Unit 5 Seminar Carbon dioxide

The Carbon Cycle Carbon comes into the living world through the plants, algae, and bacteria that take in atmospheric carbon dioxide to perform photosynthesis. Animals obtain their carbon from these photosynthesizing organisms.

The Carbon Cycle The carbon cycle is completed when carbon moves back into the atmosphere in the form of carbon dioxide, which is produced naturally through two processes: –the respiration of living things –the decomposition of them following their death

The Carbon Cycle Figure 35.1 atmospheric CO 2 photosynthesis respiration animals plants dead organisms fossil fuels decomposition by bacteria and fungi burning of fossil fuels The carbon cycle Plants and other photosynthesizing organisms take in atmospheric carbon dioxide (CO 2 ) and convert or “fix” it into molecules that become part of the plant. The physical functioning or respiration of organisms converts the carbon in their tissues back into CO 2. Plants and animals die and are decomposed by fungi and bacteria. Some CO 2 results, which moves back into the atmosphere. Some of the carbon in the remains of dead organisms becomes locked up in carbon-based compounds such as coal or oil. The burning of these fossil fuels puts this carbon into the atmosphere in the form of CO 2. Source: Krogh, D. (2009). Biology: A Guide to the Natural World. Pearson Benjamin Cummings

The Carbon Cycle Carbon dioxide makes up a small but critical proportion of the Earth’s atmosphere. It is vital to life and greatly affects global temperature.

Global Warming

The Earth’s atmospheric temperature is increasing through the phenomenon known as global warming. Scientists can now state with at least 90 percent certainty that most of the global warming seen since 1950 has come about because of human activities – deforestation –emission of such gases as carbon dioxide and methane into the atmosphere.

Global Warming Global temperatures risen 0.74 o C since 1906 to 2005 Warming trend over last 50 years nearly twice that for the last 100 years

Growing Concentration of Atmospheric CO 2 Beginning of industrialization Carbon dioxide levels over the last 10,000 yearsA closer look at the last 250 years Source: Krogh, D. (2009). Biology: A Guide to the Natural World. Pearson Benjamin Cummings

The Greenhouse Effect CO 2 and methane are referred to as greenhouse gases –trap additional quantities of the heat that comes to the Earth from the sun. –lower energy radiation (heat) cannot penetrate layer of gases

The Greenhouse Effect Figure heat trapped greenhouse gases reflection of low-energy radiation (heat) high-energy sun rays Source: Krogh, D. (2009). Biology: A Guide to the Natural World. Pearson Benjamin Cummings

Global Warming Deforestation—today, primarily of tropical forests –puts CO 2 into the atmosphere directly, when trees are burned –results in less CO 2 being taken out of the atmosphere trees that are destroyed no longer take up CO 2 to perform photosynthesis.

Global Warming The Earth appears to have warmed by 0.74°C or about 1.3°F in the 100 years that ended in 2005, according to our most authoritative source on global warming, the Intergovernmental Panel on Climate Change (IPCC).

Disappearing Glaciers Figure Source: Krogh, D. (2009). Biology: A Guide to the Natural World. Pearson Benjamin Cummings

Global Warming In 2007, the panel predicted that, over the course of the twenty-first century, the Earth is likely to warm by an addition 1.8°C to 4.0°C, depending on the additional quantity of greenhouse gases put into the atmosphere.

Global Warming The consequences of this warming –a rise in sea levels –more intense tropical storms –less snow cover globally – permafrost that thaws to increasing depths.

Rise in Sea Level 6 meters (~20 ft) sea level rise No greenhouse gases reduction

Habitat Changes: Disappearing Arctic Ice Figure Source: Krogh, D. (2009). Biology: A Guide to the Natural World. Pearson Benjamin Cummings

Australian Passerine Birds Body Size Australia average surface temp risen more than 1 o F since 1900 Passerine body size decreased by 3.6% Individuals within a species are larger the closer to a pole Smaller birds now live somewhat closer to the South Pole Nutritional deficiencies not found Jacky winter

Habitat Changes Alpine mountain regions –Native plants and animals driven to higher elevations

Global Warming Global warming cannot be stopped, the IPCC said, but it can be lessened in accordance with future human activities. –Use less energy –Reduce fossil fuel use –Store CO 2 –Slow tropical rain forest destruction

Seminar Questions If there is strong evidence indicating that CO2 levels contribute to global warming, why is the United States opposed to any reductions? Is there any science supporting those who do not wish to reduce fossil fuel CO2 emissions? If we choose to reduce fossil fuel emissions significantly, how might we do so in a way that does not damage our economy?

Seminar Questions Is there a fair method globally to reduce CO2 emissions? Support your answer. If we decide to wait until the climate is clearly too warm for the human species, is there a technological quick fix? What can be done to monitor the situation?

Questions?