El Niño Then and Now
I think the most interesting part is that satellite altimetry turns the ocean into a giant thermometer readable from space. Warm water swells upward, so sea surface height becomes a proxy for heat content, and you can literally watch an El Niño grow and collapse like a breathing creature. Thirty-five years of that data is long enough to start recognizing the personality of each event, which is what makes the comparison to past El Niños so compelling.
What I'd want to know is whether this year's event is behaving like the 1997-98 monster or the 2015-16 one, since those delivered their impacts very differently. The record length matters because El Niño has a memory that stretches beyond a single season, and the ocean's heat content carries that memory. I'd also wonder how much of what we're seeing now is El Niño proper and how much is the background of global warming pushing up baseline sea levels, which complicates any comparison to earlier decades.
Where I land is that this kind of long record is quietly transformative. Measuring temperature at buoys gives you point data. Seeing the whole basin's shape change from orbit gives you the full picture. That perspective lets us hold one El Niño against another and see both their size and their character.