Human migrationHuman migration is the movement of people from one place to another with intentions of settling, permanently or temporarily, at a new location (geographic region). The movement often occurs over long distances and from one country to another (external migration), but internal migration (within a single country) is also possible; indeed, this is the dominant form of human migration globally. Migration is often associated with better human capital at both individual and household level, and with better access to migration networks, facilitating a possible second move.
Circular migrationCircular migration or repeat migration is the temporary and usually repetitive movement of a migrant worker between home and host areas, typically for the purpose of employment. It represents an established pattern of population mobility, whether cross-country or rural-urban. There are several benefits associated with this migration pattern, including gains in financial capital, human capital, and social capital. There are also costs associated with circular migration, such as brain drain, poor working conditions, forced labor, and the inability to transfer acquired skills to home economies.
Environmental migrantEnvironmental migrants are people who are forced to leave their home region due to sudden or long-term changes to their local or regional environment. These changes compromise their well-being or livelihood, and include increased drought, desertification, sea level rise, and disruption of seasonal weather patterns (such as monsoons[1]). Though there is no uniform, clear-cut definition of environmental migration, the idea is gaining attention as policy-makers and environmental and social scientists attempt to conceptualize the potential social effects of climate change and other environmental degradation, such a deforestation or overexploitation.
Internal migrationInternal migration or domestic migration is human migration within a country. Internal migration tends to be travel for education and for economic improvement or because of a natural disaster or civil disturbance, though a study based on the full formal economy of the United States found that the median post-move rise in income was only 1%. Cross-border migration often occurs for political or economic reasons. A general trend of movement from rural to urban areas, in a process described as urbanisation, has also produced a form of internal migration.
FamineA famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased mortality. Every inhabited continent in the world has experienced a period of famine throughout history. During the 19th and 20th century, Southeast and South Asia, as well as Eastern and Central Europe, suffered the greatest number of fatalities.
DroughtA drought is a period of drier-than-normal conditions. A drought can last for days, months or years. Drought often has large impacts on the ecosystems and agriculture of affected regions, and causes harm to the local economy. Annual dry seasons in the tropics significantly increase the chances of a drought developing and subsequent wildfires. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.
Drought toleranceDrought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions, surviving with protection mechanisms such as desiccation tolerance, detoxification, or repair of xylem embolism. Other plants, specifically crops like corn, wheat, and rice, have become increasingly tolerant to drought with new varieties created via genetic engineering.
Drought in AustraliaDrought in Australia is defined by the Australian Bureau of Meteorology as rainfall over period greater than three-months being in the lowest decile of what has been recorded for that region in the past. This definition takes into account that drought is a relative term and rainfall deficiencies need to be compared to typical rainfall patterns including seasonal variations. Specifically, drought in Australia is defined in relation to a rainfall deficiency of pastoral leases and is determined by decile analysis applied to a certain area.
Bird migrationBird migration is the regular seasonal movement, often north and south, along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by humans, and is driven primarily by the availability of food. It occurs mainly in the northern hemisphere, where birds are funnelled onto specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea.
Animal migrationAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migration in ecology. It is found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The cause of migration may be local climate, local availability of food, the season of the year or for mating. To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life.
