Lesson 2: What factors, including agriculture, have caused the rise in global temperatures?
Read/view Carbon Cycle diagram and post by Courtney White.
Visit and review the “4 per Mille” website, from the initiative launched at COP21 to increase soil carbon storage by .004% in all world’s managed soils.
View soil carbon videos in supplementary materials, including The Soil Story. (Some of this info will filter in to later lessons geared towards solutions, but is helpful to painting an overall picture of how ag might contribute to vs. solve the problems of climate change).
Warm-up: Step up, Step back game. Have students stand in a straight line. Students take a step forward if they think the following statements are true, and step backwards if they think it is false. Debrief each statement. Statements:
As CO2 levels rise, so do global temperatures. [True]
CO2 is the only greenhouse gas. [False. Others include Methane, Nitrous Oxide, and CFCs/refrigerants].
Agriculture, farming, and food choices can help solve climate change. [True]
Carbon is bad for the environment. [False. Carbon as an element is the building block of life, but excess carbon in the atmosphere is bad for the environment. Need more carbon in the “right” places. Focus of this lesson is the carbon cycle.]
Mini Lesson: Draw a picture of the carbon cycle (globally), and your farm’s carbon cycle (locally; example here with good contextual description). Discuss where carbon is coming from and going to. Emphasize that we want carbon to go from the atmosphere back into the soil, where it belongs and grows healthy plants.
Sources of carbon emissions from agriculture: tilling the soil, cow farts (methane), fertilizer and pesticide production, plant respiration/decay, transporting food long distances, cutting down trees for farmland (and other land use change)
Sources of carbon emissions from other sectors (brainstorm as a group): tailpipe emissions from vehicles, smokestack emissions from power plants (gas and coal), building heating/cooling systems, manufacturing processes, any combustion process e.g. burning wood for cooking or heating (wood stoves), consumption (more abstract). Other sources of GHGs- refrigerants, CFCs, Nitrous Oxide, Water Vapor
Make or bring in model “CO2 molecule” (Example here) to more easily visualize what CO2 molecule looks like and how it traps energy as heat.
Agriculture could be a “sink” or way to lower carbon emissions if practiced differently! Some stats to consider:
FAO Report on climate change, 2017- “Agriculture has been partly responsible for climate change, but is also part of the solution”
U.S. terrestrial land carbon sink: estimated at 640-1,074 million tons CO2-equivalent, according to National Climate Assessment → lots more carbon can go back in the ground where it belongs!
Some estimates say increasing soil carbon storage just 0.4%/year globally could “halt the increase in the CO2 concentration in the atmosphere related to human activities.”
Project Drawdown ranks solutions to climate change, and 8 of the top 20 solutions are from the food and agriculture sector.
Activity 1: Carbon farm walk. Where do you see potential sources of GHG emissions in the farming or food system? How can we reduce these emissions? Where do you see carbon on the farm?
Activity 2: Carbon skit- students act out phases of the carbon cycle, with some students acting as certain carbon reservoirs (soil, trees, atmopshere, ocean), and others passing around token Carbon molecules depending on what activity is described. Full link to activity here (Credit: Janaki Jagannath).
Wrap-up (optional): Play “Greenhouse Gas Freeze tag” (out in/near garden)- Play freeze tag to simulate greenhouse effect. Some players are greenhouse gases, most are rays of sunlight. Earth is at the middle, with “atmosphere” circle around it. Sun rays run in and touch Earth, then try to run out of circle boundary without being tagged by a GHG. When tagged, stay in “atmosphere” as GHG. Eventually, all students “tagged.” Debrief- what are sources of GHGs? How do we, in real life, get these out of the atmosphere? Demo/example (see video below).