4 ms·

This is a point that we need to think carefully. The melting projections are only as good as our understanding of our planet's systems. Just look at weather, ar

This is a point that we need to think carefully. The melting projections are only as good as our understanding of our planet's systems. Just look at weather, are we really good at predicting it? We have come a long way but if we are not certain about next week's weather, how do we know what chain reactions are going to start, that can in-turn melt Greenland (Antarctic, etc.) ice way faster? We are literally scratching the tip of the iceberg (no pun intended). Our scientific models have changed recently and I am sure they will change again, soon. So why are we so sure that the melt will not accelerate to catastrophic levels? https://en.wikipedia.org/wiki/Antarctic_ice_sheet#Recent_observations https://en.wikipedia.org/wiki/Antarctic_ice_sheet#Recent_obs...

dfee 6y ago
> So why are we so sure that the melt will not accelerate to catastrophic levels? This is the sort of remark that undermines the cause.
- anigbrowl 6y ago
  No it isn't. Your tone policing undermines the cause by making people afraid of even considering worst-case scenarios in case they get labeled as alarmists.
- brainless 6y ago
  Undermines what and how? I am really interested in understanding this topic. I am an engineer by profession, I do not take things just because someone says so. And history is proof that humans barely have understanding of things. Every single recent study shows that things are accelerating. There is not a single scientific study showing a slow down of the melting process - not 1 study among hundreds. If anyone can share one, I would love to read.
  - sfkdjf9j3j 6y ago
    You want a study about something nobody has observed?
chrisco255 6y ago
Truly catastrophic would be a sudden plunge in temperatures. A glacial period like what happened in the Younger Dryas would cause severe famine and crop shortages, loss of habitable land, and extreme pressure on habitats everywhere: https://en.m.wikipedia.org/wiki/Younger_Dryas https://en.m.wikipedia.org/wiki/Younger_Dryas
- cafebabbe 6y ago
  As far as i know, no model predicts a glacial period in the next decades. Also, inhabitable land & crop failure will happen with an increase of 3 to 4 degrees (and this is the optimistic outcome), so i don't see why it's not worth or your "truly catastrophic" characterization.
  - chrisco255 6y ago
    No model for weather or climate is reliable out to a few decades. Uncertainty is an exponential function of time in chaotic systems. One good super volcano and the earth would plunge into a glacial period. A series of large volcanoes over many years would keep us there for a long, long time. We have absolutely no way to predict supervolcanoes or general volcanic activity over the next several decades. For an example of what can happen from simply a large volcanic eruption, see the Year Without a Summer in 1816: https://en.m.wikipedia.org/wiki/Year_Without_a_Summer https://en.m.wikipedia.org/wiki/Year_Without_a_Summer But that was not a super volcano. It was just one large eruption. We have only increased by about 1 degree in the past 100 years. We are still cooler than the Medieval Warm Period when Vikings were farming parts of Greenland, and cooler than the Roman Warm Period, when they were growing wine grapes in Scotland. It's doubtful that CO2 increase of even doubling would cause catastrophic crop failure. After all, the CO2 levels were thousands of PPM for most of Earth's history, and plants evolved under those conditions before the Pliestocene. Dinosaurs were very large creatures that were supported by a rich ecosystem of plant life. CO2 is plant food. Only at extremely high levels of 7000+ ppm (20x modern levels) has there ever been any geological evidence of catastrophe and even that event is hard to disentangle cause and effect.
preben 6y ago
Careful mixing weather with climate. Depending on the model used, the Lyapunov time[0] for such a model is a couple of days. The whole climate system is a different beast, so no use comparing our predictions in one with the other. [0]: https://en.wikipedia.org/wiki/Lyapunov_time https://en.wikipedia.org/wiki/Lyapunov_time

dfee 6y ago

> So why are we so sure that the melt will not accelerate to catastrophic levels? This is the sort of remark that undermines the cause.

anigbrowl 6y ago
No it isn't. Your tone policing undermines the cause by making people afraid of even considering worst-case scenarios in case they get labeled as alarmists.
brainless 6y ago
Undermines what and how? I am really interested in understanding this topic. I am an engineer by profession, I do not take things just because someone says so. And history is proof that humans barely have understanding of things. Every single recent study shows that things are accelerating. There is not a single scientific study showing a slow down of the melting process - not 1 study among hundreds. If anyone can share one, I would love to read.
- sfkdjf9j3j 6y ago
  You want a study about something nobody has observed?

chrisco255 6y ago

Truly catastrophic would be a sudden plunge in temperatures. A glacial period like what happened in the Younger Dryas would cause severe famine and crop shortages, loss of habitable land, and extreme pressure on habitats everywhere: https://en.m.wikipedia.org/wiki/Younger_Dryas https://en.m.wikipedia.org/wiki/Younger_Dryas

cafebabbe 6y ago
As far as i know, no model predicts a glacial period in the next decades. Also, inhabitable land & crop failure will happen with an increase of 3 to 4 degrees (and this is the optimistic outcome), so i don't see why it's not worth or your "truly catastrophic" characterization.
- chrisco255 6y ago
  No model for weather or climate is reliable out to a few decades. Uncertainty is an exponential function of time in chaotic systems. One good super volcano and the earth would plunge into a glacial period. A series of large volcanoes over many years would keep us there for a long, long time. We have absolutely no way to predict supervolcanoes or general volcanic activity over the next several decades. For an example of what can happen from simply a large volcanic eruption, see the Year Without a Summer in 1816: https://en.m.wikipedia.org/wiki/Year_Without_a_Summer https://en.m.wikipedia.org/wiki/Year_Without_a_Summer But that was not a super volcano. It was just one large eruption. We have only increased by about 1 degree in the past 100 years. We are still cooler than the Medieval Warm Period when Vikings were farming parts of Greenland, and cooler than the Roman Warm Period, when they were growing wine grapes in Scotland. It's doubtful that CO2 increase of even doubling would cause catastrophic crop failure. After all, the CO2 levels were thousands of PPM for most of Earth's history, and plants evolved under those conditions before the Pliestocene. Dinosaurs were very large creatures that were supported by a rich ecosystem of plant life. CO2 is plant food. Only at extremely high levels of 7000+ ppm (20x modern levels) has there ever been any geological evidence of catastrophe and even that event is hard to disentangle cause and effect.

preben 6y ago

Careful mixing weather with climate. Depending on the model used, the Lyapunov time[0] for such a model is a couple of days. The whole climate system is a different beast, so no use comparing our predictions in one with the other. [0]: https://en.wikipedia.org/wiki/Lyapunov_time https://en.wikipedia.org/wiki/Lyapunov_time