Arxiu d'etiquetes: sea level

The Arctic: who cares?

The global change is the main threat to the Arctic, due to the increasing temperature is melting their ice coverage. What will be the consequences of this for its fragile ecosystem? Who cares about it?


The Arctic, one of the few unspoiled areas of the planet, is located in the north pole. Low temperatures in the region (an average of -35°C in winter and 0ºC in summer) are explained by the low insolation due to the inclination of the globe.

Before the industrial age, the permanent ice of the Arctic occupied about 7 million square kilometers (doubling its size in winter), but it is increasingly difficult to maintain that ice in summer. The ice may reach a thickness of 50 meters in winter, dropping to 2 meters in summer.

Before you start, you can enjoy this video with stunning images of the Arctic:


The Arctic offers a wide variety of different environments: ocean, ice sheets, the coastal area, the tundra and some coniferous forests.

importancia ártico
The tundra is most notable terrestrial biome in the Arctic (Picture: Biomas).

This allows the livelihood of many plant and animal species. Only in the Arctic Ocean, it has been described more than 5,000 animal species, some of which are endemic to this area. An estimated 400 species live only in the Arctic region.

Among the best known animals, we find the bowhead whale (Balaenoa mysticetus), a large animal that can live more than 100 years, and the narwhal (Monodon monoceros), cetacean in which males have a very long tusk, used during courtship.

importancia ártico ballena groenlandia
Bowhead whale (Balaena mysticetus) is an endemic animal of the Arctic (Picture: Clarín).

On ice and snow, polar bear (Ursus maritimus), walrus (Odobenus rosmarus), the Arctic wolf (Canis lupus arctos) and the reindeer (Rangifer tarandus) are present.

lobo ártico
Arctic wolf (Canis lupus arctos) is endangered (Picture: Deanimalia).

The Arctic is also home to over 80 species of birds, including the Brünnich’s guillemoth or the king eider; and more than 400 fish.

But undoubtedly, the group that takes the cake are arthropods, with more than 1,500 documented species, although there are also representatives of almost all existing animal phyla.

Este copépodo, de la especie Euaugaptilus hyperboreus, forma parte el zoopláncton ártico (Foto: Poetic Monkey).
This copepod (Euaugaptilus hyperboreus) is part of Arctic zooplankton  (Picture: Poetic Monkey).


The Arctic, along with Antarctica, is like a natural air conditioner on the planet. Therefore, malfunction further enhances the effects of climate change.

The ice cover is responsible for a high percentage of albedo. Albedo is the effect by which a surface reflects part of the solar radiation back into the atmosphere, thus maintaining a lower temperature. Without this effect, the temperatures will be increasingly high.

El hielo es el principal elemento del albedo en la superficie de la Tierra (Foto: US Satellite).
Ice is the key element of albedo in Earth surface (Picture: US Satellite).

The physical processes taking place in the Arctic affect ocean circulation worldwide: during the formation of sea ice, water crystals exclude salt, so that water is increasingly salty. The increase of salinity, along with the low water temperatures, cause the formation of a very dense water mass that sinks to the ocean floor and is transported southward through the thermohaline circulation, responsible for regulating the global climate. Without ice, the thermohaline circulation may be interrupted or weakened, with the consequences that would follow.

La circulación termohalina es responsable del clima a nivel mundial (Foto: Blog de recursos de Cpmc).
The thermohaline circulation is responsible of worldwide climate (Picture: Blog de recursos de Cpmc).


Due to the increase in temperature on a global level, the ice covering the Arctic has been reducing. Several reports indicate that this reduction was  about 30% in just two decades. Also, if this trend continues, in twenty years might disappear all Arctic ice, at least during summer. Without ice, many species will have serious problems to survive, such as the polar bear, seals and other pinnipeds.

hielo ártico permanente
(Picture: India Today).

As we have seen, no ice, no albedo; but also if the permanent ice melts, it will cause the release of large amounts of greenhouse gases that are trapped in either the ice or in the frozen Arctic soil (permafrost); providing a positive feedback to climate change.

Some studies suggest that, if the entire Greenland ice melt the average sea level will rise 7 meters.

In addition, increasingly massive algal blooms occur, which sink and cause eutrophication of the ecosystem. The ice thickness reduction allows increasing carbon dioxide in water to penetrate, causing water acidification, which can cause bleaching of coral and shells malformations in animals.

There are many companies that see the melting of the Arctic as a commercial possibility:

  • Obtaining energy resources such as natural gas and oil (for only 3 years, according to experts).
  • Exploitation of mineral resources such as manganese, gold, lead and diamonds.
  • New fishing grounds.
  • New trade routes for shipping and tourism.

Thus, the Arctic is a very fragile ecosystem that we must protect together. Acting locally, we are acting globally.


  • Broecker, WS (2005). The role of the ocean in climate: Yesterday, today and tomorrow. Eldigio Press
  • El mar a fondo: El agua de mar y las corrientes oceánicas (Guía didáctica).
  • McIntyre, A (2010). Life in the World’s Oceans. Blackwell Publishing Ltd.
  • Greenpeace (2013). El Ártico y los efectos del cambio climático en España. Salvar el Ártico es salvar mucho más. Greenpeace.
  • Hutchinson, S & Hawkins, LE (2004). Océanos. Libros Cúpula. Coleccion Biblioteca visual
  • Palacín, B (2010). La creciente importancia el Ártico. Revista Española de Defensa
  • Perrin, WF; Würsig, B & Thewissen, JGM (2009). Encyclopedia of Marine Mammals. Academic Press (2 ed)
  • Cover picture: Kerstin Langenberger


And the waters went up

This week the topic is a worldwide problem favoured by human action, which is one of the several consequences of global change. Effectively, I’m talking about sea-level rise.


Since the end of the last ice age to the present day, sea-level has risen by about 125 meters. The causes of this sea-level rise have both a natural and human origin, despite the human-induced greenhouse effect is intensifying this process.


The sea-level rise is one of the worst consequences of global change. The coastal areas are the most densely populated of the world, so two thirds of the Earth population live in the first 8 km from the coast. They are especially vulnerable to the impacts of global change due to the presence of major agricultural zones, conurbations and heritage sites.

Sea-level is determined by natural and human-induced green house effect. Specialists distinguish between:

  • Eustatic causes: this refers to the water mass being added to the oceans. An example is the sea-level rise following the melting of large glaciers at the end of ice ages.
  • Isostatic causes (generally tectonic): it refers to the sinking or rising of Earth’s crust due to its weight. On the one side, during glaciations, the increase of ice sheets on the crust causes an increase of the weight, causing its sinking. On the other side, during the warmer periods (interglacial), the melting of the ice means a reduction of weight and, for this reason, the curst rises. This phenomenon has regional effects.


Sea level can change by 10 meters or so within the course of a few centuries and can fluctuate by more than 200 meters over millions of years. During glacial periods, sea level reduces due to the formation of big ice sheets on the continent, while in the interglacial periods its melting causes a rise in the sea level.

Nevertheless, if we compare the sea-level rise of this last century with the almost constant level of the last 6000 – 8000 years, we can observe a rise of 18 cm in just 100 years and 3.2 cm in the last decade. Experts believe that between 15 and 50% of sea-level rise is attributed to the temperature-related expansion of seawater, that 25 – 45% is caused by the melting of mountain glaciers outside the polar regions, and between 15 and 40 per cent is caused by the melting of the Greenland and Antarctic ice caps.

Sea level will significantly rise by the end of this century, although the precise extend to which it will increase is uncertain. The Intergovernmental Panel on Climate Change (IPCC) considers a rise of up to 1 meter during this century (dark green shading in the picture), while other researchers forecast a rise of more than 180 cm (light green shading in the picture). If most of the ice sheets in Greenland and West Antarctica melt, sea level could increase by as much as 20 meters in the following 1000 years in a worst-case scenario. The last time that the Earth had a similar temperature to the predicted in 2050, sea level was 4 meters above the nowadays level.

Sense títolFuture scenarios of the sea-level rise. In dark green, the IPCC's forecast and in light green the worst case. (Origin: Future Ocean)


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