Atlanta’s flash flooding risk is increasing as atmosphere warms, report finds

ATLANTA — A hotter local weather is resulting in heavier rain occasions in Atlanta and throughout the USA, a brand new report from the nonprofit journalism group Local weather Central reveals. 

Within the report, a staff of scientists examined 150 cities round the USA from 1970 by way of 2021, specializing in excessive rainfall. By calculating hourly rainfall depth throughout rain-receiving days, they had been capable of quantify a rise in brief bursts of utmost rainfall over the 51 years.

The report discovered that 90% of the 150 cities now common extra rain-per-hour than when the information set started in 1970. Extra moisture in hotter air will increase the possibilities of rain falling in heavier downpours. 

The typical improve in hourly rain depth of the stations was 13 p.c, however some cities confirmed a rise a lot larger. Fairbanks, Alaska, held the very best hourly rain charge improve of 49%. 

Atlanta has had a 9.58% improve in hourly rain charges since 1970. That is modest, but the notable improve additionally aligns with a number of different cities within the southeast.

Even a reasonable improve in hourly rain charges and rainfall depth can result in many threats, together with flash flooding and mudslides, together with well being points similar to contamination of ingesting water throughout heavy rain occasions.

Extreme Climate and Flood Security Suggestions

Heavy rain occasions in Atlanta can happen year-round and from varied climate techniques. Flash flooding isn’t unusual in North Georgia in the summertime months, like slow-moving pop-up thunderstorms. And typically, landfalling tropical techniques additionally deliver vital flash flood threats.

Cobb County firefighters evacuate greater than 20 youngsters, 4 adults after flooding at daycare heart

A flash flood is a sudden rise in water alongside a stream, river or space that’s normally land. They’ll happen inside a number of minutes or hours, and the water can transfer at surprisingly fast speeds. They’re harmful. Flooding is the #2 weather-related killer in the USA behind warmth, in response to 30 years of information from 1990 to 2020.

North Georgia’s topography contains many hills, valleys and mountains. This topography and our community of creeks, streams and smaller waterways make many areas extra liable to flash flooding. 

In flash flooding, roads and bridges can change into compromised, and the waters can conceal different lurking hazards like dwell wires and chemical contamination. It solely takes six inches of swiftly shifting water to knock you off your toes, and only a foot of fast-moving floodwaters can float away a small automobile.

Within the examine, Local weather Central highlights its methodology of calculating the Easy Hourly Rainfall Depth Index, the full annual rainfall divided by the full variety of hours with rainfall in a 12 months. They checked out days when it rained in every metropolis and the way heavy it rained on the time.

A hotter ambiance can maintain extra water vapor. An environment only one diploma Fahrenheit of warming can maintain 4 p.c extra water vapor. This is called the Clausius-Clapeyron Equation. As our ambiance continues warming, excessive rainfall occasions will change into extra widespread.

Local weather Central is a nonprofit, impartial group of scientists and journalists researching and reporting the info in regards to the Earth’s altering local weather and its influence on the general public.