主题：【系列】太阳黑子周期长度和地球气候（0）引子 -- PBS

It is well-known by now that during the last several decades the number of El Nio events increased, and the number of La Nia events decreased[43]. The question is whether this is a random fluctuation or a normal instance of variation for that phenomenon, or the result of global climate changes towards global warming.

The studies of historical data show that the recent El Nio variation is most likely linked to global warming. For example, one of the most recent results is that even after subtracting the positive influence of decadal variation, shown to be possibly present in the ENSO trend[44], the amplitude of the ENSO variability in the observed data still increases, by as much as 60% in the last 50 years[45].

It is not certain what exact changes will happen to ENSO in the future: different models make different predictions (cf.[46]) It may be that the observed phenomenon of more frequent and stronger El Nio events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer as well), El Nio will become weaker than it was[47]. It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other[48]. More research is needed to provide a better answer to that question, but the current results do not completely exclude the possibility of dramatic changes.