'El Nino' effect is closely associated with:

The correct answer is Option (2) → Global warming

Option (2) Global warming — Correct. Global warming raises the earth’s temperature and leads to odd climatic changes, such as the El Nino effect, along with melting polar ice caps and rising sea levels.

Note: This question is from Chapter 16, Environmental Issues, of the pre-rationalised NCERT book. This chapter is not in the present NCERT book (2026-27). The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 16, Environmental Issues):
Greenhouse Effect and Global Warming – “… Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming. During the past century, the temperature of Earth has increased by 0.6 oC, most of it during the last three decades. Scientists believe that this rise in temperature is leading to deleterious changes in the environment and resulting in odd climatic changes (e.g. El Nino effect) , thus leading to increased melting of polar ice caps as well as of other places like the Himalayan snow caps.”