An El Nino is a natural, temporary and occasional warming of part of the Pacific that shifts global weather patterns, and climate change is making them stronger. The National Oceanic and Atmospheric Administration announced this one in June, a month or two earlier than it usually does. This gives it time to grow. Scientists say there's a one in four chance it will expand to supersized levels.

That's bad news for rice farmers, particularly in Asia where 90% of the world’s rice is grown and eaten, since a strong El Nino typically means less rainfall for the thirsty crop.

Past El Ninos have resulted in extreme weather, ranging from drought to floods.

There are already “alarm bells,” said Abdullah Mamun, a research analyst at the International Food Policy Research Institute or IFPRI, pointing to rising rice prices due to shortfalls in production. The average price of 5% broken white rice in June in Thailand was about 16% higher than last year's average.

Eoin Treacy's view

India is talking about restricting rice exports as part of its efforts to get inflation under control. Pakistan’s ability to supplement global supply has been deeply impacted by last year’s floods. With an El Nino confirmed, there is clear potential for Asian supply to be pressured this year.

The rough rice continuation price has experienced some significant volatility over the last couple of years because of big price differentials at contract rolls. The most recent was in May and the price has been ranging in a tight manner since. It is currently firming and a sustained move above $16 would confirm a return to demand dominance beyond the short term.