Climate, Human Impacts on Climate

Question 1

How did humans impact climate systems in the past?

Answer 1

Humans previously had little impact due to the enormity of climate systems and their miniscule environmental footprint

Question 2

What are the three main ways that humans have changed global climate?

Answer 2

1. Land use change
2. Trace-gas measurements
3. Global warming hiatus

Question 3

How have humans changed land use, and what is the main consequence of this change?

Answer 3

Woodlands → Crops/grass → Lower planetary albedo

Patterns of crop environments in densely populated regions which caused more reflection of shortwave radiation

Question 4

Global warming

Answer 4

A measureable increase in global temperatures that has occured since the Industrial Revolution as a direct result of changes in the Earth’s atmospheric composition

Question 5

What are the four assumptions behind global warming?

Answer 5

1. Implies a natural balance that humans are disturbing
2. Assumes a cause and effect relationship between levels of gases and global temperarure
3. Implies that humans can accurately measure concentrations of these gases and their effect on global temperature
4. Implies that humans can understand the systems changes and their variation

Question 6

What is another name for greenhouse gases, and what is their effect on global climate?

Answer 6

Global pollutants: Push the climate in a particular direction

Question 7

What are the six characteristics of global air pollutants?

Answer 7

1. Long residence times in the atmosphere with few sinks and stable compounds
2. Have sources across the globe
3. Limited impact on local scales even at high concentrations
4. Small changes in composition at a global scale yet have a significant impact on human life
5. Emitted in high concentrations from land use changing to accomodate for more intensive agricultural or industrial use
6. Indirect effect on human health

Question 8

What are the five main greenhouse gases?

Answer 8

1. Carbon dioxide (CO2)
2. Methane (CH4)
3. Nitrous oxide (N2O)
4. Ozone (O3)
5. CFCs

Question 9

What greenhouse gas has significantly changed since the Industrial Revolution?

Answer 9

Carbon dioxide (CO2)

Question 10

How is carbon dioxide (CO2) removed from the atmosphere, and how long does it last?

Answer 10

Carbon dioxide (CO2) lasts for roughly a century in the atmosphere, and is removed via reforestation and dissolution in the ocean

Question 11

How does the lifespan of methane (CH4) and its effects on the cliamte differ from carbon dioxide (CO2)?

Answer 11

Although methane (CH4) has a shorter lifespan than carbon dioxide (CO2), its effects are worse

Question 12

Why are climatologists concerned about the methane frozen in permafrost?

Answer 12

Permafrost around Canada’s Northwest territories in the Arctic regions is melting.

This permafrost contains methane which could trigger catastrophic climate change and devestate global economy

Question 13

Global Warming Hiatus

Answer 13

The apparent decrease in the upward trend of global surface temperatures between 2000 - 2014

Question 14

What are the six main theories concerning the Global Warming Hiatus?

Answer 14

1. Quiet Sun, less sunspots
2. Aerosols from volcanic
   eruptions and China’s industry
3. Anthropogenic feedback (global warming, winds, deep storage in ocean)
4. Ocean heat exchange from ENSO
5. Lower climate sensitivity than orignally thought
6. Observational or modelling errors