Of course the increase in rat numbers in cities is caused by climate change. As the ice melts due to the seething heat caused by global warming, the melted ice-water from the arctic chills the air throughout the entire planet and so the rats get cold and they have to move closer to the cities to warm up on the hot bitumen. Also, they have to huddle up together to stay warm and thus they breed more.
The heat causes cooling which creates a feedback cycle thus releasing more heat which melts everything which causes yet more cooling. This makes sense. The science is settled. Trust the science.
You forgot to add that the majority of climate scientists agree on climate change.
This is important because science, like America, is a democracy. And we know democracy is the best thing ever. Period. Therefore, when groups of people agree on something (DEMOCRACY!!), it becomes an inviolable law of the universe. It wasn't until America became the world's greatest nation (thanks to democracy) that we discovered this natural phenomenon, however.
The heat causes cooling which creates a feedback cycle thus releasing more heat which melts everything which causes yet more cooling. This makes sense. The science is settled. Trust the science.