4 ms·

I'm just a layman, not a climate scientist, but I don't think the magnitude of the warming is our big issue. The issue is how quickly it's changing. Previous wa

by rland 8y ago

I'm just a layman, not a climate scientist, but I don't think the magnitude of the warming is our big issue. The issue is how quickly it's changing. Previous warming events happened very slowly; even the quickest ones occurred over thousands or tens of thousands of years. Ours is happening a couple orders of magnitude faster. We can look back, not at the geological record, but at the biological record. Large, fast shifts like this one cause big extinctions. The biosphere cannot react quickly without huge, unpredictable changes. I'm sure there are conceivable benefits to a warmer earth, but we have to get from here to there without dying and that's what everyone is chiefly concerned about.

cbkeller 8y ago
Coming from a geologist, you're exactly right!
- fromthestart 8y ago
  As a fellow geoscientist, you especially should be aware of the dating limitations of rock and fossil records. We simply do not have the resolution currently to know whether this kind of warming speed is truely unprecedented. Hell - a huge part of petroleum exploration is understanding conditions of the surface during deposition of sediment. We're lucky to get 10Ma uncertainty for 100Ma old formations. I've witnessed firsthand the degree of non scientific handwaving that plagues petroleum geoscience - in both geology and geophysics; and this is in a practical, applied field, where there is some degree of [loose] validation in the form of exploration success/failure. In an unfalsifiable field like climate science, where "validation" consists of retroactively adjusting models with hundreds of variables that can quite literally be tweaked to show almost any outcome? It is simply irrational to not be at least somewhat skeptical.
  - cbkeller 8y ago
    > We're lucky to get 10Ma uncertainty for 100Ma old formations. Maybe a few decades ago. Ironically, much of my background is in U-Pb CA-ID-TIMS geochronology. The current state of the art in my community is between 0.05 and 0.01 % two-sigma relative, i.e. 10 to 50 ka at 100 Ma. To give one example, the chronology of the P-T extinction (the big one) is now constrained to the decamillenial level even though it we're talking about an extinction 252 million years ago [1]. Of course, 50,000 years is still quite long compared to modern anthropogenic effects, but the timescale bias of the geologic record is neither poorly known nor taboo (there are well cited papers about this exact problem [2]). I should probably also reiterate that many records of interest to climate science are (1) much younger, so absolute precision is much higher than at 252 Ma and (2) may come with a built-in relative chronometer with annual resolution, as in ice cores, tree rings, varves, and some speleothems. Imputing incompetence or bad faith to the entire field of climate science is not productive. While I'm not a climate scientist myself, I know many of them, and find them to be both honest and competent. [1] http://www.pnas.org/content/111/9/3316.short http://www.pnas.org/content/111/9/3316.short [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5227093/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5227093/
fromthestart 8y ago
>Previous warming events happened very slowly; even the quickest ones occurred over thousands or tens of thousands of years Here's the problem - we don't actually know how quickly historic shifts have occurred, because our evidence comes from geologic and fossil records that simply do not have good resolution past 1Ma or so. Especially consider all the doomsday runaway scenarios like the clathrate gun and melting permafrost - did these conditions not exist hundreds of millions of years ago during other shifts? If these hypotheses are true, then surely historic warming has occurred with similar rapidity.
- rland 8y ago
  That's what I'm saying. Historical changes to the climate have occurred, maybe with similar rapidity, maybe slower, and they caused huge extinctions. The best case, I guess, is that the shift is slow AND life is hardier than we expected, and we get through it ok, maybe with just a few species disappearing. But the downside risk is the extinction of a huge swath of life on Earth. (The first species to go, historically, have been big animals with high metabolisms--things with similar volume/surface area ratios as us)
- hwillis 8y ago
  > because our evidence comes from geologic and fossil records that simply do not have good resolution past 1Ma or so. That's not true. For any point when oceanic life was common, their sediments give WAY better resolution than that.
  - fromthestart 8y ago
    Not even close. Fossil dating is based on whether or not certain marker species exist in a particular rock sample. The very same species that gradually evolve and become extinct on scales of millions of years. The resolution is piss poor, and so unreliable that most wells in petroleum forgo biostratigraphic dating altogether.
    - pale-hands 8y ago
      You seem to be conflating the duration of a geologic event (i.e. rate of change, which is the subject of discussion) with the absolute age.
pokemongoaway 8y ago
Disgusting HN censorship as usual... We're not even allowed to reply to dead comments. And there is no excuse! Plenty of replies and nothing mean. HN is incredibly political - it is part of fake news and censorship since so many political pieces get to #1 and so many comments that don't break the rules get censored.
dredmorbius 8y ago
The Siberian Traps massive igneous province (translation: near-continent-scale volcanic eruptions) have been dated to within 13-130ky. Still long by human timescales, but a geologic eyeblink, and well below 1My resolution. The incident waas also associated with dramatic increases in atmospheric CO2 and mass extinctions. https://www.skepticalscience.com/Burgess-Bowring-2015-Siberian-Traps-Dates.html https://www.skepticalscience.com/Burgess-Bowring-2015-Siberi...

by rland 8y ago

cbkeller 8y ago

Coming from a geologist, you're exactly right!

fromthestart 8y ago
As a fellow geoscientist, you especially should be aware of the dating limitations of rock and fossil records. We simply do not have the resolution currently to know whether this kind of warming speed is truely unprecedented. Hell - a huge part of petroleum exploration is understanding conditions of the surface during deposition of sediment. We're lucky to get 10Ma uncertainty for 100Ma old formations. I've witnessed firsthand the degree of non scientific handwaving that plagues petroleum geoscience - in both geology and geophysics; and this is in a practical, applied field, where there is some degree of [loose] validation in the form of exploration success/failure. In an unfalsifiable field like climate science, where "validation" consists of retroactively adjusting models with hundreds of variables that can quite literally be tweaked to show almost any outcome? It is simply irrational to not be at least somewhat skeptical.
- cbkeller 8y ago
  > We're lucky to get 10Ma uncertainty for 100Ma old formations. Maybe a few decades ago. Ironically, much of my background is in U-Pb CA-ID-TIMS geochronology. The current state of the art in my community is between 0.05 and 0.01 % two-sigma relative, i.e. 10 to 50 ka at 100 Ma. To give one example, the chronology of the P-T extinction (the big one) is now constrained to the decamillenial level even though it we're talking about an extinction 252 million years ago [1]. Of course, 50,000 years is still quite long compared to modern anthropogenic effects, but the timescale bias of the geologic record is neither poorly known nor taboo (there are well cited papers about this exact problem [2]). I should probably also reiterate that many records of interest to climate science are (1) much younger, so absolute precision is much higher than at 252 Ma and (2) may come with a built-in relative chronometer with annual resolution, as in ice cores, tree rings, varves, and some speleothems. Imputing incompetence or bad faith to the entire field of climate science is not productive. While I'm not a climate scientist myself, I know many of them, and find them to be both honest and competent. [1] http://www.pnas.org/content/111/9/3316.short http://www.pnas.org/content/111/9/3316.short [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5227093/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5227093/

fromthestart 8y ago

>Previous warming events happened very slowly; even the quickest ones occurred over thousands or tens of thousands of years Here's the problem - we don't actually know how quickly historic shifts have occurred, because our evidence comes from geologic and fossil records that simply do not have good resolution past 1Ma or so. Especially consider all the doomsday runaway scenarios like the clathrate gun and melting permafrost - did these conditions not exist hundreds of millions of years ago during other shifts? If these hypotheses are true, then surely historic warming has occurred with similar rapidity.

rland 8y ago
That's what I'm saying. Historical changes to the climate have occurred, maybe with similar rapidity, maybe slower, and they caused huge extinctions. The best case, I guess, is that the shift is slow AND life is hardier than we expected, and we get through it ok, maybe with just a few species disappearing. But the downside risk is the extinction of a huge swath of life on Earth. (The first species to go, historically, have been big animals with high metabolisms--things with similar volume/surface area ratios as us)
hwillis 8y ago
> because our evidence comes from geologic and fossil records that simply do not have good resolution past 1Ma or so. That's not true. For any point when oceanic life was common, their sediments give WAY better resolution than that.
- fromthestart 8y ago
  Not even close. Fossil dating is based on whether or not certain marker species exist in a particular rock sample. The very same species that gradually evolve and become extinct on scales of millions of years. The resolution is piss poor, and so unreliable that most wells in petroleum forgo biostratigraphic dating altogether.
  - pale-hands 8y ago
    You seem to be conflating the duration of a geologic event (i.e. rate of change, which is the subject of discussion) with the absolute age.

pokemongoaway 8y ago

Disgusting HN censorship as usual... We're not even allowed to reply to dead comments. And there is no excuse! Plenty of replies and nothing mean. HN is incredibly political - it is part of fake news and censorship since so many political pieces get to #1 and so many comments that don't break the rules get censored.

dredmorbius 8y ago

The Siberian Traps massive igneous province (translation: near-continent-scale volcanic eruptions) have been dated to within 13-130ky. Still long by human timescales, but a geologic eyeblink, and well below 1My resolution. The incident waas also associated with dramatic increases in atmospheric CO2 and mass extinctions. https://www.skepticalscience.com/Burgess-Bowring-2015-Siberian-Traps-Dates.html https://www.skepticalscience.com/Burgess-Bowring-2015-Siberi...