2024’s record ocean heat revved up Atlantic hurricane wind speeds: study

Sub : Geo

Sec : Climatology

Context:

Key Findings:

Human-Driven Warming:
- Climate change, driven by carbon dioxide and other greenhouse gas emissions, intensified every Atlantic hurricane in 2024.
- Ocean surface temperatures in the Gulf of Mexico were 2.5°F (1.4°C) higher than without climate change, fueling stronger storms.
Hurricane Intensification:
- Record ocean warmth intensified the maximum wind speeds of all 11 Atlantic hurricanes in 2024 by 9-28 mph (14-45 kph).
- Some hurricanes were pushed up a category on the Saffir-Simpson scale, significantly increasing their destructive potential.

Examples of Impact:

Category Escalations:
- Hurricanes Milton and Beryl: From Category 4 to Category 5.
- Helene: From Category 3 to Category 4, causing over 200 fatalities and becoming the second deadliest hurricane to hit the U.S. since Hurricane Katrina (2005).
Peak Intensification Analysis:
- At Hurricane Milton’s peak before landfall, climate change made the conditions (e.g., warm sea temperatures) 100 times more likely and increased its maximum wind speed by 24 mph.

Broader Implications:

Historical Analysis:
- From 2019 to 2023, 84% of Atlantic hurricanes were significantly strengthened by human-caused ocean warming.
Global Application:
- The study’s methodology can analyse tropical cyclones worldwide, not just in the Atlantic Basin.

Future Risks:
- Current impacts are seen with the world at 1.3°C (2.3°F) above pre-industrial levels.
- Exceeding 1.5°C (2.7°F) will likely intensify these effects further.

Hurricanes:

Hurricanes, also known as tropical cyclones or typhoons (depending on the region), are intense storm systems formed over warm ocean waters.

Process of Hurricane Formation:

Warm Ocean Waters:

Sea surface temperatures must be at least 26.5°C (80°F) to a depth of about 50 meters.
Warm water provides the energy needed for the storm to develop.

Low-Pressure System

A tropical disturbance begins as a cluster of thunderstorms over warm water.
The warm, moist air above the ocean rises, creating a low-pressure area near the surface.

Coriolis Effect

The Earth’s rotation causes the rising air to spin.
This spin organises the system into a cyclonic (rotating) pattern.
Coriolis Effect is strongest near the equator but hurricanes cannot form at the equator itself (within 5° latitude) due to insufficient Coriolis force.

Convection and Thunderstorm Development

Warm, moist air rises rapidly, cooling and condensing into clouds and releasing latent heat. This heat fuels further rising air, intensifying the system.

Development of a Core

As air rises and more heat is released, the pressure in the center drops further, creating the eye (calm, low-pressure center).
Surrounding this eye is the eyewall, a ring of intense thunderstorms with the strongest winds and heaviest rainfall.

Sustained Growth:

The hurricane draws in more warm, moist air while expelling cooler, drier air at the top.
This cycle maintains the storm’s strength as long as:
- It remains over warm water.
- There is minimal wind shear (difference in wind speeds/directions at different altitudes).

Movement and Dissipation:

Hurricanes are guided by prevailing winds and pressure systems.
They weaken when they move over land or cooler waters due to loss of energy from warm water.

Source: TH