Statistical downscaling of global climate model (GCM) HadCM3 using the A2 and B2 emission scenarios project a rise in temperature of between 1.5 - 2.0 Celsius in the Caribbean region including Trinidad and Tobago by the 2080's compared to the 1980 to 1999 period. This amounts to a projection of 0.29 Celsius per decade. If these projections are realized it is possible that an approximate 8% increase in the length of the dry season by 2050 and consequently a shorter wet season could result. Projected trends in rainfall for Trinidad and Tobago remain unclear with large uncertainties. Model consensus among 21 GCM models project annual rainfall decrease in the range of 15% for Trinidad and Tobago by the 2080's, however 3-4 of these models projected increase in annual rainfall. If the over drying trend projections are realized then it is likely that there will be intensification of dry spells and droughts in the vicinity of Trinidad and Tobago towards the 2080's.
Results from HadCM3 model downscaled for the A2 and B2 emission scenarios using the Statistical Downscale Modeling (SDSM) also project increases in the early rainy season (June – August) rainfall in Trinidad and Tobago compared to decreases in other countries in the region apart from Barbados. The drying trend projected in annual rainfall towards the 2080's is linked to a consensus in the models showing a shift to a more positive phase of the North Atlantic Oscillation (NAO) and El Nino like pattern in the Pacific with higher temperatures.
Based on the projections local water resources can be expected to be impacted. Increase intense rainfall events over shorter periods will result in lower surface water quality, reduction in the recharge of ground water as run off would be at a maximum; while Increase in longer dry spells and drought events coupled with warmer temperatures would increase agricultural irrigation demands,affect crop scheduling, increase heat related health impacts, coral bleaching and saline intrusion.
Recent modelling of the current and future water resource availability on several small islands in the Caribbean including Trinidad and Tobago, using a macro-scale hydrological model and the SRES scenarios (Arnell, 2004), found that many of these islands would be exposed to severe water stress under all SRES scenarios, and especially so under A2 and B25. Also, recent variations in sea level on the western Trinidad coast indicate that sea level in the north is rising at a rate of about 1 mm/yr, while in the south the rate is about 4 mm/yr; the difference being a response to tectonic movements 6. According to IPCC AR4 global Sea level is projected to rise between the present (1980-1999) and the end of this century (2090-2099) by 0.35 m(0.23 to 0.47 m) for the A1B scenario. Based on research evidence published over most recently, mean global sea level rise is projected to increase above that of IPCC AR4 projections by the end of the century7 8 9 10. Furthermore, recent studies also suggest that because of the close proximity of the Caribbean including Trinidad and Tobago to the equator, sea level rise may be more outstanding than some other regions.11 12 This suggests that, in the future, if projections materialize, coastal inundation, inland flooding, storm surge damage, and coastal erosion are likely to increase in the vicinity of Trinidad and Tobago, however uncertainty remains high.