Future Caribbean Climates in a World of Rising Temperatures: The 1.5 vs 2.0 Dilemma

Abstract

A 10-member ensemble from phase 5 of the Coupled Model Intercomparison Project (CMIP5) is used to analyze the Caribbean’s future climate when mean global surface air temperatures are 1.5°, 2.0°, and 2.5°C above preindustrial (1861–1900) values. The global warming targets are attained by the 2030s, 2050s, and 2070s respectively for RCP4.5. The Caribbean on average exhibits smaller mean surface air temperature increases than the globe, although there are parts of the region that are always warmer than the global warming targets. In comparison to the present (using a 1971–2000 baseline), the Caribbean domain is 0.5° to 1.5°C warmer at the 1.5°C target, 5%–10% wetter except for the northeast and southeast Caribbean, which are drier, and experiences increases in annual warm spells of more than 100 days. At the 2.0°C target, there is additional warming by 0.2°–1.0°C, a further extension of warm spells by up to 70 days, a shift to a predominantly drier region (5%–15% less than present day), and a greater occurrence of droughts. The climate patterns at 2.5°C indicate an intensification of the changes seen at 2.0°C. The shift in the rainfall pattern between 1.5°C (wet) and 2.0°C (dry) for parts of the domain has implications for regional adaptation pursuits. The results provide some justification for the lobby by the Caribbean Community and Small Island Developing States to limit global warming to 1.5°C above preindustrial levels, as embodied in the slogan “1.5 to Stay Alive.”

Characterizing heat stress on livestock using the temperature humidity index (THI)—prospects for a warmer Caribbean

“…4) strongly mirror the linear increases in temperature projected for the Caribbean (see Fig. 3 of Taylor et al 2018) and Jamaica (CSGM 2012(CSGM , 2017. This is not to suggest that other meteorological factors do not influence the THI; for example, if RH is projected to be lower, this would moderate expected THI increases.…”

“…A number of other studies also suggest similar attainment dates in the 2020s for 1.5°C (Taylor et al 2018;Karmalkar and Bradley 2017). Therefore, although the highest change in THI is noted with a global mean surface temperature increase of 2.5°C which occurs later in the century, potentially damaging heat stress is anticipated long before this and within the next decade.…”

“…To determine the future climate at global warming thresholds of 1.5, 2.0 and 2.5°C above pre-industrial values, a timesampling approach similar to that used by Taylor et al (2018) in their study of the Caribbean was followed. A 10-year running mean was applied to the time series of global mean surface air temperature anomalies derived for each of the driving GCM QUMP runs, where anomalies were with respect to the pre-industrial period taken as 1860-1900.…”

“…This is not to suggest that other meteorological factors do not influence the THI; for example, if RH is projected to be lower, this would moderate expected THI increases. Lower rainfall also negatively impacts pasture production, a major component of ruminant feed in Jamaica (Hughes et al 2011). Taylor et al (2018, however, show that for Jamaica, future changes in annual rainfall are relatively small for the global warming targets examined (though seasonal changes may be larger), with an increase of 5% at 1.5°C (statistically significant) but a decrease by 2 and 3% respectively for 2.0 and 2.5°C (not significant).…”

“…Further, studies from the Coupled Model Intercomparison Project Phase 3 (CMIP3) models have projected increases of between 1.0 and 3.5°C by the end of the century, with 95% of all days exceeding the 90th percentile of current temperatures (Campbell et al 2011;McSweeney et al 2012;Karmalkar et al 2013). Taylor et al (2018), using CMIP5 models and the Representative Concentration Pathway (RCP) scenario RCP4.5, have shown that when the global mean surface temperature reaches 1.5°C (2.0°C) above pre-industrial levels, the Caribbean will be warmer than at present (using a 1971-2000 baseline) by between 0.5 and 1.0°C (1.0 and 2.0°C).…”