Carbon Cycle Balance:
- The natural ‘greenhouse effect’ is how our atmosphere and ‘greenhouse gases’ trap heat from the sun
- Keeps the world warmer than it would be without natural greenhouse gases so the world average would be at least -18 0C (average now is around 15 0C).
- The main greenhouse gases are CO2 (carbon dioxide) and CH4 (methane).
- The greenhouse affect therefore heavily influences the patterns of temperature and precipitation around the world.
- Photosynthetic organisms (e.g. plants, phytoplankton) and soils help regulate the climate by helping control the atmospheric composition.
- However, humans have altered and tipped the balance of the carbon pathways and cycle.
Reasons For Greenhouse
Gas Emissions:
- Population growth: increases all reasons below
- Transport: oil in USA for cars
- Industry: China No1 for coal burning (for electricity)
- Development: electricity generation as countries get richer
- Agriculture: More cows and rice fields to meet demand emit methane gas
- More energy use per capita (standard living improving)
- Deforestation: releases carbon dioxide e.g. Amazon rainforest
Terrestrial Regulation
Of The Atmosphere:
- The terrestrial biological stores include vegetation, soils and leaf litter
- Forests are the main ecosystem stores
- The climate effects the ecosystem carbon store size, and also the fluxes in the system
Carbon Nutrient Cycling
Is Important For Soil Health:
- Input: Nitrogen, carbon and minerals
- Output: Lose of nutrients by leaching and runoff
- Flows: Leafs and needles fall from biomass to litter and uptake of nutrients from the soil.
Summary:
- On a short-term timescale, the carbon cycle is naturally balanced (dynamic equilibrium).
- Photosynthesis and respiration from terrestrial ecosystems (vegetation and soils) balance.
- Oceans have the biological, carbonate and physical carbon pumps.
- Climates determine how ecosystem productivity varies, such as rainforest biomass carbon stores being largest, but deserts storing more carbon in soils
- Outgassing-from and diffusion-into the oceans roughly balances
- However, anthropogenic sources e.g. fossil fuels for CO2, methane from agriculture, have created a new large input.
- This increases atmospheric GHG levels, and fluxes slightly change as the system absorbs more CO2.
- The human enhanced greenhouse effect means that global climate, ecosystems, and hydrological cycle will change e.g. more storms, rainfall, droughts, forest fires, floods, migration etc.