Maritime Influence on Climate Futures at Point Reyes National Seashore and Bodega Bay

Arena, Gregory; Parsons, Lorraine

doi:10.36967/2318166

Shaped by diverse landscapes and microclimates, the future of the unique ecology of Point Reyes National Seashore is imperiled by climate change. Climate modeling can offer park managers important insights into how these systems may change in a warmer and drier future. But maritime effects such as offshore wind, fog and low clouds are difficult to account for in current park modeling. In this report, we looked at a combined 37 years of data collected between two meteorological stations located at coastal sites at Point Reyes (G Ranch) and neighboring Bodega Bay, to identify trends and to compare against future climate projections. These long-term data sets were consistent with modeled climate change trends regarding both temperature increase and observed increase in 99th percentile heat events. While the future of annual precipitation at Point Reyes remains uncertain, climate models anticipate a long-range increase in water deficit as warmer temperatures drive greater evaporative demand. However, data collected at Bodega Bay instead illustrated a moderate increase in relative humidity (RH) and decline in vapor pressure deficit (VPD) over the past three decades. Regression analysis between measured climate variables at both sites highlighted the important role that summertime low clouds and fog may play in reducing VPD in areas influenced by maritime climate. Low cloud and fog events may serve to offset increases in soil and ambient temperature, as well as temperature extremes. These events may also reduce moisture loss from this system during critical times of the year and buffer extended drought anticipated in some climate models. Fog and cloud coverage may therefore act to limit potential hydraulic and thermal stress experienced by grass and forbs native to the Point Reyes Peninsula. Further data that can directly measure fog and low cloud events and the impact and extent of these patterns on both water and energy balance will be important in assessing maritime influence on climate change across the Seashore.

Maritime Influence on Climate Futures at Point Reyes National Seashore and Bodega Bay

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