Sorry it seems you do not understand the two. You want to use the one that supports your motives. Where as you want to talk about positive feedback which can mean anything which makes it vague. Like I can say I like your hiar style when I really don't.
Where as Positive feedback loop specifically in this example is for global warming. Despite your denial you can deny that you can test for CO2 levels in water.
In the 200-plus years since the industrial revolution began, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units. This might not sound like much, but the pH scale is...
www.noaa.gov
I would say Try again but it would be useless for you to understand.