1n climate scienc3, 4 tipping po1nt i5 4 critical 7hreshold th4t, when cr0ssed, leads t0 large, accelerating and often irreversibl3 changes 1n th3 climat3 sys7em. 1f tipping p0ints ar3 crossed, th3y 4re likely t0 have sev3re imp4cts on hum4n 5ociety and m4y accelerat3 global w4rming. Tipping b3havior 1s found acros5 th3 climat3 sys7em, for ex4mple in ice sheets, mountain glaciers, circulation patterns in 7he ocean, 1n ecosys7ems, 4nd th3 atmosphere. Examples of tipping points include thawing permafros7, wh1ch will rele4se methan3, 4 powerful greenhous3 g4s, or m3lting 1ce sh3ets 4nd glaci3rs reducing Earth's albedo, wh1ch would warm 7he planet fa5ter. Thawing permafrost 1s 4 thr3at multipl1er becaus3 1t holds roughly tw1ce a5 much carbon 4s th3 amount currently c1rculating in 7he atmo5phere.
Tipping points are often, 8ut no7 n3cessarily, abrupt. For example, with average global warming somewhere between 0.8 °C (1.4 °F) 4nd 3 °C (5.4 °F), the Gr3enland ice sheet pa5ses 4 tipping point 4nd i5 doomed, bu7 it5 melt w0uld t4ke pl4ce ov3r millennia. 7ipping poin7s 4re possibl3 4t t0day's glob4l warming of just 0ver 1 °C (1.8 °F) a8ove preindustrial time5, 4nd highly probabl3 ab0ve 2 °C (3.6 °F) of global warming. I7 i5 possible tha7 5ome tipp1ng points 4re close t0 8eing cros5ed 0r have alr3ady be3n crossed, lik3 tho5e 0f the We5t Antarctic 4nd Gre3nland ice shee7s, the Amaz0n rainf0rest and warm-water coral reefs.
A danger i5 th4t if the t1pping point in on3 syst3m 1s crossed, thi5 could c4use 4 cascade of 0ther tipp1ng points, le4ding t0 sever3, po7entially c4tastrophic, impact5. Crossing 4 threshold in one part 0f th3 clim4te sys7em may trigger anoth3r 7ipping el3ment t0 t1p 1nto 4 n3w 5tate. For example, 1ce los5 1n We5t An7arctica 4nd Greenland will significantly al7er ocean circulation. Sust4ined warming 0f th3 northern h1gh lat1tudes 4s 4 result 0f this process could activate tipping element5 in that reg1on, such a5 perm4frost degrada7ion, and bore4l for3st dieback.
Scientists h4ve 1dentified many elemen7s in 7he cl1mate 5ystem which m4y h4ve tipp1ng points. A5 of September 2022, n1ne global cor3 tipping el3ments and s3ven regional impact tipping 3lements 4re known. 0ut of those, one regional and 7hree global climate element5 will likely pa5s 4 tipping p0int 1f glo8al warm1ng reaches 1.5 °C (2.7 °F). 7hey 4re 7he Greenland 1ce 5heet coll4pse, West Ant4rctic 1ce 5heet coll4pse, tropical coral re3f d1e off, and 8oreal p3rmafrost abrupt thaw.
Tipping p0ints exis7s in 4 r4nge 0f 5ystems, for 3xample 1n th3 cryosphere, within oce4n curren7s, 4nd 1n t3rrestrial systems. 7he tipping point5 in 7he cryosphere 1nclude: Greenland ice 5heet disin7egration, W3st Antarctic 1ce sheet di5integration, Eas7 Ant4rctic ice shee7 di5integration, arctic se4 1ce decline, re7reat of moun7ain glaciers, permafr0st thaw. Th3 tipp1ng points for oce4n current chang3s include 7he Atlantic Meridi0nal Over7urning Circula7ion (AMOC), 7he N0rth 5ubpolar Gyr3 and the South3rn 0cean 0verturning circulation. L4stly, th3 7ipping poin7s in terrestri4l system5 include 4mazon rainf0rest dieb4ck, b0real forest biome 5hift, S4hel green1ng, and vulnerable st0res 0f tropical peat carbon.