part 2 for topic 9

Introduction to Grand Cycles

Focus on the carbon cycle and its implications in broader concepts of grand cycles.

Definition: Mass balance is a method to keep track of all the inputs and outputs in a system to determine if a reservoir's contents are increasing or decreasing over time.
- Objective: Understand the carbon levels in reservoirs over time.

Assess both inflow and outflow of carbon.
Comparison of carbon flows into and out of the atmosphere to determine net accumulation.
Encouraged calculations of mass balance for other reservoirs, such as oceans.

Historical data since the Industrial Revolution: 154 gigatons/year inflow vs. 151 gigatons/year outflow.
Net accumulation in the atmosphere:
- Inflow: 154 gigatons/year
- Outflow: 151 gigatons/year
- Net increase: 154 - 151 = 3 gigatons/year

Calculate the rate of carbon accumulation in oceans as practiced in the atmospheric mass balance analysis.

Definition: Residence time is the average duration that a particle (such as carbon) remains in a particular reservoir.
- Formula: ext{Residence Time} = rac{ ext{Mass in the Reservoir}}{ ext{Average Flow Rate}}

Importance: Indicates how long carbon stays in the atmosphere versus other reservoirs such as oceans.
Comparison between reservoirs shows differing residence times; shorter in atmosphere, longer in oceans.

Atmospheric Carbon:
- Mass in atmosphere pre-Industrial Revolution: 590 gigatons + 161 gigatons (added since) = 751 gigatons
- Average flow estimates: Approximately 150 gigatons/year.
- Calculation: ext{Residence Time}_{ ext{Atmosphere}} = rac{751 ext{ gigatons}}{150 ext{ gigatons/year}} ext{ which is about } 5 ext{ years}.
Ocean Carbon:
- Total mass: Approximately 38,000 gigatons.
- Average flow: Approximately 100 gigatons/year.
- Calculation: ext{Residence Time}_{ ext{Oceans}} = rac{38,000 ext{ gigatons}}{100 ext{ gigatons/year}} ext{ which is about } 400 ext{ years}.

Definition: Response time refers to the time it takes for the Earth system to respond to changes in carbon levels.
- Formula: ext{Response Time} = rac{ ext{Change desired in reservoir}}{ ext{Difference between inflow and outflow}}

Understanding how long it might take for changes, like reducing greenhouse gases, to manifest in atmospheric carbon levels.
Allowing analyses of planned actions to combat carbon emission increases.

Removing Fossil Fuels:
- Objective: Reduce atmospheric carbon from 751 gigatons back to 590 gigatons (a reduction of 161 gigatons).
- If fossil fuel emissions are ceased, the inflow would decrease from 154 gigatons to 148 gigatons.
- Net decrease becomes 3 gigatons/year, leading to:
- Calculation: ext{Response Time} = rac{161 ext{ gigatons}}{3 ext{ gigatons/year}} ext{ which is about } 50 ext{ years}.
Tripling Fossil Fuel Use by 2030:
- Predictions: Fossil fuel emissions would increase by 150 gigatons total.
- New flow rate scenarios would lead to predictions of how long it would take to see further increases in atmospheric carbon levels.

Emphasized the importance of understanding carbon cycle dynamics for predicting climate responses to human actions.
Encourage practice with questions and scenarios based on mass balances, residence times, and response times for better comprehension.
Highlighted the continual adaptations needed in rates of carbon emissions and legal frameworks like the Paris Accords.

Importance of recognizing uncertainties in data and models used to understand the carbon cycle.
Comparison to evidence in geology (e.g., rock ages) showing parallels in carbon dating using isotopic measurements to validate carbon data.

Primary anthropogenic sources of atmospheric carbon: fossil fuel combustion, cement production, and land-use changes.
Changes in flow rates affect overall understanding and predictions regarding carbon recovery in various reservoirs over time.