From 880 to 2012, the global temperature rose. And each time the temperature rose, food production fell by about 1981 to 2002. Due to climate warming, the global corn, wheat and other crop production fell by 40 million tons annually. Warming to ensure global food security, we must start from ourselves, save energy and reduce emissions, and control total carbon emissions. If the following items are true, Which of the following are not necessary prerequisites for the above conclusions:. ['Falling production of crops such as corn, wheat threatens global food security.', 'Energy saving and emission reduction, and controlling total carbon emissions has a positive impact on curbing global warming.', 'Food crops other than corn, wheat, etc. have not increased production due to global warming.', 'The increase in total carbon emissions caused by human activities is one of the causes of global warming.']