字幕表 動画を再生する 英語字幕をプリント Carbon dioxide, or CO2, is the main greenhouse gas in climate change. So how does CO2 get into our atmosphere? Well, carbon is part of a cycle. It starts with the sun, which heats the Earth's surface with more energy in one hour than the whole world uses in a year. Plants, which are kind of like biological chefs, take that sunlight, and then suck in some CO2 from the air, mix them together, and BAM! They create a stored form of energy, in the form of carbohydrates such as glucose and sucrose. The process is called photosynthesis. When animals like us eat those plants our stomachs convert that food back into energy for our own growth. Greenhouse gases are a byproduct of this process, and are released through waste. If those plants die, they decompose, and tiny microorganisms break down those carbohydrates and again, release greenhouse gases as a byproduct. As you see, energy originates from the sun. It is then transferred as it moves through the food chain. But sometimes, carbon based organisms like plants or animals get stuck in the earth. When this happens, they're compressed under tons of pressure, and turned into carbon-based fossil fuels like oil, coal or natural gas. Since the Industrial Revolution, humans have been pulling those fossil fuels out of the ground and burning them, activating the stored energy to make electricity and power engines. But the thing is it also releases millions of years worth of stored CO2 back into the air. In addition, humans breathe in oxygen and breathe out CO2. But plants do the opposite. Trees suck up huge amounts of CO2, which balances the cycle. Thus, deforestation reduces the plants that store CO2. We're attacking the cycle from both sides. Think of it like a computer. A computer can operate a few programs at a time, right? Normally, when you've finished with a document, you save, and you close it, so as not to overwork the computer. Then, imagine you stopped closing your documents. So they were all open at once. Your computer wouldn't be able to process it all. It would start to slow down, and then to freeze, and eventually it would crash. Which might be where our environment is heading if we keep overloading the carbon cycle. So is there any way to rebalance the ecosystem? What about technology? Technology is defined as a technique to solve a problem. And so, sustainable technologies are those whose output is equal to their input. They do not create negative externalities, such as CO2, in the present or the future. They sort of cancel themselves out to solve the problem. To achieve this, we need to invent sustainable technologies. If we put all the ideas and technologies ever created into one circle, then invention is the pushing of the boundaries of that circle. And the area outside of the circle is infinite, meaning the potential for invention is limitless. Think about some of the incredible clean technologies we have today. [Wind; Electric & Solar Cars; Biogas] [Biofuels; Photosynthetic Algae; Compost] All those ideas have one thing in common. They all came from people. People innovate. People create. It's the limitless potential of creative people to build unimagined technologies that is going to stop climate change and rebalance the ecosystem. And that is something to be hopeful about.