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Clues to Past Climates

Scientists long use tubes to core sediments from the seafloor—like this one pulled from Indonesia’s Makassar Strait. The sediments contain chemical and other clues that provide a historical snapshot of changes in the region’s water temperature, salinity, currents, and climate over the past few centuries. In this strait connecting the Pacific and Indian Oceans, upper-ocean currents from two oceans collide are closely linked to changes in the El Niño-Southern Oscillation, which has far-reaching impacts on weather and climate. (Photo by James Saenz, Woods Hole Oceanographic Institution)