Kalain Ho­sein

The In­ter-gov­ern­men­tal Pan­el on Cli­mate Change (IPCC) has said that for the Caribbean and oth­er small is­land de­vel­op­ing states, it has ob­served that warm­ing in small is­lands was at­trib­uted to hu­man in­flu­ence.

In ad­di­tion, it said that this in­crease in tem­per­a­ture will con­tin­ue in the 21st cen­tu­ry in all mod­elled sce­nar­ios.

In Trinidad and To­ba­go, rain­fall is pri­mar­i­ly dri­ven by heat, whether that be the tem­per­a­ture of the land dur­ing the day and dur­ing the wet sea­son when mois­ture is present, or the tem­per­a­ture of the ocean sur­round­ing the coun­try.

Warmer tem­per­a­tures re­sult in more in­tense show­ers and thun­der­storms.

The IPCC not­ed in its lat­est re­port, “The in­ten­si­ty and fre­quen­cy of ex­treme pre­cip­i­ta­tion and plu­vial floods are pro­ject­ed to in­crease (with medi­um con­fi­dence) for 2°C of glob­al warm­ing lev­el and above.”

How­ev­er, while ex­treme rain­fall is pro­ject­ed to in­crease, over­all rain­fall may suf­fer. The re­port ex­plained there was high con­fi­dence in a dom­i­nant in­crease in dry days and drought fre­quen­cy.

For the Caribbean re­gion, the de­clin­ing trend in rain­fall dur­ing June through Au­gust will con­tin­ue in the com­ing decades, par­tic­u­lar­ly if glob­al warm­ing reach­es 2°C and above.

With a warmer cli­mate, sci­en­tists al­so note that high­er evap­o­tran­spi­ra­tion will re­sult in in­creased arid­i­ty and more se­vere agri­cul­tur­al and eco­log­i­cal droughts but at medi­um con­fi­dence. Many Less­er An­tilles is­lands, in­clud­ing Trinidad and To­ba­go, de­rive their drink­ing wa­ter from ground­wa­ter sup­plied by rain­fall. These droughts can pro­duce cat­a­stroph­ic agri­cul­tur­al im­pacts and threat­en the wa­ter sup­ply for small is­lands where tourism is the main dri­ver of their econ­o­my.

Cli­mate Change is here

Sci­en­tists have been sound­ing the cli­mate change alarm bells for decades. For Trinidad and To­ba­go, the im­pacts of cli­mate change have been felt in the last two decades. In 2018, one of the worst floods in mod­ern his­to­ry af­fect­ed up to 80 per cent of the coun­try. Two years lat­er, wa­ter lev­els in the na­tion’s largest reser­voir, the Ca­roni/Are­na Dam, reached the low­est ever record­ed. The coun­try, even with short-term droughts, con­tin­ues to see se­vere flash flood­ing events with tor­ren­tial rains.

The Trinidad and To­ba­go Me­te­o­ro­log­i­cal Ser­vice (TTMS) is re­spon­si­ble for col­lect­ing and main­tain­ing the coun­try’s cli­mate records. TTMS Chief Cli­ma­tol­o­gist Ken­neth Kerr ex­plained, “Cli­mate change is the sin­gle biggest chal­lenge for Trinidad and To­ba­go as an is­land, de­vel­op­ing state.”

He added that there was ev­i­dence of changes hap­pen­ing more quick­ly than pre­vi­ous­ly es­ti­mat­ed.

“It can no longer be framed as a dis­tant threat. It is an on­go­ing threat and a dis­as­ter risk mul­ti­pli­er. Our plan­ning must be based on cli­mate ex­tremes, be­ing made worse be­cause of cli­mate change,” Kerr said.

Rainfall chart

Us­ing Arou­ca as an ex­am­ple, the area that rarely saw the lev­el of flood­ing it did un­til 2020, with mul­ti­ple sig­nif­i­cant flash flood­ing events, Kerr ex­plained this could have re­sult­ed from cli­mate change or our “bad be­hav­iour as hu­mans.”

He posed the ques­tion – will the res­i­dents now use these ex­tremes to plan for the fu­ture?

In line with the IPCC re­port, on av­er­age, rain­fall at Pi­ar­co has de­creased very slight­ly over the last 80-odd-years.

The year 2019 was the third dri­est on record since 1960. Over the last decade, eight of the ten years pro­duced less than av­er­age rain­fall.

Kerr said, “It should be not­ed that some parts of Trinidad and To­ba­go have ex­pe­ri­enced greater de­creas­es than oth­ers.”

Trinidad and To­ba­go’s new cli­mate nor­mal re­gard­ing rain­fall, shows an over­all (but slight­ly) dri­er av­er­age for 1991-2020 com­pared to 1981-2010. The on­ly mar­gin­al­ly wet­ter month is March, which is still the dri­est month of the year in T&T.

Av­er­age rain­fall for Jan­u­ary, Feb­ru­ary and De­cem­ber re­mains un­changed. No­tably, all the wet sea­son months are dri­er in the new cli­mate nor­mal.

The an­nu­al ex­treme (max­i­mum) one-day rain­fall to­tals at Pi­ar­co from 1960 to 2020, show an in­crease in ex­treme rain­fall.

Ex­treme rain­fall is al­so on the in­crease, as pro­ject­ed by the IPCC. Kerr ex­plained that a larg­er per­cent­age of rain­fall at Pi­ar­co has come in the form of in­tense pre­cip­i­ta­tion in re­cent years. There has been a steady in­crease of rain ac­cu­mu­lat­ing in the high­est an­nu­al dai­ly rain­fall to­tals. Ac­cord­ing to Kerr, six of the high­est top ten years for the high­est one-day max­i­mum rain­fall to­tals at Pi­ar­co have oc­curred since 1990. Based on the records from the TTMS, in the last 35 years, 2020 tied 2008 and 1993 for the high­est num­ber of ex­treme sin­gle-day rain­fall events in T&T, with sev­en ex­treme rain­fall days.

The new nor­mal for floods

With more in­tense, short-du­ra­tion rain­fall, se­vere street and flash flood events will be­come more com­mon.

For ar­eas along the North­ern Range like Mar­aval, St Ann’s, Cas­cade, and from Port-of-Spain to Ari­ma, an af­ter­noon thun­der­storm in a warmer cli­mate could spell dis­as­ter. For al­ready flood-prone ar­eas near ma­jor rivers like the South Orop­uche and Ca­roni Riv­er, res­i­dents may have to in­crease pre­pared­ness and flood mit­i­ga­tion mea­sures to pro­tect life and prop­er­ty.