JF, "there is no scientific evidence that such an amount is natural" is a failure to understand the nature of science.

I realise you're passionate about the problem and that's great, but let me ask you what you think "real" science might be? What differentiates it from what you obviously think is some form of "fake" science?

Craig,

I think real science is about fact and 'science' involves spin.

Which of these are facts; which of these are scientific facts?

Australia was federated in 2001;
Hannibal crossed the Alps on elephants;
Tasmania was once connected to the mainland by a land bridge;
All mammals share a common ancestor?

None, because none can be tested in a laboratory. But nutrient over-loading proliferating excessive algae can be scientifically tested and measured.

So what you're saying, JF, is that real science is about things that you feel you can understand. The problem with this form of "intuitive" definition is that oftentimes things are quite counter-intuitive: what seems to be a reasonable view of a situation is simply wrong.

There are many thousands of examples and I won't bother giving any, because I'm sure you can think of plenty for yourself.

One problem with a reliance on intuitively satisfying results is that they are often very limited or lead to a conclusion which is not complete. If used to drive policies, they may cause more harm than good - the law of unforeseen consequences. The issue of nutrient runoff arose because the obvious benefits to agriculture of having massively enhanced crop performance were obvious; the benefits to humanity of having much better food supply were obvious; the ocean's limitless extent was obvious...

And except for the last part, they're still obvious: damage to the oceans was an unforeseen consequence of an intuitively satisfying reasoning process.

The problem we face now is to work out how to fix it without causing other unforeseen consequences.

That's what real science and engineering does.

Craig,
What I am saying is that I can believe real science but not pseudo 'science'.

Can I suggest you just find the answer to the simple basic question I have asked?
Evidence of substance indicates that question should be urgently answered.