Query: Our evolving dynamic planet has survived sea level changes of hundreds of metres

Relevant passages:
Earth <=SEP=> Earth ( from Eorðe -LSB- Γαῖα , Gaia -RSB- Terra ) , otherwise known as the World or the Globe , is the third planet from the Sun and the only object in the Universe known to harbor life . It is the densest planet in the Solar System and the largest of the four terrestrial planets .   According to radiometric dating and other sources of evidence , Earth formed about 4.54 billion years ago . Earth 's gravity interacts with other objects in space , especially the Sun and the Moon , Earth 's only natural satellite . During one orbit around the Sun , Earth rotates about its axis over 365 times ; thus , an Earth year is about 365.26 days long . Earth 's axis of rotation is tilted , producing seasonal variations on the planet 's surface . The gravitational interaction between the Earth and Moon causes ocean tides , stabilizes the Earth 's orientation on its axis , and gradually slows its rotation .   Earth 's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years . About 71 % of Earth 's surface is covered with water , mostly by its oceans . The remaining 29 % is land consisting of continents and islands that together have many lakes , rivers and other sources of water that contribute to the hydrosphere . The majority of Earth 's polar regions are covered in ice , including the Antarctic ice sheet and the sea ice of the Arctic ice pack . Earth 's interior remains active with a solid iron inner core , a liquid outer core that generates the Earth 's magnetic field , and a convecting mantle that drives plate tectonics .   Within the first billion years of Earth 's history , life appeared in the oceans and began to affect the Earth 's atmosphere and surface , leading to the proliferation of aerobic and anaerobic organisms . Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago . Since then , the combination of Earth 's distance from the Sun , physical properties , and geological history have allowed life to evolve and thrive . In the history of the Earth , biodiversity has gone through long periods of expansion , occasionally punctuated by mass extinction events . Over 99 % of all species that ever lived on Earth are extinct . Estimates of the number of species on Earth today vary widely ; most species have not been described . Over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival . Humans have developed diverse societies and cultures ; politically , the world has about 200 sovereign states .

Marine life <=SEP=> Marine life , or sea life or ocean life , refers to the plants , animals and other organisms that live in the salt water of the sea or ocean , or the brackish water of coastal estuaries . At a fundamental level , marine life helps determine the very nature of our planet . Marine organisms produce much of the oxygen we breathe . Shorelines are in part shaped and protected by marine life , and some marine organisms even help create new land .   Most life forms evolved initially in marine habitats . Oceans provide about 99 percent of the living space on the planet . The earliest vertebrates appeared in the form of fish , which live exclusively in water . Some of these evolved into amphibians which spend portions of their lives in water and portions on land . Other fish evolved into land mammals and subsequently returned to the ocean as seals , dolphins or whales . Plant forms such as kelp and algae grow in the water and are the basis for some underwater ecosystems . Plankton , and particularly phytoplankton , are key primary producers forming the general foundation of the ocean food chain .   Marine vertebrates must obtain oxygen to survive , and they do so in various ways . Fish have gills instead of lungs , although some species of fish , such as the lungfish , have both . Marine mammals , such as dolphins , whales , otters , and seals need to surface periodically to breathe air . Some amphibians are able to absorb oxygen through their skin . Invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters including breathing tubes ( see insect and mollusc siphons ) and gills ( Carcinus ) . However , as invertebrate life evolved in an aquatic habitat most have little or no specialisation for respiration in water .   Altogether there are 230,000 documented marine species , including over 16,000 species of fish , and it has been estimated that nearly two million marine species are yet to be documented . Marine species range in size from the microscopic , including plankton and phytoplankton which can be as small as 0.02 micrometres , to huge cetaceans ( whales , dolphins and porpoises ) which in the case of the blue whale reach up to 33 metres ( 109 feet ) in length , being the largest known animal .

Tsunami <=SEP=> A tsunami ( from 津波 , `` harbour wave '' ;  English pronunciation : -LSB- tsuːˈnɑːmi -RSB- ) or tidal wave , also known as a seismic sea wave , is a series of waves in a water body caused by the displacement of a large volume of water , generally in an ocean or a large lake . Earthquakes , volcanic eruptions and other underwater explosions ( including detonations of underwater nuclear devices ) , landslides , glacier calvings , meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami . Unlike normal ocean waves which are generated by wind , or tides which are generated by the gravitational pull of the Moon and Sun , a tsunami is generated by the displacement of water .   Tsunami waves do not resemble normal undersea currents or sea waves , because their wavelength is far longer . Rather than appearing as a breaking wave , a tsunami may instead initially resemble a rapidly rising tide , and for this reason they are often referred to as tidal waves , although this usage is not favoured by the scientific community because tsunamis are not tidal in nature . Tsunamis generally consist of a series of waves with periods ranging from minutes to hours , arriving in a so-called `` internal wave train '' . Wave heights of tens of metres can be generated by large events . Although the impact of tsunamis is limited to coastal areas , their destructive power can be enormous and they can affect entire ocean basins ; the 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history with at least 230,000 people killed or missing in 14 countries bordering the Indian Ocean .   Greek historian Thucydides suggested in his late-5th century BC History of the Peloponnesian War , that tsunamis were related to submarine earthquakes , but the understanding of a tsunami 's nature remained slim until the 20th century and much remains unknown . Major areas of current research include trying to determine why some large earthquakes do not generate tsunamis while other smaller ones do ; trying to accurately forecast the passage of tsunamis across the oceans ; and also to forecast how tsunami waves interact with specific shorelines .