3 ms·

There is an asymmetric risk, though. Due to feedback loops like methane release, we don't know at what temperature the warming will stop, or how fast it will go

There is an asymmetric risk, though. Due to feedback loops like methane release, we don't know at what temperature the warming will stop, or how fast it will go. The upper-range estimates are well beyond any temperature from the last 10 million years.

chrisco255 7y ago
A lot of methane is coming from deep sea hydrothermal sources. You cannot stop that. But methane itself is unstable in the atmosphere and only accounts for less than 2 parts per million. If the climate were so sensitive to CO2 levels, where we've seen it go from 250 to over 400 ppm...we would see much more dramatic warming than we have. It was not that much cooler 100 years ago. So far, we have yet to have a year significantly warmer than 1998. It's been 22 years and the CO2 has been rising all that time. In spite of billions of people coming out of poverty. Minimal difference in maximum temps. Antarctica had record sea ice extent in 2014. Antarctica has been trending positive for sea ice over the past 30 years: https://earthobservatory.nasa.gov/world-of-change/sea_ice_south.php https://earthobservatory.nasa.gov/world-of-change/sea_ice_so... There's never ever been a geologic extinction event associated with high levels of CO2. In fact quite the opposite: the abundant and biodiverse periods in Earth's history are associated with high CO2. Plants literally suffocate at 150ppm. We are near historical lows for the planet Earth.
- dbingham 7y ago
  There has been a geological extinction event associated with high levels of atmospheric carbon - it was the biggest one of all time, and it nearly wiped out all life on Earth. Look up the Permian Extinction. (Yes there are multiple theories of cause, but one of which - and perhaps the most likely - is run away global warming.) And stop reading bad science.
  - chrisco255 7y ago
    First of all, I sourced from NASA. You provided no such sources despite making an extraordinary claim about the Permian extinction. The theories for that event include meteors, volcanoes, microbes, underwater methane release (from geothermal sources) and there is tons and tons of uncertainty about that event. You are oversimplifying by even attempting to attribute blame to CO2, which was already much lower in the Permian than in other eras like the Cambrian and Carboniferous [1], furthermore, temps aren't correlated with CO2 in Pre-Quarternary eras. Best indications are that a series of super-volcanic events triggered massive drought, which probably led to drying conditions and decreased sunlight for photosynthesis, which triggered massive fires which burnt up tons of oxygen and caused hypoxic conditions for tens of thousands of years. This whole episode is also associated with geomagnetic instability [2]. Now, the two are related, because geomagnetism is caused by movement of the inner and outer core of the Earth. If the earth sees periodic disruptions in the normal movement of the cores, I can easily imagine that to trigger massive volcanic activity. Now, in that case, a release of CO2 occurred from all the plant matter dying off as a result of drought, fire, flood, and volcanism. The CO2 itself didn't cause the extinction. The volcanism caused the extinction. [1] http://www.biocab.org/Geological_Timescale.jpg http://www.biocab.org/Geological_Timescale.jpg [2] https://www.sciencedirect.com/science/article/abs/pii/S1342937X08001834 https://www.sciencedirect.com/science/article/abs/pii/S13429...
caballeto 7y ago
Doesn't it bother you that the temperature rised first, the CO2 levela just followed it. To me if A happened after B, A could not be made responsible for B, i.e. rising CO2 levels for rising temperature levels.

chrisco255 7y ago

A lot of methane is coming from deep sea hydrothermal sources. You cannot stop that. But methane itself is unstable in the atmosphere and only accounts for less than 2 parts per million. If the climate were so sensitive to CO2 levels, where we've seen it go from 250 to over 400 ppm...we would see much more dramatic warming than we have. It was not that much cooler 100 years ago. So far, we have yet to have a year significantly warmer than 1998. It's been 22 years and the CO2 has been rising all that time. In spite of billions of people coming out of poverty. Minimal difference in maximum temps. Antarctica had record sea ice extent in 2014. Antarctica has been trending positive for sea ice over the past 30 years: https://earthobservatory.nasa.gov/world-of-change/sea_ice_south.php https://earthobservatory.nasa.gov/world-of-change/sea_ice_so... There's never ever been a geologic extinction event associated with high levels of CO2. In fact quite the opposite: the abundant and biodiverse periods in Earth's history are associated with high CO2. Plants literally suffocate at 150ppm. We are near historical lows for the planet Earth.

dbingham 7y ago
There has been a geological extinction event associated with high levels of atmospheric carbon - it was the biggest one of all time, and it nearly wiped out all life on Earth. Look up the Permian Extinction. (Yes there are multiple theories of cause, but one of which - and perhaps the most likely - is run away global warming.) And stop reading bad science.
- chrisco255 7y ago
  First of all, I sourced from NASA. You provided no such sources despite making an extraordinary claim about the Permian extinction. The theories for that event include meteors, volcanoes, microbes, underwater methane release (from geothermal sources) and there is tons and tons of uncertainty about that event. You are oversimplifying by even attempting to attribute blame to CO2, which was already much lower in the Permian than in other eras like the Cambrian and Carboniferous [1], furthermore, temps aren't correlated with CO2 in Pre-Quarternary eras. Best indications are that a series of super-volcanic events triggered massive drought, which probably led to drying conditions and decreased sunlight for photosynthesis, which triggered massive fires which burnt up tons of oxygen and caused hypoxic conditions for tens of thousands of years. This whole episode is also associated with geomagnetic instability [2]. Now, the two are related, because geomagnetism is caused by movement of the inner and outer core of the Earth. If the earth sees periodic disruptions in the normal movement of the cores, I can easily imagine that to trigger massive volcanic activity. Now, in that case, a release of CO2 occurred from all the plant matter dying off as a result of drought, fire, flood, and volcanism. The CO2 itself didn't cause the extinction. The volcanism caused the extinction. [1] http://www.biocab.org/Geological_Timescale.jpg http://www.biocab.org/Geological_Timescale.jpg [2] https://www.sciencedirect.com/science/article/abs/pii/S1342937X08001834 https://www.sciencedirect.com/science/article/abs/pii/S13429...

caballeto 7y ago

Doesn't it bother you that the temperature rised first, the CO2 levela just followed it. To me if A happened after B, A could not be made responsible for B, i.e. rising CO2 levels for rising temperature levels.