North Pacific Ocean Temperatures Influence SW Precipitation
Sea surface temperatures in the North Pacific Ocean have influenced precipitation in the Southwest over the 20th century, according to a new study published in Nature Geoscience. The authors used oxygen isotopic data—which can be an indicator of both the amount and origin of precipitation—from a cave speleothem in southern California to make their correlation. The entire precipitation record spans about 1150 years, but the authors only found a strong correlation with North Pacific sea surface temperatures during the 20th century, implying that other factors played a role in earlier droughts and wet periods. They also found an increase in sea surface temperatures over the past 150 years, possibly reflecting increasing atmospheric greenhouse gas concentrations. If the relationship between precipitation in the Southwest and North Pacific sea surface temperatures continues, the increase in ocean temperatures could mean less precipitation for the Southwest.