The Carbon Cycle and Climate Change What’s the Connection?

The Carbon Cycle Carbon cycles throughout the biosphere, atmosphere, hydrosphere and geosphere continuously. http://www.co2logic.com/home.aspx/en/our+climate/the+carbon+cycle

Global Warming Global warming, or the enhanced greenhouse effect, is due to an increase in greenhouse gases in our atmosphere, most notably carbon dioxide. Atmospheric carbon dioxide concentrations have increased by 30% during the past 200 years. The concentration today is almost 370 parts per million (0.037%). Human activities such as burning of fossil fuels and deforestation are thought to be responsible for the rapid increase in carbon dioxide concentrations. http://www.dar.csiro.au/publications/greenhouse_2000d.htm

The global carbon cycle. Numbers represent the mass of carbon, in gigatonnes of carbon (Gt C). (A gigatonne is a thousand million tonnes.) Source: Wheeling Jesuit University/NASA (2000)

How Does Ocean Water Carbon Exchange Affect Climate? As ocean water warms up, its molecules move faster and CO2 can be released to the atmosphere. The more CO2 there is in the atmosphere, the warmer the climate becomes, because CO2 is a greenhouse gas and absorbs infrared radiation (heat) from the sun. AND, VICE VERSA (see next page)

How Does Ocean Water Carbon Exchange Affect Climate? Cold ocean water absorbs more carbon dioxide (CO2) from the atmosphere than warm ocean water (the molecules are moving slower). As water cools down it absorbs more and more CO2. The less CO2 there is in the atmosphere, the cooler the atmosphere becomes. Eventually, an ice age can form. Cool, huh! Brrrrr…….

Earth’s Climate History Earth’s climate changes drastically depending on the amount of CO2 in the atmosphere. The oceans play a huge role in regulating this amount of change in climate. The dashed line in each graph is the Mean Global Temperature Relative to Present Day.

Ice Ages & Warming Trends (Interglacial periods) There have been many ice ages in Earth’s past. The average surface temperature has ranged from 10oC warmer to 6oC cooler than today’s average climate. Plate tectonics and Continental Drift have played huge roles in creating ice ages and warming trends. There have been times when the entire planet was covered in ice; this condition is called “Snowball Earth.”

How Does Earth Come Out of an Ice Age and Enter an Interglacial Period? Volcanic activity spews massive amounts of CO2 gas into the atmosphere eventually warming the Earth and atmosphere. An Interglacial Period begins. “Inter” means “between”. “Glacier” means “ice”. Interglacial means a time between ice ages (a warming trend).

Tilt of Earth’s Axis & Eccentricity of Earth’s Orbit Affect Global Climate The more Earth’s axis is tilted, the more variable the climate, with certain areas of Earth receiving more or less of the Sun’s radiation. The Milankovitch Theory states that “The closer Earth is to the Sun in its elliptical orbit, the warmer the Earth becomes. This orbit takes about 100,000 years.” Some researchers still have doubts about the association between the 100,000-year climate cycle and orbital variations. Thus, many questions remain about long-term climate variations and their relationship, if any, to astronomical causes. http://aa.usno.navy.mil/faq/docs/seasons_orbit.html