"The pain had to be extreme, equivalent to serious physical injury or organ failure, " the memo goes on to say.

BBC: Is torture ever right?

At the extreme end of the scale, the consequences of head injury are death, persistent vegetative state or severe physical and mental disablement.

BBC: Therapy

On top of the effects of the warming trend come more frequent and extreme weather events such as droughts, floods and storms which directly cause death and injury and open the door to other serious health problems, according to WWF.

CNN: Global warming may harm human health

But Dawson is carrying a shoulder injury, as is inspirational Samoan skipper Pat Lam - an indication of the extreme wear and tear that has become Northampton's greatest opponent at the tail-end of a long and arduous season.

BBC: Saints v Wasps: No quarter given