GMAT Critical Reasoning (CR) | Re: Some experts warn that global warming will reduce food

Some experts warn that global warming will reduce food production. Others are more hopeful, claiming that food production will change only minimally because there is little reason to expect altered rain distribution even with warmer temperatures. In the case of most crops, annual fluctuation in rainfall and increased use of agricultural technology mask the changes in yield that are due to temperature change.

The claims of the more hopeful experts are based on which of the following assumptions?