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Earth's changing climate

Earth's temperature and weather patterns have changed rapidly over the past century. This process, known as climate change, is caused mainly by human activities, especially CO₂ emissions. To avoid the worst impacts of climate change, we need to both reduce emissions and remove excess CO₂ from the atmosphere. Created by Khan Academy.

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  • leafers sapling style avatar for user git.ignore
    Did you know that if the temperature of earth rose by 3° C then the crops would die out, if the temperature rose by 8° then all of the animals on earth would go extinct.
    Even though these rises doesn't look like much, but they can be deadly. Right now scientists are trying to invent a new kind of car, Fuel Cell Car, it runs on Hydrogen and its exhaust is water vapor instead of Carbon dioxide. These kind of cars rely on electricity to combust the hydrogen and same as a car running on oil it goes *BOOM!!* than the car propels forward. The problem of this is there are almost no hydrogen refill stations, plus hydrogen is a rare kind of gas on earth. There another kind of car that runs on Ethanol a kind of oil that comes from plants like peanuts, corn, sunflower. The carbon dioxide they make is less than normal oil that the cars right now make. Scientists are trying to make Ethanol out of non-consumable parts of the plant like the leaves on the corn not its seeds.
    (11 votes)
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  • blobby green style avatar for user Gavin S.
    So, what exactly does the greenhouse affect have to do with radiation?
    (3 votes)
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  • blobby green style avatar for user LIAN TANG
    Why do many people say global warming is a hoax?
    (0 votes)
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    • primosaur seedling style avatar for user Seamus BoBlamus TurphyMcMurphy
      Some people think that, instead of global warming, the Earth is going through cycles of warmth and cold (which is based in truth), because during the age of the dinosaurs, the earth was much hotter than it is today.following the age of the dinosaurs, the earth's temperature started tofall, culminating in the ice age. Since then, temperatures have risen, so people think today's rising temperatures are because the earth is entering another warm cycle.
      (9 votes)
  • aqualine ultimate style avatar for user ShawnVF
    Are Anaerobic digesters the answer to global warming.
    (2 votes)
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  • piceratops ultimate style avatar for user Marion
    HOw come the greenhouse gases can get in but cant get out. If something can get in it should able to get out? RIght??
    (1 vote)
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  • sneak peak blue style avatar for user Karissa
    while we are on a kinda deep topic, what does everyone think will happen after we die? (honest question, I know what I belive but I wanna hear about everyone else)
    (2 votes)
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  • male robot hal style avatar for user edebarrosrego
    If chocolate is made out of coco beans and coco is a plant does that make chocolate a salad
    (1 vote)
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  • blobby green style avatar for user khasenohrl
    where i am, we have very cold winters, but now it feels like spring!
    (1 vote)
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  • blobby green style avatar for user Rhett
    I know that climate changes a thing, but back in the 90s people were talking about 2020 just how people nowadays are talking about 2050. I’m just saying, people get way overworked up. There will still be snow in 2050 and there will still be polar bears. And people from the government need to stop blaming people like us for climate changing. They ride jets on a daily basis!
    (1 vote)
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  • blobby green style avatar for user RicardoR
    why I watch the video and doesn't count as I see the video?
    (1 vote)
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Video transcript

- [Narrator] Have you ever tried to imagine what the world was like in the distant past? Maybe you'd like to explore the age of the dinosaurs when the earth was much hotter than it was today. Perhaps you'd prefer when temperatures dropped too much colder than today. You could track a mammoth alongside our early ancestors who evolved around the end of the last ice age. We know about all of these ancient climate trends because scientists learned how to estimate them using evidence from ice cores, tree rings, and other natural phenomena. We now know that for most of human history, people could expect a pattern that looks something like this graph from the National Aeronautics and Space Administration which shows how temperatures changed each year in comparison to this line, which represents the average global annual temperature from 1880 to 1899. When we look at the time period between 1880 and 1940, we can see that some years temperatures would be higher than this average, some years they would be lower, but they generally swing back to a pretty comfortable state. Around the 1950s, though, the global average temperature began to climb to unprecedented levels. Our ancient temperature records never showed such a sudden increase. When we look at the time period from 1950 to today, we can see that while temperatures still swing back down some years, these colder years are still much hotter than the average temperatures in the past. Researchers noticed a change in the concentration of greenhouse gases in the Earth's atmosphere. These greenhouse gases trap heat from the sun in our atmosphere, similar to how a greenhouse allows sunlight to pass through its glass walls but prevents the heat it creates from leaving. This greenhouse effect is what keeps our planet warm and habitable enough for life. However, the amount of one particular greenhouse gas was rising, carbon dioxide or CO2. CO2 is naturally one of the most notable greenhouse gases besides water vapor, but we can also release CO2 by burning wood or fossil fuels like coal and oil. Over time, humans have increasingly relied on these fuels to power things like planes, cars, and trains as well as to generate electricity. As a result of these human activities, more CO2 is being released into the atmosphere than ever before, much more than is normally released by the Earth and at a much faster rate. The increasingly heavy blanket of greenhouse gases is trapping excess heat in our atmosphere rather than allowing more of it to radiate into space as normal. This is what's causing Earth's average temperature to rise beyond what scientists would expect based on historical patterns. While scientists once referred to this process as global warming, most now prefer the more general term, climate change. A world that's a little bit warmer on average might not seem like such a big deal, but we've learned that even a small shift in the planet's natural processes can have drastic consequences. When studying the early signs of climate change, scientists predicted that as cold places like North and South Pole got warmer, the ice would begin to melt. All of that frozen water suddenly flowing into the oceans would cause sea levels to rise, which would affect the planet's weather system. Have you heard all the news about weird weather in the past few years? Snow in places that's usually warm and dry, or drought in places that are usually cold and rainy, huge fires during extremely hot summers, severe storms battering coastlines and flooding cities. Many of these natural hazards used to be somewhat rare, but now they're becoming more common, exactly as climate scientists predicted. People have relied on relatively consistent weather patterns for generations, so they aren't prepared to adapt to these changes in their local environment. Communities that are already feeling the effects of climate change are worried that they're gonna lose their homes, their livelihoods, or their sources of food and water. Scientists are working on technologies that can help us remove some of the excess CO2 from the atmosphere, but in the meantime they recommend that we emit less CO2 in the first place. This would allow us to limit how much the global average temperature increases, giving communities time to adapt to changes in their surroundings. Of course, it's complicated to change the way our societies work. To help reduce CO2 emissions, you may see some people advocating for tweaking individual behaviors, like eating plant-based diets or using low carbon transportation methods. You may see others saying that since large organizations in highly populated countries emit the most CO2, we need to push them to make more wide raging institutional changes. As someone who works in environmental science, I know that sorting through all of these different facts and opinions on climate change can be overwhelming. It's difficult to think about living in a world that may be very different from what I've always known in the past. I've found it helpful to both adopt simple sustainable habits in my own life, while also seeking out community groups that work on bigger initiatives. It's easier to imagine the future when you help others to shape it. Now that we've taken some time to think about Earth's past and what's happening to it in the present, try looking towards the future of our planet. What is your ideal future? And how can you help to make it happen?