Earth's Changing Climate and Rising CO2 Levels

1. Global Annual Emissions / C02 PPM • For 800,000 years CO2 ppm fluctuated between 220 and 280 depending on where the planet was in respect to the normal 100,000 years ice age cycle. • After World War II man began making a lot of stuff, and carbon emissions progressively increased at an alarming rate. • 1950  Carbon emissions to the atmosphere for 1950 hit 2000 million metric tons. CO2 ppm hits 300. • 1988  Carbon emissions to the atmosphere for 1988 hit 6000 million metric tons. CO2 ppm hits 350. • 2013  Carbon emissions to the atmosphere for 2013 hit 9000 million metric tons. C02 ppm hits 400. • 2050  At current trend of carbon emissions CO2 ppm hits 600. • ADDITIONAL TALKING POINTS: In 2009, the United States and China combined accounted for 41 percent of global carbon emissions. The top 5 emitters (U.S., China, India, Russia, and Japan) combined to account for 55 percent of worldwide emissions.*

2. The Carbon Cycle • Today the atmosphere of Mars is 95.32% CO2 , the atmosphere of Venus is 96.55% , and the atmosphere of Earth is .04% CO2 (400 ppm). At one time the atmosphere of Earth also was mostly C02. So where did most of the atmospheric CO2 go? Due to actions of life the CO2 in the atmosphere is now in the earth as carbon, where it is stored in reservoirs such as the ocean, vegetation, fossil fuels, marine sediment, and sedimentary rock. And residue oxygen is in our atmosphere. Fossil fuels include coal, gas and oil. Consequently, the burning of fossil fuels is releasing carbon which is combining with oxygen and returning to the atmosphere as CO2.

3. Negative and Positive Feedback As CO2 Builds Up in the Atmosphere • Negative feedback reduces CO2 in the atmosphere. This includes CO2 fertilization to grow plants and enhanced plant growth in a warmer climate. However, as this new vegetation dies the CO2 is released back into the atmosphere. • Positive feedback increases CO2 in the atmosphere. This includes more fires due to the warmer climate, increased microbes in the soil releasing CO2, release of methane (CH4) from wetlands, and due to warmer conditions reduced solubility of CO2 in the oceans and consequent passing of more CO2 to the atmosphere.

4. Atmosphere Composition, PPM, Life and Radiative Force • What does ppm mean? The atmosphere by volume is about 78% nitrogen, 21% oxygen, .93% argon, .040% C02, and has smaller amounts of NE, helium, methane, hydrogen, and Kr. This means nitrogen is by volume 780,000 parts per 1,000,000 total parts. Oxygen is 210,000 out of 1,000,000. CO2 is 400 parts out of 1,000,000 parts. Thus 400 ppm. All molecules with 3 or more atoms are greenhouse gases. These can vibrate to radiate energy. • The Greenhouse Gas Global Warming Potential (GWP) OF CO2 is assigned 1. Its ppm is 400. Its life is 5-200 years. Its radiative force is 1.5. The ppm of CH4 (methane) is 1.84. Its GWP is 23. Its life is 12 years. Its radiative force is .5. No change to water in the atmosphere. Holding steady as it passes back and forth between the atmosphere and the oceans.

5. Milankovitch Cycles • The eccentricity or orbit cycle of earth is 100,000 years and it not a circular orbit. A circular orbit eccentricity is 0.00. The range for the earth is .005 to 0.058. It currently is 0.017. • The Obliquity or axial tilt cycle is 41,000 years. It ranges from 22.1 to 24.5 degrees and currently is at 23.4. The axis currently points to the North Star. In 30,000 years it will point to Vega. This cycle is caused by the impact of other planets, though the moon stabilizes the impact. • The Precession of the earth has a cycle of 26,000 years. It is also known as the wobbling of the earth similar to a top. The pull of the sun and the moon causes this cycle. • These three cycles cause our ice ages every 100,000 years. • Long story short, mostly due to to the earths orbit it has an ice age about every 100,000 years and then it warms up again. However this temperature difference strictly related to the orbit is not all that great. Let’s examine the warming up process. The earth warms up ever so slightly which begins melting the ice caps. This warm water begins flushing itself throughout all the oceans over a period of about 1000 years. During this period temperatures lead CO2. However as the oceans warm up the CO2 in the oceans becomes more soluble and can enter into the atmosphere. This additional CO2 in the atmosphere accelerates the warming up of the planet, just as explained in earlier slides. As to be expected temperature leads C02 when the temperatures first start cooling due to the earth’s orbit. Over all though CO2 leads temperature 90% of the time.

6. Sometimes Temperature Leads CO2 • Over the last half million years our climate has experienced long ice ages punctuated by brief warm periods called interglacials. The Earth has an ice age about every 100,000 years. When the Earth comes out of an ice age the warming is not initiated by CO2. It is initiated by the Milankovitch Cycles. The warming of the oceans causes the oceans to release the more soluble CO2 to the atmosphere. The CO2 amplifies the warming and mixes through the atmosphere, spreading warming throughout the planet. • Consequently the temperatures lead C02 for periods of 800 to a 1,000 years. Overall about 90% of the global warming occurs after the CO2 increase. • As to be expected temperature also leads C02 as temperatures first start cooling due to the Milankovitch Cycles.

7. How Else Do We Know the Increase in CO2 is from Burning Fossil Fuels • Most of the CO2 In the atmosphere is isotope 12CO2. 1% is isotope 13CO2. A small amount is isotope 14CO2. All 3 have 6 electrons and protons. 12 , 13 and 14 have 6,7 and 8 neutrons respectively. Plants prefer 12C02 because it is lighter. A small but measureable difference. Therefore fossil fuels contain less 13C than the air. Most fossil fuels are at least 16 million years old and no longer have 14C which has a half life of 5,730 years. Adding CO2 from burning fossil fuels or decaying vegetation will decrease the proportion of 13C in the air. Adding CO2 from burning fresh vegetation will increase the proportion of 14C in the air. So how do we know that the increase in CO2 is due to burning fossil fuels? Because 13C in the air is going down! 13C is being diluted by 12C from organic carbon. Also O2 is going down. This is consistent with O2 being burned and converted to CO2.