Exploring Hydrocarbon Depletion
Cid_Yama wrote:Did you see at the end of the article, Trump's budget assault will cause Argo data to go dark as well as the satellite data. They are trying to blind us.
dohboi wrote:You pretty much had me till "geoengineering."
There's a whole thread (or two) on that kind of nonsense if you want to muck around with it. Let's keep this one to Oceans and Seas, shall we?
kiwichick wrote:@ 35 kas........how do you get a 50 foot rise in sea levels in the next few decades?
Global ocean temperatures rapidly warmed by ~5°C during the Paleocene-Eocene Thermal Maximum (PETM; ~56 million years ago). Extratropical sea surface temperatures (SSTs) met or exceeded modern subtropical values. With these warm extratropical temperatures, climate models predict tropical SSTs >35°C—near upper physiological temperature limits for many organisms. However, few data are available to test these projected extreme tropical temperatures or their potential lethality. We identify the PETM in a shallow marine sedimentary section deposited in Nigeria. On the basis of planktonic foraminiferal Mg/Ca and oxygen isotope ratios and the molecular proxy Embedded Image, latest Paleocene equatorial SSTs were ~33°C, and Embedded Image indicates that SSTs rose to >36°C during the PETM. This confirms model predictions on the magnitude of polar amplification and refutes the tropical thermostat theory. We attribute a massive drop in dinoflagellate abundance and diversity at peak warmth to thermal stress, showing that the base of tropical food webs is vulnerable to rapid warming.
...we surmise that conditions became too hot for most dinoflagellate taxa during the body of the PETM, when SSTs rose to values >36°C. Such temperatures are considered uninhabitable for most marine eukaryotic organisms today (48) even for hardy dinoflagellates, which are among the most temperature-resilient eukaryote plankton groups (49). Apart from often displaying narrow temperature tolerance ranges (9), many modern thermophilic organisms show a sharp decline in productivity and, consequently, survival above optimum temperatures (50). A similar absence of mixed-layer planktonic foraminifera was observed in Tanzania (12), suggesting that heat stress may have been more widespread in tropical marginal marine settings during the PETM.
Longstanding theories dating to the 1980s suggest that as the rest of the earth warms, the tropical temperatures would be strictly limited, or regulated by an internal 'thermostat.' These theories are controversial, but the debate is of great importance because the tropics and subtropics comprise half of the earth's surface area, greater than half of the earth's biodiversity, as well as over half the earth's human population. But new geological and climate-based research indicates the tropics may have reached a temperature 56 million years ago that was, indeed, too hot for living organisms to survive in parts of the tropics.
"The records produced in this study indicate that when the tropics warmed that last little bit, a threshold was passed and parts of the tropical biosphere seems to have died," Huber said. "This is the first time that we've found really good information, in a very detailed way, where we saw major changes in the tropics directly associated with warming past a key threshold in the past 60 million years."
If you say there's no tropical thermostat, then half of the world's biodiversity -- over half of the world's population, the tropical rainforests, the reefs, India, Brazil -- these populous and very important countries have nothing to prevent them from warming up substantially above conditions that humans can survive.
dohboi wrote:I posted this in the Antarctic thread, but since the result is massive sea level rise, possibly in our lifetimes (excluding octogenarians and older, perhaps), it should probably go here as well:
http://www.climatecodered.org/2017/01/a ... multi.html
The Amundsen Sea sector of the West Antarctic Ice Sheet has most likely been destabilized and ice retreat is unstoppable for the current conditions.
No further acceleration in climate change is necessary to trigger the collapse of the rest of the West Antarctic Ice Sheet, with loss of a significant fraction on a decadal to century time scale.
Antarctica has the potential to contribute more than a metre of sea-level rise by 2100.
A large fraction of West Antarctic basin ice could be gone within two centuries, causing a 3–5 metre sea level rise.
dissident wrote:It is looking more and more like 2 meters by 2100 is wildly optimistic. We are going to see well over 2 meters by 2100. I think 3+ meters is likely. Hansen's paper on the subject points to the nonlinearity of the melt process. This is always important to keep in mind. Humans make implicit linearizing assumptions when trying to understand problems. This is just our biology and is the simplest initial approximation approach to modeling. The human brain is a model creation engine even if we do not consciously perceive it.
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