The Carbon CycleBackground information

What is the carbon cycle?

0The carbon cycle is the natural flow of carbon through the earth.

0 It is largely influenced by plants, animals, and weather.

0A little bit of carbon -relatively speaking- in the atmosphere is good to have because it keeps our planet from freezing over.

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OIL Natural Gas

What is earth’s AGT?

0Earth’s AGT (average global temperature) has varied over its 4.5 billion year existence.

0Sometimes the AGT has been VERY LOW (an ice ball) and other times, the AGT has been VERY HIGH (no ice).

0 Ice ages occur every 150,000 years and the temperature is reduced about 12 degrees Celsius.

0 Interglacial periods result in warmer temperatures with a rise of only 4 degrees Celsius.

0Such a small change in temperature can result in vastly different environmental conditions.

Carbon influences our AGT0About 200 years ago, CO2 emissions started to influence

earth’s AGT!0CO2 emissions that are most prevalent are CONG:

0 COAL0 OIL0 NATURAL GAS

0CONG will raise earth’s AGT by 6 degrees Celsius by 2100!

0 If that happens, we will not recognize our home anymore: 0 Less water, more diseases and famines, 50% fewer

species, and hardly any capacity to support human life as we know it!

Why does CONG affect our AGT?

0All fossil fuels are made of carbon (C) and hydrogen (H) and when they are burned, they release a HUGE amount of energy.

0The energy is helpful for us, but it comes with a big price tag.

0When fuels are burned, the C and H split and the C bonds with O2 in the atmosphere… which creates CO2 (carbon dioxide).

0A little bit of CO2 is actually good because it keeps our planet from freezing solid, however, we have raised CO2 levels from 280ppm to 392ppm in just a few hundred years.

If we continue to burn carbon at our current rate, we will

reach 450ppm of CO2 in just 30 years.

This means that the AGT will increase by 2 degrees Celsius.

If the temperature rises, more carbon will be released into

the atmosphere.

If more carbon is released into the atmosphere, the temperature will rise and begin a

runaway climate change issue.

What is a carbon sink?

0Humans emit about 9 gigatons of carbon each year (2.2 trillion pounds…the weight of ALL humanity is just 1 trillion pounds).

0Oceans (40%) and land plants (30%) are carbon sinks, because they take up most of the CO2 that would otherwise be released into the atmosphere.

0Our carbon sinks are becoming less and less capable of soaking up CO2 because of the rising temperatures.

0 It’s a horrible feedback loop!!!

Hope for the future?

0The 9 GT of CO2 we emit each year is expected to rise to 16 GT by 2060 due to overpopulation.

0However, our carbon sinks can only hold 4GT of CO2…

0SO, we need to cut our CO2 emissions by 12GT in the next 40 years or so to avoid the runaway climate change that would be the result.

0There is NO WAY to reduce 12GT of our carbon emissions in one year, but some scientists have come up with a way to reduce our CO2 emissions by 1GT every year… Pacala and Socolow.

Sustainability Wedges

How do I know how much I’m contributing to earth’s AGT?0Find out what your ecological footprint is on

earthday.org0Answer slip and turn in. 0We will discuss global actions tomorrow with Pacala

and Socolow’s wedges!0https://www.youtube.com/watch?v=cJ-J91SwP8w