Climate Emergency Flashcards
What key problems make the climate emergency?
- Rising temp
- Increased climate phenomena
- Impacts on freshwater
Why do we need to learn about climate emergency in a civil engineering course?
- Caused by human activity
- Civil engineers responsible for society
- Sustainabl infrastructure
Design for avoidance, mitigation and adaption of climate effects
What’s at the heart of climate dynamics?
The sun
What is the global energy budget?
Amount of incoming solar radiation
Why does infrared occur?
Because the surface is warm
How many watts of solar radiation enter the earth?
89 PW
How many watts of infrared radiation get reflected back in to space?
10
How does solar forcing vary?
Varies spatially and temporally
How the climate system be defined?
A gigantic heat engine to transport heat between the equator and the poles
What does the “engine” drive?
Wind and ocean circulation
What is the albedo?
Albedo is a measure of the reflection of solar radiation out of the total radiation received by an astronomical body such as the Earth.
What does it mean albedo is 0?
Black body that absorbs all incident radiation
What does it mean if albedo is 1?
A body that reflects all incident radiation
What is the average albedo of the earth from the upper atmosphere?
30-35%
Give 4 examples.
What affects the surface temperature?
Optical properties of the atmosphere e.g.,
- Sunlight Intensity
- Atmosphere Composition
- Surface Albedo
- Ocean Currents
Describe what a greenhouse gas?
The earth’s atmosphere has trace gases that are transparent to sunlight but partially absorb the cooler infrared radiation from bodies at around Earth surface temperatures.
How does wavelength change?
Wavelength changes from short wavelength energy to cooler longer wavelength energy absorbed by trace gases
What are the two main atmospheric gases?
Nitrogen and oxygen
What acts as the strongest contributor to greenhouse gases?
Water vapour acts as the strongest contributor
What is the natural feedback loop?
Oceans provide water vapour which raises the earth temp and raised temp keeps oceans surfaces warm so more evaporation
How can engineers predict weather patterns?
Civil engineers look at past weather records (20-100 years) assuming climate is stable
How long does methane live in the atmosphere and what does it oxidise to?
Lives in the atmosphere for around 12 years and is oxidised to CO2
What are CFCs?
Chlorofluorocarbons
How do you usually measure greenhouse effect?
Climate forcing
What is the relationship between CF and CO2?
Climate Foricing is due to CO2 level and is given as a function of concentration of C relative to pre-industrial levels
What is climate sensitivity?
The climate sensitivity is the global average temperature rise resulting from the forcing equivalent to doubling the 𝑪𝑶𝟐 concentration over pre-industrial levels
What are some amplifying feedbacks?
- Permafrost
- Peatland - warming peat cause temp increase
- Ice sheet collapse
- Tundra
- Destroying rainforest removing carbon sink
What are the possible states of the earth?
- Snowball earth
- Grounded/floating ice and sea level
- Hothouse Earth
What does a snowball earth look like?
- Low GHG conc.
- Earth was made of ice
- Below freezing point no mechanism to put water vapour in atmosphere
What happens in a cooling environment?
Cooling tends to increase ice cover and hence the albedo, reducing the amount of solar energy absorbed and leading to more cooling
What would happen if the Arctic melted?
Weather would change not sea level
What is floating ice?
Floating ice displaces the same vol. of sea water as when it melts so no sea level change
What does grounded ice like glaciers contribute to?
Sea levels
What is the runaway greenhouse effect?
- Positive feedback between surface temp and atmosphere opacity
- More warming more evapo. in a vicious cycle until ocean boils away
What happens if released CO2 is not absorbed?
This means that if 𝐶𝑂_2becomes a problem, it will stay a problem even if we magically switched off all emissions.
How many GT of carbon in the atmosphere?
600
How many GT of carbon per year goes from the atmosphere into oceans?
2
What helps to analyse CO2 levels?
Ice cores
What is the keeling curve?
The Keeling Curve is a graph that represents the concentration of carbon dioxide (CO2) in Earth’s atmosphere since 1958.
When did the industrial revolution start?
1769
How has CO2 level changed from pre industrial to current level?
278-422ppm
What can contribute to surface temp response?
Solar activity or changes in cloud cover, but only rising GHG conc. would account for persistent rise
What are Global Circulation Models?
- A model that simulates general circulation of planetary atmosphere or oceans
- Can compute a warmer world
What type of warming would be catastrophic?
4˚C warming
Climate Emergency
What are the consideration of civil engineers?
Design for extreme events
What are two primary process affecting sea level?
- The melt of ice sheets
- Sea water expansion → heat water and it will expand and volume increases
Explain how relative sea level can contribute to sea level changes?
- Places around the earth where land is sinking
- 3 Gorges Dam caused earth beneath to sink due to such a great load
What are examples of amplified hydrological cycle?
- Higher temperature → more evaporation → increased precipitation
- Extreme events
What’s waters life span in the atmosphere?
Couple of days
What are some scientific uncertainties?
- It is easier to calculate the equilibrium climate after a change in greenhouse gas concentration than projecting the response over time to a gradual increase of 𝐶𝑂2 levels
