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Topic Review
Fire-vegetation Feedbacks and Alternative Stable States
The relationship between fire, vegetation, and climate create what is known as a fire regime. Within a fire regime, fire ecologists study the relationship between diverse ecosystems and fire; not only how fire affects vegetation, but also how vegetation affects the behavior of fire. The study of neighboring vegetations types that may be highly flammable and less flammable has provided insight into how these vegetation types can exist side by side, and are maintained by the presence or absence of fire events. Ecologists have studied these boundaries between different vegetation types, such as a closed canopy forest and a grassland, and hypothesized how climate, and soil fertility create these boundaries in vegetation types. Research in the field of pyrogeography shows how fire also plays an important role in the maintenance of dominant vegetation types, and how different vegetation types with distinct relationships to fire can exist side by side in the same climate conditions. These relationships can be described in conceptual models called fire-vegetation feedbacks, and alternative stable states.
  • 506
  • 29 Sep 2022
Topic Review
Humid Continental Climate
A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers and cold (sometimes severely cold in the northern areas) winters. Precipitation is usually distributed throughout the year. The definition of this climate regarding temperature is as follows: the mean temperature of the coldest month must be below −3 °C (26.6 °F) and there must be at least four months whose mean temperatures are at or above 10 °C (50 °F). In addition, the location in question must not be semi-arid or arid. The Dfb, Dwb and Dsb subtypes are also known as hemiboreal. Humid continental climates are generally found roughly between latitudes 40° N and 60° N, within the central and northeastern portions of North America, Europe, and Asia. They are much less commonly found in the Southern Hemisphere due to the larger ocean area at that latitude and the consequent greater maritime moderation. In the Northern Hemisphere some of the humid continental climates, typically in Hokkaido, Northern Honshu, Sakhalin island, Scandinavia, Nova Scotia, and Newfoundland are heavily maritime-influenced, with relatively cool summers and winters being just below the freezing mark. More extreme humid continental climates found in northeast China , southern Siberia, the Canadian Prairies, and the Great Lakes region of the American Midwest and Central Canada combine hotter summer maxima and colder winters than the marine-based variety.
  • 6.2K
  • 29 Sep 2022
Topic Review
Uturunku
Uturunku (Quechua for jaguar, Hispanicized spellings Uturunco, Uturuncu) is a dormant volcano in the Cordillera de Lípez in Potosí Department, Bolivia. It is located in the Sur Lípez Province, San Pablo de Lípez Municipality. It is in the Central Volcanic Zone of the Andes, and its highest summit is 6,008 metres (19,711 ft) above sea level. The volcano has two summits, with a fumarole field between them. The volcano's landforms include lava domes and lava flows. The volcano was sporadically active during the Pleistocene, with the most recent eruption dated at 271,000 years ago. Since then, Uturunku has displayed fumarolic activity. Starting in 1992, satellite observations have indicated a large area of regional uplift centered on Uturunku, which has been interpreted as an indication of large-scale magma intrusion under the volcano. This might be a prelude to large-scale volcanic activity, including "supervolcanic" activity and caldera formation.
  • 543
  • 29 Sep 2022
Topic Review
Seismic Array
A seismic array is a system of linked seismometers arranged in a regular geometric pattern (cross, circle, rectangular etc.) to increase sensitivity to earthquake and explosion detection. A seismic array differs from a local network of seismic stations mainly by the techniques used for data analysis. The data from a seismic array is obtained using special digital signal processing techniques such as beamforming, which suppress noises and thus enhance the signal-to-noise ratio (SNR). The earliest seismic arrays were built in the 1950s in order to improve the detection of nuclear tests worldwide. Many of these deployed arrays were classified until the 1990s. Today they become part of the IMS as primary or auxiliary stations. Seismic arrays are not only used to monitor earthquakes and nuclear tests, but also used as a tool for investigating nature and source regions of microseisms as well as locating and tracking volcanic tremor and analyzing complex seismic wave-field properties in volcanic areas.
  • 414
  • 29 Sep 2022
Topic Review
Revalorization of Microalgae Biomass for Synergistic Interaction
Microalgae and cyanobacteria are photosynthetic microorganisms’ sources of renewable biomass that can be used for bioplastic production. These microorganisms have high growth rates, and contrary to other feedstocks, such as land crops, they do not require arable land. In addition, they can be used as feedstock for bioplastic production while not competing with food sources (e.g., corn, wheat, and soy protein). 
  • 441
  • 29 Sep 2022
Topic Review
Global Energy and Water Cycle Experiment
The Global Energy and Water Cycle Experiment (GEWEX) is a research program of the World Climate Research Programme intended to observe, comprehend and model the Earth's water cycle. The experiment also observes how much energy the Earth receives, studies how much of that energy reaches surfaces of the Earth and how that energy is transformed. Sunlight's energy evaporates water to produce clouds and rain, and dries out land masses after rain. Rain that falls on land becomes the water budget which can be used by people for agricultural and other processes. GEWEX is a collaboration of researchers worldwide to find better ways of studying the water cycle and how it transforms energy through the atmosphere. If the Earth's climates were identical from year to year, then people could predict when, where and what crops to plant. However, instability created by solar variation, weather trends, and chaotic events create weather that is unpredictable on seasonal scales. Through weather patterns such as droughts and higher rainfall these cycles impact ecosystems and human activities. GEWEX is designed to collect a much greater amount of data, and see if better models of that data can forecast weather and climate change into the future. GEWEX is organized into several structures. As GEWEX was conceived projects were organized by participating factions, this task is now done by the International GEWEX Project Office (IGPO). IGPO oversees major initiatives and coordinates between national projects in an effort to bring about communication of researchers. IGPO claims to support communication exchange between 2000 scientist and is the instrument for publication of major reports. The Scientific Steering Group organizes the projects and assigns them to panels, which oversee progress and provide critique. The Coordinated Energy and Water Cycle Observations Project (CEOP) the 'Hydrology Project' is a major instrument in GEWEX. This panel includes geographic study areas such as the Climate Prediction Program for the Americas operated by NOAA, but also examines several types of climate zones (e.g. high altitude and semi-arid). Another panel, the GEWEX Radiation Panel oversees the coordinated use of satellites and ground-based observation to better estimate energy and water fluxes. One recent result GEWEX's Radiation panel has assessed data on rainfall for the last 25 years and determined that global rainfall is 2.61 mm/day with a small statistical variation. While the study period is short, after 25 years of measurement regional trends are beginning to appear. The GEWEX Modeling and Prediction Panel takes current models and analyzes the models when climate forcing phenomena occur (global warming as an example of a 'climate forcing' event). GEWEX is now the core project of WCRP.
  • 196
  • 28 Sep 2022
Topic Review
Ground Level Ozone
Ground level ozone (O3), also known as tropospheric ozone, is a trace gas of the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas. Ozone is also an important constituent of the stratosphere, where the ozone layer exists which is located between 10 and 50 kilometers above the Earth's surface. The troposphere extends from the ground up to a variable height of approximately 14 kilometers above sea level. Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground level or tropospheric ozone is created by chemical reactions between oxides of nitrogen (NOx gases) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone. Its concentration increases as height above sea level increases, with a maximum concentration at the tropopause. About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. Although tropospheric ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. Ozone in the troposphere is considered a greenhouse gas, and may contribute to global warming. Photochemical and chemical reactions involving ozone drive many of the chemical processes that occur in the troposphere by day and by night. At abnormally high concentrations (the largest source being emissions from combustion of fossil fuels), it is a pollutant, and a constituent of smog. Its levels have increased significantly since the industrial revolution, as NOx gasses and VOCs are some of the byproducts of combustion. With more heat and sunlight in the summer months, more ozone is formed which is why regions often experience higher levels of pollution in the summer months. Although the same molecule, ground level ozone can be harmful to our health, unlike stratospheric ozone that protects the earth from excess UV radiation. Photolysis of ozone occurs at wavelengths below approximately 310–320 nanometres. This reaction initiates the chain of chemical reactions that remove carbon monoxide, methane, and other hydrocarbons from the atmosphere via oxidation. Therefore, the concentration of tropospheric ozone affects how long these compounds remain in the air. If the oxidation of carbon monoxide or methane occur in the presence of nitrogen monoxide (NO), this chain of reactions has a net product of ozone added to the system.
  • 460
  • 28 Sep 2022
Topic Review
McClure Arctic Expedition
The McClure Arctic Expedition of 1850, among numerous British search efforts to determine the fate of the Franklin's lost expedition, is distinguished as the voyage during which Robert McClure became the first person to confirm and transit the Northwest Passage by a combination of sea travel and sledging. McClure and his crew spent three years locked in the pack ice aboard HMS Investigator before abandoning it and making their escape across the ice. Rescued by HMS Resolute, which was itself later lost to the ice, McClure returned to England in 1854, where he was knighted and rewarded for completing the passage.
  • 403
  • 28 Sep 2022
Topic Review
Stepwells as Sustainable Water Management Structures
Stepwells were one such effective water management technologies used in India. Stepwells were constructed based on their geographical and topographical suitability, which revealed socio-cultural behaviors and beliefs.
  • 1.0K
  • 28 Sep 2022
Topic Review
Action for Climate Empowerment
Action for Climate Empowerment (ACE) is a term adopted by the United Nations Framework Convention on Climate Change (UNFCCC). It refers to Article 6 of the Convention's original text (1992), focusing on six priority areas: education, training, public awareness, public participation, public access to information, and international cooperation on these issues. The implementation of all six areas has been identified as the pivotal factor for everyone to understand and participate in solving the complex challenges presented by climate change. The importance of ACE is reflected in other international frameworks such as the Sustainable Development Goals (SDGs, 2015); the Global Action Programme for Education for Sustainable Development (GAP on ESD, 2014); the Aarhus Convention (2011); the Escazú Agreement (2018) and the Bali Guidelines (2010). ACE calls on governments to develop and implement educational and public awareness programmes, train scientific, technical and managerial personnel, foster access to information, and promote public participation in addressing climate change and its effects. It also urges countries to cooperate in this process, by exchanging good practices and lessons learned, and strengthening national institutions. This wide scope of activities is guided by specific objectives that, together, are seen as crucial for effectively implementing climate adaptation and mitigation actions, and for achieving the ultimate objective of the UNFCCC.
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