100,000-year problem facts for kids

The amount of energy the Earth gets from the sun is called insolation. This energy helps decide how hot or cold our planet is. The Earth's temperature changes based on how strong the sun's energy is, how far Earth is from the sun, and how much the Earth's axis is tilted.

However, scientists have noticed something strange. Over the last million years, Earth has gone through big changes between very cold periods (called ice ages or "glacial states") and warmer periods (called "inter-glacial states"). These big changes happen about every 100,000 years. The puzzle is that these 100,000-year changes don't seem to perfectly match the usual changes in the sun's energy, Earth's distance, or tilt. This mystery is known as the 100,000-year problem.

What are Milankovitch Cycles?

The Earth's path around the sun and its tilt are not always the same. They change slowly over thousands of years. These changes are called Milankovitch cycles. Because of these cycles, the amount of sunlight reaching Earth changes over long periods. These periods are roughly 21,000, 40,000, 100,000, and 400,000 years long.

These changes in solar energy are a big reason why Earth's climate changes. They are very important for when ice ages start and end.

How Do Scientists Study Past Climates?

Scientists study Earth's past climate by looking at layers of rock and ice. They can use a method called isotope analysis. This is like taking a "fingerprint" of the past. One very good way to do this is by looking at a special type of oxygen called Oxygen-18.

The amount of Oxygen-18 found in ice or rock tells scientists two main things:

• How much ice was on the planet at that time.
• What the temperature of the planet was.

What Are the Ideas to Solve the 100,000-Year Problem?

Scientists have several ideas, or hypotheses, to explain the 100,000-year problem:

Is Earth's Climate System Resonating?

One idea is that Earth's climate system might have its own natural "beat" or frequency. This natural beat could be around 100,000 years. It's like a swing that naturally swings back and forth at a certain speed.

Does Earth's Orbit Tilt?

Another idea looks at how the Earth's orbit is tilted compared to the rest of the solar system. This tilt also changes over time, and it has a cycle of about 100,000 years. This might affect how much sunlight reaches Earth.

How Does Ice Build Up and Melt?

The Earth moves around the sun in an oval-shaped path, not a perfect circle. This oval shape changes over time. For Earth, this change happens about every 21,636 years. Scientists think that during an ice age, ice builds up very slowly. But when it's time for the ice to melt, it happens much faster. This difference in speed might help explain the 100,000-year pattern.

Does the Sun's Brightness Change?

It's possible that the sun's own brightness, or luminosity, changes over very long periods. If the sun gets a little brighter or dimmer, it would affect Earth's temperature and could influence the 100,000-year problem.

What About Photosynthesis in Water?

The amount of photosynthesis happening in plants and tiny organisms in the ocean might also play a role. Photosynthesis is how plants make their own food using sunlight. The balance between photosynthesis on land and in the ocean can affect the amount of Oxygen-18. This idea is known as the Dole effect.

Images for kids

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  A record of Oxygen-18 from ice cores in Greenland and Antarctica over the past 140,000 years.

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  An algal bloom. The amount of photosynthesis happening in the ocean might change over 100,000-year periods.

See also

In Spanish: Discrepancia energética de los cien milenios para niños