Historical global temperatures, higher or lower?

Question

Throughout the ages (all ages, not just the past 140 years), has the Earth's average temperatures been higher or lower than today?

Answer 1

I think the Earth has been gradually cooling since it was formed.  A billion years ago, suposedly when life first formed, it was much hotter and in a billion years time it will likely be much colder.

Answer 2

The temperatures of the planet fluctuate .

Answer 3

Virtually all over the board!! ------- the Earth does NOT have an "optimum" temperature.

Answer 4

Nobody can answer that question, since we have only had reasonable global temperature information for the last 100 years or so.

Anything else is speculation.

AND ICE CORES DO NOT CONSTITUTE GLOBAL TEMPERATURE, AT BEST IT"S A SPOT DATA POINT.

Answer 5

Well a cursory skim through documented history shows two periods when it was considerably warmer than it is right now and teo clear periods where it was much colder than it is right now and that is only since the time of christ which was in the middle of the Roman optimum.

Answer 6

It has been both hotter and colder in the past.

Answer 7

The temperature was higher. It changed to even having polar Ice Caps when Antarctica moved over the Southern Pole blocking the circulation of the oceans.

Answer 8

Yes, it has been much warmer and much colder.

http://www.socialtext.net/data/workspace...

http://www.geocraft.com/WVFossils/Refere...

Answer 9

The fact is  that the VIkings came across the Atlantic & set up settlements on Greenland. This was, what a thousand years ago?

http://www2.sunysuffolk.edu/mandias/lia/...

They couldnt maintain the settlements because it got cold. You cannot settle comfortably there now. Therefore, it was very much warmer climate-wise a thousand years ago. Given that fact, how can anyone worry about global warming?

Answer 10

I would add to Morbius' point that there is similar evidence from around the world.    Certainly while we are constantly told that there is no such thing as conditions local to Greenland, that Greenland is a bellweather for the global climate, the case for warmer medieval temperatures should not rest on Greenland alone - - and nor has it.

Tree lines were higher in mountain ranges around the world, droughts worse in regions as far apart as the American Southwest and Kenya, and wild as well as farmed plants grew at higher elevations and colder latitudes than is the case today.     Glacial retreat in the Alps is revealing artefacts from medieval times as well as past warm epochs.   Sea sediment evidence indicates warmer temperatures.

Only tree rings could be considered inconsistent - but tree rings are bad proxies for three reasons: (1) because the evidence is very slim - one or two trees may be used to estimate the climate of an entire continent for as long as a century;  (2) because there are several other factors that affect tree growth, and (3) because it has recently been discovered that, all other things being equal, tree rings don't just keep widening with temperature - there is a temperature level beyond which the tree rings just don't continue to widen.    To the extent samples have been updated for the 1980-2000 period, when we know it warmed, the tree rings aren't any wider than they were in the 1970s.