Extreme weather events are occurring more frequently and causing significant damages to infrastructure and loss of lives. In September the state of Oregon and California was ravaged by record wildfires. Scientist says that this is the worst wildfires in 18 years and linked to climate change (California and Oregon, 2020).
In August, torrential rains that caused devastating floods and mudslides swept across the Korean Peninsula, killing many people (South Korea, 2020).
Two years ago, in July 2018, Japan suffered the same experience, floods and mudslides from severe rainfall claimed at least 155 lives and put thousands of homes underwater (Japan floods, 2018).
A group of international scientists have found a connection between these extreme weather events and the impacts of climate change on the jet stream.
Jet streams are another term for a fast-flowing air located at 8 or 15 km above the earth’s surface and that generally blows from west to east in a wavy shape or pattern.
There are four major jet streams- two polar jet streams, near the north and south poles, and two subtropical jet streams closer to the equator. Jet streams flow between the boundaries of hot and cold air and influence the earth’s weather.
While global climate models can predict large-scale climate patterns and how it behaves over time, it cannot give an accurate prediction of extreme weather events according to the researchers, and this is where actual observations can be crucial.
To determine at what conditions extreme weather events occurs and persists, scientists examined historical atmospheric data. They found that when the jet streams become stationary and when peaks and troughs remain steady, it acts as a strong barrier of wave consisting of massive peaks and valleys. If this occurs, then sunny days can become severe heatwaves, and lasting rains can lead to flooding.
Michael Mann, distinguished professor of atmospheric science and director, Earth System Science Center, Penn State says that “We came as close as one can to demonstrating a direct link between climate change and a large family of extreme recent weather events“.
He adds that “while the models do not reliably track individual extreme weather events, they do reproduce the jet stream patterns and temperature scenarios that in the real world lead to torrential rain for days, weeks of broiling sun and absence of precipitation.”
To read the entire study, click on the link below:
California and Oregon 2020 wildfires in maps, graphics and images. (2020 September 18) BBC news. Retrieved from https://www.bbc.com/news/world-us-canada-54180049
South Korea: Torrential rains kill many, cause widespread damage. (2020, August 6). Aljazeera. Retrieved from https://www.aljazeera.com/news/2020/08/06/south-korea-torrential-rains-kill-many-cause-widespread-damage/?gb=true
Japan floods: 155 killed after torrential rain and landslides. (2018, July 10). BBC News. Retrieved from https://www.bbc.com/news/world-asia-44775627
Mann, M., Rahmstorf, S., Kornhuber, K. et al. Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events. Sci Rep 7, 45242 (2017). https://doi.org/10.1038/srep45242
Penn State. “Extreme weather events linked to climate change impact on the jet stream.” ScienceDaily. ScienceDaily, 27 March 2017. www.sciencedaily.com/releases/2017/03/170327083120.htm