NOTES 20 – The Carbon Cycle, The Greenhouse Effect, and Global Warming

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere

1. Respiration in the mitochondria of plant and animal cells produces CO 2 waste, which is released into the atmosphere

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 2. Photosynthesis in plants (land) and algae (water) remove CO 2 from the atmosphere to make glucose during photosynthesis

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 2. Photosynthesis in plants (land) and algae (water) remove CO 2 from the atmosphere to make glucose during photosynthesis

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 2. Photosynthesis in plants (land) and algae (water) remove CO 2 from the atmosphere to make glucose during photosynthesis

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 2. Photosynthesis in plants (land) and algae (water) remove CO 2 from the atmosphere to make glucose during photosynthesis

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 2. Photosynthesis in plants (land) and algae (water) remove CO 2 from the atmosphere to make glucose during photosynthesis

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 3. Combustion (burning) of wood, coal, oil, and natural gas add extra CO 2 to the atmosphere

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 3. Combustion (burning) of wood, coal, oil, and natural gas add extra CO 2 to the atmosphere

The carbon cycle continuously moves carbon dioxide (CO2) into and out of the Earth’s atmosphere 3. Combustion (burning) of wood, coal, oil, and natural gas add extra CO 2 to the atmosphere

Natural CO 2 Cycle Disrupted On a global scale, the amount of CO 2 put into the atmosphere by respiration is equal to the amount of CO 2 removed by photosynthesis. On a global scale, the amount of CO 2 put into the atmosphere by respiration is equal to the amount of CO 2 removed by photosynthesis. Humans have changed the carbon cycle. The burning of wood and fossil fuels like coal and oil adds more CO 2 to the atmosphere. As a result, the CO 2 level in the atmosphere is increasing. Humans have changed the carbon cycle. The burning of wood and fossil fuels like coal and oil adds more CO 2 to the atmosphere. As a result, the CO 2 level in the atmosphere is increasing.

Average Monthly CO

Is CO 2 in the atmosphere good or bad? It depends on the amount It depends on the amount Carbon dioxide is a greenhouse gas, which means that it traps heat close to the Earth’s surface Carbon dioxide is a greenhouse gas, which means that it traps heat close to the Earth’s surface This makes the Earth warmer This makes the Earth warmer

Carbon dioxide is a greenhouse gas which means that it traps heat close to the Earth’s surface which makes it warmer

1. Solar radiation (heat) arrives from the sun and enters the Earth’s atmosphere

Carbon dioxide is a greenhouse gas which means that it traps heat close to the Earth’s surface which makes it warmer 2. The solar radiation reaches the Earth’s surface where some is absorbed and some is reflected

Carbon dioxide is a greenhouse gas which means that it traps heat close to the Earth’s surface which makes it warmer 3. The reflected solar radiation goes back into the atmosphere. Some escapes into space and some is trapped by greenhouse gasses like CO 2.

Carbon dioxide is a greenhouse gas which means that it traps heat close to the Earth’s surface which makes it warmer 4. The trapped solar radiation warms the Earth. Normally, this is good. Without the greenhouse effect, Earth would be too cold to support life.

Too much of a good thing? More CO 2 in the atmosphere means more heat is trapped which means the average temperature of the Earth increases. More CO 2 in the atmosphere means more heat is trapped which means the average temperature of the Earth increases. I like warm days so why should I be concerned about an increase in average global temperatures? I like warm days so why should I be concerned about an increase in average global temperatures?

Consequences of Global Warming Sea-level rise (coastal flooding) Sea-level rise (coastal flooding) Drought and Wildfire increase Drought and Wildfire increase Deadly heat waves Deadly heat waves Spread of disease (mosquito range expanded) Spread of disease (mosquito range expanded) More powerful hurricanes More powerful hurricanes Ecosystem disruption/species die- offs Ecosystem disruption/species die- offs

Is Global Warming a fact? Yes Yes The Earth is definitely getting warmer, and is expected to continue to do so in the future The Earth is definitely getting warmer, and is expected to continue to do so in the future The real debate is whether or not humans are contributing to global warming, and if so, what should be done about it The real debate is whether or not humans are contributing to global warming, and if so, what should be done about it

Intergovernmental Panel on Climate Change (IPCC) Conclusion The IPCC concludes that most of the observed temperature increase since the middle of the 20th century was very likely caused by increasing concentrations of greenhouse gases which they believe result from human activity such as fossil fuel burning and deforestation. The IPCC concludes that most of the observed temperature increase since the middle of the 20th century was very likely caused by increasing concentrations of greenhouse gases which they believe result from human activity such as fossil fuel burning and deforestation. Greater than 90% likelihood that most warming over the last 50 years has occurred because of human-caused emissions Greater than 90% likelihood that most warming over the last 50 years has occurred because of human-caused emissions

But some skeptic scientists believe… …that the temperature increase has not been caused by an increase in greenhouse gases OR… …that the temperature increase has not been caused by an increase in greenhouse gases OR… …that the increase in greenhouse gases has not been caused by human activity …that the increase in greenhouse gases has not been caused by human activity Could it all be part of a larger natural warming cycle? Could it all be part of a larger natural warming cycle?

What should humans do? Carry on as usual and hope for the best? Carry on as usual and hope for the best? Stop burning fossil fuels? Stop burning fossil fuels? Figure out ways to adapt to higher average global temperatures? Figure out ways to adapt to higher average global temperatures?

Concerned? Use less stuff and convince others to do the same – “You must be the change you wish to see in the world” Use less stuff and convince others to do the same – “You must be the change you wish to see in the world”