Cooking Tropical Storms

Increasing sea surface temperature changing precipitation patterns and fuelling extreme weather conditions.

This article is part of the 4sea Project.

When you heat the water for your cup of tea, you take of the lid and you see there are lots of tiny drops under the lid. With the climate change, the same procedure is happening with the sea of our planet and that’s how climate change can change precipitation patterns by increasing sea surface temperatures that creates evaporation and increases the rainfall. And we are not just talking about small scattered showers, but tremendous rainfalls and tropical storms.

When we hear about rising temperatures and climate change, we must have in mind that there are several dimensions in which the temperature is rising: land temperature, ocean temperature, air temperature and sea surface temperature. The temperature change is worldwide causing extreme weather conditions: wet locations are likely to become wetter, and dry locations even drier. The rainfalls will not necessarily become more in numbers, but when occurring they will be more intense and there will be risk for flooding and tropical storms.

As we already are by the stove, which is the recipe to follow for cooking a storm, and what does climate change has to do with it?

The ocean is the mixing bowl and plays a fundamental role for the climate. There are only three main ingredients needed for a storm: warm water, humidity and the rotation of Earth. The sea surface temperature must be at least 26-28°C. To spice it up, add a disturbance, typically easterly winds from West Africa: a sweet-sour mix of hot and dry winds from the Sahara Desert and wetter and cooler winds from the Gulf of Guinea. The disturbance is what initiates the spin of the storm, but what really makes it cooking is the Coriolis Effect of the winds of the rotation of the Earth.

Like using a straw, the storm sucks up the warm energy from the ocean, and the wind accelerates, creating the Vortex Effect. As air always moves from areas of higher pressure to areas of lower pressure, the air is sucked up straight up from the storm creating its eye.   South of the equator, the storm rotates clockwise, and north of the equator it rotates counter-clockwise.

With the right sea surface temperature, humidity and winds in place, you can get a furious hurricane that will literally take you by storm. [1], [2]

So what happens when climate change comes and turns up the heat?

If the sea surface temperature increases, the evaporation and humidity will increase, and with just a bit of wind huge storms are cooking. Hurricanes are natural phenomena, but what we can see is that they are becoming more and more intense.

With the climate change turning up the heat with rising sea surface temperature feeding the storm provides just the perfect setting and conditions for triggering stronger storms.

 

The increasing number of intense storms tells us this is just what is happening. Hurricane’s strength is divided into five categories, and since mid-1970s, hurricanes of category four and five with 59 to more than 70m/s have doubled [3].

 

The effect we are likely to be seeing from increasing sea surface temperatures are more disasters. Stronger storms means more damage. Where the storms move forward, they leave devastating socio-economical and infrastructural damage. As the ocean is already coping with most of the climate change temperature rise, the question remains for how long the ocean will stand, and what will be the effects we can see in the future.

About the author: Emma I. Lyngedal is a Political Scientist, freelance writer and researcher and part of the 4Sea to draw attention to the Ocean and its importance to the climate system.

This article has been written in the context of 4sea. 4sea, a project about the importance of the world oceans, addresses the interdependence between the oceans and climate change, entraining everyone to become ocean lovers – for now through articles and videos on this blog and in November on our own platform. 4sea is a joint project between the youth organisations CliMates, Youth for Ocean and Vitamin Sea. Love it? Stay tuned for our platform!

References:
  1. Nathaniel C. Johnson and Shang-Ping Xie. 2010. Changes in the sea surface temperature threshold for tropical convection. Nature Geoscience 3,842–845, doi:10.1038/ngeo1008
  2. Price, C., N. Reicher, and Y. Yair.,(2015) Do West African thunderstorms predict the intensity of Atlantic hurricanes?, Geophys. Res. Lett., 42, 2457–2463, doi:10.1002/2014GL062932.
  3. Webster, P.J., G.J. Holland, J.A. Curry, and H.-R. Chang. 2005. Changes in tropical cyclone number, duration, and intensity in a warming environment. Science 309:1,844-1,846. doi:10.1126/science.1116448
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