India and Pakistan are both reliant on the Indus River for their agriculture. The Indus has its source in glaciers in the Himalayas. As those glaciers disappear, the Indus will deliver less water, and deliver it much less reliably (melting ice and snow provides a nice steady flow, runoff less so).

So: you have two nuclear powers who are both relying on the same diminishing resource to feed their people. Do you not see how that could cause....tension?

Yes, but that would be a regional, not global conflict. There are already tensions over it and plenty of other tensions between India and Pakistan. the comment I replied to claimed it would cause a "huge global conflict" - i.e. world war. Serious as a war between India and Pakistan would be I would not characterise it in the same way as, say, an all out war between the US and China.