Weather, Climate, and Predicting the Future
Tuesday, September 14th, 2010
The year 2007 will forever be remembered as the “Year of the Drought” in the Southeast. 2008 continued the same trend as we watched Lake Lanier dwindle to its lowest point in many years. I observed many contradictions during that time from experts that were predicting the future based on what they called sound science.
• During the worst of the drought, in December 2007, the lake’s level dropped 21 feet below full pool, and the Army Corps of Engineers estimated that Atlanta had a three-month supply of water remaining.
• Some experts said that it would take years to refill Lanier, and that was assuming we got a decent amount of rainfall. I remember that some of the real doom-and-gloomers even predicted that the South was in a permanently drier climate and that we might not ever see Lake Lanier at full pool again.
• In September of 2009 Atlanta received between 15 and 20 inches of rain in a year that was already well above average in rainfall. Having already come up more than 12 feet in 2009, Lake Lanier came up another four feet in only a week.
• In less than a year, the lake was full again. But during the drought, some climate experts predicted that we were possibly in a long-term drought pattern.
Predicting future weather is fraught with uncertainties simply because our climate is ever-changing. We’ve all seen how hard it is for meteorologists to accurately predict the 5 day forecast. The news stories from the drought period were dire and bleak and it is interesting to note the contradictions from different experts:
From Gainesville Times, November 30, 2008
State Climatologist David Stooksbury said he is concerned about the long-term outlook, and he wonders whether what's happening in Georgia is part of an atmospheric shift on a global scale.
He offers an intriguing theory that Georgia may not be in a three-year drought but actually a 10-year drought. The region's previous drought lasted from 1999 through 2002. After a couple of years during which the lake returned to normal and even got above full pool, Georgia slipped back into a drought again.
"Is it possible that this is a continuation of the drought that began 10 years ago, and the tropical storm seasons of 2004 and 2005 were just an aberration?" Stooksbury said.
If so, how long will the current situation persist? A year ago, many weather experts were saying that the "average" drought in Georgia lasts about two years, and they expected conditions to improve soon.
So what we learn from the above newspaper article dated November 2008 is that some weather experts predicted the drought was ending and conditions would soon improve, while other experts believed that we were possibly in the midst of a 10-year drought.
This is a great example of the human tendency to “extrapolate” (dictionary definition: the reasoning involved in drawing a conclusion or making a judgement on the basis of circumstantial evidence or prior conclusions rather than on the basis of direct observation). Experts are human too and tend to take the recent past and draw a conclusion of the unknown future as if events are already a foregone conclusion. We were in an epic drought, we knew what the implications of the drought were, and experts projected those facts into the future and concluded that it might be many years before the lake was at full pool again. What we couldn’t possibly see then was that weather patterns would change drastically and the lake would be back up to full pool in months instead of years.
While we all must remain mindful of the drought and be prepared when one inevitably returns at some point in the future, we can’t be sure that a La Niña event is going to lead to significant drought conditions in 2011, as some climate experts have recently predicted. According to the National Weather Service Climate Prediction Center, nearly all models predict La Niña to continue through early 2011. However, there is disagreement among the models over the eventual strength of La Niña (Contradiction again! The strength of a weather system has everything to do with its effect). And the article goes on to say that La Nina can cause an increase in Atlantic hurricanes, which increases our chance of significant rainfall in the Southeast.
So does it do more harm than good to attempt to predict the future, even if it’s based on “sound science”? In this case, I believe it does. If too many dire predictions of future drought don’t come to fruition, citizens will stop paying attention to the messenger. And that’s bad for all of us.
I recently spoke to Chris Butts, Georgia Green Industry Association Director of Legislative, Environmental and Public Affairs and asked him what advice he would give to folks in the Urban Ag Industry when it comes to educating customers on water issues:
“The important message for the industry to deliver is that we continue to promote best practices and putting the right plants in the right place. By coupling these principles with efficient irrigation, we will be preparing our customers to be better stewards regardless of conditions and predictions.”
So let’s all be good stewards of the land and not waste a precious resource. But let’s not put too much stock into educated guesses and predictions of the future. The rains of 2009-2010 proved a lot of experts wrong.