Scientists who studied a huge population collapse in Europe at the end of the Bronze Age said Monday that climate change, commonly assumed to be responsible, could not have been the culprit.

Researchers from several universities in Britain and Ireland found that changes in climate that scientists believed to coincide with the fall in population in fact occurred at least two generations later.

The study, published in the U.S. journal Proceedings of the National Academy of Sciences, correlated archaeological data from sites throughout Ireland to determine both population and climate dynamics from 1200 BC to 400 AD.

It showed that human activity during the Bronze Age appears to have peaked around 1000 BC with a steady decline until 800 BC and a steep population decline by 750 BC.

Paleoclimate records preserved in peat bogs, however, recorded a rapid shift to wet climate conditions around 750 BC.

"Our evidence shows definitively that the population decline in this period cannot have been caused by climate change," said Ian Armit, professor of Archaeology at the University of Bradford, and lead author of the study.

Armit said in a statement that social and economic stress is more likely to be the cause of the sudden and widespread fall in numbers.

Communities producing bronze needed to trade over very large distances to obtain copper and tin, and control of these networks enabled the growth of complex, hierarchical societies dominated by a warrior elite, he said.

As iron production took over, these networks collapsed, leading to widespread conflict and social collapse, and therefore the population collapse at the end of the Bronze Age.

The findings have significance for modern day climate change debates which, said Armit, are often too quick to link historical climate events with changes in population.

"The impact of climate change on humans is a huge concern today as we monitor rising temperatures globally," he said.

"Often, in examining the past, we are inclined to link evidence of climate change with evidence of population change. Actually, if you have high quality data and apply modern analytical techniques, you get a much clearer picture and start to see the real complexity of human/environment relationships in the past."