1000 year rainfall study suggests droughts and floods used to be longer, worse

A study done on… golly, Antarctic Ice, allegedly shows that in the catchment area for Newcastle in NSW, Australia, the last 100 years have been pretty darn nice, compared to the past when droughts and big-wet periods used to last a lot longer.

Set aside, for a moment, that the ice cores are thousands of kilometers away and in a totally different climate, if they are right, if, then natural climate change is much worse than our short climate records are telling us. And if our current records are so inadequate and don’t represent the “old-Normal”, then we have a flying pigs of predicting the “New Normal”. Has the climate changed at all, or is the new one just like the old old one?

Hydroclimatologist and lead author, Dr Carly Tozer from the ACE CRC said the research showed exposure to drought and flood risk was higher than previously estimated.

“The study showed that modern climate records, which are available for the past one hundred years at best, do not capture the full range of rainfall variability that has occurred,” Dr Tozer said.

“The wet and dry periods experienced since 1900 have been relatively mild when we look at the climate extremes of the past millennium.”
“Looking back over the past thousand years, we see that prolonged wet periods and droughts of five years or longer are a regular feature of the climate.”

The press release and interview can tell us that we are “underestimating” the risk of drought and flood, which sounds like the usual “worse than expected” scare story beat up in the media — but it is different. This time we are underestimating the risk of natural causes of floods and droughts:

“Water resources infrastructure in Australia is still mostly designed based on statistics calculated from about the last 100 years of instrumental rainfall and streamflow observations,” Dr Kiem said.

“What this study shows is that existing water management plans likely underestimate the true risk of drought and flood due to the reliance on data and statistics obtained from only the relatively short instrumental period.”

The ABC and The Conversation don’t draw the bleeding obvious next step: If follows — as day after night, that if we’ve underestimated natural climate change — then the models have been overestimating the influence of CO2.