Warmer nights, not hotter days, driving down rice productivity, says climate scientist

Rising nighttime temperatures — not daytime heat — are emerging as the more critical factor affecting rice productivity in the Philippines, a Filipino climate scientist said Saturday, citing research from the International Rice Research Institute that has gone largely undiscussed despite the country’s recent gains in rice production.

Manila Observatory Executive Director Fr. Jose Ramon “Jett” Villarin raised the finding in an interview on DZRH News program Special on Saturday on June 20, joining the program as part of a discussion on climate change and its sector-specific impacts.

“Nababasa ko mula sa IRRI na mahalaga ‘yung night time temperatures — ‘yung init sa gabi, not during the day. And if night time temperatures are increasing, which they are, bababa ‘yung productivity o output per hectare,” Villarin said.

He said various sectors of the Philippine economy — agriculture, fisheries, and logistics among them — are highly sensitive to small shifts in climate patterns, making seemingly minor changes in temperature consequential for productivity and output.

Villarin noted that the Philippines achieved record rice production of 20 to 21 million metric tons annually under the previous administration, but suggested that without the compounding effects of climate change, that figure could potentially have been significantly higher.

He said climate-sensitive metrics like nighttime temperature trends in rice-growing areas remain underexplored in public discussion, even as the country continues to grapple with an average of 20 typhoons annually and other climate-related disruptions to agriculture.

Villarin’s comments came as part of a broader explanation of how global average temperature figures — such as the often-cited 1.1 to 1.2 degree Celsius rise — translate into localized, sector-specific impacts that vary significantly depending on region, season, and time of day.