How Does Climate Change Influence Hurricanes?
Researchers reported in a report published in Environmental Research: Climate that climate change increased hurricane maximum wind speeds by an average of approximately 29 km/h from 2019 to 2023.
An analysis also showed that climate change increased the average intensity of all hurricanes in 2024 by approximately 29 km/h, increasing the risk of wind damage.
Global Warming and Hurricane Speed
It is worth noting that hurricane speed appears to be slowing. One study showed that hurricane speed slowed by approximately 10% between 1949 and 2016. The weakening of summer tropical circulation caused by global warming is likely the primary cause of this change. This slowdown in hurricane speed, in turn, led to a significant increase in precipitation, increasing the risk of disasters such as heavy rain and flooding.
A 2018 study published in the journal Nature revealed that hurricane speed had slowed by approximately 10% between 1949 and 2016. Specifically, in 1949, the average hurricane speed exceeded 19 kilometers per hour, but by 2016, it had dropped to approximately 17 kilometers per hour. While academics remain debating these results and their interpretation, new research recently published by Zhang Gan in a Science journal provides a new perspective on this phenomenon.
Reasons for the Slowing Hurricane Speed
- Simulation results further indicate that future human-induced climate warming will significantly slow the movement of hurricanes, particularly in densely populated mid-latitude regions. For example, near New York City, the forward speed of hurricanes is projected to slow by approximately 3.2 kilometers per hour, equivalent to 10% to 20% of the current hurricane speed.
- The movement speed of tropical cyclones is influenced by a complex array of factors, including environmental guiding air currents, the evolution of the typhoon's internal structure, the meridional gradient of Earth's rotational vorticity, and underlying surface conditions. However, it's generally believed that environmental winds are the key factor in determining a cyclone's trajectory, while background winds primarily influence its speed.
Impact of Slowing Hurricanes
- Global warming is weakening the summer tropical circulation, which may be one of the reasons for the slowing of hurricanes. Yu Jinhua, a professor at Nanjing University of Information Science and Technology, pointed out that rising temperatures are causing the westerlies, the powerful air currents that blow through mid-latitudes, to advance poleward, accompanied by weaker mid-latitude weather disturbances. These combined changes could lead to slower hurricane movement over densely populated areas such as Asia and North America.
- Slower hurricanes mean they linger longer in a given area, leading to significantly increased precipitation. This excess precipitation can easily cause severe flooding and waterlogging, especially in low-lying areas. Sustained strong winds also pose a risk, potentially causing severe damage to buildings exposed to prolonged strong winds. Several slow-moving hurricanes in the United States in recent years have caused significant damage. For example, in 2017, Hurricane Harvey lingered near eastern Texas for nearly a week, causing massive damage to the region totaling $125 billion.
Geographic Differences and Path Impacts
The Earth's rotation causes hurricanes to exhibit mirror-symmetric rotational characteristics in different hemispheres. The counterclockwise rotation of hurricanes in the Northern Hemisphere results in stronger winds and more severe storm surges in the right quadrant (relative to the direction of travel). Regarding their paths, the Coriolis force causes hurricanes to gradually deflect northward as they move westward within the easterly wind belt, forming a characteristic parabolic trajectory.
This path shift is directly related to the variation in the Coriolis parameter with latitude. At higher latitudes, the increased Coriolis force alters the balance between the pressure gradient and centrifugal force, causing the hurricane to turn and ultimately weaken and dissipate.
