4.4 Climate Change

U4 - The warmed earth emits longer-wave radiation (heat)

- warmed surgace of the Earth absorbs short- wave energy from the sun --> re-emits it at longer wavelengths - most re-emitted radiation is infrared

U5 - Longer-wave radiation is reabsorbed by greenhouse gases which retains the heat in the atmosphere

- 25-30% of short wavelength radiation from the sun is absorbed by atmosphere before it reaches the Earth's surface - most of solar radiation absorbed is ultraviolet light - 70-75% of solar radiation reaches Earth's surface --> converted to heat - 70-85% of longer wavelength radiation is captured by greenhouse gases in the atmosphere --> creates global warming - greenhouse gases in atmosphere only absorb energy in specific wavebands

U6 - Global temperatures and climate patterns are influence by concentrations of greenhouse gases

- concentration of any greenhouse gases increases --> more heat retained --> increase in global average temperatures and more frequent and intense heat waves - other factors influence global average temperatures such as earth's orbit and variation in sunspot activity - high temperatures --> increase evaporation of water from the ocans --> more frequent rains - higher ocean temperatures --> more frequent and powerful tropical storms and hurricanes - rise in global average temperature will most likely not be evenly distributed/spread

A2 - Evaluating claims that human activities are not causing climate change

- earth's temperature is influenced by many factors, not just greenhouse gas concentrations - global warming is continuing byt not with equal increases each year - humans are emitting CO2 by burning fossil fuesls --> strong evidence that CO2 causes warming - claim that human activities are not causing climate change is not supported by evidence

U3 - The impact of a gas depends on its ability to absorb long-wave radiation as well as on its ocncentration in the atmosphere

- factors of warming impact of greenhouse gas: how readily the gas absorbs long wave radiation and the concentration of gas in the atmosphere - ex: methane causes more warming per molecule than CO2 but at a lower concentration in the atmosphere - concentration of gas depends on the rate it is released and how long it remains there - water vapor released quickly into atmosphere and remains there for 9 days vs methane remains in atmosphere for 12 years

U1 - Carbon dioxide and water vapor are the most significant greenhouse gases

- gases in the atmosphere retain heat - cell respiration/combustion of biomass and fossil fuels --> releases CO2 in atmosphere --> removed via photosynthesis and dissolving in oceans - evaporation from oceans/transpiration in plants --> forms water vapor in atmosphere --> removed via rainfall and snow - water reatins heat after it condenses to form droplets of liquid water in clouds --> water absorbs heat --> radiates it back to earth's surface and reflects heat energy back

U8 - Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter

- increasing quantities of coal being mined/burned and the combustion of natural gas and oil --> increasing CO2 emissions - increases in burning fossil fuels (after 1950) --> rises in atmospheric CO2 - higher levels of CO2 emissions than experienced in more than 800,000 years

U7 - There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution 200 years ago and average global temperatures

- large fluctuations in past 80,000 years - glaciations = glacial period; interval of time (1000 years) within an ice age that is marked by colder temperatures and glacier advances - warm interglacial period = periods between glaciers - recent concentrations are near 400 ppm (parts per million) - atmospheric CO2 concentrations used to range between 260-280 ppm until 18th century --> main impact of industrialization happened at the 2nd half of the 20th century - increase in the combustion of coal, natural gas, and oil --> increase in atmospheric CO2 - strong correlation between atmospheric CO2 and global temperatures - relationship not directly proportional because of influences from other factors

U2 - Other gases including methane and nitrogen oxides have less impact

- methane emitted from marshes/waterlogged habitats and landfills --> releases into atmospohere during the extraction of fossil fuels and melting ice in polar regions - nitrous oxide released naturally by bacteria in some habitats, agriculture, and vehicle exhausts - all greenhouse gases together make up <1% of the atmosphere

A3 - Threats to coral reefs from increasing concentrations of dissolved carbon dioxide

- ocean acidification will become more severe if the CO2 concentration of the atmosphere continues to rise - changes in pH of surface layers and current levels - the concentration of carbonate ions that are used by marine animals is already low because they are not very soluble --> dissolved CO2 lowers the carbonate concentration even more - CO2 + H2O --> carbonic acid (H2CO3) --> dissociates into hydrogen and hydrogen carbonate ions (H+ and HCO3-) --> reduces concentration when they react - drop in carbonic ion concentration --> more difficult to build coral reefs, make exoskeletons

A1 - Correlations between global temperatures and carbon dioxide concentrations on Earth

- use ice columns drilled from Antarctica to find CO2 concetration from past - bubbles of ice can be extraacted and analyzed - global temperatures can be deduced from rations of hydrogen isotopes in the water molecules - striking correlation beteen CO2 concentration and global temperatures - higher CO2 concentration --> higher temperatures - rises in CO2 increases the greenhouse effect