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Chocolate Crisis?

A warming climate and disease threaten the future of this sweet treat

October 2018
By Alexa Kurzius

IMSTEPF STUDIOS LLC/GETTY IMAGES

FUN FACT: Most popular candy bars in the U.S. use milk chocolate, which is sweeter than dark chocolate—its more pure and bitter cousin.

Do you look forward to eating chocolate on Halloween? If your answer is yes, you’re not alone. Worldwide, people will gobble up about 8.4 million tons of chocolate this year. That’s more than the weight of 20 Empire State Buildings!

But chocolate has a dark secret: Its future is at risk. Cocoa, one of chocolate’s key ingredients, is made from cacao (kuh-KOW) beans. Most trees that produce cacao beans grow in West Africa, South America, and Southeast Asia (see World of Chocolate). In those places, warming climate patterns and diseases threaten the plants. That’s why scientists are working together to try to save cocoa—before it’s too late.

Do you look forward to eating chocolate on Halloween? Was your answer yes? Then you’re not alone. People worldwide will eat about 8.4 million tons of chocolate this year. That’s more than the weight of 20 Empire State Buildings!

But chocolate has a dark secret. Its future is at risk. Cocoa is one of chocolate’s key ingredients. It’s made from cacao (kuh-KOW) beans. Trees that produce cacao beans grow in only a few places. They include West Africa, South America, and Southeast Asia (see World of Chocolate). Warming climate patterns threaten the plants in those areas. Disease threatens them too. That’s why scientists want to save cocoa before it’s too late.

The Sweet Story of Chocolate
Watch a video describing how chocolate is made, from the cocoa bean to the candy bar.

Tropical Tree

Making chocolate is a long process. It begins with the cacao tree, an evergreen tree that grows to be up to 8 meters (26 feet) tall. Each tree takes three to five years to produce its first fruit, called cacao pods. They contain the cacao beans used to make chocolate.

Cacao trees grow best in tropical rainforests. These areas have hot temperatures and a lot of rainfall. Cacao trees thrive in these humid conditions. Healthy trees can produce pods for 40 years.

Making chocolate takes time. It begins with the cacao tree, an evergreen tree. It can growup to 8 meters (26 feet) tall. Each tree takes three to five years to grow its first fruit. They’re called cacao pods. The pods contain cacao beans. The beans are used to make chocolate.

Cacao trees grow best in tropical rainforests. Rainforests have hot temperatures. They also have a lot of rainfall. Cacao trees do well in these humid areas. Healthy trees can grow pods for 40 years.

CHRISTOPHER PILLITZ/CORBIS VIA GETTY IMAGES

Cacao trees infected with fungal diseases produce rotten cacao pods.

But if the conditions change, the trees can suffer. Global temperatures have been steadily rising in recent decades. Regions around the equator, where cacao trees grow, are experiencing more droughts than ever before. As a result, the areas of the world suitable for growing cacao trees are shrinking.

That trend isn’t expected to change. A 2014 report by the Intergovernmental Panel on Climate Change predicted that by 2050, temperatures in countries where cacao trees grow would rise by 2.1°C (3.8°F). Predictions like that have experts wondering: Will cacao trees survive?

But the trees can suffer if conditions change. Global temperatures have been steadily rising in recent years. Cacao trees grow in areas near the equator. These places are having more droughts than ever before. As a result, spots where cacao trees grow best are shrinking.

That trend isn’t likely to change. Temperatures in countries where cacao plants grow are expected to rise by 2.1°C (3.8°F) by 2050. That's based on a 2014 report. It’s by a global panel on climate change. That has experts wondering whether cacao trees will survive.

World of Chocolate

JIM MCMAHON

Think: What do these cocoa-producing countries have in common?

Think: Do you think African vultures have many animal predators?

World of Chocolate

JIM MCMAHON

Think: What do these cocoa-producing countries have in common?

Think: Do you think African vultures have many animal predators?

Tree Tester

IAN MCILGORM/REX/SHUTTERSTOCK

Paul Hadley is studying how cacao trees react to climate change.

Paul Hadley is hoping to answer that question. He grows hundreds of cacao trees in his greenhouse at the University of Reading in England. Then he puts the trees to the test.

Inside a 400 square meter (4,300 square foot) glass structure, Hadley simulates some of the conditions of climate change. He cranks up the temperature, gives the trees limited water, and injects carbon dioxide, a greenhouse gas, into the air. Then he observes how the plants grow. 

Hadley has found that in drought -like conditions, the cacao plants grow more slowly. That was not a surprise. But what he didn’t expect was that over time, the trees became more efficient at using water. That meant they needed less water during photosynthesis.

Those results give Hadley hope. “There may be ways to breed cacao that’s resilient to climate change,” he says. 

Paul Hadley is hoping to find out. He grows hundreds of cacao trees in his greenhouse. It’s at the University of Reading in England. The glass building is 400 square meters(4,300 square feet).

Inside, Hadley puts the trees to the test. He mimics some of the conditions of climate change. He cranks up the temperature. He gives the trees less water. He adds carbon dioxide, a greenhouse gas, to the air. Then he watches how the plants grow.

Hadley has found what happens in drought -like conditions. The cacao plants grow more slowly. That was not a surprise. But there was something he didn’t expect. The trees gotbetter at using water over time. That meant they needed less water during photosynthesis.

Those results give Hadley hope. “There may be ways to breed cacao that’s resilient to climate change,” he says.

Bean to Bar

FLORIAN KOPP/IMAGEBROKER/AGE FOTOSTOCK 

Farmers harvest cacao pods from the trees and remove the pulpy beans inside.

Farmers harvest cacao pods from the trees. They remove the pulpy beans inside.

PHOTONONSTOP/ALAMY STOCK PHOTO

Microorganisms break down the pulp around the beans, reducing the bitter flavor.

Microbes break down the pulp around the beans. That lessens the bitter flavor.

JAMES L. STANFIELD/NATIONAL GEOGRAPHIC/GETTY IMAGES

The beans are roasted, ground up, and mixed with milk and other ingredients.

The beans are roasted and ground up. Then they’re mixed with milk and other ingredients

RODRIGO BUENDIA/AFP/GETTY IMAGES

The chocolate is poured into molds and hardens. Enjoy your Halloween treat!

The chocolate is poured into molds and hardens. Enjoy your Halloween treat!

Think: What factors might affect the world’s chocolate supply? Which of the steps described above do you think would be affected?

Think: What factors might affect the world’s chocolate supply? Which of the steps above do you think would be affected?

Bean to Bar

FLORIAN KOPP/IMAGEBROKER/AGE FOTOSTOCK 

Farmers harvest cacao pods from the trees and remove the pulpy beans inside.

Farmers harvest cacao pods from the trees. They remove the pulpy beans inside.

PHOTONONSTOP/ALAMY STOCK PHOTO

Microorganisms break down the pulp around the beans, reducing the bitter flavor.

Microbes break down the pulp around the beans. That lessens the bitter flavor.

JAMES L. STANFIELD/NATIONAL GEOGRAPHIC/GETTY IMAGES

The beans are roasted, ground up, and mixed with milk and other ingredients.

The beans are roasted and ground up. Then they’re mixed with milk and other ingredients

RODRIGO BUENDIA/AFP/GETTY IMAGES

The chocolate is poured into molds and hardens. Enjoy your Halloween treat!

The chocolate is poured into molds and hardens. Enjoy your Halloween treat!

Think: What factors might affect the world’s chocolate supply? Which of the steps described above do you think would be affected?

Think: What factors might affect the world’s chocolate supply? Which of the steps above do you think would be affected?

Disease Defense

Other scientists are working to protect cacao trees from another major threat: disease.

About 30 years ago, a disease known as frosty pod rot killed nearly all of the cacao trees in Costa Rica. After the die-off, researchers in Costa Rica began working on developing cacao plants that can survive diseases. 

That’s the focus of Mariela Leandro. The chocolate researcher grows cacao trees in a giant garden in Costa Rica. She infects trees with diseases and observes which ones survive. Then she uses those trees to breed new and improved plants. Today, her disease-resistant plants are growing on cacao farms in six Central American countries.

For Leandro, time is of the essence. Other diseases threaten trees in West Africa, where most of the world’s cocoa is produced. “This is really important work,” Leandro says. The future of chocolate depends on it.

Other scientists are trying to protect cacao trees from disease. One is called frosty pod rot. It killed nearly all of the cacao trees in Costa Rica. That happened about 30 yearsago. Researchers in Costa Rica got to work after the die-off. They wanted to create cacao plants that can survive diseases.

That’s the focus of Mariela Leandro, a chocolate researcher. She has a giant garden in Costa Rica. She grows cacao trees there. She infects them with diseases. Then she seeswhich ones survive. She uses those trees to breed new and improved plants. Today, theyare growing on farms in six Central American countries.

The clock is ticking for Leandro. Other diseases threaten trees in West Africa. That’swhere most of the world’s cocoa comes from. “This is really important work,” Leandro says. The future of chocolate depends on it.

Chocolate Meltdown

Which type of chocolate melts faster?

KATE FRANCIS

Step 5

Observe

Different types of chocolate contain different amounts of ingredients. Dark chocolate contains more cocoa, while milk chocolate contains more milk and fat.

Different types of chocolate have different amounts of ingredients. Dark chocolate has more cocoa. Milk chocolate has more milk and fat.

Ask a Research Question

Which melts at a lower temperature: milk chocolate or dark chocolate?

 Will milk chocolate or dark chocolate melt at a lower temperature?

Materials

• 2 small, equal-sized pieces of milk chocolate
• 2 small, equal-sized pieces of dark chocolate
• 2 tall beakers
• masking tape
• marker
• baking pan
• large cardboard square
• measuring cup
• tap water
• ruler
• thermometer
• 2 craft sticks
• paper and pencil

• 2 small, equal-sized pieces of milk chocolate
• 2 small, equal-sized pieces of dark chocolate
• 2 tall beakers
• masking tape
• marker
• baking pan
• large cardboard square
• measuring cup
• tap water
• ruler
• thermometer
• 2 craft sticks
• paper and pencil

Procedure

1. Examine one piece of each type of chocolate. Record your observations. How does each type feel, smell, and taste?  

2. Use the marker and tape to label the beakers. Place one piece of each type of chocolate into each beaker. 

3. Place the baking pan on the cardboard square. (The cardboard will keep water in
the pan from cooling quickly.) 

4. Set the beakers in the pan. 

5. Use the measuring cup to pour warm water into the pan. The water should be 2.5 cm (1 inch) high. Record the water temperature. 

6. Observe the chocolate inside each beaker. Use a craft stick to touch the chocolate, and note its texture. Have the pieces started to melt? If so, record the water temperature. 

7. Add ½ cup of hot water from the faucet to the pan. 

8. Repeat steps 6 and 7 until both pieces have melted. 

1. Look closely at one piece of each type of chocolate. Write down what you see. How does each type feel, smell, and taste?  

2. Use the marker and tape to label the beakers. Place one piece of each type of chocolate into each beaker.

3. Place the baking pan on the cardboard square. (The cardboard will keep water in the pan from cooling quickly.) 

4. Set the beakers in the pan.

5. Use the measuring cup to pour warm water into the pan. The water should be 2.5 cm (1 inch) high. Write down the water temperature. 

6. Watch the chocolate inside each beaker. Use a craft stick to touch the chocolate. Note its texture. Have the pieces started to melt? If so, record the water temperature.

7. Add 1/2 cup of hot water from the faucet to the pan. 

8. Repeat steps 6 and 7 until both pieces have melted.

Results

At what temperature did each piece melt? Record your results in a data table.

At what temperature did each piece melt? Write down your results in a data table.

Conclusions

1. The temperature at which a solid becomes a liquid is called its melting point. Which type of chocolate has a lower melting point, milk or dark chocolate?

2. What factors might affect chocolate’s melting point?

1. The temperature at which a solid becomes a liquid is called its melting point. Does milk chocolate or dark chocolate have a lower melting point?

2. What factors might affect chocolate’s melting point?

Take it Further

How do you think the melting point of white chocolate compares to milk and dark chocolate? Make a prediction, then investigate it.

How might white chocolate’s melting point compare with that of milk and dark chocolate? Make a prediction. Then investigate it.

Chocolate Meltdown

Which type of chocolate melts faster?

KATE FRANCIS

Step 5

Observe

Different types of chocolate contain different amounts of ingredients. Dark chocolate contains more cocoa, while milk chocolate contains more milk and fat.

Different types of chocolate have different amounts of ingredients. Dark chocolate has more cocoa. Milk chocolate has more milk and fat.

Ask a Research Question

Which melts at a lower temperature: milk chocolate or dark chocolate?

 Will milk chocolate or dark chocolate melt at a lower temperature?

Materials

• 2 small, equal-sized pieces of milk chocolate
• 2 small, equal-sized pieces of dark chocolate
• 2 tall beakers
• masking tape
• marker
• baking pan
• large cardboard square
• measuring cup
• tap water
• ruler
• thermometer
• 2 craft sticks
• paper and pencil

• 2 small, equal-sized pieces of milk chocolate
• 2 small, equal-sized pieces of dark chocolate
• 2 tall beakers
• masking tape
• marker
• baking pan
• large cardboard square
• measuring cup
• tap water
• ruler
• thermometer
• 2 craft sticks
• paper and pencil

Procedure

1. Examine one piece of each type of chocolate. Record your observations. How does each type feel, smell, and taste?  

2. Use the marker and tape to label the beakers. Place one piece of each type of chocolate into each beaker. 

3. Place the baking pan on the cardboard square. (The cardboard will keep water in
the pan from cooling quickly.) 

4. Set the beakers in the pan. 

5. Use the measuring cup to pour warm water into the pan. The water should be 2.5 cm (1 inch) high. Record the water temperature. 

6. Observe the chocolate inside each beaker. Use a craft stick to touch the chocolate, and note its texture. Have the pieces started to melt? If so, record the water temperature. 

7. Add ½ cup of hot water from the faucet to the pan. 

8. Repeat steps 6 and 7 until both pieces have melted. 

1. Look closely at one piece of each type of chocolate. Write down what you see. How does each type feel, smell, and taste?  

2. Use the marker and tape to label the beakers. Place one piece of each type of chocolate into each beaker.

3. Place the baking pan on the cardboard square. (The cardboard will keep water in the pan from cooling quickly.) 

4. Set the beakers in the pan.

5. Use the measuring cup to pour warm water into the pan. The water should be 2.5 cm (1 inch) high. Write down the water temperature. 

6. Watch the chocolate inside each beaker. Use a craft stick to touch the chocolate. Note its texture. Have the pieces started to melt? If so, record the water temperature.

7. Add 1/2 cup of hot water from the faucet to the pan. 

8. Repeat steps 6 and 7 until both pieces have melted.

Results

At what temperature did each piece melt? Record your results in a data table.

At what temperature did each piece melt? Write down your results in a data table.

Conclusions

1. The temperature at which a solid becomes a liquid is called its melting point. Which type of chocolate has a lower melting point, milk or dark chocolate?

2. What factors might affect chocolate’s melting point?

1. The temperature at which a solid becomes a liquid is called its melting point. Does milk chocolate or dark chocolate have a lower melting point?

2. What factors might affect chocolate’s melting point?

Take it Further

How do you think the melting point of white chocolate compares to milk and dark chocolate? Make a prediction, then investigate it.

How might white chocolate’s melting point compare with that of milk and dark chocolate? Make a prediction. Then investigate it.

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