I think that there are couple of ways to make this argument.
First, you can argue that it is not really happening. Some scientists try to make this argument.
Second, and I think that this is an easier argument to make, climate change is not necessarily a bad thing. Let's say that the world warms up a few degrees. This might mean that some crops can no longer grow where they now grow. But maybe those crops could be grown somewhere else and new crops that can deal with the warmer weather can be grown where they used to be.
In other words, so what if now we have to grow grain in Alaska and we can grow bananas in Kansas -- there will be somewhere for everything to grow even so.
Alternately, maybe the growing season will get longer -- you can grow more crops per year because it will get warm earlier in spring and stay warm later in fall.
In addition, as one of the links below argues, people enjoy warm weather more than cold and warm weather is healthier for people than cold