On 22/08/2011 17:02, Granity wrote:
Wiki is usually reliable on most scientific and mathematical topics and
you can always check the references from the bibliography.

But not, unfortunately, on global warming matters, as there was the case
where one of the AGW activists who was also a Wiki editor went through
and rewrote all the articles about the Medieval warm period and the mini
ice-age saying that scientists had now come to the conclusion that they
didn't exist, (not true) just to try and give credence to the now
defunct hockey-stick graph which had eliminated them to back up the
claim by M. Mann of unprecedented warming. He was exposed and banned
from wiki.

You have to be careful on controversial topics. And your paraphrasing of
this incident is a travesty against the scientific evidence and a slur
against perfectly good climate science researchers.

Even the sceptics admit that there has been an unprecedented rapid rise
in global temperatures during the last three decades of the twentieth
century and that you have to include greenhouse gas forcing to balance
the energy budget. The suns output is monitored by satellites over that
period and did not change by anything like enough.

I don't defend hacking at Wiki articles by either side but both of them
do it. And the anti-science lobby groups working for the oil and coal
industry have been using slur tactics and smoke and mirror techniques
they perfected in their campaign to keep suckers smoking tobacco.

Look under the skin of many of the prominent deniers for hire and you
will find someone with previous for denying that smoking tobacco can
cause cancer and/or CFCs damage the ozone layer. You can use this as a
pretty good empirical test of their scientific integrity.

What has been determined is that the Medieval Warm period and the
mini-ice age were mainly local European and northern hemisphere effects
rather than a *GLOBAL* synchronous warming or cooling. Unfortunately,
there are no contemporaneous written records of Southern hemisphere
weather of the period so we are reliant on painstakingly derived proxy
data for sites with suitable core samples or slow growing trees.

The hockey stick was only wrong in the sense that its shaft was a bit
too straight. It does not alter the conclusion that we are changing the
climate through the addition of CO2 to the atmosphere.

Regards,
Martin Brown