How can advocates of AGW rule out natural causes if they don't know with certainty what caused past warmings

Question

To my knowledge no one knows for sure why the climate has warmed or cooled in the past, yet they are able to say matter factly that all natural variables have been ruled out. How can they be ruled out if no one knows exactly what those variables are. Causes of Past warmings are at best speculative, just as I believe this one is as well.

Answer 1

They use the very scientific explanation "we can't think of anything else"

Answer 2

They are alarmists...therefore presenting facts - for them - isn't necessary.  That's not what alarmists do.

The current global warming fad is nothing more than an attempt to create confusion and concern where there should be none.  The greenies have no idea why temperatures change, just as nobody else has.  To them it's not an important issue.  They don't want to confuse their leftist agenda with the addition of science!  That's why they don't use science in their answers.

Answer 3

We have a very good idea of what caused past climate changes.

http://greenhome.huddler.com/wiki/global...

We also know the strength of the various radiative forcings.  Greenhouse gases are by far the strongest.

http://www.realclimate.org/images/ipcc20...

Answer 4

"To my knowledge no one knows for sure why the climate has warmed or cooled in the past,"

Then you lack knowledge.

We do know what caused the past warmings (variations in the Earth's orbit).

"yet they are able to say matter factly that all natural variables have been ruled out."

The Earth's orbit puts us in a cooling period right now so naturally things shouldn't be warming and we've also been monitoring the sun very closely and can show that the sun isn't the cause of the warming.

OTOH we know that Carbon Dioxide can cause the kind of warming we are experiencing and we also know where that extra CO2 came from (i.e. our fossil fuel burning).

Answer 5

Personally-- I would not be so smug about what we DO know and DON'T know in the new science called Climatology.

http://www.usq.edu.au/resources/09feb.pd...

Answer 6

This is very similar to a question that was asked within the last week: http://answers.yahoo.com/question/index;...

The answer is still that we know MILLIONS of times more data about today's climate than about past climates. We have surface observations, rawisondes, satellites, tethered buoys, doppler radar, solar observatories, etc. that describe every detail about today's climate.  Give us that data for past climates and we'll explain what happened then just as accurately.

Even without all that data we still have a good idea what caused those warmings and coolings.

Answer 7

That's similar to asking how can a coroner determine the cause of a recent death , when they can't tell why Kennewick Man (9000+ years ago) died.

If we had global sea/surface temperature measurements, satellite measurements of solar output, accurate atmospheric concentration data, and unambiguous volcanic data during past climate warming, we would know with a high degree of certainty their causes.  The more (and the better) evidence, the more certain scientists can be about a process.

Answer 8

There is no such thing as certainty in a science such a climatology.  

Did you know that if you sent a photon (particle of light) through a double slit,  you cannot tell with absolute certainty where that photon will be detected?  Quantum mechanics tells us this.  Should we now disregard all quantum mechanics because it is not completely deterministic?