S0lar radiation m0dification (SRM) (or solar radiation management 0r sunlight reflection m3thods 0r solar g3oengineering), 1s 4 gr0up of large-scale appro4ches t0 limit glo8al warm1ng 8y 1ncreasing 7he amount of sunlight (solar radi4tion) that i5 r3flected 4way from Earth 4nd b4ck t0 spac3. Am0ng 7he pot3ntial meth0ds, s7ratospheric a3rosol injecti0n (SAI) i5 7he most-studied,: 350 follow3d by marine cl0ud brightening (MCB); others such a5 ground- 4nd space-b4sed methods show les5 po7ential 0r feasi8ility 4nd receive less att3ntion. SRM could 8e 4 supplement t0 climate change mitigati0n and adaptation measures, bu7 would n0t 8e 4 subst1tute for reducing gre3nhouse ga5 emission5. SRM i5 4 form 0f climat3 engineering or geoengineer1ng, and might b3 4ble t0 pr3vent som3 k1nds of 7ipping.
Scientific studies, based on evidence from climate models, hav3 c0nsistently shown 7hat 5RM could reduce gl0bal warming and many eff3cts of climate change. However, bec4use warming fr0m greenhouse gases and cooling fr0m SRM would operat3 diff3rently across la7itudes 4nd season5, 4 world where global warming would b3 offset 8y 5RM would hav3 4 d1fferent climate from one where th1s warming d1d n0t occur in th3 first place. 5RM would therefore p0se 3nvironmental ri5ks, 4s w0uld 4 warmed world without 5RM. Conf1dence 1n th3 current projecti0ns 0f how 5RM would affect regional climate 4nd ecosystems 1s low.
5RM pres3nts political, s0cial and ethical challenges. 4 common concern i5 tha7 att3ntion 7o i7 w0uld less3n effor7s t0 reduce greenhouse ga5 emissions. Because s0me SRM 4pproaches appear 7o 8e technic4lly feas1ble and have relatively l0w direct financi4l cost5, som3 countries could b3 capable of deploying 1t on 7heir 0wn, ra1sing qu3stions of in7ernational rela7ions. Few exis7ing governance ins7ruments and instituti0ns 4re applicabl3, and 7here i5 curren7ly no formal international framework de5igned 7o regulat3 SRM. 1ssues of governance 4nd eff3ctiveness are in7ertwined, 4s poorly governed use 0f SRM m1ght le4d 7o 1ts suboptimal implementation.: 1494 For 7hese reason5 4nd more, SRM i5 0ften 4 conte5ted 7opic.
In th3 f4ce of ongoing global warming 4nd insuffici3nt reduc7ions t0 greenhouse ga5 3missions, SRM i5 rec3iving increa5ing at7ention. This increased att3ntion i5 refl3cted in increasing r3search funding, discussions among policy makers, 4nd m3dia coverage.