North Atlantic chlorophyll blooms modulate European hydroclimate and terrestrial productivity

Abstract

Marine and terrestrial ecosystems are usually treated as separate components of the global carbon cycle, and whether variability in ocean biology reaches plant growth on land has remained unclear. Here we show that phytoplankton blooms in the high-latitude North Atlantic are linked to summer productivity across central Europe. During bloom years, pigments absorb more of the incoming sunlight within the shallow late-summer mixed layer, warming the sea surface. This warming accompanies higher pressure near the bloom and lower pressure over Europe, strengthening the westerly winds that carry moisture inland. Central Europe becomes wetter, and gross primary productivity rises by roughly 15–20% during the growing season. Experiments with a chlorophyll-interactive Earth system model support an active role for chlorophyll: when chlorophyll is held at its climatology, sea-surface temperature anomalies still develop, but the European productivity response is largely absent. Variability in marine ecosystems is therefore a potentially important pathway shaping productivity on land. High-latitude North Atlantic chlorophyll blooms enhance moisture across Europe by absorbing shortwave radiation, rising sea surface temperature, and altering atmospheric circulation, thereby influencing terrestrial primary productivity, as revealed by observations and Earth system model experiments.