The Hydrologic and Carbon Cycles: Always Recycle! - Crash Course Ecology #8

Adorable Story Introduction

• Personal anecdote with a 2-year-old second cousin at the ocean in Florida.

• Fun jumping with waves, conversation about waves stopping.

• Child's insightful response: "It's a cycle!"

• Highlights the importance of cycles in nature, referencing the recycling of the universe's materials since the Big Bang.

Understanding Biogeochemical Cycles

• Earth functions as a closed system for matter.

• Matter continuously moves through biogeochemical cycles, including water, carbon, nitrogen, and phosphorus.

• Introduction focuses on the carbon cycle and the hydrologic cycle (water cycle).

Hydrologic Cycle Overview

• Describes movement of water on Earth; powered by the Sun and wind.

• Water exists in reservoirs: oceans, atmosphere (clouds), and polar ice caps.

• Different states: liquid, solid, gas.

• Starts with precipitation (rain, snow, etc.), occurring when atmospheric water vapor condenses into liquid.

Key Processes in the Hydrologic Cycle

• Precipitation: Water falls from clouds when they become heavy.

• Evaporation: Liquid water turns into vapor.

• Sublimation: Solid to gas transition without being liquid.

• Deposition: Gas to solid transition.

• Clouds form when air containing water vapor cools and condenses into droplets.

Movement of Water after Precipitation

• After precipitation, gravity pulls water down:

  • Runoff: Water flows over land to the lowest point, reaching rivers, lakes, or oceans.

  • Storage: Water can be stored temporarily in lakes, ponds, and wetlands.

• Cold regions may have frozen water (ice) for long periods.

• Oceans receive most of the water through runoff; they are crucial for the hydrologic cycle.

The Salty Ocean

• Oceans' salinity explained: water erodes minerals from soil and carries them to the ocean.

• When water evaporates, the salt is left behind, leading to salty oceans over billions of years.

• Oceans collect all liquid water; water must evaporate to exit the ocean.

Role of Living Organisms

• Living beings participate in the hydrologic cycle by producing water as a waste product (e.g., respiration).

• Evapotranspiration: Loss of water from plants through evaporation from surfaces.

• Plants absorb water through roots and release it from leaves.

• The Sun's energy drives evaporation across the landscape.

Carbon Cycle Overview

• Carbon is a key element necessary for all living things.

• Carbon cycles through reservoirs, including living organisms, oceans, and the atmosphere.

Functions of Carbon in Nature

• Plants absorb carbon dioxide (CO2) for photosynthesis and release it during respiration.

• More CO2 is absorbed than released, contributing to the plant's biomass.

• Possible fates of carbon in plants:

  • Respiration back to atmosphere.

  • Consumption by animals.

  • Formation of fossil fuels when plants die and are buried (e.g., coal).

Carbon Reservoirs

• Oceans dissolve CO2 and utilize it in marine photosynthesis.

• Phytoplankton use carbon to create shells, which form limestone upon settling.

• Human activities, such as burning fossil fuels, release long-stored carbon back into the atmosphere.

Impact on Climate Change

• Increased CO2 in the atmosphere results in global warming.

• Melting permafrost releases additional greenhouse gases (CO2 and methane).

• The cycle is perpetuated, exacerbating climate change issues.

Conclusion

• Emphasizes the need to study ecology due to the impact of human actions on global climate stability.

• Acknowledgment of the educational contributors and promotional invitation to engage through questions or comments.