66 milyon y\u0131l \u00f6nce, dinozorlar\u0131n ani yok olu\u015fu, en sonunda insanlar\u0131n yery\u00fcz\u00fcnde h\u00fck\u00fcm s\u00fcrmesiyle nihayetlenecek memelilerin y\u00fckseli\u015fine yol a\u00e7m\u0131\u015ft\u0131r. \u0130klimbilimciler, b\u00fcy\u00fck bir asteroitin bilinen etkisiyle, birka\u00e7 y\u0131l boyunca g\u00fcne\u015f \u0131\u015f\u0131\u011f\u0131n\u0131 engelleyerek d\u00fcnyadaki canl\u0131lar \u00fczerinde derin etkilere yol a\u00e7an s\u00fclf\u00fcrik asit damlac\u0131klar\u0131n\u0131n havada ne kadar y\u00fckseldi\u011fini yeniden hesaplad\u0131lar. Bitkiler \u00f6ld\u00fc ve \u00f6l\u00fcm besin a\u011f\u0131 \u00fczerinden yay\u0131ld\u0131. \u00d6nceki teoriler, s\u00f6z konusu \u00e7arp\u0131\u015fmadan \u00e7\u0131kan daha k\u0131sa \u00f6m\u00fcrl\u00fc toz bulutu \u00fczerine odaklanm\u0131\u015ft\u0131. Yeni bilgisayar sim\u00fclasyonlar\u0131, damlac\u0131klar\u0131n uzun s\u00fcren so\u011fumayla sonu\u00e7land\u0131\u011f\u0131n\u0131 g\u00f6steriyor; bu da, arazide ya\u015fayan dinozorlar\u0131n \u00f6l\u00fcm\u00fcne b\u00fcy\u00fck olas\u0131l\u0131kla etki yapm\u0131\u015ft\u0131. Ek bir \u00f6l\u00fcm mekanizmas\u0131 okyanuslar\u0131n kuvvetli bir bi\u00e7imde kar\u0131\u015fm\u0131\u015f olmas\u0131 olabilir; bu, deniz ekosistemlerini ciddi \u015fekilde olumsuz etkileyen y\u00fczey so\u011fumas\u0131na yol a\u00e7m\u0131\u015ft\u0131r.<\/p>\n
\u201cJeolojik Ara\u015ft\u0131rma Yaz\u0131lar\u0131\u201dnda (Geophysical Research Letters<\/em>) yay\u0131mlanan \u00e7al\u0131\u015fman\u0131n ba\u015fyazar\u0131 Potsdam \u0130klim Etki Ara\u015ft\u0131rmas\u0131 Enstit\u00fcs\u00fc\u2019nden Julia Brugger (PIK), \u201cChicxulub kraterini olu\u015fturan asteroidin etkisini takip eden Meksika\u2019daki b\u00fcy\u00fck so\u011fuk d\u00f6nem, d\u00fcnya tarihinde bir d\u00f6n\u00fcm noktas\u0131 oldu\u201d diyor, \u201c\u015eimdi, Cretace d\u00f6neminin sonunu ya\u015famakta olan dinozorlar\u0131n \u00f6l\u00fcm\u00fcne yol a\u00e7an tart\u0131\u015fmal\u0131 sebebi anlayabilmek i\u00e7in yeni bilgiler sunabiliriz.\u201d Olay\u0131 ara\u015ft\u0131rmak i\u00e7in, biliminsanlar\u0131 ilk defa farkl\u0131 ba\u011flamlara uygulanan \u00f6zel bir bilgisayar sim\u00fclasyonu t\u00fcr\u00fcn\u00fc, okyanus, deniz buzu ve atmosferi e\u015fle\u015ftiren bir iklim modelini kulland\u0131lar. Ara\u015ft\u0131rmalara dayanarak, gezegenimizin y\u00fczeyinde \u015fiddetli asteroit etkisinden dolay\u0131 buharla\u015fan k\u00fck\u00fcrt i\u00e7eren gazlar\u0131n, g\u00fcne\u015f \u0131\u015f\u0131\u011f\u0131n\u0131 bloke etmesinin D\u00fcnya\u2019n\u0131n so\u011fumas\u0131n\u0131n ana fakt\u00f6r\u00fc oldu\u011funu ortaya koydular.<\/p>\n <\/p>\n Tropik b\u00f6lgelerde y\u0131ll\u0131k ortalama s\u0131cakl\u0131k 27 dereceden 5 dereceye d\u00fc\u015ft\u00fc Buna ek olarak, okyanus dola\u015f\u0131m\u0131 bozuldu. Y\u00fczey sular\u0131 so\u011fudu, b\u00f6ylece yo\u011funla\u015ft\u0131 ve a\u011f\u0131rla\u015ft\u0131. Bu daha serin su k\u00fctleleri derinliklere inerken derin okyanus katmanlar\u0131ndan gelen daha s\u0131cak su y\u00fczeye \u00e7\u0131kt\u0131. Y\u00fczeye \u00e7\u0131kan bu sular besin maddeleri ta\u015f\u0131yordu ve muhtemelen yosunlar\u0131n yo\u011fun olarak geli\u015fmesine yol a\u00e7t\u0131. Bu yosun k\u00f6p\u00fcklerinin toksik maddeler \u00fcretti\u011fi ve k\u0131y\u0131lardaki ya\u015fam\u0131 daha da etkiledi\u011fini akla getirilebilir. Her hal\u00fck\u00e2rda, deniz ekosistemleri \u015fiddetle sars\u0131ld\u0131 ve muhtemelen okyanuslarda, ammonit gibi t\u00fcrlerin yok olmas\u0131na neden oldu.<\/p>\n <\/p>\n \u0130klim gezegenimizdeki t\u00fcm canl\u0131lar i\u00e7in \u00f6nemli <\/p>\n Dergi Referans\u0131:<\/strong> Julia Brugger, Georg Feulner, Stefan Petri; \u201cBaby, it’s cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous\u201d, \u00a0Geophysical Research Letters<\/em>, 2016; DOI: 10.1002\/2016GL072241<\/p>\n <\/p>\n
\n<\/em><\/strong>Brugger \u201cSo\u011fuktu, yani demek istedi\u011fim ger\u00e7ekten \u00e7ok so\u011fuktu\u201d diyor. Y\u00fczeydeki hava s\u0131cakl\u0131\u011f\u0131, k\u00fcresel y\u0131ll\u0131k ortalamada en az 26 santigrat dereceye d\u00fc\u015fm\u00fc\u015ft\u00fc. Dinozorlar yemye\u015fil bir iklimde ya\u015f\u0131yordu. Asteroid \u00e7arpmas\u0131ndan sonra, y\u0131ll\u0131k ortalama s\u0131cakl\u0131k yakla\u015f\u0131k 3 y\u0131l boyunca donma noktas\u0131n\u0131n alt\u0131ndayd\u0131. A\u00e7\u0131k\u00e7a buz \u00f6rt\u00fcleri geni\u015fledi. Tropik b\u00f6lgelerde bile, y\u0131ll\u0131k ortalama s\u0131cakl\u0131klar 27 dereceden 5 dereceye d\u00fc\u015ft\u00fc. PIK\u2019deki ara\u015ft\u0131rma ekibini y\u00f6neten yazarlardan Georg Feulner \u201cS\u00fclfat aerosollerinden kaynaklanan uzun vadeli so\u011fuma kitlesel yok olma \u00fczerinde, atmosferde sadece k\u0131sa bir s\u00fcre kalan tozdan \u00e7ok daha \u00f6nemli. Bu ayr\u0131ca, yang\u0131nlar,\u00a0 tsunamiler, \u00e7arp\u0131\u015fmaya yak\u0131n a\u015f\u0131r\u0131 s\u0131cakl\u0131k gibi yerel olaylardan da daha \u00f6nemliydi\u201d diyor. Biliminsanlar\u0131, iklimin iyile\u015fmesi i\u00e7in yakla\u015f\u0131k 30 y\u0131l ge\u00e7ti\u011fini tespit etti.<\/p>\n
\n<\/em><\/strong>Dinozorlar o zamana kadar d\u00fcnyan\u0131n efendileriydiler, sonras\u0131nda memelilerin y\u00fckseli\u015fi ba\u015flad\u0131 ve sonunda insano\u011flunun \u00f6n\u00fc a\u00e7\u0131ld\u0131. D\u00fcnya ge\u00e7mi\u015finin incelenmesi, gelecekteki asteroitlerle ilgili tehditlerin ara\u015ft\u0131r\u0131lmas\u0131na y\u00f6nelik \u00e7abalar\u0131n sadece akademik menfaatlere y\u00f6nelik olmad\u0131\u011f\u0131n\u0131 g\u00f6steriyor. Feulner \u201cEvrimin k\u0131smen bir asteroit etkisi gibi bir kaza taraf\u0131ndan y\u00f6nlendirildi\u011fini g\u00f6rmek b\u00fcy\u00fcleyici; kitlesel yokolu\u015flar d\u00fcnyadaki ya\u015fam\u0131n savunmas\u0131z oldu\u011funu g\u00f6steriyor\u201d diyor. \u201cAyr\u0131ca iklimin gezegenimizdeki t\u00fcm canl\u0131lar i\u00e7in ne kadar \u00f6nemli oldu\u011funu da g\u00f6steriyor. \u0130ronik olarak bug\u00fcn en tehlikeli \u015fey, do\u011fal so\u011fumadan de\u011fil, insandan dolay\u0131 ger\u00e7ekle\u015fen k\u00fcresel \u0131s\u0131nmadan kaynaklan\u0131yor.\u201d<\/p>\n