Changes in the Global Energy Balance Shape the Earth's Climate
- The Earth's energy balance is a fragile system that regulates global temperatures and climate patterns.
- Factors like variations in solar radiation as well as natural and human-induced pollution disrupt this balance, impacting weather systems and contributing to global warming and cooling effects.
Definition
Energy balance
The energy balance refers to the equilibrium between the incoming solar energy absorbed by the Earth and the outgoing energy re-radiated back into space.
Variations in Solar Radiation
- The Earth's temperature is influenced by changes in the Sun's energy output.
- This is evident in an 11-year solar cycle and longer cycles like the Milankovitch Cycles.
- Variations in Earth's orbit affect solar radiation distribution, initiating climate changes like ice ages.
- Albedo also plays a role in global warming: melting ice reduces reflectivity, increasing heat absorption by darker surfaces like rocks, soil, and vegetation.
Definition
Milankovitch cycles
Milankovitch cycles are long-term variations in the Earth's orbit, axial tilt, and wobble (precession) that influence the amount and distribution of solar energy the Earth receives.
Global Dimming: A Hidden Cooling Effect
- Following events like the 1991 Mount Pinatubo volcanic eruption, a temporary temperature decrease of approximately 0.5°C (0.9°F) for about 1-2 years was observed, highlighting the cooling effect of pollution, termed global dimming.
- The predominant source of air pollution (aerosols, particulate matter) causing global dimming is linked to human-induced activities.
- Polluted air contains particles like ash and sulfur dioxide, forming smaller water droplets in clouds, which reflect more sunlight and reduce heat reaching Earth's surface.
- This phenomenon has led to a 9% decrease in solar energy reaching Earth's surface globally between 1950 and 1990.
Definition
Global dimming
Global dimming is the gradual decrease in the amount of sunlight reaching the Earth's surface due to an increase in atmospheric pollutants arriving from natural phenomena (volcanic eruptions) and human activities.
Feedback Loops Play a Crucial Role in Global Climate Change
- Feedback loops involve processes where the output of a system influences its own activity, often with cascading effects on global temperatures.
- These loops can either enhance warming (positive feedback) or counteract it (negative feedback).
