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Unlock This CourseGreenhouse gases are invisible gases in our atmosphere that trap heat from the sun, keeping Earth warm enough for life. Without them, our planet would be a frozen wasteland! However, human activities are increasing these gases too much, causing our planet to warm up dangerously fast.
Key Definitions:
Imagine Earth wearing a blanket. Solar energy comes in, warms the surface and some heat tries to escape back to space. Greenhouse gases act like the blanket, trapping some of this heat and keeping us warm. More greenhouse gases mean a thicker blanket and a warmer planet!
Several gases contribute to the greenhouse effect, but some are much more powerful than others. Let's explore the main culprits and where they come from.
Carbon dioxide is the most important greenhouse gas because of the huge amounts we produce. It makes up about 76% of all greenhouse gas emissions from human activities.
Cars, lorries, ships and aeroplanes burn fossil fuels, releasing CO₂. A typical car produces about 4.6 tonnes of CO₂ per year!
Power stations burning coal, oil and gas to make electricity. Coal is the worst offender, producing twice as much CO₂ as natural gas.
Cutting down forests releases stored carbon and removes trees that absorb CO₂. We lose 10 million hectares of forest each year!
Methane is 25 times more powerful at trapping heat than CO₂, but there's less of it in the atmosphere. It makes up about 16% of greenhouse gas emissions.
Cows and other ruminants produce methane when they digest grass. Rice fields also release methane because they're flooded, creating perfect conditions for methane-producing bacteria.
A single cow produces about 100-200 litres of methane per day through burping! With over 1 billion cattle worldwide, that's a lot of greenhouse gas from our four-legged friends.
Since the Industrial Revolution began around 1750, human activities have dramatically increased greenhouse gas concentrations in the atmosphere. Let's examine the main ways we're changing our planet's atmosphere.
This is the biggest source of greenhouse gas emissions, accounting for about 75% of the total. When we burn coal, oil and natural gas for energy, we release carbon that's been locked underground for millions of years.
Factories making cement, steel and chemicals release huge amounts of CO₂. Making one tonne of cement produces nearly one tonne of CO₂! Manufacturing also uses lots of energy, usually from fossil fuels.
How we use land has a massive impact on greenhouse gas levels. Forests are brilliant at storing carbon, but when we cut them down, all that stored carbon gets released.
The Amazon rainforest stores about 150-200 billion tonnes of carbon. Deforestation for cattle ranching and soy farming releases this carbon whilst removing the trees that could absorb more CO₂. Brazil lost over 13,000 square kilometres of Amazon rainforest in 2020 alone.
The natural greenhouse effect keeps Earth at a comfortable average temperature of 15°C. Without it, our planet would be -18°C - far too cold for most life! However, human activities are enhancing this effect, making Earth warmer than it should be.
Natural greenhouse effect: Essential for life, keeps Earth warm. Enhanced greenhouse effect: Too much of a good thing, caused by human activities, leading to dangerous warming.
Scientists have overwhelming evidence that our planet is warming due to increased greenhouse gases:
Global average temperature has risen by about 1.1°C since 1880. The last decade was the warmest on record.
Arctic sea ice is shrinking by 13% per decade. Glaciers worldwide are retreating rapidly.
Sea levels have risen 20cm since 1900 due to thermal expansion and melting ice.
Rising greenhouse gas levels are causing serious changes to our planet's climate system, affecting both natural environments and human societies.
Climate change is altering ecosystems around the world, threatening biodiversity and natural processes that life depends on.
Oceans absorb CO₂, making them more acidic. This harms coral reefs and shellfish. Warmer oceans also fuel stronger hurricanes and change ocean currents that regulate climate.
Polar bears depend on sea ice to hunt seals. As Arctic ice melts earlier and forms later each year, bears have less time to hunt and build up fat reserves. Some populations have declined by 40% since the 1980s.
Climate change affects people everywhere, but some communities face greater risks than others.
Changing rainfall and temperatures affect crop yields. Heat waves and droughts can destroy harvests.
Rising sea levels threaten low-lying islands and coastal cities. Storm surges become more destructive.
Heat waves cause more deaths. Changing disease patterns as mosquitoes spread to new areas.
The good news is that we know how to reduce greenhouse gas emissions! It requires changes at every level - from individual actions to international cooperation.
Switching from fossil fuels to renewable energy sources is crucial for reducing CO₂ emissions. Solar and wind power are now cheaper than coal in many places!
Renewable energy capacity is growing rapidly. Solar power costs have fallen by 90% since 2010, making it the cheapest electricity source in many countries.
Everyone can help reduce greenhouse gas emissions through daily choices:
Walk, cycle, use public transport, or choose electric vehicles. Flying less makes a huge difference.
Use LED bulbs, improve insulation, choose renewable energy suppliers.
Eat less meat, choose local and seasonal foods, reduce food waste.
Costa Rica generates over 99% of its electricity from renewable sources (mainly hydroelectric, wind and solar). The country has also reversed deforestation, with forest cover increasing from 24% in 1985 to over 50% today, helping absorb CO₂ from the atmosphere.
The next decade is crucial for tackling climate change. Scientists say we need to halve greenhouse gas emissions by 2030 to avoid the worst impacts. This requires rapid changes in how we produce energy, grow food and live our lives.
Technology is improving rapidly, costs of clean energy are falling and young people worldwide are demanding action. With determination and cooperation, we can solve the climate crisis!