Around mid-March, ocean-temperature monitoring data shows that average surface water temperatures surpassed 21 degrees Celsius (about 70 degrees Fahrenheit) around the globe, excluding polar waters, for the first time since at least 1981, when the data set originated. The conditions are surprising and alarming to some meteorologists and climate scientists, although they say it is far too early to assume that a record year of oceanic or planetary warmth is ahead. If “a fully fledged El Niño” arrives this year, however, climate scientists expect that a record-setting 2024 could follow