Physical geography (also known as geosystems or physiography) is one of the two major sub-fields of geography. Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere, biosphere, and geosphere, as opposed to the cultural or built environment, the domain of human geography.
Within the body of physical geography, the Earth is often split either into several spheres or environments, the main spheres being the atmosphere, biosphere, cryosphere, geosphere, hydrosphere, lithosphere and pedosphere. Research in physical geography is often interdisciplinary and uses the systems approach.
Physical oceanography is the study of physical conditions and physical processes within the ocean, especially the motions and physical properties of ocean waters.
Physical oceanography is one of several sub-domains into which oceanography is divided. Others include biological, chemical and geological oceanographies.
The effects of global warming are the ecological and social changes caused by the rise in global temperatures. There is a scientific consensus that climate change is occurring, and that human activities are the primary driver. Evidence of climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the Northern Hemisphere. According to the Intergovernmental Panel on Climate Change (IPCC), most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in human greenhouse gas concentrations.
Projections of future climate change suggest further global warming, sea level rise, and an increase in the frequency and severity of some extreme weather events. Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have agreed to "stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system."
Mean sea level (MSL) is a datum representing the average height of the ocean's surface (such as the halfway point between the mean high tide and the mean low tide); used as a standard in reckoning land elevation. MSL also plays an important role in marine navigation as a chart datum and aviation, where standard sea level pressure is used as the measurement datum of altitude at flight levels. Detection of long-term variations of mean sea level requires careful measurement but can provide information on climate change. Over geologic time, sea levels have changed dramatically.
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The term specifically excludes seawater and brackish water although it does include mineral-rich waters such as chalybeate springs. The term "sweet water" has been used to describe fresh water in contrast to salt water.
Current sea-level rise is about 3 mm/year worldwide. According to the National Oceanic and Atmospheric Administration (NOAA), "this is a significantly larger rate than the sea-level rise averaged over the last several thousand years", and the rate may be increasing. This rise in sea levels around the world potentially affects human populations (e.g., those living in coastal regions and on islands) and the natural environment (e.g., marine ecosystems). Between 1870 and 2004, global average sea levels rose 195 mm (7.7 in). From 1950 to 2009, measurements show an average annual rise in sea level of 1.7 ± 0.3 mm per year, with satellite data showing a rise of 3.3 ± 0.4 mm per year from 1993 to 2009, a faster rate of increase than previously estimated. It is unclear whether the increased rate reflects an increase in the underlying long-term trend.
Two main factors contributed to observed sea level rise. The first is thermal expansion: as ocean water warms, it expands. The second is from the contribution of land-based ice due to increased melting. The major store of water on land is found in glaciers and ice sheets.
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi), thus also known as continental glacier. The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.
Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.
Hospitality is the relationship between the guest and the host, or the act or practice of being hospitable. This includes the reception and entertainment of guests, visitors, or strangers.