4 ms·

awi didn't claim that catastrophe is unavoidable. In fact, the implication is that catastrophic consequences of anthropogenic climate change can be mitigated by

by arebop 17y ago

awi didn't claim that catastrophe is unavoidable. In fact, the implication is that catastrophic consequences of anthropogenic climate change can be mitigated by international cooperation. Some actual IPCC reports are available from [1] and [2]. They describe observations of "The atmospheric concentration of CO2 and CH4 in 2005 exceeds by far the natural range of the last 650,000 years," "wide-spread melting of ice margins [...] with implications for sea level rise," and increased frequency of extreme precipitation events. They predict "irreversible changes in climate and ocean chemistry" and "rapid and large changes of the statistics of extreme events." Droughts, floods, cyclones, and ecological disruptions all threaten human life. The IPCC data and reports suggest that these and other adverse events have increased in frequency and severity, that human activity had a causal role, that things will probably get worse, and that our future behavior matters. Not that someone's death is the only possible justification for international cooperation in limiting pollution. [1] http://www.ipcc.ch/publications_and_data/publications_and_data_technical_papers.htm http://www.ipcc.ch/publications_and_data/publications_and_da... [2] http://www.ipcc.ch/presentations_and_speeches/presentations_and_speeches_presentations.htm http://www.ipcc.ch/presentations_and_speeches/presentations_...

yummyfajitas 17y ago
I know, and even if we don't cooperate, most of the consequences of climate change are not catastrophic. I'm aware of much of what the IPCC claims. Note that by "catastrophic", I mean "causing major harm to human civilization". I don't consider requiring a few million people to relocate 100 meters inland over 100 years (or stay put and build landfill) to be catastrophic. Nor do I consider a few more hurricanes to be catastrophic -- we handle hurricanes adequately, and as our economy grows, handling them will become even cheaper (relative to our wealth). Caribbean nations will handle them adequately as well once they become richer. Al Gore's and Greenpeace's dire predictions of the death of humanity are simply way outside the scientific consensus. Incidentally, the response of climate to CO2 is logarithmic -- i.e., if doubling CO2 increases climate by 1 degree, then an eight-fold increase in CO2 will increase climate by 3 degrees (not 8). (This is all to leading order, of course.) Big increases are only marginally worse than small ones.
- lutorm 17y ago
  the response of climate to CO2 is logarithmic Reference? I don't see how that can be the case at all. The basic physics of radiation balance have no logarithms, and the naive expectation would be that the amount of escaping radiation depend exponentially on the CO2 column density.
  - Daniel_Newby 17y ago
    Go play with an online MODTRAN simulator: http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.orig.html http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.o... (If you want to know the simulated temperature change, adjust "Ground T offset" to restore "Iout" to its original value.) You are referring to Beer's law, which describes radiation transmission at a single wavelength. However consider its meaning for the broad absorption band of CO2, whose graph is the shape of a wide lump with low shoulders. For parts of the band above some threshold, exponential absorption will have eliminated almost all the radiation, and further increase in concentration will not change this: you cannot go below zero. Parts of the band below that threshold will absorb very little radiation, and increasing the concentration will change this very little: double almost zero is still almost zero. Concentration change only makes a practical difference at the edges of the band, and the CO2 band's shoulders are so steep that even drastic concentration changes only make for small growth in the width of the total absorption band. P.S. MODTRAN assumes a nonmoving atmosphere, so its temperature predictions are not to be believed. The actual atmosphere experiences stronger vertical convection as ground temperature rises, which in turn produces secondary effects on vegetation, evaporation, and clouds that affects temperature. Predicting the net effect on temperature requires an accurate biological/meteorological simulation. And those are mighty thin on the ground. P.P.S. Convection effects are why greenhouses actually get hot: the glass obstructs natural convection from cooling the ground. Calling radiation effects the "greenhouse effect" is scientific fraud.
    - lutorm 17y ago
      Ah, the band centers are optically thick. I guess that makes sense. Thanks for pointing that out.

by arebop 17y ago

yummyfajitas 17y ago

I know, and even if we don't cooperate, most of the consequences of climate change are not catastrophic. I'm aware of much of what the IPCC claims. Note that by "catastrophic", I mean "causing major harm to human civilization". I don't consider requiring a few million people to relocate 100 meters inland over 100 years (or stay put and build landfill) to be catastrophic. Nor do I consider a few more hurricanes to be catastrophic -- we handle hurricanes adequately, and as our economy grows, handling them will become even cheaper (relative to our wealth). Caribbean nations will handle them adequately as well once they become richer. Al Gore's and Greenpeace's dire predictions of the death of humanity are simply way outside the scientific consensus. Incidentally, the response of climate to CO2 is logarithmic -- i.e., if doubling CO2 increases climate by 1 degree, then an eight-fold increase in CO2 will increase climate by 3 degrees (not 8). (This is all to leading order, of course.) Big increases are only marginally worse than small ones.

lutorm 17y ago
the response of climate to CO2 is logarithmic Reference? I don't see how that can be the case at all. The basic physics of radiation balance have no logarithms, and the naive expectation would be that the amount of escaping radiation depend exponentially on the CO2 column density.
- Daniel_Newby 17y ago
  Go play with an online MODTRAN simulator: http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.orig.html http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.o... (If you want to know the simulated temperature change, adjust "Ground T offset" to restore "Iout" to its original value.) You are referring to Beer's law, which describes radiation transmission at a single wavelength. However consider its meaning for the broad absorption band of CO2, whose graph is the shape of a wide lump with low shoulders. For parts of the band above some threshold, exponential absorption will have eliminated almost all the radiation, and further increase in concentration will not change this: you cannot go below zero. Parts of the band below that threshold will absorb very little radiation, and increasing the concentration will change this very little: double almost zero is still almost zero. Concentration change only makes a practical difference at the edges of the band, and the CO2 band's shoulders are so steep that even drastic concentration changes only make for small growth in the width of the total absorption band. P.S. MODTRAN assumes a nonmoving atmosphere, so its temperature predictions are not to be believed. The actual atmosphere experiences stronger vertical convection as ground temperature rises, which in turn produces secondary effects on vegetation, evaporation, and clouds that affects temperature. Predicting the net effect on temperature requires an accurate biological/meteorological simulation. And those are mighty thin on the ground. P.P.S. Convection effects are why greenhouses actually get hot: the glass obstructs natural convection from cooling the ground. Calling radiation effects the "greenhouse effect" is scientific fraud.
  - lutorm 17y ago
    Ah, the band centers are optically thick. I guess that makes sense. Thanks for pointing that out.