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Climate Processes and Greenhouse Gases

Climate processes and greenhouse gases are central to understanding how Earth's climate system functions and how it is changing. Greenhouse gases, such as carbon dioxide and methane, trap heat in the atmosphere, creating the greenhouse effect, which warms the planet. Without this natural process, Earth would be too cold to support life as we know it. However, human activities, especially the burning of fossil fuels, have significantly increased the concentration of these gases, enhancing the greenhouse effect and leading to global warming. Studying these processes helps scientists predict future climate changes and develop strategies to mitigate their impacts.

Figures (10)

CO2 concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black)
Knowledge about carbon in the core can be gained by analysing shear wave velocities.
Carbon cycle schematic showing the movement of carbon between land, atmosphere, and oceans in billions of tons (gigatons) per year. Yellow numbers are natural fluxes, red are human contributions, and white are stored carbon. The effects of the slow (or deep) carbon cycle, such as volcanic and tectonic activity are not included.[1]
Amount of carbon stored in Earth's various terrestrial ecosystems, in gigatonnes[20]
A portable soil respiration system measuring soil CO2 flux
Diagram showing relative sizes (in gigatonnes) of the main storage pools of carbon on Earth. Cumulative changes (thru year 2014) from land use and emissions of fossil carbon are included for comparison.[20]
The slow (or deep) carbon cycle operates through rocks.The fast carbon cycle operates through the biosphere, see diagram at start of article ↑.

These gases, like carbon dioxide and methane, let sunlight through but absorb the heat Earth emits back into space. But human actions, like burning fossil fuels, have added more of these gases, making the planet warmer than it would naturally be. The greenhouse effect is the process that keeps Earth warm.

The Sun's energy reaches Earth as sunlight, which passes through the atmosphere. Earth's surface absorbs this energy and emits it as heat. This trapped heat raises Earth's average temperature from about -18°C to a much warmer 15°C.

The carbon cycle moves carbon between the atmosphere, oceans, land, and living things. Plants take in carbon dioxide during photosynthesis, and when they die, the carbon returns to the soil or air. Human activities, like cutting forests and burning fossil fuels, disrupt this balance, adding more carbon dioxide to the air.

This extra carbon dioxide increases the greenhouse effect, leading to more warming. The nitrogen cycle is another key process. Nitrogen in the air is converted into forms plants can use, like ammonia and nitrates.

Bacteria help with this, and when plants and animals die, the nitrogen returns to the soil or air. Human actions, like using fertilizers and burning fuels, add extra nitrogen to the environment, which can harm ecosystems and contribute to air and water pollution.

Key Points

  • Greenhouse gases are gases which contribute to the trapping of heat by impeding the flow of longwave radiation out of a planet's atmosphere.
  • The carbon cycle is a part of the biogeochemical cycle where carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth.
  • The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems.

Terms

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