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Why do the solar magnetic field and solar intensity change?
The strong El Niños of 1998 and 2016 increased global temperatures by more than 0.5 °C. Since the end of 2020, we have been in a La Niña phase, which led to globally lower temperatures in the first months of 2021 and was partly responsible for the cool spring and summer temperatures here.
b. Pacific Decadal Oscillation (PDO)
The graph shows the index of the PDO from 1854 to 2020 (https://meteo.plus/pdo-index.php).
The PDO affects the jet stream and therefore has consequences for the entire northern hemisphere. It was strongly positive from 2014 to 2017, increasing temperatures in North America and Europe.
c. Atlantic Multidecadal Oscillation (AMO).
The graph shows the AMO index from 1856 to 2020 (https://meteo.plus/amo-index.php).
The AMO has been strongly positive since 1998. How much longer? It influences the climate of almost the entire Northern Hemisphere and has contributed significantly to the warming of the last 30 years. Because of the cycle duration of 60 to 70 years, we must assume that the AMO will become negative within the next 5 to 10 years.
An indication for the end of the positive phase of the AMO could be the reducing sea water temperatures around Greenland. Wood et al. have shown recently, that the temperature in all ocean segments around Greenland decrease since 2008 (Wood et al., Sci. Adv. 2021; 7: eaba7282, https://pubmed.ncbi.nlm.nih.gov/33523831/).
