Query: The noted oceanographer Walter Munk referred to sea-level rise as an “enigma”

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Seamount <=SEP=> A seamount is a mountain rising from the ocean seafloor that does not reach to the water 's surface ( sea level ) , and thus is not an island . Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1000 - in height . They are defined by oceanographers as independent features that rise to at least 1000 m above the seafloor , characteristically of conical form . The peaks are often found hundreds to thousands of meters below the surface , and are therefore considered to be within the deep sea . During their evolution over geologic time , the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface . After they have subsided and sunk below the sea surface such flat-top seamounts are called `` guyots '' or `` tablemounts ''   A total of 9,951 seamounts and 283 guyots , covering a total of 8,796,150 km2 have been mapped but only a few have been studied in detail by scientists . Seamounts and guyots are most abundant in the North Pacific Ocean , and follow a distinctive evolutionary pattern of eruption , build-up , subsidence and erosion . In recent years , several active seamounts have been observed , for example Loihi in the Hawaiian Islands .   Because of their abundance , seamounts are one of the most common marine ecosystems in the world . Interactions between seamounts and underwater currents , as well as their elevated position in the water , attract plankton , corals , fish , and marine mammals alike . Their aggregational effect has been noted by the commercial fishing industry , and many seamounts support extensive fisheries . There are ongoing concerns on the negative impact of fishing on seamount ecosystems , and well-documented cases of stock decline , for example with the orange roughy ( Hoplostethus atlanticus ) . 95 % of ecological damage is done by bottom trawling , which scrapes whole ecosystems off seamounts .   Because of their large numbers , many seamounts remain to be properly studied , and even mapped . Bathymetry and satellite altimetry are two technologies working to close the gap . There have been instances where naval vessels have collided with uncharted seamounts ; for example , Muirfield Seamount is named after the ship that struck it in 1973 . However , the greatest danger from seamounts are flank collapses ; as they get older , extrusions seeping in the seamounts put pressure on their sides , causing landslides that have the potential to generate massive tsunamis .

Sea level rise <=SEP=> A sea level rise is an increase in the volume of water in the world 's oceans , resulting in an increase in global mean sea level . Sea level rise is usually attributed to global climate change by thermal expansion of the water in the oceans and by melting of Ice sheets and glaciers on land . Melting of floating ice shelves or icebergs at sea raises sea levels only slightly .   Sea level rise at specific locations may be more or less than the global average . Local factors might include tectonic effects , subsidence of the land , tides , currents , storms , etc. .  Sea level rise is expected to continue for centuries . Because of the slow inertia , long response time for parts of the climate system , it has been estimated that we are already committed to a sea-level rise of approximately 2.3 m for each degree Celsius of temperature rise within the next 2,000 years . IPCC Summary for Policymakers , AR5 , 2014 , indicated that the global mean sea level rise will continue during the 21st century , very likely at a faster rate than observed from 1971 to 2010 . Projected rates and amounts vary . A January 2017 NOAA report suggests a range of GMSL rise of 0.3 -- 2.5 m possible during the 21st century .   Sea level rises can considerably influence human populations in coastal and island regions and natural environments like marine ecosystems .

Walter Munk <=SEP=> Walter Heinrich Munk ( born October 19 , 1917 ) is an American physical oceanographer . He is professor of geophysics emeritus and holds the Secretary of the Navy/Chief of Naval Operations Oceanography Chair at Scripps Institution of Oceanography in La Jolla , California .