Talk:4th millennium

Move discussion in progress

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Sea level rise prediction

Here's my (more detailed) rationale for removing this entry:

• The end date is arbitrary. Why 3000? Why not 2500 or 3500 or any other year? Indeed, it represents an ongoing process, so singling out one specific point in time is inappropriate.
• The cited article includes several different future emissions scenarios. Including only the worst case is cherry picking.
• Those emissions scenarios are contrived and unrealistic. After 2100, ${\ce {CO2}}$ levels abruptly become constant and stay constant for the next 900 years.

While the cited article may be useful for better understanding the impact of increasing ${\ce {CO2}}$ levels on sea level rise, it's not useful for making any kind of specific prediction about what sea level will actually be 1000 years from now. And related to the third point above, the paper (understandably) neglects the possibility of any future geoengineering. --Deacon Vorbis (talk) 15:49, 11 May 2017 (UTC)

I've revised the entry. As for it being contrived, well that's an issue to take up with the experimenters. They claim their results show stabilization after 2100. If you disagree, you're welcome to run your own experiment. Serendi^podous 19:56, 11 May 2017 (UTC)

I agree with Deacon Vorbis. This projection does not meet the "almost certain to take place" standard articulated by WP:CRYSTAL. The timeframe is so long there's absolutely no way to make reliable guesses about the carbon dioxide levels used as inputs, given the inevitability of unpredictable social and technological change. They could plausibly vary from we burn all the fossil fuels in the ground, to the world goes carbon-neutral in 2035 and successfully removes all the human-created CO₂ from the atmosphere by 2050, sending any excess ocean water to terraform Mars by 2500. If anything, this single study (which is itself problematic) might best be mentioned on sea level rise where projections are discussed with ample context. So far the predictions there don't go beyond 2100, which is still pushing the boundary of what can be reliably forseen, and probably represent the limit of actual scientific consensus. -- Beland (talk) 23:34, 28 September 2020 (UTC)

Sea levels continuing to rise according to current trends is certainly more likely to happen than terraforming Mars. If anything, the estimate is exceptionally conservative. Worst case global warming could hit us with a Permian level extinction by 2200. Serendi^podous 00:46, 29 September 2020 (UTC)

For this claim to remain on this page, it'd have to show that the terraforming scenario was almost certainly not going to happen over a 1000 year period, and I don't know how that's even possible given we've only been a spacefaring species for 70 years. There are a hundred other economic, social, and technological scenarios that would take us off current trends, either for better or for worse, and all of them would also have to be almost certain not to happen over 1000 years. Since we have two editors in support of that idea and one against, I'm removing the claim for now. -- Beland (talk) 00:25, 1 October 2020 (UTC)

Barnard's Star prediction

On why that prediction should be removed...The assumption that world economic growth will hold steady at 1.4% has not held true since 2006, and there's no way any model could possibly predict that it's "almost certain" to do so (the standard required at WP:CRYSTAL) for over 1000 years. And in addition to that it would have to be "almost certain" that power output will correlate with economic growth and that society in 1000 will care about interstellar travel and not blown itself to bits or bombed itself back to the stone age. And that all these things are "almost certain" to happen in 1000 years and not 500 or 2000. -- Beland (talk) 00:40, 1 October 2020 (UTC)