氣候變遷及聖嬰現象對於稻米單位產量之非線性影響研究

Nonlinear Effects of Climate Change and El Niño Phenomena on Rice Yield in Taiwan

面對氣候變遷與聖嬰、反聖嬰現象，本文運用縱橫平滑移轉迴歸（panel smooth transition regression, PSTR）模型來估計氣象參數對稻米單位產量的非線性影響，並將不同的聖嬰指標設定為轉換變數，藉此估計聖嬰現象對稻米單位產量之結構性變動。
依1996年至2022年間臺灣各縣市及兩期稻作與氣象資料，實證結果指出：平均氣溫的上升會對於稻米單位產量有顯著的負面影響，而日照時數的增加會對於稻米單位產量則有顯著的正面影響，但是平均氣溫及日照時數對於稻米單位產量的影響幅度將會隨著聖嬰現象或反聖嬰現象而有所改變。若由低海面溫度異常值（Oceanic Niño Index, ONI）區間轉換至高ONI區間，會使稻米單位產量增加1.47%。由於平均氣溫對於稻米單位產量的邊際影響（1.51%）大於日照時數對於稻米單位產量的邊際影響（−0.04%），因此在其他條件不變下，聖嬰時期的稻米單位產量會相較反聖嬰時期來得高。
本文以PSTR模型確認氣象參數對臺灣稻米單位產量的非線性影響，並為氣候變遷與稻米產出之間的關係提供了新的量化證據。本文發現在不同的聖嬰情況下，平均氣溫與日照時數對於稻米單位產量的影響皆有所差異，因此，當國際科學機構指出未來將可能出現聖嬰或反聖嬰現象時，建議政府宜同步檢視對於糧食自給的影響，包括用水及稻作面積的規劃，以確保我國糧食安全。

In the face of climate change and El Niño and La Niña phenomena, this study employed the panel smooth transition regression model to estimate the nonlinear effects of meteorological parameters on rice yield in Taiwan. The study set different El Niño indicators as transition variables to estimate structural changes in rice yield caused by El Niño phenomena.
The study analyzed meteorological and rice yield data obtained from different counties in Taiwan across two growing seasons between 1996 and 2022. The results indicated that an increase in average temperature had a significant negative effect on rice yield, whereas an increase in hours of sunshine had a significant positive effect. However, the extent of these effects varied with El Niño or La Niña phenomena. Transitioning from a low-Oceanic Niño Index (ONI) system to a high-ONI system increased rice yield by 1.47%. Additionally, because the marginal effect of average temperature on rice yield (1.51%) was greater than the marginal effect of sunshine hours on rice yield (−0.04%), rice yield during El Niño periods was higher than that during La Niña periods, ceteris paribus.
This study provides quantitative evidence of the relationship between climate change and rice yield. The findings reveal that the effects of average temperature and sunshine hours on rice yield vary across El Niño conditions. Therefore, when international scientific institutions predict the potential occurrence of El Niño or La Niña phenomena, the Taiwanese government should assess the potential effects on food self-sufficiency, such as planning for water use in rice cultivation areas, to ensure Taiwan’s food security.