Question 1

How does the greenhouse effect actually work?

Accepted Answer

Through a difference in how the atmosphere treats **incoming sunlight** and **outgoing heat** — and that asymmetry is the entire mechanism.

**The sequence:**

**Sunlight arrives** as mostly visible and near-infrared radiation, because the Sun is very hot. The atmosphere is largely **transparent** to these wavelengths, so most of it passes through to the surface.

**The surface absorbs it and warms.**

**The surface radiates heat back** as **long-wave infrared**, because Earth is far cooler than the Sun and cooler objects radiate at longer wavelengths.

**Greenhouse gases absorb that outgoing infrared.** Molecules with three or more atoms — **water vapour, carbon dioxide, methane, nitrous oxide, ozone** — have vibrational modes that match infrared wavelengths, so they absorb this radiation and re-emit it in all directions, including back down.

**Nitrogen and oxygen, which make up 99% of the atmosphere, are transparent** to infrared. Their two identical atoms give them no dipole moment to interact with it. This is why trace gases at parts-per-million concentrations matter so much: they are doing work the bulk of the atmosphere cannot.

**The net effect** is that heat leaves the planet more slowly than it arrives, so the surface settles at a higher temperature. Without it, Earth's average surface temperature would be roughly **−18°C** rather than about 15°C. The greenhouse effect is why the planet is habitable; the concern is its **enhancement**.

**The name is a misnomer.** An actual greenhouse works mainly by **preventing convection** — stopping warm air escaping — not by trapping radiation. The atmospheric mechanism is genuinely radiative.

**Why adding CO₂ still matters when absorption bands seem saturated.** Absorption occurs throughout the atmospheric column. Adding CO₂ raises the **effective emission altitude** — the height from which radiation finally escapes to space. Higher means colder, colder means less radiated, so the surface must warm to restore balance.

**Water vapour is a feedback**, not a driver — warming increases it, amplifying the effect.

Question 2

What is a carbon sink, and how much CO₂ do the oceans absorb?

Accepted Answer

A carbon sink is any reservoir absorbing more carbon than it releases. The two dominant natural sinks are the ocean and land vegetation and soils, and together they absorb roughly half of human CO₂

Question 3

What are the main causes of climate change and how do they affect the environment?

Accepted Answer

Climate change is caused by human activities like burning fossil fuels, deforestation, and agriculture, leading to rising temperatures, extreme weather, and ocean acidification.

Question 4

Why is the ozone layer a rare environmental success story?

Accepted Answer

Because it is the clearest case of the world identifying a global environmental problem, agreeing binding action, and measurably fixing it — which makes it the standard reference point in arguments

Question 5

What is permafrost, and why does thawing matter?

Accepted Answer

Ground that has remained frozen for at least two consecutive years — covering roughly a quarter of the northern hemisphere's land — and its thaw matters because of what has been locked inside it for

Question 6

How much of climate change comes from food and farming?

Accepted Answer

Roughly a quarter to a third of global greenhouse gas emissions depending on what is counted — and the distinctive feature is that these emissions are mostly not carbon dioxide from burning fuel,

Question 7

Is hydrogen a realistic fuel?

Accepted Answer

For some uses yes, for others almost certainly not — and the debate is confused by treating hydrogen as a single proposition when its viability differs enormously by application. Why it is

Related Questions