Why '61 to '90?

thetonynator

Does anyone know what the reason for using the data from 1961 to 1990 as the base to compare conditions against?

Seeing as there is reliable data from around 1961 onwards, why not use a 50 year average i.e. 1961 to 2010.

Or if met eireann etc only want to use 30 years data, why not use the most recent 30 years, i.e. 1981 to 2010, which would be surely more relevant for comparison?

We refer to temps for a period of time being above or below the 61 to 90 average, but given that the 81 to 10 averages are usually different would it not be more relevant now.

So why?!

Pangea

You should email Met Eireann and ask them, I'm sure they will respond.

Mothman

It is the WMO (World Meteorological Organization) standard that most met agencies follow.

The UK Met office do use 71-00 reference period as well as 61-90.

lovelyhurler

Like Mothman said, it was a standard set down at the time by the WMO.
From reading various sources, they (WMO) decided at the time (1960-61) that they need a base line to compare everything else to, so the 30 year period was decide upon.

SeaFields

Have often thought of this before myself. No reason why that dataset shouldn't be available for reference even if it isn't the WHO standard. Surely things will have only gotten more accurate as the years passed by.

Would also be interesting to see the datasets 61-90, 71-00 and 81-10 in the context of the global warming and climate change debate.

NIALL D

Would also be interesting to see the datasets 61-90, 71-00 and 81-10 in the context of the global warming and climate change debate.

true , that defo would be interesting to see the differences ..

SeaFields

NIALL D wrote: »

true , that defo would be interesting to see the differences ..

or lack of them

Su Campu

They say that 61-90 was chosen because there was no real net increase or decrease in temperature throughout the period, so it offered a stable reference. However, temperatures fell at the start, then recovered in the 80s, so I wouldn't exactly call that steady!

People have been made to think that "normal" or "average" values mean that the climate was once steady and "perfect", and that now it's all gone variable and wild.......:rolleyes:

thetonynator

Su Campu wrote: »

They say that 61-90 was chosen because there was no real net increase or decrease in temperature throughout the period, so it offered a stable reference. However, temperatures fell at the start, then recovered in the 80s, so I wouldn't exactly call that steady!

People have been made to think that "normal" or "average" values mean that the climate was once steady and "perfect", and that now it's all gone variable and wild.......:rolleyes:

Hence why i think a '61-'10 average, increasing every 10 years would make more sense!!!