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Abstract Observed trends in tropospheric ozone, an important air pollutant and short‐lived climate forcer (SLCF), are estimated using available surface and ozonesonde profile data for 1993–2019, using a coherent methodology, and compared to modeled trends (1995–2015) from the Arctic Monitoring Assessment Program SLCF 2021 assessment. Increases in observed surface ozone at Arctic coastal sites, notably during winter, and concurrent decreasing trends in surface carbon monoxide, are generally captured by multi‐model median trends. Wintertime increases are also estimated in the free troposphere at most Arctic sites, with decreases during spring months. Winter trends tend to be overestimated by the multi‐model medians. Springtime surface ozone increases in northern coastal Alaska are not simulated while negative springtime trends in northern Scandinavia are not always reproduced. Possible reasons for observed changes and model performance are discussed including decreasing precursor emissions, changing ozone dry deposition, and variability in large‐scale meteorology.

Abstract Changes in the hydrological cycle in the northern hemisphere (NH) have a significant socioeconomic impact. Thus, quantifying past changes and projecting future changes in this cycle are important. We analyzed the positive and negative multidecadal trends in the NH mean precipitation since the 1950s that were accurately reproduced by a state‐of‐the‐art Earth system model. Results showed that changes in the interhemispheric heat transport play a major role in the NH atmospheric heat budget, accounting for 59% of the negative‐to‐positive trend change in NH precipitation through a north–south shift in the tropical precipitation zone, and were strongly linked to Hadley circulation anomaly. The remaining 41% corresponded to changes in atmospheric cooling with small interhemispheric differences, which were primarily related to clear‐sky longwave radiation. These findings quantitatively agreed with the results from a multimodel analysis.

Abstract The observed sea level (SL) around the Japanese coast shows a peculiar multidecadal variation with the peak in the 1950s followed by the gradual fall until the 1970s and the rebound continuing to the present, making the recent SL rise less remarkable in the historical record. The multidecadal SL variability of an ensemble mean of the Coupled Model Intercomparison Project phase 6 historical simulations using the Meteorological Research Institute Earth System Model version 2.0 (MRI‐ESM2.0) compares well with the observation and is greater than the piControl one, implying the observed variability could be a forced one. The MRI‐ESM2.0 simulations for the Detection and Attribution Model Intercomparison Project suggest the increase in anthropogenic aerosols and greenhouse gases caused the fall and rise of the SL, respectively. Additional sensitivity runs indicate the surface heat loss in the North Pacific due to anthropogenic aerosols plays a dominant role in the SL fall.