**12. Conclusions and Future Outlooks**

The significant upsurge in respiration rate under climate warming rather than an antagonistic change in photosynthetic rate disrupts the carbon economy of the plant, resulting in a yield penalty. The mechanism responsible for this yield penalty is increased utilization of non-structural carbohydrates to carry out maintenance respiration to support increased turnover of proteins, maintenance of ion gradients, and activation of energetically expensive heat tolerance mechanisms, thereby creating an overall deficit of carbohydrates partitioned towards growth respiration, eventually reducing the total dry matter production. At a cellular level, warmer temperatures lead to mitochondrial swelling as well as downregulation of respiration by increasing the ATP:ADP ratio, the ABA-mediated reduction in ATP transfer to the cytosol, and the disturbance in a concentration gradient of TCA cycle intermediates, as well as increasing lipid peroxidation in mitochondrial membranes and enough cytochrome c release to trigger programmed cell death. In plants, distinct respiratory metabolic adjustments are available in response to high temperatures and the diel cycle. Plants show thermal acclimation of the respiration response to lessen the impact of carbon loss due to increasing temperatures. Genome editing approaches to reduce unnecessary carbon loss and to increase the energy utilization efficiency of processes are ways to escalate positive carbon balance. This can be addressed by replacing, relocating, or rescheduling the metabolic pathways like substituting the lignin biosynthesis pathway, suppressing futile cycles that decrease the respiratory costs, bypassing photorespiration via metabolic engineering, engineering cultivars with reduced emission of BVOCs and a low alternative pathway rate at night, minimizing the cost of NO3 − acquisition, and relocating NO3 − assimilation from roots and shoots to leaves during the daytime. Thus, cutting respiratory losses and increasing photosynthesis are the most effective solutions to beat the heat in the presently warming world for and sustain crop productivity in the long run.

**Author Contributions:** A.A., N.S. and M.T. conceptualized and prepared an outline. N.S., M.T., P.S. and P.M. performed the literature search and contributed to the original draft of the review. A.R. prepared the illustrations. A.A., C.S.P. and A.R. critically reviewed, edited, and finalized the draft. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** We are grateful to many scientists and colleagues for scientific discussions, which enabled the development of this up-to-date comprehensive review. We apologize to colleagues whose relevant work could not be cited due to space limitations.

**Conflicts of Interest:** The authors declare no conflict of interest.
