Inter-comparison of past and projected climatic trends in Puerto Rico: 1950–2100

Abstract

Abstract Past and projected climatic trends in Puerto Rico in the period 1950–2100 are evaluated by detection of slope and fit in smoothed time series and by the mapping of local and regional trends using 5- to 50-km resolution products. New outcomes include second-order upward trends for evaporation and sea surface height. At a regional scale, Hadley Cell overturning is drying the mid-troposphere, inducing a northerly tendency for trade winds. The past rainfall trend (1950–2020) has increased ∼10% on the Atlantic-facing seaboard. Warming seas (+.02 °C/year) and rising vegetation fraction induce more evaporation that is deepening the moist boundary layer and sustaining thermal orographic precipitation over the island. Historical trends and model projections show a decrease in rainfall in spring and an increase in autumn, attributable to the retreat of the jet stream and the influence of transpiration, respectively. Outcomes reveal competition between small- and large-scale processes, and an island-wide water balance sustained by diurnal cycling. Adapting to the rising sea level makes pro-active coastal management a necessity. HIGHLIGHTS Past and future climate changes are similar. Dataset and model resolution of <50 km help to quantify climate change for small islands. New research suggests that second-order trends are replacing linear trends. Impacts due to sea level rise and coastal erosion require management.