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Redwoods Tell Surprising Climactic History That Suggests A Difficult Future

“This long record is really now painting a new picture that drought is probably more common than we thought in the tree ring records,” Dawson says. “So the redwoods are telling us a new drought story.” Embedded in the tree ring data is evidence of not one but three distinct cycles ranging from the yearly to the centennial. The most familiar, the El Niño-La Niña cycle, takes place over a few years and involves dramatic changes to the pattern of winds and water temperatures across the Equatorial Pacific. The Pacific Decadal Oscillation is a decades-long cycle in the Northern Pacific in which the waters off the West Coast fluctuate between warmer and cooler surface temperatures. The longest cycle the team found spans over a century and potentially involves wind patterns that connect the North Pacific with the North Atlantic. Dawson says the redwood cores hold the first record of all three cycles. The tree ring records show that California is caught in the middle of climatic cycles that are so long, we’ve been ignorant of them until recently. What it also means is that the worst drought we’ve seen may actually be the norm when taking the long perspective. (Click on title for full story.)