yr BP and over the last 3000 years. The second record gives 15,000-year temperature and precipitation reconstructions from a peatbog in northern New Zealand (38°S), based on pollen and charcoal analysis. Temperature changes are assessed based on two quantitate reconstructions, whereas precipitation trends are inferred from variations in arboreal taxa with different drought tolerances. A long-term warming is inferred between 14,600-10,000 cal yr BP. Persistent dry conditions are recorded between 12,000-10,000 cal yr BP, followed by a long-term wet period between 10,000-6000 cal yr BP. The last 7000 years feature a long-term drying trend that culminates with persistent drier conditions over the last 3000 years. The third record provides a 16,000-year reconstruction from a small lake in Northwestern Patagonia (43°S), based on pollen and charcoal analysis. Climate conditions are inferred from the relative variations of pollen types with distinctive climate tolerances and complemented with changes in fire activity. These variations are in turn interpreted as resulting from changes in the position and/or strength of the Southern Westerly Winds (SWW). Cold and moist conditions attributable to stronger/northward-shifted SWW winds are observed between 16,000-13,600 cal yr BP. In contrast, warm and dry conditions suggestive of weaker/southward-shifted SWW are detected between 12,000-10,000 cal yr BP. The last 6000 years shows a trend towards colder conditions and increasing precipitation variability, suggesting a highly variable westerly flow over Patagonia. A comparison between the New Zealand and the Patagonia records suggest: (1) weakened/southward-shifted westerly flow over the southern mid-latitudes between 13,000-10,000 cal yr BP caused rapid warming and peak temperatures in New Zealand, as well as dry conditions in Northern New Zealand, (2) Enhanced/northward-shifted SWW over the southern mid-latitudes between 9000-4000 cal yr BP caused decreasing temperatures in the South Island and increasing precipitation in Northern New Zealand and (3) Overall weakened/southward-shifted SWW after 4000 cal yr BP caused a decrease in temperature in the southern New Zealand site. Drier conditions in Northern New Zealand and the overall increase in climate instability at all sites may have resulted from more frequent El Niño events along with an increase in sub-tropical climate variability.</p>

scholarly journals Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex

2017 ◽  
Vol 30 (18) ◽  
pp. 7125-7139 ◽  
Author(s):  
Nicholas J. Byrne ◽  
Theodore G. Shepherd ◽  
Tim Woollings ◽  
R. Alan Plumb
Keyword(s):  
Climate Variability ◽  
Southern Hemisphere ◽  
Seasonal Cycle ◽  
Vortex Breakdown ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Summer ◽  
Stratospheric Polar Vortex ◽  
Time Symmetry

Abstract Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological seasonal cycle and long-term trends, and the assumption of stationary statistics is only an approximation. The variability of the Southern Hemisphere zonal-mean circulation in the period encompassing late spring and summer is an important climate phenomenon and has been the subject of numerous studies. It is shown here, using reanalysis data, that this variability is rendered highly nonstationary by the organizing influence of the seasonal breakdown of the stratospheric polar vortex, which breaks time symmetry. It is argued that the zonal-mean tropospheric circulation variability during this period is best viewed as interannual variability in the transition between the springtime and summertime regimes induced by variability in the vortex breakdown. In particular, the apparent long-term poleward jet shift during the early-summer season can be more simply understood as a delay in the equatorward shift associated with this regime transition. The implications of such a perspective for various open questions are discussed.

Deglacial and postglacial climate history in east-central Isla Grande De Chiloé, Southern Chile (43°S)

2004 ◽  
Vol 62 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Ana M. Abarzúa ◽  
Carolina Villagrán ◽  
Patricio I. Moreno
Keyword(s):  
Climate Variability ◽  
Geographic Distribution ◽  
Fine Scale ◽  
Southern Chile ◽  
Lake Levels ◽  
Climate History ◽  
East Central ◽  
Cool Temperate ◽  
Paleoclimate Records ◽  
Temperate Rainforests

Palynologic and stratigraphic data from Laguna Tahui (42°50′S, 73°30′W) indicate cool–temperate and humid conditions there between 14,000 and 10,000 14C yr B.P., followed by warmer and drier-than-present conditions between 10,000 and 7000 14C yr B.P., and subsequent cooling and rise in precipitation over the last 5800 14C yr. The thermophilous Valdivian trees Eucryphia cordifolia and Caldcluvia paniculata reached their maximum abundance during the early Holocene warm–dry phase (10,000–7000 14C yr B.P.), followed by a rise in lake levels and reexpansion of North Patagonian conifers starting at 7000 and 5800 14C yr B.P., respectively. Variations in the stratigraphic and geographic distribution of temperate rainforests in southern Chile suggest multimillennial trends in temperature and westerly activity, which are spatially and temporally coherent with paleoclimate records from neighboring regions. Climate variability at millennial and submillennial time scales may account for the establishment and persistence of fine-scale mosaics of Valdivian and North Patagonian rainforest species in low- to mid-elevation communities since ∼5800 14C yr B.P.

scholarly journals Climate variability and grain production in Scania, c. 1702–1911

2021 ◽  
Author(s):  
Martin Karl Skoglund
Keyword(s):  
Climate Variability ◽  
18Th Century ◽  
Interesting Case ◽  
Grain Production ◽  
Climate History ◽  
Late 18Th Century ◽  
Contextual Understanding ◽  
Dry Conditions ◽  
History Of ◽  
The Relationship

Abstract. Scania (sw. Skåne), southern Sweden, offers a particularly interesting case for studying the historical relationship between climate variability and grain production, given the favourable natural conditions in terms of climate and soils for grain production, as well as the relative lack of heat-sensitive grain varieties like wheat in its production composition. In this article, I combine a contextual understanding of historical grain production in Scania, including historical, phenological and natural geographic aspects, with quantitative analysis of available empirical sources to estimate the relationship between climate variability and grain production between the years c. 1702–1911. The main result of this study is that grain production in Scania was primarily sensitive to climate variability during the high summer months of June and July, preferring relatively cool and humid conditions, and to some extent precipitation during the winter months, preferring relatively dry conditions. Furthermore, grain production was relatively insensitive to climate variability during the spring, autumn and harvest seasons. At the end of the study period, these relationships were shifting as the so-called early improved cultivars were being imported from other parts of Europe. Finally, I also shed new light on the climate history of the region, especially for the late 18th century, previously argued to be a particularly cold period, through homogenization of the early instrumental series from Lund (1753–1870).

scholarly journals Blocking and Rossby Wave Breaking on the Dynamical Tropopause in the Southern Hemisphere

2007 ◽  
Vol 64 (8) ◽  
pp. 2881-2898 ◽  
Author(s):  
P. Berrisford ◽  
B. J. Hoskins ◽  
E. Tyrlis
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Potential Temperature ◽  
Upper Troposphere ◽  
Rossby Wave Breaking ◽  
The Pacific ◽  
Westerly Flow

Rossby wave breaking on the dynamical tropopause in the Southern Hemisphere (the −2-PVU surface) is investigated using the ERA-40 dataset. The indication of wave breaking is based on reversal in the meridional gradient of potential temperature, and persistent large-scale wave breaking is taken as a strong indication that blocking may be present. Blocking in the midlatitudes is found to occur predominantly during wintertime in the Pacific and is most vigorous in the east Pacific, while during summertime, the frequency of blocking weakens and its extent becomes confined to the west Pacific. The interannual variability of blocking is found to be high. Wave breaking occurs most frequently on the poleward side of the polar jet and has some, but not all, of the signatures of blocking, so it is referred to as high-latitude blocking. In general, cyclonic wave breaking occurs on the poleward side of the polar jet, otherwise anticyclonic breaking occurs. However, at least in wintertime, wave breaking in the New Zealand/west to mid-Pacific sector between the polar and subtropical jets is a mixture between cyclonic and anticyclonic types. Together, episodes of wave breaking and enhanced westerly flow describe much of the variability in the seasonal Antarctic Oscillation (AnO) index and give a synoptic manifestation of it with a focus on the date line and Indian Ocean that is in agreement with the centers of action for the AnO. During summertime, anticyclonic wave breaking in the upper troposphere is also to be found near 30°S in both the Pacific and Atlantic, and appears to be associated with Rossby waves propagating into the subtropics from the New Zealand region.

Interannual Extremes in New Zealand Precipitation Linked to Modes of Southern Hemisphere Climate Variability

2007 ◽  
Vol 20 (21) ◽  
pp. 5418-5440 ◽  
Author(s):  
Caroline C. Ummenhofer ◽  
Matthew H. England
Keyword(s):  
New Zealand ◽  
Climate Variability ◽  
Southern Hemisphere ◽  
Large Scale ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Heat Fluxes ◽  
Ekman Transport ◽  
The South ◽  
Climate Modes

Abstract Interannual extremes in New Zealand rainfall and their modulation by modes of Southern Hemisphere climate variability are examined in observations and a coupled climate model. North Island extreme dry (wet) years are characterized by locally increased (reduced) sea level pressure (SLP), cold (warm) sea surface temperature (SST) anomalies in the southern Tasman Sea and to the north of the island, and coinciding reduced (enhanced) evaporation upstream of the mean southwesterly airflow. During extreme dry (wet) years in South Island precipitation, an enhanced (reduced) meridional SLP gradient occurs, with circumpolar strengthened (weakened) subpolar westerlies and an easterly (westerly) anomaly in zonal wind in the subtropics. As a result, via Ekman transport, anomalously cold (warm) SST appears under the subpolar westerlies, while anomalies of the opposite sign occur farther north. The phase and magnitude of the resulting SST and evaporation anomalies cannot account for the rainfall extremes over the South Island, suggesting a purely atmospheric mode of variability as the driving factor, in this case the Southern Annular Mode (SAM). New Zealand rainfall variability is predominantly modulated by two Southern Hemisphere climate modes, namely, the El Niño–Southern Oscillation (ENSO) and the SAM, with a latitudinal gradation in influence of the respective phenomena, and a notable interaction with orographic features. While this heterogeneity is apparent both latitudinally and as a result of orographic effects, climate modes can force local rainfall anomalies with considerable variations across both islands. North Island precipitation is for the most part regulated by both local air–sea heat fluxes and circulation changes associated with the tropical ENSO mode. In contrast, for the South Island the influence of the large-scale general atmospheric circulation dominates, especially via the strength and position of the subpolar westerlies, which are modulated by the extratropical SAM.

Enhancing the power generation of Rhodopseudomonas palustris-based MFC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1261-1268
Author(s):  
Shu Otani ◽  
Dang-Trang Nguyen ◽  
Kozo Taguchi
Keyword(s):  
Activated Carbon ◽  
Rhodopseudomonas Palustris ◽  
Ozone Treatment ◽  
Maximum Power Density ◽  
On Demand ◽  
Long Time ◽  
Dry Conditions ◽  
Carbon Sheet ◽  
Uv Ozone

In this study, a portable and disposable paper-based microbial fuel cell (MFC) was fabricated. The MFC was powered by Rhodopseudomonas palustris bacteria (R. palustris). An activated carbon sheet-based anode pre-loaded organic matter (starch) and R. palustris was used. By using starch in the anode, R. palustris-loaded on the anode could be preserved for a long time in dry conditions. The MFC could generate electricity on-demand activated by adding water to the anode. The activated carbon sheet anode was treated by UV-ozone treatment to remove impurities and to improve its hydrophilicity before being loaded with R. palustris. The developed MFC could generate the maximum power density of 0.9 μW/cm2 and could be preserved for long-term usage with little performance degradation (10% after four weeks).

Plant mortality and seedling recruitment responses to flupropanate in grassland populations of Nassella trichotoma

2017 ◽  
Vol 70 ◽  
pp. 160-164 ◽  
Author(s):  
G.W. Bourdôt ◽  
S. Jackman ◽  
D.J. Saville
Keyword(s):  
New Zealand ◽  
Dose Response ◽  
Sodium Salt ◽  
Seedling Recruitment ◽  
Residual Activity ◽  
Application Rate ◽  
Plant Mortality ◽  
Complete Control ◽  
Bio Synthesis

Flupropanate (sodium 2,2,3,3 tetrafluoropropanate), a slow-acting lipid bio- synthesis-inhibiting herbicide, was recently registered in New Zealand as Taskforce (745 g/L flupropanate as the sodium salt) for the selective and long-term control of Nassella trichotoma (nassella tussock) in pastures. In five dose-response experiments in permanent hill pastures in Canterbury, conducted between 2012 and 2016, we measured the efficacy of the herbicide against established plants of N. trichotoma and its residual activity against recruiting seedlings. Mortality, as an average across the five sites, was 93% 1.5 years after applying 1.49 kg flupropanate/ha (the label-recommended rate), and 100% at 2.98 kg/ha. This indicates that an application rate higher than the label rate will be necessary for complete control of a N. trichotoma infestation. The presence of 1,000 and 6,250 visible seedlings of N. trichotoma/ha in the autumn 3.2 and 2.1 years after applying 1.49 kg flupropanate/ha (at a Greta Valley and Scargill site respectively) indicates that the herbicide’s soil residues had decayed within 12 months to a concentration lower than necessary to kill the germinating seedlings of N. trichotoma.

Co-Design and Open Trial of Starship Rescue, a Cognitive Behavior Therapy, Biofeedback, and Game-Based eHealth Intervention to Treat Anxiety in Children and Young People with Long-Term Physical Conditions (Preprint)

2020 ◽  
Author(s):  
Hiran Thabrew ◽  
Karolina Stasiak ◽  
Harshali Kumar ◽  
Tarique Naseem ◽  
Christopher Frampton ◽  
...  
Keyword(s):  
Quality Of Life ◽  
New Zealand ◽  
Young People ◽  
Preliminary Evidence ◽  
Children And Young People ◽  
Physical Conditions ◽  
System Usability Scale ◽  
Ehealth Intervention

BACKGROUND Approximately 10% to 12% of New Zealand children and young people have long-term physical conditions (also known as chronic illnesses) and are more likely to develop psychological problems, particularly anxiety and depression. Delayed treatment leads to worse physical and mental healthcare, school absence, and poorer long-term outcomes. Recently, electronic health (eHealth) interventions, especially those based on the principles of Cognitive Behavior Therapy (CBT), have been shown to be as good as face-to-face therapy. Biofeedback techniques have also been shown to enhance relaxation during the treatment of anxiety. However, these modalities have rarely been combined. Young people with long-term physical conditions have expressed a preference for well-designed and technologically-based support to deal with psychological issues, especially anxiety. OBJECTIVE This study aimed to co-design and evaluate the (i) acceptability and (ii) usability of a CBT and biofeedback-based, 5-module eHealth game called ‘Starship Rescue’ and (iii) to provide preliminary evidence regarding its effectiveness in addressing anxiety and quality of life in young people with long-term physical conditions. METHODS Starship Rescue was co-designed with children and young people from a tertiary hospital in Auckland, New Zealand. Following this, 24 young people aged 10 to 17 years were enrolled in an open trial, during which they were asked to use the game for an 8-week period. Acceptability of the game to all participants was assessed using a brief, open-ended questionnaire, and more detailed feedback was obtained from a subset of 10 participants via semi-structured interviews. Usability was evaluated via the System Usability Scale (SUS) and device-recorded frequency and duration of access on completion of the game. Anxiety levels were measured prior to commencement, on completion of the game, and 3 months later using the Generalized Anxiety Disorder 7-item scale (GAD-7) and Spence Child Anxiety Scales (SCAS), and at the start of each module and at the end of the game using an embedded Likert/visual analog scale. Quality of life was measured prior to commencement and on completion of the game using the Pediatric Quality of Life Scale (PEDS-QL). RESULTS Users gave Starship Rescue an overall rating of 5.9 out of 10 (range 3-10 and a mean score of 71 out of 100 (SD 11.7; min 47.5; max 90) on the System Usability Scale (SUS). The mean time period for use of the game was just over 11-weeks (78.8 days, 13.5 hours, 40 minutes). Significant reductions in anxiety were noted between the start and end of the game on the GAD-7 (-4.6 (p=0.000)), SCAS (-9.6 (p=0.005)), and the Likert/visual analogue scales (-2.4 (p=0.001)). Quality of life also improved on the PedsQL scale (+4.3 (p=0.042)). All changes were sustained at 3-month follow-up. CONCLUSIONS This study provides preliminary evidence for Starship Rescue being an acceptable, usable and effective eHealth intervention for addressing anxiety in young people with long-term physical conditions. Further evaluation is planned via a more formal randomized controlled trial. CLINICALTRIAL Australian New Zealand Clinical Trials Network Registry (ANZCTR): ACTRN12616001253493p;https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371443 (Archived by WebCite at http://www.webcitation.org/6sYB716lf)

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