Exercises: Consequences and sustainable habits

Name three consequences of climate change and briefly explain one of them.

Order the three Rs — recycle, reduce, and reuse — according to their environmental priority and give an everyday example of each.

What is a carbon footprint? Name two actions from your daily life that would reduce it.

Name two consequences of climate change for people and two for nature.

Explain what a heat wave is and cite two precautions that should be taken during one.

State which bin each item of waste should go in and explain why separating them is important: a glass bottle, a battery, a banana peel, a can, and a plastic bag.

Explain what responsible consumption is and give an example of a sustainable purchasing decision.

Many devices keep using electricity on standby even though they seem to be off. Name two examples from home and explain which habit avoids this consumption and how it helps the climate.

Explain two causes of sea level rise (the melting of ice caps and glaciers, and the thermal expansion of water as it warms) and one consequence for coastal areas and islands.

The "One Health" approach links human health, animal health, and ecosystem health. Explain this using an example, such as the spread of disease-carrying mosquitoes due to rising temperatures.

Your high school wants to become more sustainable. Propose three specific measures (one regarding energy, one regarding transportation, and one regarding waste) and justify each one.

Sea level rise threatens deltas such as the Ebro delta. Explain two effects it can have on that ecosystem and on the human activities carried out there.

With rising temperatures, many plants flower earlier and some birds start their migrations earlier. Explain what problem arises if flowering and the arrival of pollinating insects become out of sync.

Corals expel the algae they live with when the water gets too warm (coral bleaching) and can die. Explain what this phenomenon consists of and why the loss of a reef affects the entire marine food web.

Composting organic waste prevents it from decomposing in a landfill and releasing methane, and it also produces natural fertilizer. Explain this double benefit for the climate and for the soil.

Your family wants to reduce its carbon footprint. Propose a plan with three changes (food, transportation, and energy) ordered according to the emissions savings you estimate for each one, justifying the order.

The graph shows the average daily direct $\text{CO}_2$ emissions per student according to the means of transportation used to travel to school.

1. a) A high school with 300 students who currently travel alone by private car is considering two emission-reduction measures for a school year of 180 school days:

• Option 1: Create a city school bus route that manages to attract 60% of those students.

• Option 2: Build a secure bicycle parking facility that gets 30% to cycle and another 20% to carpool (at a rate of 4 students per vehicle, dividing car emissions by 4).

Quantitatively calculate the total $\text{CO}_2$ savings (in kg) that would be obtained with each option and justify which one is more effective.

1. b) A classmate claims that the graph proves that cycling has zero environmental impact (0 kg of $\text{CO}_2$) under any circumstance. Refute this statement by distinguishing between direct emissions during use and indirect emissions throughout its entire life cycle.

In a natural park in southeastern Spain, increasingly prolonged droughts and recurrent heat waves are being recorded. Technicians observe that reforested pine stands are dying due to water stress and bark beetle infestations (scolytids), which drastically increases the risk of large wildfires.

1. a) Explain the positive feedback loop generated between drought, the weakening of forest cover, wildfires, and the intensification of climate change at a regional level.
2. b) In response to this problem, two measures are debated: 1) watering the pine stands with tanker trucks in summer; 2) progressively replacing the dead pines with mosaics of Mediterranean maquis and native oak species (holm oaks, wild olives) adapted to aridity. Justify which of the two measures represents genuine ecological adaptation and which is unfeasible in the medium term.

In the municipal plenary session of a town of 4 000 inhabitants, the budget to install community composters and pedestrian lanes is being debated. A councilor argues: "Our emissions are 0.001 % of those of the region; if large metropolises do not act, whatever we do here is a waste of money that will not alter the global climate."

1. a) Refute the councilor's stance by applying the motto "Think globally, act locally", using the concepts of ecological co-responsibility and multiplier effect.
2. b) Describe in detail the biological or physical mechanism by which collecting and composting organic waste instead of depositing it in a conventional landfill prevents the emission of a potent greenhouse gas into the atmosphere.

The average annual carbon footprint of a citizen in Spain is distributed approximately as follows: transportation (2.1 t of $\text{CO}_2$), heating/cooling and electricity consumption at home (1.6 t), food (1.3 t), and consumption of manufactured goods (0.9 t).

A person sets a goal to reduce their total footprint by at least 20 % in one year and is hesitating between two independent alternatives:

• Alternative A: Replace all light bulbs with state-of-the-art LEDs and always turn off appliances on standby, achieving a 10 % reduction in home energy consumption.

• Alternative B: Replace their private vehicle with public transportation and a bicycle for their regular commutes, reducing their transportation impact by 40 %.

1. a) Calculate the baseline footprint and verify quantitatively whether either of the two alternatives allows reaching the 20 % target.
2. b) Many people believe that acting only on domestic electricity savings is enough. Based on the numerical results, justify why having an impact on transportation and diet is quantitatively much more decisive in curbing global warming.

In an agricultural region in the southern part of the country, persistent droughts and spring heat waves have caused a 40 % loss in rainfed cereal harvests, making bread and livestock feed more expensive.

1. a) Design a cause-and-effect flowchart connecting five successive stages: anthropogenic greenhouse gas emissions $\rightarrow$ climate alteration $\rightarrow$ physiological process in the plant $\rightarrow$ agricultural production $\rightarrow$ socioeconomic impact on the population.
2. b) To buffer the losses, one group of farmers proposes overexploiting the local underground aquifer to flood-irrigate the cereal, while another proposes using regenerative agriculture techniques (no-till farming on stubble and crop rotation with legumes). Justify which of the two proposals is a sustainable adaptation and which one results in "maladaptation".

A coastal town is debating between building a concrete seawall or restoring the dune system and the coastal wetland. Compare both adaptation options (cost, benefits for biodiversity, long-term effectiveness) and defend one of them.

Producing 1 kg of beef requires around 15 000 L of water and emits about 27 kg of $\text{CO}_2\text{ eq}$, whereas producing 1 kg of legumes (chickpeas or lentils) requires about 1 300 L of water and emits about 0.9 kg of $\text{CO}_2\text{ eq}$.

1. a) Apply the 10 % rule on the transfer of biomass and energy between consecutive trophic levels to justify biologically why the ecological and water footprint of primary consumers (livestock) is inevitably much higher than that of primary producers (edible plants).
2. b) A school cafeteria serves 250 people per day. Its menu currently includes beef two days a week (150 g per serving). If both weekly servings were replaced by equivalent servings of legumes over a 4-week school month, calculate how many liters of water would be saved and argue two benefits of this measure to mitigate climate change.

Analyze the following climate and socioeconomic data corresponding to two countries:

• Country A (small Pacific island state): Emits 0.6 t of $\text{CO}_2$ per capita annually. Maximum elevation: 3 m above sea level. Main impacts: soil loss due to marine erosion and salinization of potable freshwater.

• Country B (high-income industrialized nation): Emits 13.8 t of $\text{CO}_2$ per capita annually. Has high financial capacity and technology to build sea walls and desalination plants.

1. a) Based on the data, justify why the impact of climate change generates a climate injustice situation, distinguishing between "responsibility for emissions" and "socio-environmental vulnerability".
2. b) At an international climate summit, Country B proposes that all countries in the world reduce their emissions by exactly the same percentage (20 %) and that each country pay for its own defense works. Argue in a reasoned manner why this measure violates the principle of equity and predict what consequences it would have on the population of Country A if loss and damage compensation funds are not implemented.

Topic Challenge. What is your household's carbon footprint and how can you reduce it? Become an environmental auditor by following these phases:

1. Causes and data collection: Find a recent household electricity bill and write down the consumption in $\text{kWh}$ (if you do not have one, use an average of $270\text{ kWh}$). Check the daily energy mix on the U.S. Energy Information Administration (EIA) website and calculate your household's monthly emissions using an average factor of $0.25\text{ kg CO}_2/\text{kWh}$.

2. Consequences in your area: Go to the NOAA climate change viewer and check the recent temperature anomaly for your state. Write a short paragraph explaining how the increase in greenhouse gases intensifies local problems such as heat waves, drought, or biodiversity loss.

3. Action plan (final product): Design a brief report (one page) with a summary table of your emissions and a proposal of three realistic sustainable habits to reduce the family footprint by $15\,\%$, explaining their environmental impact.

Evaluation criteria:

• Accuracy in calculating emissions from real sources and data.

• Clear scientific connection between emitting activities and local consequences.

• Feasibility and ecological justification of the proposed sustainable habits.