Environmental Science
Global Warming
Quick fact
The last decade (2011–2020) was the warmest on record, and the concentration of carbon dioxide in the atmosphere is now higher than at any point in the last 800,000 years.
Why this is interesting
You've seen the headlines about record-breaking heat, but have you ever wondered what's really turning up the thermostat on our entire planet?
Read the full explanation
Understanding Global Warming
Imagine Earth wrapped in a cozy blanket. That blanket is our atmosphere, and it naturally traps some heat from the sun, keeping our planet warm enough for life—a process called the greenhouse effect. Global warming is when humans add extra layers to that blanket by releasing huge amounts of greenhouse gases like carbon dioxide and methane. These gases come mainly from burning coal, oil, and gas for energy, as well as from agriculture and deforestation. As the blanket thickens, more heat is trapped, and the planet's average temperature rises, leading to changes in weather, melting ice, and rising sea levels.
A deeper explanation
The mechanism behind global warming is the enhanced greenhouse effect. Sunlight reaches Earth and warms the surface, which then emits infrared radiation (heat) back toward space. Greenhouse gases in the atmosphere—especially CO2, methane, and water vapor—absorb much of this outgoing radiation and re-emit it in all directions, including back to the surface. This natural process keeps Earth about 33°C (59°F) warmer than it would be otherwise. Human activities have significantly increased the concentration of these gases, especially CO2 (up 48% since the Industrial Revolution). This extra absorption traps more heat, raising global average temperatures. Importantly, this warming triggers reinforcing feedback loops—such as melting ice (which reduces sunlight reflection) and thawing permafrost (which releases methane)—that accelerate the warming further. This is why global warming is not just a slow, steady rise; it can amplify itself, making it a critical concept for understanding modern climate dynamics.