matsukura masaki

What can something smaller than a grain of sand reveal about Earth's past? Meet pollen and spores, tough little grains built to survive. These microscopic structures are produced by plants as part of their reproductive cycle. Once they are dispersed by wind, insects, or other means, they can settle into sediments and remain preserved for thousands or even millions of years. The oldest known land plant spores date back about 480 million years, and pollen from flowering plants has been found in rocks at least 125 million years old. So how does pollen help us understand climate? Because plant distribution is shaped by temperature, moisture, and other environmental conditions, the pollen preserved in a layer of sediment acts like a snapshot of the vegetation (and climate) that existed when it was deposited. Scientists study these fossil grains to reconstruct patterns of past vegetation and piece together how climate has shifted over time. These records, combined with modern measurements, show past climate conditions across timescales, from year-to-year variation to fluctuations spanning millions of years. USGS paleoclimate scientists use evidence from pollen, ice cores, tree rings, marine microfossils, corals, and isotopes to characterize past environmental conditions, helping researchers improve climate models, predict changes in the water cycle, and anticipate future shifts in El Niño and La Niña patterns. This understanding of ancient climate also informs real-world decisions, from assessing how sea level rise might affect coastal fishing industries to evaluating how shifting vegetation could shape future agriculture. 📷: Pollen and spores preserved in sediments. Credit: USGS #paleoclimatology