Blowing global warming out of the bath

The link in the previous post to the Telegraph alerted me to the Manhattan Declaration, issued last year by almost 800 distinguished scientists of climate and related fields, arguing:

Hereby declare:
That current plans to restrict anthropogenic CO2 emissions are a dangerous
misallocation of intellectual capital and resources that should be dedicated to
solving humanity’s real and serious problems.
That there is no convincing evidence that CO2 emissions from modern
industrial activity has in the past, is now, or will in the future cause
catastrophic climate change.
That attempts by governments to inflict taxes and costly regulations on
industry and individual citizens with the aim of reducing emissions of CO2 will
pointlessly curtail the prosperity of the West and progress of developing
nations without affecting climate.
That adaptation as needed is massively more cost-effective than any
attempted mitigation, and that a focus on such mitigation will divert the
attention and resources of governments away from addressing the real problems of
their peoples.
That human-caused climate change is not a global crisis.

Now, therefore, we recommend –
That world leaders reject the views expressed by the United Nations
Intergovernmental Panel on Climate Change as well as popular, but misguided
works such as “An Inconvenient Truth”.
That all taxes, regulations, and other
interventions intended to reduce emissions of CO2 be abandoned forthwith.

Why had I not heard about this before? Surely not a global political and media conspiracy to silence the 'unhelpful' voices?