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A new geologic age—started by us

Jan. 25, 2008
World Science staff

A rad­i­cal pro­pos­al is gain­ing ground among ge­ol­o­gists: We have en­tered a new ge­o­log­ic time pe­ri­od on Earth, thanks to ma­nkind’s own ac­ti­vi­ties.

We’ve so dras­tic­ally changed the land­scape through pol­lu­tion and in oth­er ways, it's time to ac­knowl­edge the new “ep­och” is here, a group of ge­ol­o­gists writes Jan. 25 in GSA To­day, a jour­nal of the Geo­lo­gi­cal So­ciety of Am­er­ica.

An at­las pub­lished by the Unit­ed Na­tions in 2005 showed through sat­el­lite im­ages how var­i­ous parts of the world have phys­i­cal­ly changed in the past two to three dec­ades alone. These im­ages show the mouth of Chi­na's Yel­low Riv­er in 1979 (a­bove) and 2000 (be­low). A new pen­in­su­la in the low­er im­age arises from sed­i­ment de­posits from the riv­er part­ly re­sult­ing from farm­ing ac­tiv­i­ty, U.N. ex­perts say. (Cour­te­sy U.N. En­vi­ron­ment Pro­gramme) 
The new era would be called the An­thro­po­cene, from the Greek an­thro­pos (man) and ceno (new). 

“The dom­i­nance of huma­ns has so phys­ic­ally changed Earth that there is in­creas­ingly less jus­tifica­t­ion for link­ing pre- and post-in­dus­tri­al­ized Earth with­in the same ep­och,” the re­search­ers said in an an­nounce­ment of their pro­pos­al.

The tra­di­tion­al name for our cur­rent ep­och—soon to be­come the form­er one, if they have their way—is the Hol­o­cene. The Hol­o­cene has spanned the last 10,000 years and fol­lowed the Pleis­to­cene, com­monly called the Ice Age.

The re­search­ers at the Un­ivers­ity of Leices­ter, U.K. and the Ge­o­log­i­cal So­ci­e­ty of Lon­don said human im­pact on Earth is show­ing in ma­ny ways: changed ero­sion pat­terns; ma­jor dis­tur­bances to the car­bon cy­cle; glob­al warm­ing; whole­sale changes to plant and an­i­mal life; and ocean acid­i­fi­ca­t­ion.

Al­though ge­ol­o­gy is mainly the study of Earth’s rocks, soil and phys­ical struc­ture—rather than an­i­mals and life forms as such—all these fac­tors can ul­ti­mately in­flu­ence that struc­ture, re­search­ers say. Man’s al­tera­t­ions to Earth are “strati­graphic­ally sig­nif­i­cant,” the group said in the an­nounce­ment.

The idea for rec­og­niz­ing a new ge­o­log­ic era is­n’t new, though: No­bel Prize-winning chem­ist Paul Crut­zen sug­gested it in 2002. The U.K. re­search­ers’ work rep­re­sented an at­tempt to further assess his pro­po­sal.

The group said their find­ings pre­s­ent the schol­arly ground­work for con­sid­era­t­ion by the In­terna­t­ional Com­mis­sion on Stra­tig­ra­phy for for­mal adop­tion of the An­thro­po­cene as the new­est ad­di­tion to the ge­o­log­ical timescale.

Be­fore the Hol­o­cene and pre­ced­ing Pleis­to­cene, the ma­jor era pre­ced­ing that is called the Ter­tiary Pe­ri­od, from about 26 to 66 mil­lion years ago. That was when mam­mals largely took over the Earth from the by then-defeated di­no­saurs. All these ages are con­sid­ered part of a larg­er one, called the Ce­no­zo­ic era. Be­fore that was the Mes­o­zo­ic, the age of di­no­saurs; and still ear­li­er, the Pa­le­o­zo­ic, which saw the ev­o­lu­tion­ary ex­plo­sion of the first an­i­mals. Eve­ry­thing be­fore that is the “Pre­cam­bri­an.”

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Homepage image: Detail from Lake Blanch, Wasatch Mountains, 1886, by Alfred William Lambourne (1850–1926)

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A radical proposal is gaining ground among geologists: We have entered a new geologic time period on Earth, thanks to mankind’s own activities. We’ve so drastically changed the landscape through pollution and in other ways, it’s time to acknowledge the new epoch, a group of geologists proposes Jan. 25 in the geological journal GSA Today. The new era would be called the Anthropocene, from the Greek anthropos (man) and ceno (new). “The dominance of humans has so physically changed Earth that there is increasingly less justification for linking pre- and post-industrialized Earth within the same epoch,” the researchers said in an announcement of their proposal. The traditional name for our current epoch—soon to become the former one, if they have their way—is the Holocene. The Holocene has spanned the last 10,000 years and followed the Pleistocene era, commonly called the Ice Age. The researchers at the University of Leicester, U.K. and the Geological Society of London said human impact on the Earth is making itself felt in many ways: changed patterns of erosion; major disturbances to the carbon cycle and global temperature, through global warming; wholesale changes to the world’s plants and animals; and ocean acidification. Although geology is mainly the study of Earth’s rocks and its physical structure—rather than animals and life-forms—all these factors can ultimately influence that structure, researchers say. Man’s alterations to Earth are “stratigraphically significant,” the group said in the announcement. The idea for recognizing a new geologic era isn’t new, though: Nobel Prize-winning chemist Paul Crutzen suggested it in 2002. The U.K. researchers’ work represented an attempt to follow up on this proposal by further researching its validity. The group said their findings present the scholarly groundwork for consideration by the International Commission on Stratigraphy for formal adoption of the Anthropocene as the youngest epoch of, and most recent addition to, the Earth’s geological timescale. Before the Holocene and preceding Pleistocene, the major era preceding that is called the Tertiary Period, from about 26 to 66 million years ago. That was when mammals largely took over the Earth from the by then-defeated dinosaurs. All these timespans are considered part of a larger one, called the Cenozoic era. Before that was the Mesozoic, the age of dinosaurs; and still earlier, the Paleozoic, which saw the evolutionary explosion of the first animals. Everything before that time is the “Precambrian.”