What is the real datum for climate?

Question

What determines the norm?Objective-Subjective....I'm really confused on this one.

Answer 1

It depends which aspect is being studied... temps, atmospheric content, etc.  Sources include:

Global weather station data

weather balloon temperature data

earth bore hole temperatures

ocean temperature data

ice core pollen analysis,

ice core gas content analysis

Dendrochronology (tree ring analysis)

satellite measurement of ice shelf extent

satellite measurement of ice sheet mass

photographic observation of glacial movement

Arctic ice sheet extent & thickness data (U.S. Navy)

glacier meltback records (from photos, etc)

measurements of sun radiation, sunspots

Analysis of ocean sediments & fossils (see what species are present and in what quantity)

In the most general sense long term, a combination of the sun's energy and the greenhouse gas content of the atmosphere determine the norm.  For shorter intervals and regional effects, ocean currents and their variations such as the El Nino Southern Oscillation play a role.

For researchers the norm may be influenced by the accuracy and extent (time range) of the data set(s) they're working from.

The norm is an imaginary point that we may calculate and refer to, but it's not necessarily a point that the climate will sit at for any length of time.  It may be more valuable to know the trajectory of the climate (direction) and rate of change and to determine if human-influenced processes are affecting either the direction or the rate of change.

Answer 2

This does not answer you question - but it's an interesting accumulation of temperature data from about 1200 'stations' over a period of over 120 years.  The claimed average increase in every decade is about 0.05 degree C.

Global Historical Climatology Network (GHCN)

Temperature Calculations

http://www.co2science.org/scripts/CO2Sci...

Interesting that the southern hemisphere shows a slight difference compared to the nothern.  Malinkovitch Cycle???

Edit:  When you think about it = We have been slowly warming since the last ice age and there can be no measurable 'normal' - actual records don't back thousands of years.

Answer 3

There is no Datum.  Datums are a well defined established starting points.  There is no such thing in the regard to weather.

Answer 4

I agree with Jonh F. All we have is historic averages.

Answer 5

i must agree with mccorr55.....Australian Weather data only goes back to 1865 and is not `Accurate` enough to determine how "Cyclic" weather patterns (Word-wide) are.

nor are the records of other Countries , World-wide.

the current Standards we use today are only                GUESS-TIMATES and APPROXIMATIONS , designed to Calculate info. to assess the `probable` out-come of the Weather.

Ancient Civilisations do have very good records , though no Modern Civilisation Scholar has been able to Decipher the Heiroglyphics to under-stand them..!

by the term `Cyclic` ..... i present to you that no-one knows if a weather pattern/phase = 1yr , 35yrs , 264yrs , 17yrs...etc. in it`s length/duration and/or what type of pattern/phase will follow-on from the previous..!      Halleys Comet IS cyclic and so are a few other phenomena , but Weather remains a Mystery..until the `old data` can be revealed.

remember , older Civilisations depended on the Weather more than we do Today , other-wise they couldn`t feed them-selves..!

Answer 6

That's the problem.  Datum, anomalies and computer models are being used.  NOT actual temp measurement.  Between 1860 and 1972 there are only about 4000 USA sites used to determine global temps.  There is no other data available that I can find.  More global temp sites were added after 192 until about 1998 when computer model anomalies took over.  There is no validation of past and present measuring systems.  Only "Chicken Little" observations.

Answer 7

Al Gore, the "consensus", and the IPCC had a vote and determined that 58 F is the datum.  By datum I mean the most PC temperature possible.  Hilary Clintoons backside, the vast plains of desolate cottage cheese flab, is about 58 F.

Answer 8

It is just all guesses.

Answer 9

It depends wether you want to make your own mind up in which case subjective examples of your own experience are more important. Or trying to inform others, there you will have to resort to objective.