4 ms·

No, the energy doesn’t accumulate in Earth over time. Disregarding the energy of radioactive decay within Earth, the Earth is in steady state with respect to en

by xyzzyz 4y ago

No, the energy doesn’t accumulate in Earth over time. Disregarding the energy of radioactive decay within Earth, the Earth is in steady state with respect to energy. All energy it receives from the Sun is radiated away promptly. The greenhouse effect works by delaying this radiation. The more the radiation is delayed by, the more energy is buffered in steady state. Make no mistake though: all of the energy from the Sun is radiated away rather quickly. > If you compared that earth to another one without those years of increased levels, the one without would be less warm. No, after the methane from the fields decays to CO2, both would be the same.

Timon3 4y ago
> All energy it receives from the Sun is radiated away promptly. The greenhouse effect works by delaying this radiation. The more the radiation is delayed by, the more energy is buffered in steady state. Make no mistake though: all of the energy from the Sun is radiated away rather quickly. This is easily disproven. The Earth does trap heat - we can measure this, it's called the Earth Energy Imbalance. This imbalance has been rising since more greenhouse gases were introduced: https://www.nasa.gov/feature/langley/joint-nasa-noaa-study-finds-earths-energy-imbalance-has-doubled https://www.nasa.gov/feature/langley/joint-nasa-noaa-study-f... The amount trapped is rising because we retain the same input longer. A fraction of the total heat is radiated away (not all of it, and not "rather quickly"). If that fraction drops more heat will be trapped. Now you have a system with additional energy due to additional greenhouse gases. Over time the gases will reduce, but the radiation is still only a fraction of the total heat! Of course over time this will very slowly trend back towards the same temperature, but even when the gases themselves have returned to previous levels, the additional heat will take a number of years to be radiated away.
- Retric 4y ago
  That’s true, but we’ve been cultivating rice for thousands of years. When people talk about returning the earth to pre industrial levels that’s a world with significant rice cultivation going back long enough to account for such differences. The global energy imbalance is simply lag before temperature’s equilibrium, when you turn up the heat in your house it takes longer to heat your fireplace than a wood door. That same effect takes longer on the scale of the earth but it’s an exponential decay. Compared to the history of rice cultivation you very quickly get to millions of a degree difference in surface temperatures. We just keep adding ever more greenhouse gasses.
  - Timon3 4y ago
    > That’s true, but we’ve been cultivating rice for thousands of years. How much rice did we previously cultivate, and how many of those fields were flooded? Around 1900 the world population was around 2 billion, so I feel confident in assuming that we've since strongly increased the amount of farms. As such I don't see how this matters. Cultivation is not a boolean state. > The global energy imbalance is simply lag before temperature’s equilibrium, when you turn up the heat in your house it takes longer to heat your fireplace than a wood door. That same effect takes longer on the scale of the earth but it’s an exponential decay. Yes, this is what I've been saying. Increasing the amount of methane in the atmosphere by increasing rice production will lead to an increased temperature even after you stop.
    - Retric 4y ago
      > Around 1900 the world population was around 2 billion, so I feel confident in assuming that we've since strongly increased the amount of farms Actually not so much, due to vastly increased agricultural output per acre the tendency is to have less acres under cultivation. https://www.statista.com/statistics/196104/total-area-of-land-in-farms-in-the-us-since-2000/ https://www.statista.com/statistics/196104/total-area-of-lan... Further agriculture has also reduced quite a bit of methane production by draining swamps etc. So it’s difficult to do direct comparisons even just back in 1900. > Increasing the amount of methane in the atmosphere by increasing rice production will lead to an increased temperature even after you stop. That’s true of CO2 across the next few decades but not methane because it breaks down so fast. Assuming net zero CO2 the lag would be in the other direction where it would get colder for several years after you stopped.
      - Timon3 4y ago
        > Actually not so much, due to vastly increased agricultural output per acre the tendency is to have less acres under cultivation. Your source shows data for America between 2000 and 2022. Why do you think that is a good source for the topic at hand? > Further agriculture has also reduced quite a bit of methane production by draining swamps etc. So it’s difficult to do direct comparisons even just back in 1900. There is no reason to do so, my argument is not affected by it in any way. > That’s true of CO2 across the next few decades but not methane because it breaks down so fast. No, breakdown time doesn't affect anything, since I'm specifically talking about the time after it broke down. If you understood my comments differently, try re-reading them in that light. > Assuming net zero CO2 the lag would be in the other direction where it would get colder for several years after you stopped. Am I understanding you correctly - you believe that temperature is like a pendulum, where after a period with increased greenhouse gases, it will somehow swing to be colder than it would have been without that period? Why do you think so, and how do you believe this to work from a thermodynamics perspective?

by xyzzyz 4y ago

Timon3 4y ago

> All energy it receives from the Sun is radiated away promptly. The greenhouse effect works by delaying this radiation. The more the radiation is delayed by, the more energy is buffered in steady state. Make no mistake though: all of the energy from the Sun is radiated away rather quickly. This is easily disproven. The Earth does trap heat - we can measure this, it's called the Earth Energy Imbalance. This imbalance has been rising since more greenhouse gases were introduced: https://www.nasa.gov/feature/langley/joint-nasa-noaa-study-finds-earths-energy-imbalance-has-doubled https://www.nasa.gov/feature/langley/joint-nasa-noaa-study-f... The amount trapped is rising because we retain the same input longer. A fraction of the total heat is radiated away (not all of it, and not "rather quickly"). If that fraction drops more heat will be trapped. Now you have a system with additional energy due to additional greenhouse gases. Over time the gases will reduce, but the radiation is still only a fraction of the total heat! Of course over time this will very slowly trend back towards the same temperature, but even when the gases themselves have returned to previous levels, the additional heat will take a number of years to be radiated away.

Retric 4y ago
That’s true, but we’ve been cultivating rice for thousands of years. When people talk about returning the earth to pre industrial levels that’s a world with significant rice cultivation going back long enough to account for such differences. The global energy imbalance is simply lag before temperature’s equilibrium, when you turn up the heat in your house it takes longer to heat your fireplace than a wood door. That same effect takes longer on the scale of the earth but it’s an exponential decay. Compared to the history of rice cultivation you very quickly get to millions of a degree difference in surface temperatures. We just keep adding ever more greenhouse gasses.
- Timon3 4y ago
  > That’s true, but we’ve been cultivating rice for thousands of years. How much rice did we previously cultivate, and how many of those fields were flooded? Around 1900 the world population was around 2 billion, so I feel confident in assuming that we've since strongly increased the amount of farms. As such I don't see how this matters. Cultivation is not a boolean state. > The global energy imbalance is simply lag before temperature’s equilibrium, when you turn up the heat in your house it takes longer to heat your fireplace than a wood door. That same effect takes longer on the scale of the earth but it’s an exponential decay. Yes, this is what I've been saying. Increasing the amount of methane in the atmosphere by increasing rice production will lead to an increased temperature even after you stop.
  - Retric 4y ago
    > Around 1900 the world population was around 2 billion, so I feel confident in assuming that we've since strongly increased the amount of farms Actually not so much, due to vastly increased agricultural output per acre the tendency is to have less acres under cultivation. https://www.statista.com/statistics/196104/total-area-of-land-in-farms-in-the-us-since-2000/ https://www.statista.com/statistics/196104/total-area-of-lan... Further agriculture has also reduced quite a bit of methane production by draining swamps etc. So it’s difficult to do direct comparisons even just back in 1900. > Increasing the amount of methane in the atmosphere by increasing rice production will lead to an increased temperature even after you stop. That’s true of CO2 across the next few decades but not methane because it breaks down so fast. Assuming net zero CO2 the lag would be in the other direction where it would get colder for several years after you stopped.
    - Timon3 4y ago
      > Actually not so much, due to vastly increased agricultural output per acre the tendency is to have less acres under cultivation. Your source shows data for America between 2000 and 2022. Why do you think that is a good source for the topic at hand? > Further agriculture has also reduced quite a bit of methane production by draining swamps etc. So it’s difficult to do direct comparisons even just back in 1900. There is no reason to do so, my argument is not affected by it in any way. > That’s true of CO2 across the next few decades but not methane because it breaks down so fast. No, breakdown time doesn't affect anything, since I'm specifically talking about the time after it broke down. If you understood my comments differently, try re-reading them in that light. > Assuming net zero CO2 the lag would be in the other direction where it would get colder for several years after you stopped. Am I understanding you correctly - you believe that temperature is like a pendulum, where after a period with increased greenhouse gases, it will somehow swing to be colder than it would have been without that period? Why do you think so, and how do you believe this to work from a thermodynamics perspective?