Climate science at a glance
- There have been changes in virtually every measure of tropical cyclone activity in the Atlantic since the 1970s, including tropical cyclone steering.
- Tropical cyclones have shifted toward the poles and this shift is likely due to global warming.
- The fingerprint of human-caused climate change has been found in the slowdown, or stalling, of tropical cyclones worldwide.
- Slower-moving tropical cyclones carry bigger flood risks.
What is tropical cyclone steering?
The movement of a hurricane from one location to another is known as hurricane propagation. In general, hurricanes are steered by global winds.
Steering winds, also called steering currents, are the dominant large-scale air flows that govern the movement of smaller features within, such as tropical cyclones.
US tropical cyclone steering trends and climate change
- There is some evidence for a slowing of tropical cyclone motion over the continental United States since 1900.
Global tropical cyclone steering trends and climate change
- There has been a substantial increase in virtually every measure of tropical cyclone activity in the Atlantic since the 1970s, including tropical cyclones steering. These increases are linked, in part, to higher sea surface temperatures in the region that Atlantic tropical cyclones form in and move through.
- Models suggest that storm tracks shift poleward under global warming due to stronger upper-level winds and increased atmospheric water vapor.
- Observational data indicates a general slowdown of atmospheric summer circulation in the mid-latitudes. Models also support this pattern.
Global studies attribute changes in tropical cyclone steering to climate change
- (Baldini et al. 2016): The mean track of Cape Verde tropical cyclones has shifted gradually north-eastward from the western Caribbean toward the North American east coast over the last 450 years. Since about 1870, these shifts were largely driven by anthropogenic greenhouse gas and sulfate aerosol emissions.
- (Kossin 2018) finds that tropical cyclones worldwide have increasingly stalled, their forward speed decreasing, over the past 70 years, due to a slowing in steering patterns attributed to global warming.