5 ms·

The rate at which the temperature is changing is probably at historic highs, but both the current temperature and atmospheric CO2 concentrations are close to hi

by avar 3y ago

The rate at which the temperature is changing is probably at historic highs, but both the current temperature and atmospheric CO2 concentrations are close to historic lows. See [1], that xkcd is picking a really biased starting point by using the last ice age as a baseline. Ice ages themselves being extreme abnormalities from the general historic trend. 1. https://www.researchgate.net/figure/Global-Temperature-and-CO2-levels-over-600-million-years-Source-MacRae-2008_fig1_280548391 https://www.researchgate.net/figure/Global-Temperature-and-C...

hatthew 3y ago
That xkcd is not demonstrating the amount of warming, it is demonstrating the velocity of warming. Historic temperatures on a time scale of millions of years are completely irrelevant to the current discussion of climate change, unless you think we have a chance to evolve into dinosaurs in the next few centuries (/s).
- avar 3y ago
  The temperature and CO2 concentrations are also unusually low for the Cenozoic Era. That's the post-Dinosaur era (if we're not including avians): https://www.researchgate.net/figure/Dynamics-of-global-surface-temperature-during-the-Cenozoic-Era-reconstructed-from-18-O_fig6_309651389 https://www.researchgate.net/figure/Dynamics-of-global-surfa... The rise of mammals happened almost immediately after the extinction of dinosaurs, when the average surface temperature was around 10°C hotter than today.
  - hatthew 3y ago
    I had hoped that my point was clear without too much elaboration, and that you were joining this discussion in good faith. My understanding: At the moment, climate projections are that within the next few centuries we will reach temperatures not seen since the eocene. The mammals of the eocene were quite small, because larger mammals had trouble surviving the hot climate. While the broad categories of animals that still exist today also existed back then, in aggregate they looked very different from today. Given current trends, the majority of animals of today will be unable to adapt to the new climate, and will die off. Please correct me if I'm wrong, and then also follow that up with correcting the scientific consensus of experts who are forecasting drastic and damaging changes to the earth caused by humans.
    - avar 3y ago
      You no longer believe that we're conversing in good faith? > At the moment, climate projections are that within the next few centuries we will reach temperatures not seen since the eocene. That seems about right, see e.g.: https://www.marum.de/en/Dr.-thomas-westerhold/CENOGRID.html https://www.marum.de/en/Dr.-thomas-westerhold/CENOGRID.html > The mammals of the eocene were quite small, because larger mammals had trouble surviving the hot climate. What makes you think mammal size was limited by the temperature differences we're discussing? I think the predominant theory is that the asteroid impact killed off the larger ones, and it took a while for larger mammals to evolve. See e.g.: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645244/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645244/ In any case, even if the Earth as a whole was much warmer on average that just means that you'd get the average temperatures that now occur closer to the equator (where some of the largest land mammals presently live) closer to the poles. So higher average surface temperatures shouldn't preclude the existence of larger mammals. > Given current trends, the majority of animals of today will be unable to adapt to the new climate, and will die off. I think this has less to do with climate change per-se, and more to do with the widespread ecological destruction that's followed industrialization, and the reduction in wild habitats. Although there's surely some species that'll go extinct mainly due to temperature changes, e.g. ones confined to a small atoll that'll get overrun by sea levels rising.
      - hatthew 3y ago
        Based on the context of your first comment I thought you were trying to argue that the environment isn't really in trouble. If you agree that humans are negatively impacting the environment, that's good enough for me :)

by avar 3y ago

hatthew 3y ago

That xkcd is not demonstrating the amount of warming, it is demonstrating the velocity of warming. Historic temperatures on a time scale of millions of years are completely irrelevant to the current discussion of climate change, unless you think we have a chance to evolve into dinosaurs in the next few centuries (/s).

avar 3y ago
The temperature and CO2 concentrations are also unusually low for the Cenozoic Era. That's the post-Dinosaur era (if we're not including avians): https://www.researchgate.net/figure/Dynamics-of-global-surface-temperature-during-the-Cenozoic-Era-reconstructed-from-18-O_fig6_309651389 https://www.researchgate.net/figure/Dynamics-of-global-surfa... The rise of mammals happened almost immediately after the extinction of dinosaurs, when the average surface temperature was around 10°C hotter than today.
- hatthew 3y ago
  I had hoped that my point was clear without too much elaboration, and that you were joining this discussion in good faith. My understanding: At the moment, climate projections are that within the next few centuries we will reach temperatures not seen since the eocene. The mammals of the eocene were quite small, because larger mammals had trouble surviving the hot climate. While the broad categories of animals that still exist today also existed back then, in aggregate they looked very different from today. Given current trends, the majority of animals of today will be unable to adapt to the new climate, and will die off. Please correct me if I'm wrong, and then also follow that up with correcting the scientific consensus of experts who are forecasting drastic and damaging changes to the earth caused by humans.
  - avar 3y ago
    You no longer believe that we're conversing in good faith? > At the moment, climate projections are that within the next few centuries we will reach temperatures not seen since the eocene. That seems about right, see e.g.: https://www.marum.de/en/Dr.-thomas-westerhold/CENOGRID.html https://www.marum.de/en/Dr.-thomas-westerhold/CENOGRID.html > The mammals of the eocene were quite small, because larger mammals had trouble surviving the hot climate. What makes you think mammal size was limited by the temperature differences we're discussing? I think the predominant theory is that the asteroid impact killed off the larger ones, and it took a while for larger mammals to evolve. See e.g.: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645244/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645244/ In any case, even if the Earth as a whole was much warmer on average that just means that you'd get the average temperatures that now occur closer to the equator (where some of the largest land mammals presently live) closer to the poles. So higher average surface temperatures shouldn't preclude the existence of larger mammals. > Given current trends, the majority of animals of today will be unable to adapt to the new climate, and will die off. I think this has less to do with climate change per-se, and more to do with the widespread ecological destruction that's followed industrialization, and the reduction in wild habitats. Although there's surely some species that'll go extinct mainly due to temperature changes, e.g. ones confined to a small atoll that'll get overrun by sea levels rising.
    - hatthew 3y ago
      Based on the context of your first comment I thought you were trying to argue that the environment isn't really in trouble. If you agree that humans are negatively impacting the environment, that's good enough for me :)