CEW - Climate Change Lesson

 

Climate Change

Variations in climate over time are normal. For millions of years, the Earth has gone through cold and warm spells - some of which are short and others that last 1,000's of years. Through these cold periods, glaciers spread over large regions and then during hotter times, the ice retreats. These cold and warm periods have had profound effects on the landscape, plants, and animals. The most recent cooling off period from 1850, referred to as the "Little Ice Age" spread over parts of Western Europe. The winters were bitterly cold and the summers were cool and wet. The change in climate led to widespread crop failure, famine, and population decline.

The reconstructed depth of the Little Ice Age varies between different studies (anomalies shown are from the 1950-80 reference period).

There are many natural processes that can change the climate.

• Volcanic eruptions - Volcanoes emit aerosols into the atmosphere. This affects the amount of sunlight reflected back into space, which can cause the Earth's temperatures to fluctuate.
• Ocean circulation - Changes in the ocean's water currents can cause short-term climate variations.
• Plate tectonics - The moving of plate tectonics can have long term effects on climate. The formation of mountains can cool the climate by removing carbon dioxide from the air.
• Earth's orbital motions - The Earth's orbit, as well as tilt changes over time, can also have an effect on time scales. The Earth's orbit rotates between being more and less elliptical. This affects the distance from the sun, which then changes climate.
• Solar activity - On average, the amount of solar radiation given off by the sun increases over time. The presence or absence of sunspots can have a short term impact on climate. A sunspot is a dark, cooler region on the surface of the sun. They may reduce the amount of solar energy that reaches the Earth.

While slight, slow variations in climate are normal, since the beginning of the 20^th century, temperatures have risen at a steady rate throughout the world. According to the Japan Meteorological Agency (JMA) 2014 "The average temperature was 1.1°F above the 20th century average" Source: Climate Central, January 5, 2015). In addition to being a record breaking year for temperatures, 2014 included record breaking droughts, flooding, cold winters, and record heat waves world wide.

It is unsure how much of this warming is due to the natural ebb and flow of global climate or how much of it is coming from human activities.

Watch this video and think about the questions below:

 

Click the questions below to see the answers.

Effects of Climate Change

For the past century, the Earth's temperature has increased over 1º F and scientists predict it will rise 3º to 10º over the next 100 years. Think about the effects that will have on local vegetation, weather patterns, and over all existence.

Watch the video below:

 

Why should we care about this rise in temperatures? Aren't fluctuations in temperature normal? Yes they are, but scientists are worried about the rate of change. Living things, including humans, can adapt to changes in climate that take place slowly, over 1,000's of years. However, adapting to the changes that are happening on a smaller time scale such as decades is hard.

We can see the effects of climate change already. Increased temperatures have caused some snow and ice to melt and the oceans to rise. There are some plants that are growing outside of their normal range or typical seasons and some animal migration patterns have been interrupted or changed (which is often based off of seasons).

Learn more in the video below:

 

While there are many natural forces that can change global climate, human activity is having one of the greatest impacts and increasing the rate at which the global climate is changing.

Watch NASA's video on climate change:

 

There is a positive correlation between temperature and carbon dioxide or CO₂ in the air. Carbon dioxide is a greenhouse gas that traps heat from the Earth and holds it in the atmosphere. Scientists have learned that, throughout Earth's history, temperature and CO₂ levels in the air are closely tied.

Complete the climate change activity:

 

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