Shop Windows to the Universe

Ready, Set, SCIENCE!, by the National Research Council, focuses on K-8 science classsrooms. Check out the other publications in our online store, as well as classroom materials.
Warm ocean waters fuel hurricanes. There was plenty of warm water for Hurricane Katrina to strengthen once it moved into the Gulf of Mexico.
Click on image for full size
Courtesy of NASA

Are Hurricanes Becoming Stronger and More Frequent?

Hurricanes can be the deadliest, strongest, and costliest storms in the world and they have been more severe than usual in recent years, causing an amazing amount of damage to coastal towns and cities. In 2004, a record number of hurricanes affected Florida and typhoons struck Japan. A hurricane even formed in the South Atlantic Ocean, off the coast of Brazil, where no one had ever seen a hurricane before. The 2005 Atlantic hurricane season was predicted to be above normal as well and one of those storms, Hurricane Katrina, devastated the gulf coast of the United States as it passed through.

Why are these monster storms becoming even more monstrous? Some scientists have identified that the number of hurricanes probably waxes and wanes with a regular and natural cycle. Other scientists have identified that the strength and length of storms is probably affected by global warming. Both processes might be at work, and reserchers continue their studies so that we can better understand these monsterous storms. Read on to learn more about these theories.

A natural cycle may control the number of storms
There is evidence that the number of storms each year is controlled, at least in part, by a natural 20 to 40-year cycle. For example, the number of hurricanes each year was less than usual from the mid-1960’s to the mid-1990’s. This was the part of the cycle when there were fewer hurricanes. But since 1995 there have been typically more hurricanes than usual each year. This means we are currently in the phase of the cycle when there are more hurricanes than usual. Scientists predict that the number of storms will be higher than normal until about 2015.

Global warming causes stronger storms
As global warming causes oceans to become warmer, and more moisture is held in the atmosphere, the intensity of hurricanes and the amount of rain they produce will likely increase, according to NCAR scientist Kevin Trenberth and others. There is strong evidence that global warming has been increasing the intensity of hurricanes for over the past few decades.

In the past 30 to 50 years the oceans have warmed about 0.1 degree Fahrenheit. This may not seem like much of a temperature change, but it is quite significant. Think about a pot of water heating on a stove. A small pot of water will heat quickly, while a large pot of water will heat very slowly. This is due to a difference in heat capacity. The oceans have an enormous heat capacity because of their large size, thus, they are like an enormous pot of water, and so it takes a great amount of heat to warm them. The fact that they have warmed significantly in 30 to 50 years is remarkable. And this change appears to be causing a remarkable change in the strength and length of hurricanes.

The warming oceans are very likely causing the strength of hurricanes to increase. According to MIT scientist Kerry Emmanuel, hurricanes have become 70-80% more powerful over this time. Hurricanes take heat energy from the oceans and convert it into the energy of the storm. The warmer oceans offer more heat energy to hurricanes. This makes them become stronger storms.

Last modified February 15, 2011 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Hurricanes (also known as Tropical Cyclones)

As a strong hurricane heads towards the coast, people prepare - boarding up houses, packing the car, and evacuating. These storms can spell disaster for people in hurricane prone areas, so they are taken...more

Climate Change Impacts, Adaptation and Vulnerability - Present and Future

A second report from the Intergovernmental Panel on Climate Change (IPCC) shares the current scientific understanding of how people and natural ecosystems are affected by climate change, and how they will...more

Effects of Climate Change Today

Over 100 years ago, people worldwide began burning more coal and oil for homes, factories, and transportation. Burning these fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere....more

A New Plan to Help Earth’s Changing Climate

Leaders from 192 countries are meeting in Copenhagen, Denmark December 7-18, 2009 to decide how the world will deal with climate change. They are trying to decide how to limit the amount of greenhouse...more

What Is Climate?

The climate where you live is called regional climate. It is the average weather in a place over more than thirty years. To describe the regional climate of a place, people often tell what the temperatures...more

Earth's Greenhouse Gases

Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate. There are several different types of greenhouse gases. The major ones are carbon...more

Space Missions to study Earth's Atmosphere & Climate

Satellites that orbit Earth help us study Earth's atmosphere, weather, and climate. Here are a few of the many spacecraft that study our atmosphere. Aura was launched in July 2004. It is studying pollution,...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA