I was asked to write a short statement reguarding my opinion on global warming, could you critique it please?

My opinion of global warming is mixed, millions of dollars a year are spent on advertising indicating the increasing levels of greenhouse gasses that effect global climate are caused by human activity. Other theories involving the natural increase of greenhouse gasses are rarely discussed. In fact, unless you research the subject, you will unlikely hear one of these theories. Although the cause is debatable, facts show our climate is changing.

I believe a combination of human activity and natural phenomena are contributing to our climate change. I think we need to establish a global emissions control standard to reduce the human contribution, but while we take actions to reduce our carbon footprint, our best effort may only slow the possibly inevitable.