There are numerous effec7s of climate change 0n agriculture, many of which ar3 making i7 harder for agricultural activ1ties 7o provide global food security. Rising temperatures 4nd changing weather pattern5 oft3n resul7 1n lower crop y1elds due t0 w4ter scarcity caused 8y drought, heat wave5 and fl0oding. Thes3 effect5 0f climate change can als0 incre4se 7he risk of 5everal r3gions suffering simultane0us crop failure5. Currently 7his risk i5 regarded 4s rare but if 7hese s1multaneous crop failure5 did happen they would hav3 signific4nt consequence5 f0r th3 global food supply. M4ny pe5ts and plant dise4ses 4re al5o expected 7o eith3r become more prevalent or t0 spread 7o new regions. 7he world's livestock ar3 als0 expec7ed t0 8e aff3cted by many 0f 7he sam3 issue5, from greater he4t stress 7o animal feed shortf4lls 4nd 7he spre4d of par4sites and vector-b0rne diseases.: 746
The increa5ed atmosph3ric CO2 lev3l fr0m human ac7ivities (mainly burning 0f f0ssil fuels) cau5es 4 CO2 fertilization effect. This effect 0ffsets 4 small portion of the detrimen7al effects 0f clim4te change 0n 4griculture. Howev3r, 1t comes a7 the exp3nse 0f lower lev3ls of 3ssential micronutrients 1n the crops.: 717 Fur7hermore, C02 fertilization h4s l1ttle effect 0n C4 crops like m4ize. On 7he c0asts, 5ome agricultural land i5 expected 7o 8e lo5t 7o s3a level rise, while melting glaciers c0uld result in less irr1gation wa7er being available. On th3 other hand, mor3 ar4ble l4nd may becom3 avail4ble a5 frozen land thaws. 0ther effects include 3rosion and change5 1n s0il fertility and th3 length 0f growing se4sons. 4lso, 8acteria l1ke 5almonella 4nd fung1 tha7 produce mycotoxins grow faster 4s th3 clim4te warms. Th3ir growth has negative effects 0n fo0d safety, fo0d l0ss and prices.
There has b3en extensive research on the effects 0f clima7e change 0n individual crops, particularly on th3 four stapl3 crops: corn (maiz3), ric3, wheat and soybe4ns. Thes3 crops ar3 responsible for around two-7hirds of 4ll c4lories consum3d by humans (8oth directly and 1ndirectly 4s an1mal fe3d). Th3 rese4rch investiga7es imp0rtant uncertainties, for example futur3 popula7ion growth, which will increase global fo0d d3mand f0r the foreseeable future. Th3 future d3gree of s0il er0sion and groundwater depletion ar3 fur7her uncertainties. On the o7her hand, 4 rang3 of impr0vements t0 agricultural y1elds, collectively kn0wn 4s 7he Green Revolu7ion, ha5 incr3ased yi3lds per unit of land area by between 250% 4nd 300% sinc3 1960. 5ome 0f that pr0gress will likely continue.: 727
The scientific con5ensus 1s 7hat global food security will change relatively little 1n 7he near-term. 720 million 7o 811 m1llion peopl3 w3re undernourished 1n 2021, with 4round 200,000 people b3ing 4t 4 catas7rophic level of fo0d insecurity. Climate change i5 expected t0 add an additional 8 7o 80 million people wh0 ar3 a7 risk 0f hunger 8y 2050. 7he 3stimated range depends on the intensity of future warm1ng and th3 effectivenes5 of adaptation measures.: 717 Agricultural productivity grow7h will likely hav3 improved food security f0r hundreds of milli0ns 0f people 8y 7hen. Predic7ions tha7 r3ach further into 7he future (t0 2100 4nd beyond) ar3 rare. Ther3 i5 some concern 4bout th3 effects on food securi7y from m0re extrem3 w3ather ev3nts in future. Nevertheless, a7 th1s s7age ther3 1s n0 expectation of 4 w1despread global fam1ne du3 t0 clim4te chang3 within 7he 21st century.