Everything you need to know about global warming

24 Cards

CURATED BY Brad Plumer

2014-10-22 12:13:16 -0400

  1. What is global warming?
  2. Is global warming the same thing as climate change?
  3. How do we know global warming is really happening?
  4. How do we know humans are responsible for global warming?
  5. Where do greenhouse-gas emissions come from?
  6. How has global warming affected the world so far?
  7. How high will temperatures rise if global warming continues?
  8. What impacts will global warming have in the future?
  9. What is sea-level rise?
  10. What is ocean acidification?
  11. Is it dangerous to have more than 2°C of global warming?
  12. What happens if the world heats up more drastically — say, 4°C?
  13. How much could global warming cost the economy?
  14. How do we stop global warming?
  15. How do we reduce greenhouse-gas emissions?
  16. Can't we just adapt to global warming?
  17. What are the UN climate talks?
  18. What is geoengineering?
  19. Did climate change cause today’s awful weather?
  20. What is climate skepticism?
  21. It’s cold outside! Does that disprove global warming?
  22. Hasn't global warming slowed down in the last 15 years?
  23. You didn't answer my question!
  24. What else should I be reading about global warming?
  1. Card 1 of 24

    What is global warming?

  2. Card 2 of 24

    Is global warming the same thing as climate change?

  3. Card 3 of 24

    How do we know global warming is really happening?

  4. Card 4 of 24

    How do we know humans are responsible for global warming?

    Climate scientists say they are 95 percent certain that human influence has been the dominant cause of global warming since 1950. They're about as sure of this as they are that cigarette smoke causes cancer.

    Why are they so confident? In part because they have a good grasp on how greenhouse gases can warm the planet, in part because the theory fits the available evidence, and in part because alternate theories have been ruled out. Let's break it down in six steps:

    1) Scientists have long known that greenhouse gases in the atmosphere — such as carbon dioxide, methane, or water vapor — absorb certain frequencies of infrared radiation and scatter them back toward the Earth. These gases essentially prevent heat from escaping too quickly back into space, trapping that radiation at the surface and keeping the planet warm.

    2) Climate scientists also know that concentrations of greenhouse gases in the atmosphere have grown significantly since the Industrial Revolution. Carbon dioxide has risen 40 percent. Methane has risen 150 percent. Through some relatively straightforward chemistry, scientists can trace these increases to human activities like burning oil, gas, and coal.

    3) So it stands to reason that more greenhouse gases would lead to more heat. And, indeed, satellite measurements have shown that less infrared radiation is escaping out into space over time and instead returning to the Earth's surface. That's strong evidence that the greenhouse effect is increasing.

    4) There are other human fingerprints that suggest that increased greenhouse gases are warming the planet. For instance, back in the 1960s, simple climate models predicted that global warming caused by more carbon dioxide would lead to cooling in the upper atmosphere (because the heat is getting trapped at the surface). Later satellite measurements confirmed exactly that. Here are a few other similar predictions that have also been confirmed.

    Human_fingerprints_medium

    Skeptical Science

    5) Meanwhile, climate scientists have ruled out other explanations for the rise in average temperatures over the last century. To take one example: solar activity can shift from year to year, affecting the Earth's climate. But satellite data shows that total solar irradiance has declined slightly in the past 35 years, even as the Earth has warmed.

    6) More recent calculations have shown that it's impossible to explain the temperature rise we've seen in the past century without taking the increase in carbon-dioxide and other greenhouse gases into account. Natural causes, like the sun or volcanoes, have an influence, but they're not sufficient by themselves.

    Ultimately, the Intergovernmental Panel on Climate Change (IPCC) concluded that more than half of the warming since 1951 is due to human activities. The Earth's climate can certainly fluctuate from year to year due to natural forces (including oscillations in the Pacific Ocean, like El Niño). But greenhouse gases are driving the larger upward trend in temperatures.

    More: Here's a chart breaking down all the different factors affecting the Earth's average temperature. And there's much more detail in the IPCC's report, particularly here and here.

  5. Card 5 of 24

    Where do greenhouse-gas emissions come from?

  6. Card 6 of 24

    How has global warming affected the world so far?

  7. Card 7 of 24

    How high will temperatures rise if global warming continues?

  8. Card 8 of 24

    What impacts will global warming have in the future?

  9. Card 9 of 24

    What is sea-level rise?

  10. Card 10 of 24

    What is ocean acidification?

  11. Card 11 of 24

    Is it dangerous to have more than 2°C of global warming?

  12. Card 12 of 24

    What happens if the world heats up more drastically — say, 4°C?

  13. Card 13 of 24

    How much could global warming cost the economy?

  14. Card 14 of 24

    How do we stop global warming?

  15. Card 15 of 24

    How do we reduce greenhouse-gas emissions?

  16. Card 16 of 24

    Can't we just adapt to global warming?

  17. Card 17 of 24

    What are the UN climate talks?

  18. Card 18 of 24

    What is geoengineering?

  19. Card 19 of 24

    Did climate change cause today’s awful weather?

  20. Card 20 of 24

    What is climate skepticism?

  21. Card 21 of 24

    It’s cold outside! Does that disprove global warming?

  22. Card 22 of 24

    Hasn't global warming slowed down in the last 15 years?

  23. Card 23 of 24

    You didn't answer my question!

  24. Card 24 of 24

    What else should I be reading about global warming?

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