21st century The 21st century was , as Jack Harkness cryptically said , " when everything changes " . ( TV : " Everything Changes " ) Earth was a very tempting target for invasion ; by 2009 , half of the species from Earth to the Verlixix Spiral Cluster had plans to invade . ( TV : " Enemy of the Bane " ) According to some accounts , the early 21st century was when the whole human race on Earth learned that extraterrestrial life existed . ( TV : " The Christmas Invasion " ) While in the past alien incursions were generally covered up or dismissed as hoaxes , ( TV : " Remembrance of the Daleks " , " World War Three " , PROSE : " Who Killed Kennedy " ) the early 21st century saw frequent large - scale attacks on Earth which couldn ' t be covered up , such as the Battle of Canary Wharf , ( TV : " Doomsday " ) the March of the Adipose , ( TV : " Partners in Crime " ) the Dalek Invasion of Earth , ( TV : " The Stolen Earth " ) the 456 incident , ( TV : " " ) and the Year of the Slow Invasion . ( TV : " The Power of Three " ) This century saw many organisations - such as UNIT , ( TV : " The Zygon Invasion " ) ICIS , ( AUDIO : " The Coup " ) Torchwood Three , ( TV : " Everything Changes " ) the Torchwood Institute , ( AUDIO : " New Girl " ) MIAOW , ( PROSE : " Enter Wildthyme " ) the Forge , ( PROSE : " Project : Valhalla " ) the Department , ( TV : " The Eclipse of the Korven " ) and UNISYC ( PROSE : " Alien Bodies " ) - defend the Earth against alien attacks . Indeed , the Shift once remarked , " one can barely materialise on the planet without being fought over by five different covert paramilitary organisations " . ( PROSE : " Head of State " ) However , the century also saw a number of independent alien defenders , such as the Bannerman Road gang , ( TV : " Revenge of the Slitheen " ) the Torchwood team , ( TV : " Dead of Night " ) the Coal Hill defenders , ( TV : " Brave - ish Heart " ) the Ghost , ( TV : " The Return of Doctor Mysterio " ) Erimem & friends , ( PROSE : " The Last Pharaoh " ) and the K9 Unit . ( TV : " Regeneration " ) Ashildr , a 9th century Viking girl who was rendered effectively immortal when she was brought back to life by the Twelfth Doctor through a self - repairing Mire repair kit , ( TV : " The Girl Who Died " ) was known to have lived on Earth up to at least the early part of the 21st century , by which point she was the Mayor of the trap street . ( TV : " Face the Raven " ) She would ultimately live all the way to the end of the universe . ( TV : " Hell Bent " ) This century was a period of great technological advancement , but also great political , economic , and ecological turmoil . The T - Mat ( TV : " The Seeds of Death " ) and the weather - controlling Gravitron ( TV : " The Moonbase " ) were developed in the middle part of this century , and the first excursions outside the Solar System occurred towards the century ' s end . ( TV : " The Waters of Mars " ) Space travel increased dramatically . Many more missions were undertaken by NASA , the Russian Federal Space Agency , and European Space Agency ( later the Eurozone Space Agency AUDIO : " The Feast of Axos " ) . All - German teams achieved ten lunar missions by 2050 . Australia , Spain , and ( possibly ) the Philippines all got involved in space travel . The Branson Inheritance ( TV : " The Waters of Mars " ) and Ironclad Industries ( who bought the British Rocket Group ) were two private space organisations . ( AUDIO : " The Feast of Axos " ) In 2071 , India ' s space agency collaborated with Britain in clearing space junk out of Earth orbit . ( AUDIO : " Scavenger " ) This new space race ended when T - Mat was invented , causing rockets to be seen as obsolete . This was shown to be an error when the Ice Warriors seized control of T - Mat Control ( TV : " The Seeds of Death " ) in 2086 . ( PROSE : " Transit " ) The nations of Europe began to unify more under the Eurozone . ( PROSE : " Trading Futures " ) For forty years after 2019 , Earth suffered through climate change ( including both extreme storms and a 22 + weeks without rain ) , ozone degradation , the " Great Cataclysm " , and " the oil apocalypse " . Millions of refugees streamed out of North Africa and the Baltics . In 2059 , it was believed mankind came close to extinction . ( TV : " The Waters of Mars " , TV : " Aeolian " , AUDIO : " Hothouse " ) People in the future would remember Earth ' s ecosystem collapsed during this century . ( AUDIO : " Davros " ) The Eleventh Doctor once referred to the dangerously corrosive acid rain of the mid - 21st century . ( COMIC : " Strange Loops " ) In 2049 , a dragon - like creature hatched out of the Moon , laying an egg that became the new Moon . ( TV : " Kill the Moon " ) Earth ' s first off - world colony , Bowie Base One , was both established on Mars and lost in the late 2050s . ( TV : " The Waters of Mars " ) It would later establish a permanent base . ( PROSE : " Home " ) The Thousand Day War between the United Nations and Mars was fought between 2086 and 2088 , following the T - Mat attack . Over 45 , 000 UN soldiers were killed and Paris was bombarded in an act of terror , but the weakened Ice Warriors were defeated . Most of the Warriors left Mars for a new planet and humans started to colonise it en masse . ( PROSE : " Transit " , " GodEngine " , " Legacy " ) Earth sent its first lightspeed ship to Proxima Centauri , under the command of Susie Fontana Brooke . ( TV : " The Waters of Mars " ) Various nations had political changes during this century : Italy suffered civil war and China split into North China and South China in the early 21st century ( PROSE : " Trading Futures " ) , Britain become the dictatorship of New Britain for part of the mid - 21st century , and the United States fell . ( PROSE : " Christmas on a Rational Planet " ) At some point during this century , on an Istanbul rooftop , the Ninth Doctor fought two Sontaran s in a sword fight . Sally Sparrow , who had become " some sort of spy " , saved the Doctor from one of them , and gave him her Christmas homework from 2005 , which would help him when the TARDIS would later hop forward in time twenty years without the Doctor . Sally told the Doctor to keep the essay with him at all times . ( PROSE : " What I Did on My Christmas Holidays by Sally Sparrow " ) Using gold as currency fell out of favour in the late 21st century . ( AUDIO : " The Evil One " )