**6. Consequences and effects of climate change on the temperature characteristics affecting agriculture**

The global warming process over the past two centuries, in addition to the effects on the amount of each atmospheric element, can also impact the time of each atmospheric component occurrence during the crop year. Investigation of possible changes in the time series of the onset and endset of 0 and 5°C temperatures and their trend indicates that these changes are global. It is estimated that the minimum temperature increase caused by climate change will increase wheat yields in Australia by 30–50% [9].

Changes in precipitation patterns and rising temperatures may alter land use for food production and consequently cause pathogens or new plant pests [9–11].

Research reveals that overnight temperatures have increased significantly in recent decades [12]. This has caused a decrease in diurnal variation. Naturally, with increasing temperatures during the year, seasonal fluctuations, i.e. the difference between winter and summer temperatures also decrease. Under these conditions, some crops such as sugar beet and sugarcane which react to diurnal variation [13] are affected and this increase in night temperature and decrease in the diurnal variation reduces sugar concentration in those plants.

Research shows that the temperature of winter has increased compared to the past and decreased the intensity of winter frosts [12, 14–17] and the start date of 0°C temperatures have also been postponed, which could have important implications on agricultural production. Roshan et al. [18] to predict the effects of global warming on wheat degree-day changes in Iran, used the general circulation model of INMCM-30 and the P50 scenario, which is the average SERS emission scenario. The results of this study showed that the degree-day values in most climatic regions of Iran have an increasing trend until 2100.
