The Roman emperor Tiberius liked fresh cucumbers every day. His gardeners planted them in wheeled carts with open frames they left out in the sun all day long. However, they took the plants inside into a shed at night, and covered the frames over with oiled cloth to trap the heat. This is the earliest example of the greenhouse effect we know, although nowadays gardeners trap the heat with glass frames.
How Modern Glasshouses Exploit the Greenhouse Effect
Solar radiation passes through the glass roofs and walls, and warms the soil and the plants. However it cannot escape and so the greenhouse effect keeps the plants warm all day and night. Skylights may open manually or automatically if it gets too warm inside.
Nature’s garden, Earth also absorbs Sun’s heat and its atmosphere prevents some of it escaping. However the process is technically different but we won’t go into that here. What’s important for us is a balance evolved over billions of years. And that life that evolved and adapted perfectly to the global average temperature this balance achieved.
How the Composition of Earth’s Atmosphere is Critical to Life
In simple, fundamental terms, Earth’s atmosphere acts as a thermal filter. It admits a certain amount of heat, but allows the rest to radiate away. Mars is freezing cold because the atmosphere is so thin it traps no heat at all.
The first industrial revolution changed the composition of Earth’s atmosphere by burning fossil fuels. This released certain ‘greenhouse gases’ into the atmosphere that reduced the heat radiating away as it used to. This process is gradual but the effect is cumulative. Even if we stopped burning fossils entirely this instant, the greenhouse gases would take a century to dissipate.
But we haven’t stopped burning fossil fuels because science, business and politics can’t agree. That’s why the greenhouse effect is still warming Earth, and the climate around us is changing. The political will is not mature enough to respond sufficiently robustly to this. And when there is the will, there will no ‘undo button for a quick fix.
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Ancient Roman Greenhouse Shadows Remain
Preview Image: Greenhouses in the Westland Region
