Tipping point (climatology)

Tipping point (climatology)

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A climate tipping point is a point when global climate changes from one stable state to another stable state, in a similar manner to a wine glass tipping over. After the tipping point has been passed, a transition to a new state occurs. The tipping event may be irreversible, comparable to wine spilling from the glass—standing up the glass will not put the wine back.

Global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

 proceeds by changing the composition of gases in the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 by the emission of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

es such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

. As warming proceeds it brings about changes to the natural environment
Natural environment
The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....

 which may result in other changes. For example, warming may begin to melt the Greenland ice sheet
Greenland ice sheet
The Greenland ice sheet is a vast body of ice covering , roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. The ice sheet is almost long in a north-south direction, and its greatest width is at a latitude of 77°N, near its...

. At some level of temperature rise, the melt of the entire ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...

 will become inevitable, even though complete melting may not occur for millennia. Thus a tipping point may be passed without any immediately obvious consequences. Nor does the use of tipping point necessarily imply any acceleration of the warming process.

James E. Hansen believes this point has already been reached with carbon dioxide levels currently at 391.7 ppm. "Further global warming of 1°C defines a critical threshold. Beyond that we will likely see changes that make Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 a different planet than the one we know." He has further suggested potential projections of Runaway climate change
Runaway climate change
Runaway climate change describes a theoretical scenario in which the climate system passes a threshold or tipping point, after which internal positive feedback effects cause the climate to continue changing without further external forcings...

 on Earth creating more Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

-like conditions in his book Storms of My Grandchildren
Storms of My Grandchildren
Storms of My Grandchildren is climate scientist James Hansen's first book, published by Bloomsbury Press in 2009. The book is about threats to people and habitability for life on earth from global warming.-Themes:...

.

Other scientists maintain the term is too vague for a non-linear system such as the Earth's climate, in which there may be transitions between several equilibrium states. It has been speculated that geoengineering
Geoengineering
The concept of Geoengineering refers to the deliberate large-scale engineering and manipulation of the planetary environment to combat or counteract anthropogenic changes in atmospheric chemistry The Intergovernmental Panel on Climate Change concluded in 2007 that geoengineering options, such...

 may be used to reverse, prevent, or postpone a tipping point event.

Examples


Lenton
Tim Lenton
-References:...

 et al. highlights a number of tipping points, including:
  • Boreal forest dieback
    Dieback
    Dieback may refer to a number of plant problems and diseases including:* Forest dieback caused by acid rain, heavy metal pollution, or imported pathogens* The death of regions of a plant or similar organism caused by physical damage, such as from pruning...

  • Amazon rainforest
    Amazon Rainforest
    The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...

     dieback
  • Loss of Arctic
    Arctic
    The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

     and Antarctic
    Antarctic
    The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...

     sea ice
    Sea ice
    Sea ice is largely formed from seawater that freezes. Because the oceans consist of saltwater, this occurs below the freezing point of pure water, at about -1.8 °C ....

     (Polar ice packs
    Polar ice packs
    Polar ice packs are large areas of pack ice formed from seawater in the Earth's polar regions, known as polar ice caps: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean, fringing the Antarctic ice sheet. Polar packs significantly change their size during...

    ) and melting of Greenland
    Greenland
    Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

     and Antarctic
    Antarctic
    The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...

     ice sheets
  • Disruption to India
    India
    India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

    n and West African monsoon
    Monsoon
    Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea...

  • Formation of Atlantic deep water
    Deep Water
    Deep Water is a suspense novel by Patricia Highsmith, first published in 1957 by Harper & Row.-Synopsis:In the small town of Little Wesley, intellectual publisher Victor Van Allen decides to discourage his wife Melinda’s many lovers by hinting to them that he may have killed her previous beau,...

     near the Arctic ocean
    Arctic Ocean
    The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...

    , which is a component process of the thermohaline circulation
    Thermohaline circulation
    The term thermohaline circulation refers to a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes....

    .
  • Loss of permafrost
    Permafrost
    In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of...

    , leading to potential Arctic methane release
    Arctic methane release
    Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic, as part of a more general release of carbon from these soils and seas. Whilst a long-term natural process, it may be exacerbated by global warming. This results in a weak positive feedback...

     and clathrate gun effect

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