The causes of climate change

Explain the difference between weather and climate, and give an example of each.

The diagram represents the greenhouse effect in four numbered steps.

1. a) Explain what happens in each of the steps labeled with the numbers 1 to 4.
2. b) Which number corresponds to the heat returned by the atmosphere toward the surface?
3. c) Name two greenhouse gases.

Explain in your own words what the greenhouse effect is and why it is called that.

The greenhouse effect is a natural phenomenon necessary for life. Explain why this is so and clarify the current problem (the enhanced greenhouse effect due to human emissions).

Following the eruption of Mount Pinatubo in 1991, the global average temperature dropped by about 0.5 °C for almost two years, even though the volcano ejected millions of metric tons of $\text{CO}_2$. Investigate the role of sulfur dioxide ($\text{SO}_2$) aerosols and emitted ash to explain the physical mechanism that caused this temporary cooling, and use this fact to refute those who mistakenly claim that volcanic eruptions are the cause of sustained global warming in recent decades.

In a school debate, someone argues: «In the Cretaceous there was no ice at the poles and the Earth was much warmer than today without human intervention; therefore, the current warming is natural and we should not worry». Refute this statement by comparing the timescale (rate) at which those geological changes occurred versus that of the current change, and explain what direct consequence this difference in speed has on the adaptive capacity of ecosystems and species survival.

Name three human activities that increase emissions of greenhouse gases into the atmosphere.

Order these ways of getting to school from lowest to highest emissions: one person traveling by car, walking, traveling by bus. Explain the criterion you have followed.

State whether these statements are true or false and correct the false ones: the greenhouse effect is a phenomenon created by humans; burning gasoline emits $\text{CO}_2$; solar energy emits more greenhouse gases than coal.

Explain the relationship between burning fossil fuels (coal, oil, natural gas) and the increase of $\text{CO}_2$ in the atmosphere.

Name two energy sources that do not emit $\text{CO}_2$ when producing electricity and two that do.

How is deforestation linked to climate change? Explain two different mechanisms: the reduced absorption of $\text{CO}_2$ and the emissions caused by cutting down or burning forests.

The concentration of atmospheric $\text{CO}_2$ was 317 ppm in 1960, 354 ppm in 1990, and 414 ppm in 2020. Calculate the increase between 1960 and 2020, express it as a percentage, and relate the trend to human activities.

Cattle emit methane during digestion. Explain how livestock farming contributes to climate change and cite one measure that would reduce this impact.

A car emits about 120 g of $\text{CO}_2$ per kilometer. Calculate the emissions of a daily 30 km trip and those of a whole year (250 days), and propose two alternatives to reduce them.

Coal-fired power plants emit much more $\text{CO}_2$ per kilowatt-hour than renewable ones. Explain why the transition to renewable energy is considered key in the fight against climate change.

Flying fruit in from another continent emits much more $\text{CO}_2$ than buying it in season at the local farmers market. Explain the relationship between these emissions and climate change and explain why local, seasonal consumption is recommended.

Country A emits 15 t of $\text{CO}_2$ per year per capita and has 10 million inhabitants. Country D emits 1.5 t per year per capita and has 200 million inhabitants. An international treaty requires both to reduce their total emissions by 20 % in five years. Calculate the total emissions of each country, compare the real impact that this cut would demand on the lifestyle of an average citizen of A versus one of D, and justify why negotiating reductions based solely on the national total is unfair.

Permafrost, the permanently frozen soil of the Arctic, stores enormous amounts of carbon. Explain what can happen if it thaws and why scientists consider it a process that feeds back into warming.

A climate model warns that a 1 °C increase in Arctic water temperature can trigger a positive feedback loop. Design a cause-and-effect flow chart that links in an orderly manner: increase in atmospheric temperature, melting of sea ice, variation in surface albedo, and absorption of solar radiation by the ocean. Based on your diagram, predict what would happen to the planet's thermal self-regulation capacity if the Arctic Ocean became completely ice-free during the summer.

Analyse the following global temperature anomaly data: −0.2 °C in 1880, +0.2 °C in 1980, and +1.2 °C in 2023. Calculate the average warming rate per decade in the period 1880-1980 compared to the period 1980-2023. Based on the result, justify whether global warming follows a constant or an accelerated progression, and predict what temperature anomaly we would reach in 2050 if the rate of the last period were maintained compared to if the rate of the first had been maintained.