Climate change has been proven to impose significant threats to the agricultural sector. Understanding the climate change impacts on agricultural productivity is critical for fostering appropriate and effective adaptation and mitigation stragaties. A large body of literature studied the impacts of climate change on crop yields including corn and soybean mostly in developed countries, such researches are less prevalent in developing economies which are considerably more vulnerable to climate change. Moreover, solid evidence on the climate change impacts on wheat is still limited. In this paper, we aim to fill this gap by empirically examining the impacts of climate change on winter wheat yield in China. We compiled a unique data set consisted of hourly temperature distribution and county-level agricultural data from 1981 to 2015. Unlike most of the previous studies on winter wheat, we explored the winter wheat’s different responses to temperature fluctuation across seasons (growing stages) which is meaningful given winter wheat has a relatively long growing period (September to June next year). We highlighted the importance of taking the potential benefits stemmed from the reduction of freezing temperature into consideration when projecting the future yield consequences of climate change. If omitted, the damages of climate change will be significantly overstated.

Surface ozone pollution has been proven to impose significant damages on crops. However, the quantification of the damages was extensively derived from chamber experiments, which is not representative of actual results in farm fields due to the limitations of spatial scale, time window, etc. In this work, we attempt to empirically fill this gap using county level data in the United States from 1980 to 2015. We explore ozone impacts on corn, soybeans, spring wheat, winter wheat, barley, cotton, peanuts, rice, sorghum, and sunflower. We also incorporate a variety of climate variables to investigate potential ozone-climate interactions. More importantly, we shed light on future yield consequences of ozone and climate change individually and jointly under a moderate warming scenario. Our findings suggest significant negative impacts of ozone exposure for eight of the ten crops we examined, excepting barley and winter wheat, which contradicts experimental results. The average annual damages were estimated at $6.03 billion (in 2015 U.S. dollar) from 1980 to 2015. We also find rising temperatures tend to worsen ozone damages while water supply would mitigate that. Finally, elevated ozone driven by future climate change would cause much smaller damages than the direct effects of climate change itself.