Final answer:
The four variable gases important to weather and life systems are water vapor, carbon dioxide, methane, and ozone, with water vapor being the most significant for the natural greenhouse effect. These gases trap heat within the atmosphere due to the greenhouse effect, which is essential for maintaining life-sustaining temperatures on Earth. Human activities have increased the concentration of these gases, leading to altered weather patterns and climate change.
Step-by-step explanation:
There are four key variable gases in the Earth's atmosphere that significantly influence weather patterns and life systems on the planet. These gases are water vapor, carbon dioxide (CO2), methane (CH4), and ozone (O3). Among these, water vapor is the most abundant greenhouse gas, accounting for about 80 percent of the natural greenhouse effect, with a significant impact on weather and climate change. Carbon dioxide is another essential greenhouse gas, which, since the Industrial Revolution, has increased in atmospheric concentration due to human activities, affecting the global energy balance and contributing to climate alteration. Methane, a more potent greenhouse gas than CO2 on a molecular basis, and ozone are also important components of the atmosphere's regulation of Earth's temperature.
The greenhouse effect is essential for maintaining temperatures on Earth that sustain life. Without these greenhouse gases, the Earth's surface would be, on average, more than 30°C colder. Nowadays, human activity is responsible for the increased concentration of these gases, which in turn leads to an amplified greenhouse effect. This increase in greenhouse gases can cause changes in temperature, which affect precipitation patterns and alter weather conditions, potentially impacting agriculture, economy, and ecosystems.