Stratospheric ozone is important as protection from harmful ultraviolet solar radiation. Ozone in the stratosphere blocks almost all UVC radiation, which is extremely energetic and harmful. Ozone within the ozone layer is destroyed through chemical reactions involving chlorine atoms and the ozone molecules. The main anthropogenic source of chlorine in the atmosphere is chlorofluorocarbons (CFCs). Emissions of CFCs began to increase after 1960 and continued to increase until the 1990s.

There are two ozone problems in the atmosphere. Tropospheric ozone in the form of photochemical smog is sometimes dangerously high whereas stratospheric ozone concentration is sometimes dangerously low. Photochemical smog is created through chemical reactions between UV radiation from the run and nitrogen oxides that are emitted from automobiles. High concentrations of tropospheric ozone are dangerous because of the damage ozone can cause to a person’s airway if it is inhaled. The EPA has specified limits of ozone concentration but several counties in the USA exceed these limits.

Climate sensitivity is defined as either the temperature change resulting from a doubling of atmospheric carbon dioxide concentration or the temperature change resulting from a 1W/m2 increase in radiative forcing. There are several different climate sensitivities that take into account different feedbacks in the climate system. The simplest climate sensitivity is black body sensitivity, which does not account for any feedbacks but gives the temperature change resulting just from a change in radiative forcing.

Several greenhouse gas emissions scenarios have been developed by the IPCC to determine possible affects on atmospheric greenhouse gas concentrations and related climate warming. The largest estimates show a carbon dioxide concentration of about 800ppmv by the year 2100. Lower estimates rise to 450ppmv by the year 2100. The amount of projected warming associated with these emissions scenarios range from about 2-4°C. Several possible disadvantages and advantages of such a warming are discussed, as well as possible methods to reduce global warming.

The current Holocene epoch is considered to be a time period of relatively stable climate compared to earlier geological periods. Still, some significant changes in temperature and sea level did occur. These climatic fluctuations include the Medieval Warm Period and the Little Ice Age, and more recently global warming. Temperature data for the 20th century shows a strong warming from about 1970 to the present day, typically associated with anthropogenic forcing including greenhouse gas and aerosol emissions.

The issue of global warming is discussed. Recent climate change over the last half of the 20th century is thought to be driven largely by greenhouse gas emissions, with carbon dioxide playing a large role. The carbon cycle describes the reservoirs of carbon (atmosphere, terrestrial biomass and ocean) and the exchanges that occur between these reservoirs. Inputs of carbon to the atmosphere include burning of fossil fuels and respiration from biomass.

Isotopes are used to measure past climate properties. Deuterium and oxygen 18 are the most commonly used climate proxies. Lighter isotopes evaporate more readily from the ocean, so water vapor in the atmosphere is isotopically lighter than ocean water. This vapor gets lighter still as it is transported to higher latitudes while losing mass by precipitation. These processes leave an isotopic signal of temperature and continental ice volume in ice cores and deep sea sediment cores.

The atmosphere forces the ocean in three ways: addition and removal of heat, precipitation and evaporation, and wind stress. The former two processes influence the density of sea water. Gravity acts on these density differences to cause large-scale thermohaline currents Wind driven ocean currents are forced by the wind stress acting on the ocean surface which indirectly causes geostrophic currents.

Discoverers of the structure and biological activity of steroid hormones won seven Nobel Prizes between 1927 and 1975. Studying the steps involved in Woodward's 1951 "total" synthesis of cortisone provides a review of the organic reactions covered this semester. Many steps involved novel insights, others were based on lore from previous work in the area. The overall yield of such sequential syntheses is typically much lower than that of convergent syntheses. Practical syntheses of cortisone were based on modification of related steroids readily available from nature.

Modern spectroscopic tools show not only the constitution, configuration, and conformation of glucose but also how it interconverts between isomeric hemiketal pyranose rings. One of mankind's great accomplishments was determinining its constitution and especially its configuration before such spectroscopy. By 1887 Heinrich Kiliani had established the constitution of glucose as an aldohexose, and with help from Emil Fischer, he developed a method for homologating aldoses.