Es­ca­lat­ing cli­mate change im­pacts on species prompt new re­view


Ama­jor pa­per co-au­thored by the In­ter­na­tional Union for Con­ser­va­tion of Na­ture (IUCN) pub­lished re­cently re­views the rel­a­tively new ield of as­sess­ing species’ vul­ner­a­bil­ity to cli­mate change, as ex­perts warn that time is run­ning out for many species. The pa­per, “Cli­mate change vul­ner­a­bil­ity as­sess­ment of species”, was pub­lished in the jour­nal WIREs Cli­mate Change.

The pa­per also pro­vides guid­ance on car­ry­ing out rig­or­ous as­sess­ments, which take into ac­count the broad range of ways in which cli­mate change may be­come a threat to species. This work will help bet­ter in­te­grate cli­mate change threats into the IUCN Red List of Threat­ened SpeciesTM. The pa­per is au­thored by eigh­teen lead­ing sci­en­tists, all of them mem­bers of the IUCN SSC Cli­mate Change Spe­cial­ist Group.

The im­pacts of cli­mate change on species range from ris­ing sea lev­els de­stroy­ing habi­tats to shifts in the avail­abil­ity of food, as in the case of many seabirds. The au­thors stress that as­sess­ments should iden­tify the full range of pres­sures that plants, an­i­mals and fungi face from a chang­ing cli­mate, and then choose suit­able as­sess­ment meth­ods.

There is grow­ing ev­i­dence of the in­creas­ing like­li­hood of ex­tinc­tions due to cli­mate change, with the irst doc­u­mented ex­tinc­tion, of the Bram­ble Cay mo­saic-tailed rat, recorded in 2016. An­thro­pogenic cli­mate change al­ready af­fects species at most lat­i­tudes and in most habi­tat types, in­clud­ing co­ral reefs, forests, tun­dra, deserts, grass­lands and wet­lands, ac­cord­ing to the pa­per. Cli­mate change is listed as a threat for al­most a ifth of species threat­ened with ex­tinc­tion on the IUCN Red List.

To date, cli­mate change vul­ner­a­bil­ity as­sess­ments have tended to over­look species that have small dis­tri­bu­tions, such as many sub-Sa­ha­ran am­phib­ians, and to un­der­es­ti­mate risk for those de­clin­ing in num­ber or distri­bu­tion, ac­cord­ing to the pa­per. This is of par­tic­u­lar con­cern as these types of species are also at great­est risk of ex­tinc­tion, the au­thors warn.

The au­thors con­trib­uted ex­per­tise from their work across six con­ti­nents, most ecosys­tems, from oceans to deserts, and a broad range of species groups, from mam­mals to plants and in­sects. The guid­ance they present is based on con­sen­sus de­vel­oped through work on the IUCN SSC Guide­lines for As­sess­ing Species’ Vul­ner­a­bil­ity to Cli­mate Change.

Ac­cord­ing to the In­tro­duc­tion to the SSC Guide­lines, changes have al­ready been ob­served in a wide range of com­po­nents of the Earth’s cli­mate sys­tem, and on­go­ing changes are pre­dicted, in­clud­ing in long-term cli­mate pat­terns and trends, the mag­ni­tude and fre­quency of acute ex­treme weather events, and se­condary im­pacts such as loss of sea ice and sea-level rise. In­creases in at­mo­spheric car­bon diox­ide con­cen­tra­tion and ocean acidi­ica­tion ac­com­pany them. These changes are hav­ing far­reach­ing im­pacts on bio­di­ver­sity, in­clud­ing at or­gan­is­mal, sub­pop­u­la­tion, species and ecosys­tem lev­els. For some species, the net im­pacts have been pos­i­tive, but for many more, the speed, mag­ni­tude and rate of change are hav­ing neg­a­tive it­ness con­se­quences for in­di­vid­u­als which can lead to lo­cal or even global ex­tinc­tion of species. IPCC pro­jec­tions show that even un­der the most op­ti­mistic emis­sions sce­nar­ios, cli­mate change im­pacts on bio­di­ver­sity will be in­creas­ingly se­vere over the next cen­tury and be­yond.

Cli­mate change im­pacts may man­i­fest di­rectly, such as through the phys­i­o­log­i­cal stress ex­pe­ri­enced when am­bi­ent sum­mer tem­per­a­tures ex­ceed or­gan­isms’ tol­er­ances. Di­rect im­pacts typ­i­cally in­clude changes in be­hav­iour, phe­nol­ogy and re­pro­duc­tion, and ul­ti­mately in sur­vival of the or­gan­ism and po­ten­tially its sub­pop­u­la­tion and species. Other im­pacts oc­cur in­di­rectly through ef­fects on in­ter­ac­tions with other species in­clud­ing prey, preda­tors, com­peti­tors, par­a­sites or hosts, or on a species’ habi­tat, as well as through in­ter­ac­tions with other threat­en­ing pro­cesses such as habi­tat loss. Hu­mans’ re­ac­tions and re­sponses to cli­mate change (e.g., shift­ing agri­cul­tural ar­eas, build­ing dams and sea­walls, mi­gra­tion) may also have marked im­pact ‘on species’ sur­vival and ca­pac­ity to adapt to cli­mate change. It is likely that some mech­a­nisms of cli­mate change im­pacts on species are yet to be dis­cov­ered.

Ac­cord­ing to the IUCN, cli­mate change is one of the most press­ing en­vi­ron­ment and de­vel­op­ment chal­lenges con­fronting hu­man­ity to­day. Healthy ecosys­tems such as forests, oceans and wet­lands make a crit­i­cal and well-known con­tri­bu­tion to cli­mate change mit­i­ga­tion by ab­sorb­ing and stor­ing car­bon. They also help vul­ner­a­ble com­mu­ni­ties, es­pe­cially those who de­pend on nat­u­ral re­sources, to bet­ter adapt and be­come more re­silient to the ad­verse ef­fects of cli­mate change. At the same time, they pro­vide a num­ber of other valu­able eco­nomic, so­cial and en­vi­ron­men­tal beneits.

The Global Cli­mate Ac­tion Sum­mit (Sept. 13-14, 2018) and as­so­ci­ated events pro­vided a self­de­scribed, “launch­pad for deeper world­wide com­mit­ments and ac­cel­er­ated ac­tion from coun­tries sup­ported by all sec­tors of so­ci­ety - that can put the globe on track to pre­vent danger­ous cli­mate change and re­alise the his­toric Paris Agree­ment.”

An im­por­tant na­ture­based so­lu­tion for all lev­els of gov­ern­ment, the pri­vate sec­tor, civil so­ci­ety and in­ter­na­tional or­gan­i­sa­tions, com­mu­ni­ties and oth­ers, of­fer­ing the largest and most cost ef­fec­tive po­ten­tial to mit­i­gate cli­mate change, is for­est land­scape restora­tion (FLR).

A fre­quent con­cern for both gov­ern­ments and com­pa­nies that are con­sid­er­ing adopt­ing FLR as a cli­mate so­lu­tion is the cost. Saint-Lau­rent al­layed such con­cerns by point­ing to an ev­er­grow­ing body of ev­i­dence on the eco­nomic ben­e­fits of FLR. Some of these ben­e­fits can be per­ceived in the short term, such as through jobs and in­come gen­er­ated from eco­tourism or nurs­eries, oth­ers in the medium term such as soil re­ten­tion and im­proved pro­duc­tiv­ity for farm­ers, and still oth­ers are long-term like the restora­tion of ecosys­tem ser­vices.

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