[Mathgod]

Originally Posted by TherapyforGlencross

Now mind you an event like the Younger Dryas (onset) took about 100 years so not too long. About a global 7 degree change. So dramatic change can and will occur again in the future.

Originally Posted by TherapyforGlencross

Absolutely not. Unless positive feedbacks occur, I’m suggesting rate of change will likely take millennia. Of course, we’re seeing effects occurring already, so I understand the gravity of the situation, but the doomsday talk doesn’t exactly help with understanding how changes occur. (I.e: ice sheet lag time, meltwater pulses, ect).

The Younger Dryas was preceded by warming, and the warming caused meltwater pulses to flow into the Atlantic, essentially changing the direction of the Gulf Stream (glacial Lake Agassiz redirected it meltwater flow from Gulf of Mexico to St.Lawerence, hence AMOC change) , and thus causing dramatic cooling (I’m not taking into account the ridiculous hypothesis of a meteor impact). This along with 8.2 Kya events are known as D-O cycles/Heinrich Events, which isn’t happening now as IIRC ocean currents and air currents regulate temperature. While I think it would take millennia for change to occur, I also wanted to point out anomalies in the recent geological timescale of fast occurring events. I believe that we don’t really know too much about negative feedback loops. Do all feedbacks amplify or reduce in radiative forcing?

It was a 7 degree change in Greenland's temperature, not a 7 degree change in global temperature. There was a change in global temperature but it was not 7 degrees. And the cause is more likely to be volcanic activity rather than freshwater melt. https://en.wikipedia.org/wiki/Younger_Dryas

... Atlantic meridional overturning circulation, which transports warm water from the Equator towards the North Pole, was interrupted by an influx of fresh, cold water from North America into the Atlantic.[5] However, several issues do exist with this hypothesis, one of which is the lack of a clear geomorphological route for the meltwater. In fact, the originator of the meltwater hypothesis, Wallace Broecker, stated in 2010 that "The long-held scenario that the Younger Dryas was a one-time outlier triggered by a flood of water stored in proglacial Lake Agassiz has fallen from favor due to lack of a clear geomorphic signature at the correct time and place on the landscape".[6] A volcanic trigger has been proposed more recently,[7] and the presence of anomalously high levels of volcanism immediately preceding the onset of the Younger Dryas has been confirmed in both ice cores[8] and cave deposits.[9]

My question for you is, why are you paying so little attention to the 99.9% of evidence which points to one conclusion, and are scouring history to find the 0.1% of things that might (to the untrained eye) appear to cast some doubt? Why is it so hard for you to accept that the increase in global average temperature since 1880 is the direct result in the dramatic increase in CO2 levels? Why pretend that you know better than the scientists?

Clinging to a prayer that some kind of unanticipated negative feedback will save us, basically equates to playing Russian Roulette with our future as a species. Sure, when you pull the trigger, a bullet might not be in the chamber, and you survive by dumb luck. But is it really the kind of risk you're interested in taking? Really?

And I also don't understand this "stop the doomsday talk" sentiment. If we fail to take appropriate action to adress the climate crisis, then yes the doomsday talk is completely justified. People need to understand the enormity and severity of the trouble our species has gotten itself into. The level of human suffering and death that will be caused in the worst-case climate scenarios, far surpasses the amount that took place under the worst dictatorships in human history - Hitler, Mao, Pol Pot, etc. And the anticipation of the upcoming suffering and death is not some random speculation either - it is rooted in an understanding of climate science, human nature, and world politics.

Here's the thing - humans act civilized insofar that they continue to have access to safe water and food... once this goes away, the civility goes away. Anticipating a collapse (either full or partial) of human civilization is not a stretch whatsoever. It's a reasonable thing to predict given that droughts, fires, and floods are already impacting food supplies, drying up fresh water sources, and ravaging portions of the planet. We're headed for WAY worse... the science backs it up.

So no, the "doomsday" talk is not the type of talk that should be shamed and shouted down. If anything, the endless peddling of doubt and complacency is what ought to be shamed. To appropriately address a situation, one must first fully understand it.

And in fact, my message here (as anyone who has been actually been paying attention knows) is the exact opposite of doomerism. Simply put we are screwed if (get it... if) we do not act appropriately and take serious action to sharply cut emissions now and transition to a zero-carbon economy by 2050. But if we DO act responsibly, we can avoid worst-case scenarios and likely avert catastrophe. Or at the very least, we'll stand a fighting chance of averting catastrophe.

Me: "We're on a very bad trajectory. Very bad things will happen to us and our home if we continue on our current course. But there's good news! We still have a chance to avoid the worst consequences if we wise up to the situation, make some sacrifices, and choose a better path forward."

CP: "SHADDAP YOU DOOMMERRRR!!!!!!!"