I teach Phy-Chem and AP Biology in an urban magnet high school. Being a magnet school we draw 65% of our students from the city, New Haven and the remaining 35% from surrounding districts. Phy-Chem is the mandatory freshmen science class and despite the name is heavily focused on environmental sciences. AP Biology is a high school biology class that uses a college curriculum provided by the College Board. Although much of the content and concepts of this unit may be applicable and adaptable to the AP Biology curriculum, the target audience of this unit are Phy-Chem students. This curriculum unit was developed with the Next Generation Science Standards (NGSS) in mind. The state of Connecticut has adopted the NGSS and this unit allows an instructor to effortlessly weave many of them into their classroom activities. The unit will allow one to meet NGSS from chemistry, life science, physical science, and environmental science as well as engineering.
My high school utilizes a block schedule wherein we have four classes per day, each running for about 90 minutes. Students have eight classes total and any given class meets either 2 or 3 times per week. This presents challenges for teachers concerning homework and turn-around time for feedback because of long gaps between class meetings. What the block schedule does offer is a longer class period wherein lab experiments are more easily carried out.
Central components of high school science curriculum are the carbon cycle and climate change. These two topics are robust as stand-alone units, and a cohesive curricular practice is to weave the topics together. The common thread in this case can easily be ocean acidification. A unit on ocean acidification can breathe life, literally, into a carbon cycle unit. As our oceans absorb excess atmospheric carbon dioxide, carbon released by human activity that is also affecting our climate, the millennia-old processes that sequester that carbon are being compromised by the chemical reactions occurring. The acidification of the ocean is disrupting the carbon cycle in ways that we had not previously thought of.
In accordance with the new NGSS standards and the need for a phenomenon to facilitate multi-dimensional learning, ocean acidification presents itself as an effective phenomenon. Through climate change and specifically elevated concentrations of CO
2
in the atmosphere and oceans, humans have significantly increased the concentration of oceanic free hydrogen ions in less than 250 years. These free hydrogen ions (hydronium ions; free protons) are what is reflected by a pH reading. This has resulted in an ocean pH drop from preindustrial times of 8.16 to the present 8.07(1). This rate of oceanic pH change has not been seen for 55 million years. Humans have altered something so massive, the ocean, in a relative “blink” of time when considered on a geologic or evolutionary time scale. Organisms cannot adapt in such a short time frame and we may be on the cusp of the next major extinction event.
This unit will present an explanation of how carbon dioxide released into the atmosphere is resulting in a drop of pH in our oceans. The chemistry will be addressed as well as an explanation of the impacts on shell forming organisms as they are affected directly by a change in seawater alkalinity. The unit will also examine the interconnectedness of marine and terrestrial organisms as we understand that micro and macroscopic organisms in the ocean are the base for enormous food webs that reach beyond the ocean. Furthermore, phytoplankton, which are vulnerable to ocean acidification (2), are responsible for a significant portion of the oxygen production on this planet (3). This unit will also tie in the carbon cycle as it is inextricably linked and impacted by this event. The unit will also discuss some of the more recent findings concerning the immediate impact on organisms, some findings promising and others alarming. Lastly, the possibility of the being on the verge of a major extinction event will be examined. The purpose of the unit is not to prove an extinction event, but merely to force one to consider how significant an impact anthropogenic carbon dioxide may be having on this planet.
