A large discontinuity in the mid-twentieth century in observed global-mean surface temperature

摘要: The record of global sea-surface temperatures spanning the past century provides key evidence for warming and is much scrutinized with a view to distinguishing between anthropogenic natural climate variability. It has been assumed that this now largely free substantial uncorrected instrument biases. Not so, according team assembled from four world's leading research institutes. They have identified pronounced discontinuity in — sudden drop about 0.3 °C temperature 1945 coincides significant change shipboard instrumentation used collect data. This 40% as large century-long upward trend temperatures, so correcting it likely overall its interpretation substantially. A identified. marked was source data at time. interpretation, particularly middle 20th century. Data sets monitor Earth’s indicate surface Earth warmed ∼1910 1940, cooled slightly ∼1940 1970, then markedly ∼1970 onward1. weak cooling apparent part interpreted context variety physical factors, such atmosphere–ocean interactions emissions sulphate aerosols2. Here we call attention previously overlooked 1945, which prominent feature mid-twentieth evident published versions global-mean time series1, but stands out more clearly after are filtered effects internal We argue abrupt ∼0.3 °C result instrumental biases sea record. Corrections expected alter character variability not estimates temperatures.