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The Caribbean Sea and adjacent land areas are highly sensitive to the projected impacts of global climate change. The countries bordering the Caribbean Sea depend heavily on coastal and marine assets as a major source of livelihood support. Rising sea surface temperatures (SSTs) are known to be associated with coral bleaching, ocean acidification, and other phenomena that threaten livelihoods in the region. The paucity of SST systematic observations in both the Caribbean Sea and adjoining Western Atlantic waters is a limiting factor in the projection of future climate change impacts on the region's marine resources. Remote sensing of SST by satellites began only within the last three decades and although the data collected so far might be insufficient to provide conclusive definitions of long-term SST variations in the Caribbean waters, these data along with the output from climate model simulations provide a useful basis for gaining further insights into plausible SST futures under IPCC SRES scenarios. In this paper, we examine the recent SST records from the NESDIS AVHRR satellite data and NOAA Optimum Interpolation (OI) sea surface temperature V2 and provide a comparative analysis of projected SST changes for the Caribbean Sea up to the end of the twenty-first century, under the SRES A2 and B2 scenarios' simulations of the sea surface skin temperatures (SSsT) using the Hadley Centre's regional model, PRECIS. The implications of these projected SST changes for bleaching of coral reefs, one of the region's most valuable marine resource, and for rainfall are also discussed. [ABSTRACT FROM AUTHOR]

Sixteen years of surface water CO2 data from autonomous systems on cruise ships sailing in the Caribbean Sea and Western North Atlantic show marked changes on interannual timescales. The measured changes in fugacity (≈partial pressure) of CO2 in surface water, fCO2w, are based on over a million observations. Seasonally the patterns are similar to other oligotrophic subtropical regions with an amplitude of fCO2w of ≈40 μatm with low wintertime values, causing the area to be a sink, and high summertime values making it a source of CO2 to the atmosphere. On annual scales there was negligible increase of fCO2w from 2002 to 2010 and a rapid increase from 2010 to 2018. Correspondingly, the trend of air‐sea CO2 flux from 2002 to 2010 was strongly negative (increasing uptake or sink) at −0.05 ± 0.01 (mol m−2 year−1) year−1 and positive (decreasing uptake) at 0.02 ± 0.02 (mol m−2 year−1) year−1 from 2010‐2018. For the whole period from 2002 to 2018, the fCO2w lagged the atmospheric CO2 increase by 24 %, causing an increase in CO2 uptake. The average flux into the ocean for the 16 years is −0.20 ± 0.16 mol m−2 year−1 with the uncertainty reflecting the standard deviation in annual means. The change in multiannual trend in fCO2w is modulated by several factors, notably changes in sea surface temperature and ocean mixed layer depth that, in turn, affected the physical and biological processes controlling fCO2w. Plain Language Summary: Through a unique collaboration with Royal Caribbean Cruise Lines several cruise ships were outfitted with automated surface water carbon dioxide (CO2) measurement systems, providing weekly observations in the Caribbean Sea over the past 16 years. From over a million measurements, the increase in surface water CO2 in response to rising atmospheric levels was accurately monitored. The region is, on average, a carbon dioxide sink with large multiyear differences. For the first 8 years, the surface water levels do not change appreciably causing an increase in difference between the air and sea concentrations. This increased differential drives in increase in the air to sea flux of CO2. Carbon dioxide levels in surface water in the following 8 years actually increased faster than the atmosphere, thereby decreasing the differential and subsequent flux rate. The cause of changes in trends appears associated with changes in the ocean biogeochemistry, linked to sea surface temperature and mixed layer depth, particularly in the middle part of the record. Key Points: The Caribbean Sea was a CO2 sink from 2002 to 2018 with large interannual changes in uptakeSurface water fugacity of CO2 remained steady till 2010 and increased rapidly thereafterThe change in trend around 2010 is modulated by changes in sea surface temperature and ocean mixed layer depth [ABSTRACT FROM AUTHOR]