Essays / How to write an argumentative essay about global warming? Need a good topic. [7]

Controversial argumentative research thesis on global warming. Looking for a right thesis.

Hello, everyone! I need dire help narrowing down my controversial argumentative research essay thesis. My assignment is to write an eight page argument research paper on a topic that is controversial. However, I can't seem to find the right thesis to come up with. The topic I choose is on global warming which can be really broad. And so the thesis I have so far is: Man-made carbon emissions must be reduced if we want to avoid a global warming disaster, therefore, we should look to nuclear power plants for an alternative source. My professor said that my thesis is too broad still and needs to be narrowed down in order for me to have a good argument. She suggested going into talking about one problem such as the burning of coal itself. So now I'm at a road block. What should I do?

Thanks in advance to anyone who takes their time to help.