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Climate Change and Its Influence on Microbial Diversity, Communities, and Processes
Published in Javid A. Parray, Suhaib A. Bandh, Nowsheen Shameem, Climate Change and Microbes, 2022
Irteza Qayoom, Haika Mohi-Ud-Din, Aqsa Khursheed, Aashia Altaf, Suhaib A. Bandh
Furthermore, moisture and temperature fluctuations due to climate variability affect the microbial processes, including the rate of respiration, fermentation, methanogenesis, and decomposition (Weiman, 2015). In polar soil environments, such as in Arctic permafrost, changes, for example, warming, melting, thawing, drying, and changes in plant communities, are expected to drive changes in the composition and diversity of microbial communities (Jansson and Tas, 2014). The elevated temperature and levels CO2 also affect the marine planktonic communities, thus, affecting the productivity, nitrification, denitrification, and photosynthetic C fixation mediated by them (Glockner et al., 2012). Climate change also influences processes like oceanic stratification, mixing, the availability of nutrients, thermohaline circulation, and extreme weather events. These changes upset marine microbiota in significant ways, including some significant changes in productivity, oceanic food webs, and carbon exports and burial in the sea bed (Hurd, 2018; Gao, 2012; Boyd, 2013; Portner, 2014; Brennan and Collins, 2015; Hutchins et al., 2016; Hutchins and Fu., 2017; Rintoul et al., 2018; Cavicchioli et al., 2019). Furthermore, there are cyanobacterial algal blooms that exemplify a significant deleterious effect of climate change in aquatic ecosystems (Dutta and Dutta, 2016) like eutrophic lakes, reservoirs, and estuaries.
The Biosphere
Published in John C. Ayers, Sustainability, 2017
There is also the possibility that increased ocean surface temperatures could eventually shut off oceanic circulation (Broecker 1997). Currently warm surface waters move toward the poles and lose heat, causing them to become denser and eventually sink to the bottom of the ocean, displacing cold, deep, oxygen-poor waters that rise to the surface and become reoxygenated. Now, however, rising surface temperatures are causing the ocean’s surface waters to become less dense, potentially disrupting thermohaline circulation. Furthermore, melting glaciers are adding freshwater to the oceans, which mixes with surface waters and make them even less dense. If ocean surface waters become so light that they no longer sink at the poles, the oceans will no longer be well-mixed, and an oxygen-depleted dead zone will develop in deep waters around the globe. This is what happens in freshwater lakes in temperate zones, which become stratified and develop a deep oxygen-depleted layer in the summer, but in the case of the oceans the oxygen-depleted dead zone would be permanent rather than seasonal. Further, this would dramatically change regional climates—some regions would get warmer while some would get colder (e.g., the United Kingdom, where currently thermohaline circulation is responsible for warm waters from the Gulf of Mexico moving northward and yielding more mild climates).
Environmental Chemistry and the Five Spheres of the Environment
Published in Stanley Manahan, Environmental Chemistry, 2017
As noted above, a particularly important aspect of the Earth System is the continuous exchange of matter and energy among the five major environmental spheres. One of the major factors in these exchanges consists of two great fluids that circulate in the Earth System: (1) surface water, especially in the oceans and rivers, and (2) air in the atmosphere, both of which transport matter and energy. Air heated in equatorial regions expands and flows away from the equator carrying heat energy as sensible heat in the air molecules and latent heat in water vapor toward polar regions. A plume of water called the Gulf Stream heated in the Caribbean region flows northward near the surface of the Atlantic along the east coast of North America and releases heat off the coast of Europe before sinking and flowing back at greater depths (the thermohaline circulation of the North Atlantic). This phenomenon is responsible in part for the relatively warm temperatures of Ireland, England, and Western Europe despite their more northern latitudes, and its possible demise is of great concern with respect to global climate change. In addition to large quantities of water, flowing rivers carry sediments and are very much involved in the transport of waterborne pollutants.
The geostrophic regime of rapidly rotating turbulent convection
Published in Journal of Turbulence, 2021
Turbulent, buoyancy-driven flows in geophysics and astrophysics are almost invariably and decisively shaped by the rotation of the celestial body on which they reside. On our Earth, perhaps the most prominent and visible example is the atmosphere [1]. In fact, the notion that rotation shapes atmospheric flows can be traced back more than 280 years to Hadley's work [2] on the trade winds. Oceanic deep convection in polar regions [3] drives the thermohaline circulation that is of eminent importance for our climate. Hidden to the eye is the convective flow in Earth's liquid-metal outer core [4,5] that sustains the magnetic field [6,7] that protects our planet from harmful cosmic radiation. Moving away from our own planet, further examples are found in the giant gas planets with their characteristic zonal flows [8,9]. Our Sun also possesses a convective outer layer where its rotation shapes the flow [10].
What Limits Our Understanding of Oceans? Challenges in Marine Instrumentation
Published in IETE Journal of Education, 2020
Arathy R. Nair, S. Muthukumaravel, Tata Sudhakar
Wider temperature ranges: The oceanographic instruments should be able to work under wider temperature ranges, from 32°C to −2°C. The temperature of the ocean varies widely both horizontally and vertically. Warmer waters are observed near the equator and coldest waters are found near the poles. In contrast to the variation of pressure with respect to depth, vertical temperature variation displays a decreasing profile with increasing depth. There occurs, beneath the well-mixed isothermal layer near the surface, a thermocline layer, where the temperature decreases rapidly over a short distance. Beyond the thermocline, the decrease in temperature is gradual. The differences in temperature and salinity cause density variation and this density variation leads to deep ocean circulation known as thermohaline circulation. As the instrument descends through the ocean, the decreasing ambient temperature causes condensation of air inside the pressure vessel. These condensation droplets are detrimental to the electronic components inside. In order to avoid this, desiccant packs may also be strapped inside along with electronics to absorb any moisture developed. Another method is to use the vacuum purge system. Purging is the process of filling inert gas like nitrogen in the pressure vessel to displace the interior air so that a stable environment is established in the housing.