Global climate change

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Lektionsnotizen

The Greenhouse Effect

The greenhouse effect is the natural warming of Earth's atmosphere: greenhouse gases let sunlight in but trap some of the heat that would otherwise escape to space, acting like a blanket around the planet.
Greenhouse gases include carbon dioxide (CO2), water vapor (H2O), methane (CH4), ozone (O3), and nitrous oxides — together less than 1% of the atmosphere, which is otherwise mostly nitrogen and oxygen.
Carbon dioxide comes from respiration, volcanic eruptions and the decomposition of plant material; methane comes from decomposition and from digestion in animals such as livestock; nitrous oxide is produced by bacteria.
Without the greenhouse effect, Earth's average surface temperature would be about -18°C (0°F), too cold for life as we know it; with it, the average is about 15°C (59°F).
About 30% of incoming solar radiation is reflected straight back to space; the rest is absorbed as heat, and some of what the surface then radiates outward is trapped again by greenhouse gases.

The greenhouse effect: sunlight reaching Earth's surface and infrared radiation being absorbed and re-emitted by greenhouse gases

Earth's Energy Balance

The diagram's numbers are in watts per square metre (W/m²), a measure of how much energy flows in or out of the atmosphere.
Of the solar radiation Earth absorbs (235 W/m²), some heats the atmosphere directly and some heats the surface; some of that energy radiates straight out to space (195 W/m²) without being trapped.
Earth's surface itself emits thermal radiation; most of it (350 W/m²) is absorbed by greenhouse gases rather than escaping directly, and much of that absorbed energy (452 W/m²) is sent back down to warm the surface again.
This balance between incoming and outgoing energy keeps Earth's land and ocean surface at an average of about 14°C.

Diagram of Earth's energy balance, showing solar radiation absorbed, thermal radiation into space, and greenhouse gas absorption in watts per square metre

Comparing Earth, Venus and Mars

Venus, Earth and Mars all have atmospheres, but very different amounts of carbon dioxide and very different surface temperatures.
Venus: atmosphere about 92 times Earth's surface pressure and 96.5% CO2 — an extreme greenhouse effect gives an average surface temperature of about 462°C, the hottest planet in the solar system.
Mars: atmosphere less than 1% of Earth's surface pressure, even though it is about 95% CO2 — too thin to trap much heat, so the average surface temperature is about -55°C.
Earth: about 78% nitrogen, 21% oxygen and only 0.03% CO2 — just enough greenhouse effect to keep the planet at a temperature that supports life.
Comparing the three shows it is the amount of a greenhouse gas in an atmosphere, not just its presence, that determines how strong the greenhouse effect is.

Venus, Earth and Mars

Human Causes of Global Climate Change

Global climate change is a long-term, worldwide change in climate — average temperature and weather patterns — unlike normal day-to-day or year-to-year weather.
Since the Industrial Revolution, burning fossil fuels (coal, oil and gas) for energy has released large additional amounts of CO2 into the atmosphere.
Other human activities add greenhouse gases too: growing rice and raising livestock release methane, and clearing land removes vegetation that would otherwise absorb CO2 through photosynthesis.
Natural factors — changes in solar radiation, volcanic activity — also affect climate, but scientists confirm the recent rapid rise in global temperature is due mainly to human activity, not natural variation.
Global annual CO2 emissions from burning fossil fuels have risen from almost nothing in 1850 to more than 35 billion tonnes a year by 2020.

Annual global CO2 emissions from burning fossil fuels for energy and cement production, 1750-2020

Evidence: Rising Carbon Dioxide

Air bubbles trapped in Antarctic ice let scientists measure CO2 levels going back 800,000 years; over that time CO2 cycled naturally between about 180 ppm (ice ages) and a highest previous level of about 300 ppm (warm interglacial periods).
By 2020 the global average CO2 concentration had reached about 412.5 ppm — far above any level in that 800,000-year record.
Direct instrument measurements since 1960 show CO2 climbing every single year, from roughly 316 ppm in 1960 to over 415 ppm by 2020.
This rise does not match the pattern of natural ice-age cycles; it matches the timeline of industrial fossil-fuel burning.

Carbon dioxide over 800,000 years, with the 2020 average (412.5 ppm) and the highest previous concentration (300 ppm) marked

Evidence from Ice Cores

Ice cores are cylinders drilled from polar ice; the deepest ice is the oldest, and each layer traps tiny bubbles of the air present when it froze.
Analysis of one Antarctic ice core (covering the last 160,000 years) shows CO2 levels varying naturally between about 180 and 280 ppm.
Current CO2 levels are over 387 ppm in that same dataset — far higher than any natural value in the ice-core record.
Ice cores are one of the main lines of evidence that today's CO2 levels are unusual compared with the recent geological past.

Ice-core diagram and photographs of drilling and sawing an ice core for CO2 analysis

Effects of Climate Change

Global average temperature has risen by about 1°C since the early 1900s, with some regions warming more than others.
Rising temperatures are melting polar ice: the Arctic's summer sea-ice minimum in 2011 was much smaller than the 1979-2000 average, and sea level has risen about 9 inches since the late 1800s.
Changing temperatures shift regional weather patterns — more rainfall in some areas, drought in others — which affects agriculture and food production.
Long-term climate change can push species and crops outside the temperature range they need to survive, leading to habitat loss and, in some cases, extinction.

Arctic sea ice minimum extent in 2011 (white) compared with the 1979-2000 median extent (yellow outline)

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Übungsfragen

Gratis-Vorschau — 8 von 43 Fragen. Registriere dich, um alle zu sehen.

1.The greenhouse effect is a natural process that helps keep Earth warm enough to support life.
Easy
True or false?
2.Which of the following is NOT a greenhouse gas?
Easy
- AOxygen
- BCarbon dioxide
- CMethane
- DWater vapour
3.Mars has a thicker atmosphere than Earth, which causes its surface to be warmer than Earth's.
Easy
True or false?
4.What is the approximate average surface temperature of Earth with the natural greenhouse effect?
Easy
- A-18°C
- B15°C
- C59°C
- D0°C
5.Which gas is the most abundant greenhouse gas in Earth's atmosphere?
Easy
- ACarbon dioxide
- BWater vapour
- CMethane
- DOzone
6.Which of the following is a human activity that increases the amount of carbon dioxide in the atmosphere?
Easy
- APlanting trees
- BBurning fossil fuels
- CUsing solar panels
- DRecycling paper
7.Which of the following are human activities that contribute to the increase of greenhouse gases in the atmosphere? (Select all that apply)
Medium
- ABurning fossil fuels
- BDeforestation
- CPlanting trees
- DRaising livestock
- EUsing solar panels
8.Which of the following is a method used by scientists to study past carbon dioxide levels?
Medium
- AAnalyzing ice cores
- BMeasuring ocean temperature
- CObserving volcanic eruptions
- DCounting tree rings

Mehr Fragen

9.A student investigated the greenhouse effect using two bottles: one filled with air and one filled with carbon dioxide. Both were exposed to the same heat source. The temperature in the CO2 bottle increased more than in the air bottle. What is the most likely conclusion?
Medium
- ACarbon dioxide absorbs more heat than air.
- BAir absorbs more heat than carbon dioxide.
- CBoth absorb the same amount of heat.
- DThe CO2 bottle was closer to the heat source.
10.Which of the following are methods scientists use to study past climate and carbon dioxide levels? (Select all that apply)
Medium
- AAnalyzing ice cores from Antarctica
- BMeasuring ocean temperatures directly with thermometers
- CStudying tree rings
- DUsing satellites to measure current temperatures
- EObserving volcanic eruptions in real time
11.Venus has a higher surface temperature than Mercury despite being farther from the Sun because Venus has a thick atmosphere rich in carbon dioxide that causes a strong greenhouse effect.
Medium
True or false?
12.Match each greenhouse gas with its primary natural source.
Medium
- Carbon dioxide
- Methane
- Nitrous oxide
- Respiration and volcanic eruptions
- Decomposition of plant material
- Produced by bacteria
13.Arrange the following steps in the correct order to describe how an increase in greenhouse gases leads to global warming.
Medium
- More greenhouse gases trap more infrared radiation.
- Human activities release extra greenhouse gases.
- Earth's surface warms and emits more infrared radiation.
- Global temperatures rise.
14.In the greenhouse effect model experiment, why is it important to use two identical bottles and place them at the same distance from the heat source?
Medium
- ATo ensure the experiment is fair and only the type of gas is changed
- BTo make the experiment more complicated
- CTo allow the bottles to heat up at different rates
- DTo ensure the thermometers are the same
15.In the greenhouse effect model experiment, the bottle containing carbon dioxide will cool down faster than the bottle containing air after the heat source is turned off.
Easy
True or false?
16.In an experiment to model the greenhouse effect, two identical bottles are set up: one contains air and the other contains carbon dioxide. Both are exposed to the same heat source. What is the independent variable?
Medium
- AType of gas in the bottle
- BTemperature increase
- CTime of exposure
- DDistance from heat source
17.In an experiment to model the greenhouse effect, two identical bottles are set up: one contains air and the other contains carbon dioxide. Both are exposed to the same heat source. After 10 minutes, the temperature in the CO2 bottle is 35°C and in the air bottle is 30°C. What is the temperature increase in the CO2 bottle if the starting temperature of both bottles was 20°C?
Medium
- A15°C
- B10°C
- C5°C
- D20°C
18.In the ice core analysis investigation, why is it important to drill ice cores from Antarctica to study past carbon dioxide levels?
Easy
- ABecause Antarctica is the coldest place on Earth, so ice cores remain frozen.
- BBecause ice cores trap air bubbles from past time periods, preserving samples of ancient atmosphere.
- CBecause Antarctica is the only place where ice cores can be drilled.
- DBecause ice cores are easier to transport than other samples.
19.In the ice core data table, what is the general trend in CO2 levels from 160,000 years ago to the present?
Medium
- ACO2 levels have steadily increased over the entire period.
- BCO2 levels have decreased over the entire period.
- CCO2 levels have fluctuated but show a sharp increase in recent times.
- DCO2 levels have remained constant over the entire period.
20.Complete the sentence.
Easy
The three main greenhouse gases mentioned in the text are water vapour, carbon dioxide and ____. (Answer in lowercase)
21.What is the name of the gas that is the most abundant greenhouse gas in Earth's atmosphere?
Easy
22.What is the term for the average weather patterns in an area over a long period of time?
Easy
23.One methane molecule traps about 23 times as much heat as one CO2 molecule. If a certain amount of CO2 traps 100 units of heat, how many units of heat would the same amount of methane trap?
Medium
24.Explain why the temperature on Venus is much higher than on Mars, even though both have atmospheres rich in carbon dioxide.
Hard
25.What is the average surface temperature of Mars, in degrees Celsius?
Easy
- A-61 °C
- B-55 °C
- C-43 °C
- D-49 °C
26.What is the average surface temperature of Venus, in degrees Celsius?
Medium
- A554 °C
- B416 °C
- C462 °C
- D508 °C
27.The greenhouse effect is caused by the reflection of all solar radiation back into space.
Easy
True or false?
28.The table shows the percentage of some gases in the atmospheres of Venus, Earth and Mars. | Gas | Venus | Earth | Mars | |---|---|---|---| | Carbon dioxide (CO2) | 96.5% | 0.03% | 95% | | Nitrogen (N2) | 3.5% | 78% | 2.7% | | Oxygen (O2) | trace | 21% | 0.13% | Which planet has the highest surface temperature, and why?
Hard
- AVenus, because it has a thick atmosphere with high CO2 causing a strong greenhouse effect.
- BMercury, because it is closest to the Sun.
- CEarth, because it has oxygen and water vapour.
- DMars, because it has a thin atmosphere with CO2.
29.An ice core analysis shows that carbon dioxide levels 160,000 years ago were 190 ppm, and today they are about 387 ppm. Which statement best explains the change?
Hard
- ANatural variations alone account for the increase
- BHuman activities such as burning fossil fuels have increased CO2 levels beyond natural variations
- CThe ice core data is unreliable and should be ignored
- DThe increase is due to volcanic eruptions only
30.Which of the following are appropriate steps in the greenhouse effect model experiment? (Select all that apply)
Medium
- AUse two identical bottles
- BUse different types of thermometers
- CMeasure starting temperatures before switching on the heat source
- DPosition the heat source at different distances from each bottle
- ERecord temperature at regular time intervals
31.Arrange the following steps in the correct order to describe how scientists obtain and analyze ice cores to study past CO2 levels.
Medium
- Drill ice core from Antarctic ice
- Analyze the ice core for CO2 levels
- Cut the ice core into sections
- Identify air bubbles trapped in the ice
32.Arrange the following steps in the correct order to describe how the greenhouse effect warms the Earth.
Medium
- Sun's visible light reaches Earth's surface
- Earth's surface absorbs light and warms up
- Earth's surface emits infrared radiation
- Greenhouse gases absorb infrared radiation and re-emit it in all directions
- Some infrared radiation is directed back to Earth, warming the surface
33.The table shows results from an Antarctic ice-core analysis of carbon dioxide levels. | Years ago | CO2 (ppm) | |---|---| | 160,000 | 190 | | 130,000 | 280 | | 100,000 | 225 | | 70,000 | 250 | | 40,000 | 180 | | 10,000 | 260 | | 0 (present) | 387 | What is the approximate difference in CO2 concentration (in ppm) between the highest and lowest values shown in the table?
Medium
- A100 ppm
- B207 ppm
- C280 ppm
- D387 ppm
34.The graph shows carbon dioxide levels over the past 800,000 years. About how many ppm higher is the 2020 average than the natural ice-age low shown on the graph?
Hard
- Aabout 115 ppm
- Babout 230 ppm
- Cabout 300 ppm
- Dabout 410 ppm
35.The graph shows atmospheric carbon dioxide measured directly from 1960 to 2021. Reading the graph, about how much did CO2 rise between 1960 and 2010?
Medium
36.Explain why Venus is hotter than Mercury even though Mercury is closer to the Sun.
Medium
37.Describe two long-term effects of an increase in carbon dioxide on life on Earth.
Hard
38.The graph shows carbon dioxide levels over the past 800,000 years. What is the main trend shown by the graph?
Medium
- ACO2 levels have remained constant
- BCO2 levels have increased dramatically since the industrial revolution
- CCO2 levels have decreased steadily over time
- DCO2 levels have always been higher than 400 ppm
39.The chart shows global average surface temperature each year compared with the 1901-2000 average. What does it mainly show?
Medium
- ATemperature stayed the same from 1880 to 2020
- BMost years since the late 1970s have been warmer than the 1901-2000 average
- CTemperatures have been falling steadily since 1980
- DThere is no pattern in the yearly temperatures
40.The image shows the Arctic sea ice minimum in 2011 (white) against the median extent for 1979-2000 (yellow outline). Compared with the 1979-2000 median, the 2011 minimum was
Easy
- Amuch larger in extent
- Babout the same extent
- Cmuch smaller in extent
- Dcompletely melted, with no ice left
41.The diagram models sunlight reaching Earth and thermal energy moving back out through the atmosphere. Which labelled arrow best shows the movement of thermal energy that is causing global temperatures to rise?
Medium
- Aarrow W - sunlight reaching Earth's surface
- Barrow X - infrared radiation absorbed by greenhouse gases and sent back down to Earth's surface
- Carrow Y - infrared radiation escaping upward through a gap in the greenhouse gases
- Darrow Z - infrared radiation escaping straight out to space
42.The graph shows atmospheric carbon dioxide from 1900 to 2020. Select the three human activities that have most contributed to this rise. (Select all that apply)
Medium
- ACutting down forests to build farms and cities
- BRiding bicycles instead of driving cars
- CBurning coal at power plants to make electricity
- DInstalling solar panels to collect energy from the Sun
- EBurning fossil fuels to power trucks and cars
43.Select the three activities that would help reduce the amount of greenhouse gases added to Earth's atmosphere. (Select all that apply)
Easy
- AUsing bicycles as a form of transportation
- BImplementing public transportation systems
- CCutting down forests to build farms and cities
- DBurning coal at power plants to make electricity
- EUsing solar panels to collect energy from the Sun

Lernnotizen

## Global Climate Change - Night-Before Exam Notes ### What is Climate Change? - **Climate change** = long-term shifts in temperatures and weather patterns. - **Global warming** = the ongoing increase in Earth's average surface temperature, mainly due to human activities. - **Anthropogenic climate change** = climate change caused by humans. ### The Greenhouse Effect - Sunlight warms Earth; Earth radiates heat back toward space. - **Greenhouse gases** (CO₂, methane, water vapor) absorb some of this heat, warming the lower atmosphere. - Human activities (burning fossil fuels, deforestation, agriculture) release extra greenhouse gases, strengthening the natural greenhouse effect → **global warming**. ### Human Causes - **Fossil fuels** (coal, oil, natural gas) burned for energy since the Industrial Revolution (≈1850). - Deforestation and certain farming/industrial practices. - CO₂ is the main gas driving warming. Atmospheric CO₂ is now **~50% higher** than pre-industrial levels, reaching levels not seen for millions of years. ### Evidence of Warming - **Global temperature rise**: 2024 was the warmest year on record at **+1.60 °C (2.88 °F)** above 1850 levels. - **Arctic amplification**: melting sea ice, retreating glaciers, thawing permafrost. - **Extreme weather**: more heat waves, wildfires, intense storms, droughts. - **Sea level rise** and **ocean acidification** (CO₂ dissolving in seawater makes it more acidic). ### Impacts - **Environmental**: species extinction, coral reef loss, ecosystem disruption. - **Human**: flooding, extreme heat, food/water scarcity, disease, economic loss, migration, conflict. - **Vulnerability**: poorer communities contribute least to emissions but are most at risk. ### Solutions & Mitigation - **Paris Agreement** (2015): nations aim to keep warming **well below 2 °C**. - **Phase out fossil fuels**: switch to **renewable energy** (wind, solar, hydro, nuclear). - **Energy conservation** and efficiency. - **Carbon removal**: reforestation, soil carbon storage. - **Adaptation**: flood defenses, drought-resistant crops. ### Key Numbers - Current CO₂: ~50% above pre-industrial levels. - 2024 warming: +1.60 °C since 1850. - Paris target: well under 2 °C warming. - Current pledges: ~2.8 °C warming by 2100. ### Important Distinction - **Global warming** = only temperature increase. - **Climate change** = warming + all its effects (e.g., precipitation changes, storms).

Global warming: The ongoing increase in Earth's average surface temperature, primarily due to human activities that release greenhouse gases.
Climate change: Long-term shifts in temperatures and weather patterns; includes global warming and its effects on Earth's climate system (e.g., precipitation changes, storms).
Greenhouse effect: The process by which greenhouse gases absorb heat radiated from Earth's surface, warming the lower atmosphere.
Greenhouse gases: Gases such as carbon dioxide (CO₂), methane, and water vapor that trap heat in the atmosphere.
Fossil fuels: Coal, oil, and natural gas; burned for energy, releasing large amounts of CO₂ and other greenhouse gases.
Anthropogenic climate change: Climate change resulting from human activities.
Paris Agreement: A 2015 international treaty where nations agreed to limit global warming to well below 2 °C above pre-industrial levels.
Sea level rise: Increase in the average level of the world's oceans due to melting ice and thermal expansion of water as it warms.
Ocean acidification: Decrease in pH of ocean water caused by absorption of excess CO₂ from the atmosphere.
Climate adaptation: Adjustments to natural or human systems in response to actual or expected climate change effects (e.g., flood defenses, drought-resistant crops).

Karteikarten

What is the difference between 'global warming' and 'climate change'?

Global warming refers only to the increase in global average surface temperature, while climate change includes both global warming and its effects on Earth's climate system, such as changes in precipitation.

What is the main human activity driving modern global warming?

Burning fossil fuels (coal, oil, and natural gas) since the Industrial Revolution is the main human activity driving modern global warming.

What are greenhouse gases?

Greenhouse gases are gases that absorb some of the heat that Earth radiates after it warms from sunlight, warming the lower atmosphere. Examples include carbon dioxide and methane.

How much has atmospheric carbon dioxide increased since pre-industrial times?

Earth's atmosphere now has roughly 50% more carbon dioxide than at the end of the pre-industrial era.

What is the greenhouse effect?

The greenhouse effect is the process by which greenhouse gases trap heat in the lower atmosphere, warming the planet. It is a natural process, but human activities have strengthened it.

List three human activities that release greenhouse gases.

Burning fossil fuels, deforestation, and some agricultural and industrial practices release greenhouse gases.

What was the warmest year on record as of 2024?

2024 was the warmest year on record, with global average temperature 1.60 °C (2.88 °F) above pre-industrial levels.

What are some observed impacts of climate change?

Observed impacts include more frequent heat waves and wildfires, thawing permafrost, retreating glaciers, sea ice decline, more intense storms and droughts, and rising sea levels.

How does climate change affect species?

Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct.

What are some ways climate change threatens people?

Climate change threatens people with increased flooding, extreme heat, food and water scarcity, more disease, and economic loss.

What is the Paris Agreement?

The Paris Agreement is a 2015 international agreement in which nations collectively agreed to keep global warming 'well under 2 °C' above pre-industrial levels.

What is a tipping point in climate change?

A tipping point is a threshold beyond which changes become self-accelerating and irreversible, such as melting all of the Greenland ice sheet.

List two ways to reduce carbon dioxide emissions.

Switching to renewable energy sources (like wind, solar, hydro, and nuclear) and conserving energy can reduce carbon dioxide emissions.

How can carbon be removed from the atmosphere?

Carbon can be removed by increasing forest cover and using farming methods that store carbon in soil.

What is the difference between climate change mitigation and adaptation?

Mitigation involves reducing greenhouse gas emissions to limit future warming, while adaptation involves adjusting to the effects of climate change, such as building flood controls or using drought-resistant crops.

Why are poorer communities more vulnerable to climate change?

Poorer communities are responsible for a small share of global emissions but have the least ability to adapt and are most vulnerable to climate change impacts.

What are climate proxies?

Climate proxies are natural records like tree rings and ice cores that provide information about past climates before thermometer records existed.

How much higher were sea levels during the Last Interglacial (125,000 years ago) compared to today?

During the Last Interglacial, sea levels were 5 to 10 meters higher than today.

What is ocean acidification?

Ocean acidification is the decrease in pH of ocean water caused by increased carbon dioxide absorption, which harms marine life.

What is the term for climate change caused by human activities?

Anthropogenic climate change is the term for climate change resulting from human activities.

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