Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi all,
Vanilla are planning an update to the site on April 24th (next Wednesday). It is a major PHP8 update which is expected to boost performance across the site. The site will be down from 7pm and it is expected to take about an hour to complete. We appreciate your patience during the update.
Thanks all.
Vanilla are planning an update to the site on April 24th (next Wednesday). It is a major PHP8 update which is expected to boost performance across the site. The site will be down from 7pm and it is expected to take about an hour to complete. We appreciate your patience during the update.
Thanks all.
2020 officially saw a record number of $1 billion weather and climate disasters.
Comments
-
-
-
-
-
-
Advertisement
-
-
-
-
-
-
Advertisement
-
-
-
-
-
-
-
-
-
Gaoth Laidir wrote: »Just for the record, here are the IPCC's statements on Equilibrium Climate Sensitivity (the equilibrium temperature-rise due to a doubling of CO2 from pre-industrial levels (280 ppm -> 560 ppm) over their past three Assessment Reports (spanning 13 years). We're no closer to understanding it now that we were back in then. The 1.5 - 4.5-degree range actually goes back further to the SAR too (1996). Nineteen years and no progress.
Fifth Assessment Report (AR5)
there is high confidence that ECS is extremely unlikely to be less than 1 °C and medium confidence that the ECS is likely between 1.5 °C and 4.5 °C and very unlikely greater than 6 °C"
Fourth Assessment Report (FAR)
"likely to be in the range 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C. Values substantially higher than 4.5°C cannot be excluded, but agreement of models with observations is not as good for those values."
Third Assessment Report (TAR)
The equilibrium climate sensitivity, that is, the range of the surface air temperature response to a doubling of the atmospheric CO2 concentration, was estimated to be between 1.5 and 4.5°C in the SAR (Kattenberg et al., 1996). That range still encompasses the estimates from the current models in active use.
The biggest change is that earlier estimates left the possibility of very low ECS as advocated by the likes of Bates and Lindzen, and allowed people like you to cling to the idea that climate change could be a storm in a teacup.
The latest estimates almost completely rule out the possibility of ECS below 1c but still leave open the possibility of ECS between 4.5c and 6c
Do you accept now that an ECS of 1.5c is now the lowest plausible ECS we can expect?
What do you think the most likely value for ECS is in your opinion?
The reason for the wide range of uncertainty is because the Physical direct effect of doubling CO2 concentration in the atmosphere is locked in at about 1c the science behind this is pretty much nailed down already
what is uncertain is the impact of the feedbacks associated with this warming. We do not yet know how fast thermafrosts will thaw, methane will be released from soils and ocean floors, how long it will take for the Arctic to melt fully in summer, exactly how much of an impact forest fires in the tundra will have, dark snow from extra soot changes albedo etc), changes in ocean and atmospheric currents that can drive changes in land use or release/sequester heat in the deep ocean with positive or negative feedbacks etc
Will there be self sustaining tipping points where climate can suddenly flip up a new equilibrium. Many scientists believe this is very likely to be true, but nobody knows what exactly would trigger such a tipping point
There is very active scientific research and debate on the nature and extent of these complex feedbacks and the only certainty we can arrive at, is the more warm the planet, the greater the risk that we may cross event horizons beyond which there is no going back
What is the danger that we enter a ‘hothouse earth’ I don’t know how to quantify that risk. What level of risk should we be comfortable with? 50/50? A 1 in 10 chance? 1 in 50?
What are acceptable odds to gamble the future of our planet?
https://www.pnas.org/content/115/33/8252
The above paper suggests we could start setting off tipping points at 2c, this is less than the most likely ECS value
This risk is represented in Figs. 1 and 2 by a planetary threshold (horizontal broken line in Fig. 1 on the Hothouse Earth pathway around 2 °C above preindustrial temperature). Beyond this threshold, intrinsic biogeophysical feedbacks in the Earth System (Biogeophysical Feedbacks) could become the dominant processes controlling the system’s trajectory. Precisely where a potential planetary threshold might be is uncertain (15, 16). We suggest 2 °C because of the risk that a 2 °C warming could activate important tipping elements (12, 17), raising the temperature further to activate other tipping elements in a domino-like cascade that could take the Earth System to even higher temperatures (Tipping Cascades). Such cascades comprise, in essence, the dynamical process that leads to thresholds in complex systems (section 4.2 in ref. 18).0 -
-
Advertisement
-
-
-
-
-
The biggest change is that earlier estimates left the possibility of very low ECS as advocated by the likes of Bates and Lindzen, and allowed people like you to cling to the idea that climate change could be a storm in a teacup.
The latest estimates almost completely rule out the possibility of ECS below 1c but still leave open the possibility of ECS between 4.5c and 6c
Do you accept now that an ECS of 1.5c is now the lowest plausible ECS we can expect?
What do you think the most likely value for ECS is in your opinion?
The reason for the wide range of uncertainty is because the Physical direct effect of doubling CO2 concentration in the atmosphere is locked in at about 1c the science behind this is pretty much nailed down already
what is uncertain is the impact of the feedbacks associated with this warming. We do not yet know how fast thermafrosts will thaw, methane will be released from soils and ocean floors, how long it will take for the Arctic to melt fully in summer, exactly how much of an impact forest fires in the tundra will have, dark snow from extra soot changes albedo etc), changes in ocean and atmospheric currents that can drive changes in land use or release/sequester heat in the deep ocean with positive or negative feedbacks etc
Will there be self sustaining tipping points where climate can suddenly flip up a new equilibrium. Many scientists believe this is very likely to be true, but nobody knows what exactly would trigger such a tipping point
There is very active scientific research and debate on the nature and extent of these complex feedbacks and the only certainty we can arrive at, is the more warm the planet, the greater the risk that we may cross event horizons beyond which there is no going back
What is the danger that we enter a ‘hothouse earth’ I don’t know how to quantify that risk. What level of risk should we be comfortable with? 50/50? A 1 in 10 chance? 1 in 50?
What are acceptable odds to gamble the future of our planet?
https://www.pnas.org/content/115/33/8252
The above paper suggests we could start setting off tipping points at 2c, this is less than the most likely ECS value
I note you have once again reverted to the use of near apocalyptic terminology on climate change and the end of times as favoured by the screamers in Extinction Rebellion and others.
I posted on this when you previously went down the same rabbit hole. No change there.
It remains that the IPCC has stated that - "a 'runaway greenhouse effect'—analogous to [that of] Venus—appears to have virtually no chance of being induced by anthropogenic activities."
IPCC current thinking on "Tipping Points" is that the precise levels of climate change sufficient to trigger a tipping point, remain uncertain.
As for the Hothouse Earth” scenario
This from Professor Richard Betts, Climate scientist University of ExeterAnother is that (the use of the term - Hothouse Earth)
The term "Hothouse " describes a scientific climatic extreme. The popularity of the term is growing because it allows for some to use it as a "dramatic narrative" and not surprisingly this has led to this term being used in some sensationalist articles to describe a largely doomsday scenario"With some exceptions, much of the highest-profile coverage of the essay presents the scenario as definite and imminent. The impression is given that 2°C is a definite “point of no return”, and that beyond that the “hothouse” scenario will rapidly arrive.
Many articles ignore the caveats that the 2°C threshold is extremely uncertain, and that even if it were correct, the extreme conditions would not occur for centuries or millennia.
https://theconversation.com/hothouse-earth-heres-what-the-science-actually-does-and-doesnt-say-101341
*Richard Betts is Head of Climate Impacts Research at the Met Office Hadley Centre in addition to his role at the University of Exeter. He receives funding from the UK government department of Business, Energy and Industrial Strategy (BEIS) and Department for Environment, Food and Rural Affairs (Defra), and from the Natural Environment Research Council (NERC). He was director of the European Union-funded project HELIX (High-End cLimate Impacts and eXtremes) which supported the contribution of Tim Lenton as a co-author of the paper by Steffen et al discussed in this article.0 -
Can you tell me what you think people mean when they say ‘the science is settled’
Hmmm, I'm not sure anymore. They say it's "unequivocal" that we are greatly affecting the climate, with almost every weather event now being automatically attributed to this, yet on the other hand they're still not sure to what extent we're affecting it because they still don't know how much our actions up to now have affected it so they can't know how much we will affect it in the future because the possible range is multiples of the alleged affect we've already had. It's all very confusing...
The most likely is 3c which is an extremely dangerous level of warming by itself and a state that ought to be avoided. The fact that 4.5c and even 6 c are within the plausible range at all means we should be even more concerned and take very decisive action to reduce that risk
Well "the most likely" depends knowing how we've affected it up to now, which, if you understood my rambling sentence above, is anything but pinned down. It could be closer to the 1.5 end, given that we saw a sizeable period of observations on the low end. We could see an equally sizeable period on the high end, who knows, but for now it's still anything but "settled".0 -
-
-
-
Advertisement
-
You’re confusing yourself needlesslyGaoth Laidir wrote: »Hmmm, I'm not sure anymore. They say it's "unequivocal" that we are greatly affecting the climate, with almost every weather event now being automatically attributed to this, yet on the other hand they're still not sure to what extent we're affecting it because they still don't know how much our actions up to now have affected it so they can't know how much we will affect it in the future because the possible range is multiples of the alleged affect we've already had. It's all very confusing...
Well "the most likely" depends knowing how we've affected it up to now, which, if you understood my rambling sentence above, is anything but pinned down. It could be closer to the 1.5 end, given that we saw a sizeable period of observations on the low end. We could see an equally sizeable period on the high end, who knows, but for now it's still anything but "settled".
It is confusing for people new to this ‘debate’ but you’ve been here long enough to know the context around this statement.
When anyone says the ‘science is settled’ in the context of climate change, they are only referring to one single question. The question of whether Anthropogenic Climate Change is real or not. In
other contexts you could say “the science is Settled “ in relation to the ‘great debate’ in quantum physics, or evolution, or plate tectonics’
It means the existential debate is over, refusing to accept ‘ the consensus’ is now science denialism
We can know plate tectonics is real without having to know when every earthquake or volcanic eruption will occur. We can say evolution is true without knowing every detail relating to epigenitics or Speciation
That is the singular question that ‘the science is settled’ is an answer for.
If you believe AGW is real, then you agree with the ‘settled’ side of the argument if you still think it’s a conspiracy or that there isn’t enough evidence to say this isn’t natural variability then you should disagree with that statement but you’re on extremely dodgy territory given the overwhelming scientific evidence that the greenhouse effect is real and humans are driving up CO2 concentrations in our atmosphere
Nobody who has ever said ‘the science is settled’ means all science is settled, or that no further uncertainty exists, or that we should stop studying and researching because we already know everything
It ONLY means that serious people need to move on from Debating the reality of AGW0
Advertisement