Update: as expected, Williamson has declined to
take up my suggestion. But here is a chart summarising over a
thousand experimental results of acidification, taken from here. Note that the effect is more positive
than negative in the region of expected pH change (up to 0.3)

I have sent the following letter to Dr Phil Williamson at the
University of East Anglia:

Dear Dr Williamson,

In your recent piece about my Times article, you wrote:

`Those wishing to draw attention to ocean
acidification as an environmental threat should not overstate the
case. It is possible that ocean acidification impacts may be less
widespread than indicated by “pessimistic predictions”.

Would you agree that the following quotes from an article by
Charlie Veron on the Yale 360 website (
http://e360.yale.edu/feature/is_the_end_in_sight_for_the_worlds_coral_reefs_/2347/),
which were relayed by the New York Times, represent an egregious
example of `overstating the case’ and a highly unbalanced analysis.
Will you be criticizing this? If not, I would be interested to know
why not.

`The potential consequences of such
acidification are nothing less than catastrophic.’

Nothing less?

`No doubt different species of coral,
coralline algae, plankton, and mollusks will show different
tolerances, and their capacity to calcify will decline at different
rates. But as acidification progresses, they will all suffer from
some form of coralline osteoporosis.’

All? Many studies show increased calcification rates at
realistic falls in pH.

`The result will be that corals will no
longer be able to build reefs or maintain them against the forces
of erosion. What were once thriving coral gardens that supported
the greatest biodiversity of the marine realm will become red-black
bacterial slime, and they will stay that way.’

Will become?

The article is entirely free of real results of any kind. It
completely ignores recent meta-analyses and many recent studies, as
I am sure you will agree.

Or are you only required to respond to those who argue that the
threat is exaggerated, not to those who do the exaggerating?

All the best

Matt Ridley