Investigating the origins and significance of low‐frequency modes of climate variability

Abstract

An analysis of the 130‐year record of the Earth's global mean temperature reveals a significant warming trend and a residual consistent with an auto‐correlated (“red”) noise process whose predictability decays with a timescale of two years. Thus global temperatures, in isolation, do not indicate oscillations at 95% confidence against a red noise null hypothesis. Weak signals identified in the global series can, however, be traced to significant sea surface temperature oscillations in the equatorial Atlantic (period ∼10 years) and the El Niño region of the Pacific (3–5 years). No robust evidence is found in this data for interdecadal oscillations, The 10‐year Atlantic oscillation corresponds to a pattern of temperature anomalies which has been associated with interannual variations in West African rainfall and in U.S. hurricane landfall frequency.