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Earlier quoted context omitted.
This is a great question, and it seems that our methods can't detect temperature variation in past data that's similar to the recent rise. See the bottom answer: https://earthscience.stackexchange.com/questions/8746/is-thi...
To clarify, the method is not sufficient to detect a temperature variation within 100 years - current methods aren’t that specific with dates. One could read your comment as “we haven’t detected temperature variation in past data that’s similar to the recent rise”, but what you are trying to say (and what the link says) is that we’ve seen the variation before, we just can’t tell exactly how quickly it happened.
"no temperature variability is preserved in our reconstruction at cycles shorter than 300 years"
This means if there was temperature variation in past data current methods couldn't detect it, so the absence of spikes in the data is not proof of absence. In other words, if global warming was reversed and 200 years from now temperatures went back to pre-industrial levels it would be undetectable 10000 years into the future with our current methods.
I often wonder about terraforming (on places like Mars planet). Earth obviously had the leg up on water accumulation during its accretation stage (Hadean period). Perhaps we can start generating oxygen early over there on Mars using a one-step CO2->O2+C catalyst. This comes to mind: https://www.pnas.org/content/109/39/15606
It is interesting to keep these numbers in mind, but these facts are not sufficient to think correctly about climate. The earth is a dynamic system, and the rate of temperature growth is as much, if not more, important than temperature average here. A car going from 100 to 0 kmph in 15 seconds is definitely not the same as a car going from 100 to 0 kmph in 0.1 seconds in terms of damage. the temperature rises describ…
Without any knowledge in the field I wonder if the timescale difference could be attributed to the measurement methods used for the last centuries vs literal ages ago. I.e. if we (or someone a million years from now) tried to estimate the 21th century's temperatures using the same techniques used to estimate temperatures a million years ago, would we be able to detect that 4 degree change? Conversely, can scientists…
Future archaeologists and ice core samplers would definitely find a "wtf" layer in all their ice cores: higher radioactivity! If they attempt carbon-dating there will be a huge discontinuity in the results.
Probably also a microplastics layer.
Earlier quoted context omitted.
To clarify, the method is not sufficient to detect a temperature variation within 100 years - current methods aren’t that specific with dates. One could read your comment as “we haven’t detected temperature variation in past data that’s similar to the recent rise”, but what you are trying to say (and what the link says) is that we’ve seen the variation before, we just can’t tell exactly how quickly it happened.
No, our methods simply can't detect narrow spikes in past data: "no temperature variability is preserved in our reconstruction at cycles shorter than 300 years" This means if there was temperature variation in past data current methods couldn't detect it, so the absence of spikes in the data is not proof of absence. In other words, if global warming was reversed and 200 years from now temperatures went back to pre-in…
Earlier quoted context omitted.
To clarify, the method is not sufficient to detect a temperature variation within 100 years - current methods aren’t that specific with dates. One could read your comment as “we haven’t detected temperature variation in past data that’s similar to the recent rise”, but what you are trying to say (and what the link says) is that we’ve seen the variation before, we just can’t tell exactly how quickly it happened.
No, our methods simply can't detect narrow spikes in past data: "no temperature variability is preserved in our reconstruction at cycles shorter than 300 years" This means if there was temperature variation in past data current methods couldn't detect it, so the absence of spikes in the data is not proof of absence. In other words, if global warming was reversed and 200 years from now temperatures went back to pre-in…
Furthermore, there will be massive cooroborating evidence in the form of fossile records showing a mass extinction event and ice core samples (assuming we will still have icesheets) showing the accompanying rise in co2 levels as ice layers are deposited on a yearly basis.
Earlier quoted context omitted.
Which data sources have persuaded you that the realistic and likely increases of 3 or 5 degrees are more probable? "In 1979, the Charney Report from the US National Academy of Sciences suggested that ECS was likely somewhere between 1.5C and 4.5C per doubling of CO2. Nearly 40 years later, the best estimate of sensitivity is largely the same. This has led some to question why there has been so little progress on esti…
I could cite individual observations and reports, but the field is difficult to summarize in a single HN comment. There are many factors that we cannot completely oversee, primarily tipping points (disappearing reflective polar caps) and feedback loops (melt of permafrost with methane release). More concretely, have a look at the latest IPCC report [1], page SPM-16. Three of the five scenarios include temperature ris…
It is strange why many politicians and countries (Germany included) appear to close their eyes and still promote or work on the 1.5 °C goal, which seems pretty unrealistic at this stage. Maybe it is to calm the public, besides knowing better. Instead, there is a need for more realistic plans to model and prepare for 3°C or 5°C increase of average temperature by 2060 (or 2100). Looking at these bigger swings in temper…
The thing is that, for businesses and governments, complying with the 1.5ºC goals/projections is already a monumental task. If it does happen, even though it won't be enough, we should at least get an A for effort ... too bad nature is not forgiving. Anyway, what is still nice is that it should be easier to adapt to 3-5ºC once we're all doing something for 1.5ºC than if we were doing nothing at all, i.e. static frict…
5 degrees is a nightmare scenario for the whole world. Albeit I think it’s far more likely if we have to finally admit we’re on the pathway to 3 degrees, many countries might independently deploy solar geoengineering projects to save their skin (especially island nations)