Why is it easier to predict climate change far into the future like say 20,000 years time?

Question

But more difficult to predict what the weather shall be tomorrow or in the immediate future?

Answer 1

becoz any way no one lives tht long.....soo doesnt matter wht u say....

most of those predictions are very roughh

Answer 2

It's not, we just have a bunch of pseudo-science guys telling us things that they won't have to validate because they will be dead.

Answer 3

Because it's always easier to project a long-term trend than day-to-day fluctuations

Answer 4

To be fair we don't know that it is.  20,000 years ago we didn't have the weather prediction models we have these days and we haven't checked our predictions against the actual weather 20,000 years into the future.

However, far distant forecasts are easier for a few reasons.  Daily or weekly forecasts tend to deal with local weather conditions, which can be changeable especially on a day to day basis (sometimes on an hour to hour basis).  Random weather changes are noticeable.  If we say it will be sunny in Denver we have a chance of being right.  The probability of being right is enhanced by knowledge of local weather patterns to refine our modelling but we could still be wrong due to unpredictable changes.  A weather person that said it might rain really meant there is a certain chance of rain based on forecast modelling.

Long term forecasts tend to be more general.  For instance we might say the mean temperature of the planet in 20 years time will be such and such.  Since we're dealing with average weather conditions the localised variations are reduced by averaging over larger areas and longer times.  i.e. we'd say the average temp for the US over the year will be.  We wouldn't say the temperature in Denver on the 25th of October, 2067 at 3:42pm will be this.

Even long term predictions can be wrong.  If we'd modelled the weather based on the data before the industrial revolution our estimates now would be far off.  Global changes, such as volcanic eruptions, meteorite impact (dinosaurs 65million years ago), and human activity can significantly affect weather patterns for 100s of years after the event.  Those, of course, can't be predicted and would invalidate any weather forecasts that didn't make allowances for the event.