Variation in the rotation rate of Earth and its role as a climate change indicator between 1972 and 2022

The universal time (UT1-UTC) and length of day change (ΔLOD) are two parameters that describe the Earth's rotation rate variations. UT1-UTC is typically used in space projects, whereas ΔLOD is used for scientific investigations. Therefore, studying the variations between the two parameter sequences is very important. In this study, we reviewed the Earth's rotation rate over the last five decades and revealed an abnormal phenomenon in UT1-UTC. Since May 2020, the Earth's rotation has reversed from a deceleration trend to an acceleration trend. Besides, we used ΔLOD to find the possible geophysical contributors and focused on the climate-related contributions. Results revealed that the interannual LOD exhibited a notable degree of consistency with ENSO indices after using the Difference+FDSR method to remove the internally and externally induced signals. Notably, two La Nina with intermediate strength and the beginning of a closely followed third trough were detected in the last three years. The contributions of these events to the latest rotation acceleration are approximately 9%.