North Pacific sea surface temperatures: Past variations inferred from treerings

March-August sea surface temperatures (SST) are reconstructed for the Gulf of Alaska (GOA) from 1750-1983 based on tree-ring data from coastal and sou th-central Alaska and the Pacific Northwest. Some of the trends resemble th ose documented in other northern instrumental and proxy records, including cooler SSTs in the early and middle 1800s, during the Little Ice Age. There is overall warming in this century, including a positive trend from the mi d-1970s to 1980s, following cooler 1960s-1970s. The twentieth century warmi ng exceeds maxima in the reconstructed SSTs back to AD 1750 and is consiste nt with other evidence for unusual Northern Hemisphere warming. Changes ove r the period of recorded North Pacific SST have been linked to a pattern of variability known as the Pacific Decadal Oscillation (PDO). Maps comparing the reconstruction to the North Pacific SST field and other analyses sugge st that it may reflect variations related to the PDO over several centuries .