Assumption College Mathayom 1, Foundation Science Miss Anna

Essential question: What are the causes and effects of climate change?

P. 239, #1: Predict True or false: There have been periods on Earth when the climate was colder than the climate is today.

Answer: TRUE!

True or false? The ocean does not play a role in climate.

Answer: FALSE!

True or false? Earth’s climate is currently warming.

Answer: TRUE!

True or false? Humans are contributing to changes in climate.

Answer: True!

Vocabulary Ice age Greenhouse effect Global warming

What are some natural causes of climate change? Movement of tectonic plates

The continents once fit together as a single land mass called “Pangaea” Pangaea started to break up about 200 million years ago By 20 million years ago, the continents had moved to their current positions Some continents grew warmer as the moved towards the equator; others grew colder as they moved closer to the poles

Pangaea

p. 240, #5 Infer Today, Antarctica is the coldest desert on Earth. But fossils of trees and dinosaurs have been found on this harsh continent. Explain how life could thrive on ancient Antarctica.

Answer to 5: Antarctica once had a warmer climate because it was closer to the equator when it was in Pangaea

What are some natural causes of climate change? Particles in the atmosphere Short-term changes in climate can be due to natural events that send particulates (tiny, solid particles that are suspended in air or water) into the atmosphere These particulates absorb some of the sun’s energy and reflect some of the sun’s energy back into space This process temporarily lowers the temperatures on Earth

Where do particulates come from? Asteroid impacts 65 million years ago, dinosaurs may have gone extinct due to an asteroid impact Volcanic eruptions Clouds of ash and gases are released into the atmosphere; particulates from these circle Earth

p. 241 Describe Give one example of a long-term and one example of a short-term change in climate caused by natural factors

Answer Example of long-term climate change: tectonic plate motion, which changes the climate of continents Example of short-term change: a volcanic eruption that releases particulates into the atmosphere.

What are some causes of repeating patterns of climate change? Sun Cycles Most of Earth’s energy comes from the sun Output from the sun is slightly higher during times of higher sunspot activity Sunspots: dark areas on the sun that appear and disappear (cycle of about 11 years)

What are some causes of repeating patterns of climate change? El Niño and La Niña Changes in ocean temperature also affect climate During El Niño years, temperatures are higher than usual in the tropical Pacific Ocean; the warmer water causes changes in global weather patterns The opposite effect occurs during La Niña years: ocean temperatures are cooler than normal in the equatorial eastern Pacific Ocean El Niño and La Niña conditions usually alternate, and both can lead to conditions such as drought or flooding

Flood caused by El Niño

What are some causes of repeating patterns of climate change? Ice Ages Earth’s climate has been both warmer and colder than it is today Earth’s history contains many ice ages Ice age: a long period of cooling during which ice sheets spread beyond their polar regions.

Ice Ages Geologic evidence indicates that ice ages occur over widely spaced intervals of time: approximately every 200 million years Each ice age lasts for millions of years The most recent ice age began about 2 million years ago; large ice sheets still cover Greenland and Antarctica

p. 243, #10 List What are some possible causes of ice ages?

Possible Answers Changes in Earth’s orbit Shifts in the balance of incoming and outgoing solar radiation Changes in heat exchange rates between the equator and the poles

How do humans effect climate change? Although natural events cause climate change, human activities may also effect Earth’s climate Human activities can cause the planet to warm when greenhouse gases are released into the atmosphere These greenhouse gases warm Earth’s surface and atmosphere by a process known as the Greenhouse effect

How do humans effect climate change? The greenhouse effect is the process by which gases in the atmosphere absorb and radiate energy as heat back to Earth Greenhouse gases include carbon dioxide, water vapor, methane, and nitrous oxide Without greenhouse gases, energy would escape into space, and Earth would be colder Two ways humans release greenhouse gases into the atmosphere are (1) burning fossil fuels and (2) by deforestation

How do humans effect climate change? (1) Burning fossil fuels There is evidence to support that humans are causing a rise in global carbon dioxide levels burning fossil fuels (such as gasoline and coal) adds greenhouse gases to the atmosphere Surface temperatures of the Earth are rising with increased carbon dioxide emissions

(1) Burning Fossil Fuels

Carbon sources vs Carbon Sinks Some processes, such as burning fossil fuels, add carbon dioxide and other carbon based gases to the atmosphere Processes that emit carbon into the atmosphere are called carbon sources Processes such as growth of plants and trees remove carbon from the atmosphere Processes that remove carbon from the atmosphere are called carbon sinks

How do humans effect climate change? (2) Deforestation Deforestation is the mass removal of trees for farming, timber, and development The loss of trees represents the loss of an important carbon sink Deforestation often includes the burning of trees, which is another source of carbon dioxide

p.245, #12 Describe How does deforestation affect the amount of carbon dioxide that is in the atmosphere?

Answer: Deforestation destroys plants and trees that remove carbon dioxide from the atmosphere. Burning trees increases the amount of carbon dioxide that is released into the atmosphere.

Global Warming Global warming is the gradual increase in average global temperature Global warming will affect global weather patterns, global sea level, and life on Earth

Global warming effects on the atmosphere Scientists predict that as the Earth gets warmer, the weather will become more severe They predict that storms will become more powerful and occur more frequently They also predict that as much as half of Earth’s surface may be affected by dought

Global warming effects on the hydrosphere and cryosphere As temperatures on Earth increase, some of the ice on Earth’s mountains and glaciers will melt When ice on land melts, global sea levels rise because water flows into the ocean Higher sea level is expected to increase flooding in costal areas

p. 246 Infer :How do melting ice caps and glaciers affect sea level?

15 Answer: As ice caps melt, sea levels rise globally

Global warming effects on the biosphere Scientists predict that global warming will change ecosystems These changes may threaten the survival of many plant and animal species

How can people reduce their impact on climate change? Reduce greenhouse gas emissions Reduce use of fossil fuels Turn off lights Replace light bulbs as needed Recycle

How can people reduce their impact on climate change? Use new technologies Clean-energy technologies, such as solar and wind power Reduce the rate of deforestation Plant trees, provide education

What are some economic and political issues related to climate change? The cost of climate change includes the costs of crop failure, storm damage, and human disease; developing countries may not be able to afford technologies needed to reduce human impact on climate Political action can lead to regulations that reduce greenhouse gas emissions. These laws may be challenged by groups who disagree with the need for changes.

Visual Summary p ) Tectonic plates have moved across Earth’s surface over time and once formed a super-continent called Pangea

Visual Summary, p ) Scientists think that there is a connection between rising levels of carbon dioxide and rising temperatures

Visual Summary, p ) If average global surface temperatures continues to rise, then severe storms may become more frequent.

Visual Summary p. 252 People can reduce their impact on climate change by reducing greenhouse emissions and deforestation, and by using new technologies

p. 252 #29 Synthesize How can burning fossil fuels cause global warming?

Sample Answer: Burning fossil fuels releases carbon dioxide, a greenhouse gas. Greenhouse gases warm Earth’s surface and lower atmosphere by absorbing some of the energy that would escape into space and reradiating that energy back to Earth.