Query: Surface temperatures on Earth "have stabilized."

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 .

Water on Mars <=SEP=> Almost all water on Mars today exists as ice , though it also exists in small quantities as vapor in the atmosphere and occasionally as low-volume liquid brines in shallow Martian soil . The only place where water ice is visible at the surface is at the north polar ice cap . Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole and in the shallow subsurface at more temperate latitudes . More than five million cubic kilometers of ice have been identified at or near the surface of modern Mars , enough to cover the whole planet to a depth of 35 meters . Even more ice is likely to be locked away in the deep subsurface .   Some liquid water may occur transiently on the Martian surface today , but only under certain conditions . No large standing bodies of liquid water exist , because the atmospheric pressure at the surface averages just 600 Pa -- about 0.6 % of Earth 's mean sea level pressure -- and because the global average temperature is far too low ( 210 K ) , leading to either rapid evaporation ( sublimation ) or rapid freezing . Before about 3.8 billion years ago , Mars may have had a denser atmosphere and higher surface temperatures , allowing vast amounts of liquid water on the surface , possibly including a large ocean that may have covered one-third of the planet . Water has also apparently flowed across the surface for short periods at various intervals more recently in Mars ' history . On December 9 , 2013 , NASA reported that , based on evidence from the Curiosity rover studying Aeolis Palus , Gale Crater contained an ancient freshwater lake that could have been a hospitable environment for microbial life .   Many lines of evidence indicate that water is abundant on Mars and has played a significant role in the planet 's geologic history . The present-day inventory of water on Mars can be estimated from spacecraft imagery , remote sensing techniques ( spectroscopic measurements , radar , etc. ) , and surface investigations from landers and rovers . Geologic evidence of past water includes enormous outflow channels carved by floods , ancient river valley networks , deltas , and lakebeds ; and the detection of rocks and minerals on the surface that could only have formed in liquid water . Numerous geomorphic features suggest the presence of ground ice ( permafrost ) and the movement of ice in glaciers , both in the recent past and present . Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars , although to a far lesser degree than in the ancient past .   Although the surface of Mars was periodically wet and could have been hospitable to microbial life billions of years ago , the current environment at the surface is dry and subfreezing , probably presenting an insurmountable obstacle for living organisms . In addition , Mars lacks a thick atmosphere , ozone layer , and magnetic field , allowing solar and cosmic radiation to strike the surface unimpeded . The damaging effects of ionizing radiation on cellular structure is another one of the prime limiting factors on the survival of life on the surface . Therefore , the best potential locations for discovering life on Mars may be in subsurface environments . On November 22 , 2016 , NASA reported finding a large amount of underground ice on the planet Mars -- the volume of water detected is equivalent to the volume of water in Lake Superior .   Understanding water on Mars is vital to assess the planet 's potential for harboring life and for providing usable resources for future human exploration . For this reason , ` Follow the Water ' was the science theme of NASA 's Mars Exploration Program ( MEP ) in the first decade of the 21st century . Discoveries by the 2001 Mars Odyssey , Mars Exploration Rovers ( MERs ) , Mars Reconnaissance Orbiter ( MRO ) , and Mars Phoenix lander have been instrumental in answering key questions about water 's abundance and distribution on Mars . The ESA 's Mars Express orbiter has also provided essential data in this quest . The Mars Odyssey , Mars Express , MER Opportunity rover , MRO , and Mars Science Lander Curiosity rover are still sending back data from Mars , and discoveries continue to be made .

Global warming <=SEP=> Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years .   In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing .   Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years .   Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) ,  whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change .   Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned .