scholarly journals Factors Limiting the Range Extension of Corals into High-Latitude Reef Regions

Diversity ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 632
Author(s):  
David Abrego ◽  
Emily J. Howells ◽  
Stephen D. A. Smith ◽  
Joshua S. Madin ◽  
Brigitte Sommer ◽  
...  
Keyword(s):  
High Latitude ◽  
Light Limitation ◽  
Potential Range ◽  
Research Areas ◽  
Algal Symbionts ◽  
Settlement Cues ◽  
Sediment Loads ◽  
Total Species Richness ◽  
Abiotic And Biotic Factors ◽  
The Tropics

Reef-building corals show a marked decrease in total species richness from the tropics to high latitude regions. Several hypotheses have been proposed to account for this pattern in the context of abiotic and biotic factors, including temperature thresholds, light limitation, aragonite saturation, nutrient or sediment loads, larval dispersal constraints, competition with macro-algae or other invertebrates, and availability of suitable settlement cues or micro-algal symbionts. Surprisingly, there is a paucity of data supporting several of these hypotheses. Given the immense pressures faced by corals in the Anthropocene, it is critical to understand the factors limiting their distribution in order to predict potential range expansions and the role that high latitude reefs can play as refuges from climate change. This review examines these factors and outlines critical research areas to address knowledge gaps in our understanding of light/temperature interactions, coral-Symbiodiniaceae associations, settlement cues, and competition in high latitude reefs.

scholarly journals Obliquity forcing of low-latitude climate

2015 ◽  
Vol 11 (1) ◽  
pp. 221-241 ◽  
Author(s):  
J. H. C. Bosmans ◽  
F. J. Hilgen ◽  
E. Tuenter ◽  
L. J. Lourens
Keyword(s):  
High Latitude ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Rotational Axis ◽  
Low Latitude ◽  
Low Latitudes ◽  
Paleoclimate Records ◽  
Induced Changes ◽  
The Tropics

Abstract. The influence of obliquity, the tilt of the Earth's rotational axis, on incoming solar radiation at low latitudes is small, yet many tropical and subtropical paleoclimate records reveal a clear obliquity signal. Several mechanisms have been proposed to explain this signal, such as the remote influence of high-latitude glacials, the remote effect of insolation changes at mid- to high latitudes independent of glacial cyclicity, shifts in the latitudinal extent of the tropics, and changes in latitudinal insolation gradients. Using a sophisticated coupled ocean–atmosphere global climate model, EC-Earth, without dynamical ice sheets, we performed two experiments of obliquity extremes. Our results show that obliquity-induced changes in tropical climate can occur without high-latitude ice sheet fluctuations. Furthermore, the tropical circulation changes are consistent with obliquity-induced changes in the cross-equatorial insolation gradient, implying that this gradient may be used to explain obliquity signals in low-latitude paleoclimate records instead of the classic 65° N summer insolation curve.

scholarly journals Obliquity forcing of low-latitude climate

2015 ◽  
Vol 11 (10) ◽  
pp. 1335-1346 ◽  
Author(s):  
J. H. C. Bosmans ◽  
F. J. Hilgen ◽  
E. Tuenter ◽  
L. J. Lourens
Keyword(s):  
High Latitude ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Rotational Axis ◽  
Tropical Circulation ◽  
Low Latitude ◽  
Low Latitudes ◽  
Induced Changes ◽  
The Tropics

Abstract. The influence of obliquity, the tilt of the Earth's rotational axis, on incoming solar radiation at low latitudes is small, yet many tropical and subtropical palaeoclimate records reveal a clear obliquity signal. Several mechanisms have been proposed to explain this signal, such as the remote influence of high-latitude glacials, the remote effect of insolation changes at mid- to high latitudes independent of glacial cyclicity, shifts in the latitudinal extent of the tropics, and changes in latitudinal insolation gradients. Using a sophisticated coupled ocean–atmosphere global climate model, EC-Earth, without dynamical ice sheets, we performed two idealized experiments of obliquity extremes. Our results show that obliquity-induced changes in tropical climate can occur without high-latitude ice sheet fluctuations. Furthermore, the tropical circulation changes are consistent with obliquity-induced changes in the cross-equatorial insolation gradient, suggesting that this gradient may be used to explain obliquity signals in low-latitude palaeoclimate records instead of the classical 65° N summer insolation curve.

scholarly journals An Industry of R&D

2014 ◽  
Vol 136 (10) ◽  
pp. 44-47
Author(s):  
Harry Hutchinson
Keyword(s):  
Electronic Systems ◽  
Massachusetts Institute ◽  
Massachusetts Institute Of Technology ◽  
Research Areas ◽  
Federal Institute ◽  
University Of Munich ◽  
World Class ◽  
Institute Of Technology ◽  
The University ◽  
The Tropics

This article discusses how Singapore is amassing a brain trust to compensate for resources that nature didn’t provide to it. CREATE or “Campus for Research Excellence and Technological Enterprise” is one of the most ambitious projects of Singapore’s National Research Foundation. CREATE seeks to unite Singapore’s universities with world-class research institutions to study issues ranging from urban planning to medical treatment. The organization has partnerships with 10 foreign universities, including Massachusetts Institute of Technology, the Technical University of Munich, Cambridge University, and the Swiss Federal Institute of Technology. There are five research groups in CREATE’s partnership with Massachusetts Institute of Technology. The research areas are infectious diseases, environmental sensing and modeling, biosystems and micromechanics, urban mobility, and low-energy electronic systems. The University of California, Berkeley, has two research programs with CREATE. One aims to improve the efficiency of buildings in the tropics, and the other is working on raising the electrical output of photovoltaic devices.

scholarly journals Evaluating the dominant components of warming in Pliocene climate simulations

2014 ◽  
Vol 10 (1) ◽  
pp. 79-90 ◽  
Author(s):  
D. J. Hill ◽  
A. M. Haywood ◽  
D. J. Lunt ◽  
S. J. Hunter ◽  
F. J. Bragg ◽  
...  
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
High Latitude ◽  
Model Comparison ◽  
Climate Models ◽  
Climate Model ◽  
Clear Sky ◽  
Air Temperatures ◽  
Planetary Albedo ◽  
The Tropics

Abstract. The Pliocene Model Intercomparison Project (PlioMIP) is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 °C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean–atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with the cloud component of planetary albedo enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere midlatitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo, only partially offset by the increases in the cooling impact of cloud albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with clouds in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that albedo feedbacks, particularly those of sea ice and ice sheets, provide the most significant enhancements to high latitude warming in the Pliocene.

scholarly journals Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport

2017 ◽  
Vol 30 (1) ◽  
pp. 189-201 ◽  
Author(s):  
Nicole Feldl ◽  
Simona Bordoni ◽  
Timothy M. Merlis
Keyword(s):  
Heat Transport ◽  
High Latitude ◽  
Surface Albedo ◽  
Hadley Cell ◽  
Lapse Rate ◽  
The Arctic ◽  
Albedo Feedback ◽  
Atmospheric Heat Transport ◽  
The Tropics ◽  
Atmospheric Heat

The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic.

Wood evolution: Baileyan trends and Functional traits in the fossil record

IAWA Journal ◽  
2019 ◽  
Vol 40 (3) ◽  
pp. 488-529 ◽  
Author(s):  
Elisabeth A. Wheeler ◽  
Pieter Baas
Keyword(s):  
High Latitude ◽  
Fossil Record ◽  
Tropical Conditions ◽  
Low Levels ◽  
Low Incidence ◽  
Wood Evolution ◽  
Tropical Woods ◽  
Almost All ◽  
The Tropics ◽  
Transformation Series

ABSTRACTWe revisited questions about changes in the incidences of functional wood anatomical traits through geologic time and compared the incidences of these traits in the fossil record with modern wood anatomical diversity patterns in order to test classical (“Baileyan”) and more recent ecophyletic hypotheses of xylem evolution. We contrast patterns through time for tropical and higher (paleo)latitudes. Data are from the InsideWood database. There are striking differences between woods from high and mid latitudes versus tropical (paleo)-latitudes. At temperate and subtropical latitudes (Laurasia and high latitude Gondwana), the epoch by epoch time series supports the Baileyan transformation series of vessel-bearing woody angiosperms (basal woody angiosperms and eudicots): “primitive” features such as scalariform perforations, exclusively solitary vessels, apotracheal diffuse parenchyma and heterocellular rays abound in the Cretaceous and become much less frequent in the Cenozoic, especially post-Eocene. In contrast, in the paleotropics hardly any changes occur in the incidences – each epoch has an equally “modern” spectrum of wood anatomical attributes. Although climatic gradients from the poles to the equator were less steep in the Cretaceous than in the late Cenozoic, the wood anatomical differences between mid-high latitude woods and tropical woods were much more pronounced in the Cretaceous than in later epochs. This seeming paradox is discussed but we cannot resolve it.We suggest that tropical conditions have accelerated xylem evolution towards greater hydraulic efficiency (simple perforations), biological defense and hydraulic repair (elaborate paratracheal parenchyma patterns) as evidenced by late Cretaceous tropical latitude woods having near modern incidences of almost all traits. At higher paleolatitudes of both the Northern and Southern Hemisphere “ancestral” features such as scalariform perforations were retained in cooler and frost-prone regions where they were not selected against in mesic habitats because of lower demands on conductive efficiency, and could even be advantageous in trapping freeze-thaw embolisms. The fossil wood record remains too incomplete for testing hypotheses on the wood anatomy of the earliest angiosperms. The low incidence of so-called “xerophobic” woods sensu Feild with scalariform perforations with numerous (over 40) closely spaced bars in the Cretaceous tropical fossil record is puzzling. At higher paleolatitudes such woods are common in the Cretaceous.Ring porosity, an indicator of seasonal climates and deciduousness, occurs at low levels in the Cretaceous and Paleogene at higher paleolatitudes only, and reaches modern levels in the Miocene. In Neogene and Recent temperate Northern Hemisphere, wide vessels are virtually restricted to ring-porous woods. In the tropics, there is a low incidence of ring porosity throughout all epochs.The fossil record indicates that ecophysiological adaptation to tropical or temperate conditions was already evident in the Cretaceous with considerable latitudinal differences.

Extratropical–Tropical Interaction during Onset of the Australian Monsoon: Reanalysis Diagnostics and Idealized Dry Simulations

2007 ◽  
Vol 64 (10) ◽  
pp. 3475-3498 ◽  
Author(s):  
Noel E. Davidson ◽  
Kevin J. Tory ◽  
Michael J. Reeder ◽  
Wasyl L. Drosdowsky
Keyword(s):  
Wave Propagation ◽  
High Latitude ◽  
Monsoon Trough ◽  
Background Flow ◽  
Australian Monsoon ◽  
Subtropical Jet ◽  
Westerly Winds ◽  
Rossby Wave Propagation ◽  
Upper Level ◽  
The Tropics

Abstract The onset of the Australian monsoon is examined using (i) reanalysis data for seasons when enhanced observational networks were available and (ii) a 15-yr onset composite. Similar to previous findings, onset is characterized by a sudden strengthening and deepening in tropical westerly winds, which are overlain with upper-tropospheric easterlies. All onsets are preceded by up to a 7-day preconditioning period of enhanced vertical motion and moistening. During the transition season, the 6 weeks prior to onset, a number of moist westerly events occur. Generally they are only sustained for short periods and overlain by upper-level westerly winds, suggesting an association with midlatitude troughs, which protrude into the deep Tropics. For individual years and for a 15-yr composite, monsoon onset is associated with major cyclogenesis events over the southwest Indian Ocean in the presence of a subtropical jet over the eastern Indian Ocean. The proposed mechanism for extratropical–tropical interaction is northeastward Rossby wave propagation from the cyclogenesis region toward the Tropics at upper levels. At these levels, westerly winds extend to nearly 10°S and provide a favorable background flow for such propagation. The process eventually results in the amplification of an equatorward-extending midlatitude upper trough and tropical ridge, which appears to trigger the development of the underlying monsoon trough. To test the hypothesis, the influence of high-latitude cyclogenesis on the tropical circulation is investigated with the aid of an idealized, dry, three-dimensional, baroclinic wave channel model. The initial state consists of (i) a zonally constant baroclinic region centered on 40°S, from which the high-latitude cyclogenesis develops, (ii) a weak monsoon trough at 15°S, and (iii) a subtropical jet at 25°S. The major findings from the simulations are as follows: 1) There is evidence of northeastward Rossby wave propagation from the cyclogenesis region toward low latitudes. 2) Consistent with theoretical studies, the subtropical jet plays a key role by providing a favorable westerly background flow for group propagation into the Tropics. 3) High-latitude cyclogenesis in the presence of a subtropical jet can influence the meridional location, zonal structure, vorticity, and divergence in the monsoon trough. 4) Vorticity and divergence changes are consistent with enhancement of the monsoon trough (increases in low-level cyclonic vorticity) and the potential for triggering a large-scale convective outbreak (changes in upper-level divergence).

scholarly journals Evaluating the dominant components of warming in Pliocene climate simulations

2013 ◽  
Vol 9 (2) ◽  
pp. 1599-1625
Author(s):  
D. J. Hill ◽  
A. M. Haywood ◽  
D. J. Lunt ◽  
S. J. Hunter ◽  
F. J. Bragg ◽  
...  
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
High Latitude ◽  
Model Comparison ◽  
Climate Models ◽  
Climate Model ◽  
Cloud Albedo ◽  
Clear Sky ◽  
Air Temperatures ◽  
The Tropics

Abstract. The Pliocene Model Intercomparison Project is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 °C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean–atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with cloud albedo feedbacks enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere mid-latitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with cloud albedo feedbacks in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that high latitude albedo feedbacks provide the most significant enhancements to Pliocene greenhouse warming.

scholarly journals Study of UV Transmission through a Few Edible Oils and Chicken Oil

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
K. Anil Kumar ◽  
K. Viswanathan
Keyword(s):  
Uv Radiation ◽  
Vegetable Oils ◽  
High Latitude ◽  
Edible Oils ◽  
Atmospheric Ozone ◽  
Human Beings ◽  
Neem Oil ◽  
Solar Uv ◽  
The Tropics ◽  
Absorption Characteristics

Effects of solar UV radiation on the biosphere are well known and a lot of studies are going on to reduce its dangerous effects on human beings. Atmospheric ozone layer is not uniform over the globe, so that less ozone over tropics makes it receive more UV insolation, than high latitude places. People in the tropics are continuously exposed to high UV dosage, leading to skin reddening and the dangerous “sun stroke.” In southern India people use some vegetable oils to protect the skin from sun heat. Studies of “sun stroke” show that people having skin of moderate colour are the main victims. In some parts of Southern Kerala like Kottayam, Ernakulam, and Alappuzha traditional people were using oil extracted from chicken, called “chicken oil,” for the treatment of “heat burns” and other types of burns. This motivated us to study the UV absorption characteristics of chicken oil, and compare them with that of other commonly used vegetable oils. It is found that the chicken oil shows maximum absorption of UV radiation of about 85%, and neem oil shows absorption of about 60%. Other oils show comparatively very low absorption of UV radiation. So this property of chicken oil may be the reason for using it as remedy for heat burns.

Role of photosymbiosis and biogeography in the diversification of early Paleogene acarininids (planktonic foraminifera)

Paleobiology ◽  
2001 ◽  
Vol 27 (2) ◽  
pp. 311-326 ◽  
Author(s):  
Frédéric Quillévéré ◽  
Richard. D. Norris ◽  
Issam Moussa ◽  
William. A. Berggren
Keyword(s):  
High Latitude ◽  
Planktonic Foraminifera ◽  
Evolutionary Diversification ◽  
Tropical Environments ◽  
Low Latitudes ◽  
Low Diversity ◽  
Close Relationship ◽  
The Tropics ◽  
Early Paleogene

Radiations are commonly believed to be linked to the evolutionary appearance of a novel morphology or ecology. Previous studies have demonstrated a close relationship between the evolutionary appearance of algal photosymbiosis in planktonic foraminifera and evolutionary diversification of Paleogene photosymbiotic clades. For example, the evolution of photosymbiosis was synchronous with the abrupt evolution of four major groups of Paleogene planktonic foraminifera including two clades within the genus Morozovella, as well as the genera Acarinina and Igorina. Our new isotopic and biogeographic data suggest that the acarininids evolved from a photosymbiotic ancestor (which we identify as Praemurica inconstans or early representatives of Praemurica uncinata), but also demonstrate that photosymbiosis did not trigger an immediate species-level radiation in this group. Instead, the acarininids remained a low-diversity taxon restricted to high latitudes for nearly 1.8 million years before radiating ecologically and taxonomically. The eventual radiation of the acarininids is tied to an expansion of their geographic range into the mid and low latitudes. Biogeographic analyses of modern plankton suggest that high-latitude environments may be less conducive to establishing radiations simply because there are fewer niches available to be filled than there are in the tropics. Accordingly, the acarininids may have initially failed to diversify because they started off in environments that presented few opportunities to sustain a large radiation. The high-latitude origin of the acarininids continued to retard their overall diversification until they were able to develop strategies that allowed them to expand into tropical environments and fully exploit their photosymbiotic ecology.

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