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why is global warming so catastrophic? the globe has been much warmer in the past and we are all here today
by yters 6y ago
why is global warming so catastrophic? the globe has been much warmer in the past and we are all here today
- kolinko 6y agowe weren't here the last time globe has been much warmer
- hn_throwaway_99 6y agoI actually think this is a fair question, because I feel like there are 2 issues that get conflated: 1. First, you are correct, the Earth was much hotter in the past, and I haven't seen anything convincing that global warming will lead to a fundamental "runaway greenhouse" effect a la Venus that makes life as we know it on Earth unsustainable. 2. That said, a huge climate change in a relatively short amount of time could easily lead the the deaths of billions of people, with a B. One third of the human population lives within 60 miles of the coast. Rising temperatures will lead to huge portions of the planet that are currently densely populated that will no longer support humans. The resulting migrations, "resource wars", and overall increase in extreme weather events (more hurricanes, more droughts, more floods) will lead to death and misery to a huge portion of humanity.
- yters 6y agobut if this change happens on the order of 100 years, that seems enough time to respond
- ALittleLight 6y agoYes, and we should start responding.
- core-questions 6y agoSea level has to actually start rising enough that the rich folks who live waterfront are affected and then we will see some geoengineering efforts or at the very least some solid seawalls. I'm waiting for someone to figure out how to use solar + hotter temperatures + seawater to give us desalinated water
- peterashford 6y agoYou say that, but its effecting Florida now and they're still just denying AGW
- hn_throwaway_99 6y agoBut it doesn't and won't. E.g. the sea level may creep up slowly, and then all of a sudden you get a giant flood or hurricane that makes a huge portion of the coast unlivable. And regardless, if you think moving a third of humanity to vastly different lands will be hunky dory smooth sailing, you should study history.
- InitialLastName 6y agoNot just that, but the places we currently grow our food have been primed to fertility over thousands of years of relatively stable climates. If many of those areas become substantially less useful for growing crops (because of storms, temperature changes, drought, whatever have you), it's foolish to assume that we will see just as many places that haven't had millennia of vegetation growing on them become fertile.
- ldargin 6y agoThat depends. Migrations and wars are the responses we can expect if its not handled in an organized way.
- AnIdiotOnTheNet 6y agoWe've known about it for over 50 years and have done basically nothing. Why would you expect another 100 to matter?
- catawbasam 6y agoUS CO2 per capita is down 1/3 from peak. Europe is way down. China is peaking out. It's a start.
- hn_throwaway_99 6y agoMuch of this decrease in CO2 per capita in 1st world countries is just because we have outsourced much of our CO2 production to 3rd world countries
- adrianN 6y agoThis is the graph that counts, and there is no discernible improvement in the curve: https://de.wikipedia.org/wiki/Datei:Mauna_Loa_CO2_monthly_mean_concentration_DE.svg#/media/Datei:Mauna_Loa_CO2_monthly_mean_concentration.svg https://de.wikipedia.org/wiki/Datei:Mauna_Loa_CO2_monthly_me...
- nullsense 6y agoHundreds of years starting in 1800s gives us until about 2100. 80 years will be within our childrens lifetimes for us millennials.
- rtx 6y agoYou need to look at arable land distribution, most of them are far from seas.
- peterashford 6y agoNZ is the worlds largest dairy exporter. ALL of NZ is close to the sea. Many islands are the world's food basket for bananas, coffee, coconut, palm oil (which is MASSIVE) and those are just the ones I can think of off the top of my head.
- kanox 6y ago> Rising temperatures will lead to huge portions of the planet that are currently densely populated that will no longer support humans. This does not seem likely, the bar for a region being "unable to support humans" is very high. People already live in cities that need to support themselves with food from elsewhere, and worldwide calorie production per capita is increasing.
- amanaplanacanal 6y agoLand that is underwater would count as unable to support humans, I think.
- dodobirdlord 6y agoA few areas of the world that are unusually low-lying and situated over permeable rock like limestone will be flooded. For the rest of the world, dikes are a well-understood technology, and quite cheap compared to sacrificing large land areas or moving cities. Even worst-case shortest-timeline estimates of sea level rise are not an existential crisis.
- peterashford 6y agoThere are pacific islands losing land to water rise NOW. This is an existential crisis for them. What do you say to them? Sorry, we couldn't be bothered to fix the problem? (That we created and you are suffering the consequences of)
- dodobirdlord 6y agoThey should move. Perhaps it would soften the blow if they were also told platitudes about fault and blame, but realistically (a) the problem is not going to be solved in time, and (b) the plight of a small number of people is not going to move the needle in regards to the willingness of the world to address the issue. People who still think that the damage can be averted entirely are just as deluded as people who think that sea level rise is an existential threat to human civilization.
- deleted 6y ago[deleted]
- vkou 6y agoA two-degree average increase in temperatures would significantly reduce crop yields in the world's breadbaskets. If we didn't need to eat, we wouldn't be worried very much about global warming. I do need to eat, though, and I'd rather avoid having to eat global warming deniers when things get rough. The earth was warmer in the past, but it also didn't support planet-scale agriculture of hyper-specialized, high-yield grains that are expected to feed 8+ billion people.
- yters 6y agois adapting our food production out of the question? it seems that might be a bit easier than fixing global warming
- vkou 6y agoIt hasn't been done, it's not clear that it can be, and the problem is not in the grains that we grow, the problem is in the land. If a formerly arable area becomes a dustbowl, there's no adaptation of our food production that you can do to fix this problem. Moving our agriculture north doesn't work either, because of the poor quality of soil in what is currently the tundra/taiga. If you have a handful of magic beans that will grow a magic beanstalk, that will be resistant to the temperature and weather and soil changes caused by global warming, sure, by all means, share it with us, and I'll stop worrying. We don't have that handful, though, and I'm not keen on hope-based planning.
- jjoonathan 6y ago> there's no adaptation of our food production that you can do to fix this problem Norway got good enough at growing things in greenhouses to be considered a breadbasket. Norway. I think you severely underestimate human adaptability.
- Arnt 6y ago1. Norway's a breadbasket with lots of greenhouses? Here's some prime land in Norway, see if you find a greenhouse. https://goo.gl/maps/Vzn3J3HS2Nm1P1mZ7 https://goo.gl/maps/Vzn3J3HS2Nm1P1mZ7 Norway has fed itself, more or less, for a few hundred years except the odd bad year, but never exported enough to feed even one big nearby city (say Copenhagen or Edinburgh). 2. You may be adaptive and want to move to some better place, but you're also just another penniless would-be immigrant with a big house loan in the country you want to leave, you don't speak the language, so what makes you think you'd be welcome in that better place?
- macrael 6y agoGenuinely, this was helpful to my gut understanding of this issue: https://xkcd.com/1732/ https://xkcd.com/1732/
- yters 6y agoaccording to that graph the world was as warm if not warmer relatively recently
- Arnavion 6y agoIt shows literally the exact opposite of that. 2016 is the highest temperature and at no previous point does the graph reach that value.
- yters 6y agoit looks like the line marked gold metalworking is the same, although hard to tell for sure. But long periods of history were at least pretty close to today's remperature according to that graph
- krastanov 6y agoThis is kinda missing the point. Look at the slope. And think how a system responds to a gentle slow perturbation and how it responds to a fast drastic change.
- sergeykish 6y agoThe alarming part is rate. Earth warmth comes from CO2 blanket, we can't suck it from atmosphere, we hardly can reduce CO2 production worldwide. Also his "best case scenario" is humanity wiped from Earth ten years ago, not base case for me. "Optimistic scenario" is if world acted on current policies. And "current path" is denial (4°C–5°C raise). https://ourworldindata.org/future-emissions https://ourworldindata.org/future-emissions
- peterashford 6y ago1. No, the gold metalworking part is lower on the graph. 2. It's the slope of the change - systems that evolve over millennia aren't set up to adjust over decades
- nullsense 6y agoMass extinction I'm guessing? Ecosystems are systems. They are resilient to a point, but losing enough diversity to the point it can't sustain itself leads to a collapse. It's happened numerous times before.
- scythe 6y agoOne reason (of many): https://www.pnas.org/content/107/21/9552 https://www.pnas.org/content/107/21/9552
- TYPE_FASTER 6y ago>we are all here today We weren't here then
- rtkwe 6y agoBecause for starters a huge portion of the world's population lives on the coast so rising sea levels will wipe out a lot of cities. Secondly the entire human civilization has lived in the warming period coming out of the last ice age, we've never lived in that hot weather. Climate change isn't an end all life on Earth but it will drastically change how humans live on Earth.
- dodobirdlord 6y agoRising sea levels will wipe out a few cities here and there that are exceptionally low-lying and built over permeable rock like limestone that allows the rising sea to infiltrate the water table. By and large cities will build dikes, as the Dutch have been doing for centuries.
- rtkwe 6y agoWhere do you build a dike in NYC where everything is built up to the waterfront?
- dodobirdlord 6y agoWell, first of all, sacrificing the outermost 10-20m of development to build a dike along the shore is a trivial expense compared to abandoning the city or dealing with regular flooding. But more likely the dikes will be built over the first 10-20m of what is currently the sea to avoid demolishing buildings built up against the water. That, or existing barriers will simply be raised. Whenever buildings are built directly against the sea they already require some sort of barrier to cover the difference between high and low tides and to deal with storm surge.
- rufus_foreman 6y agoYou make a new waterfront, the same way NYC has already done. You can look at the map at https://www.thirteen.org/dutchny/interactives/interactive-map-manhattan-in-1609/ https://www.thirteen.org/dutchny/interactives/interactive-ma... to see how much land was added. Most of lower Manhattan is built on what was ocean in 1609. It's an engineering problem, and NYC can afford to solve it.
- btilly 6y agoOn top of everything else, rate matters. An example of a climate effect that nobody mentioned is ocean acidification. It turned out that if you add CO2 to water, you get carbonic acid. This melts calcium carbonate at the bottom of the sea. The buffering makes the pH of the oceans relatively constant no matter what CO2 levels happen to be. Unfortunately that buffering takes place on the order of thousands of years. Which is fine when CO2 slowly increases in level. But when it rises suddenly, as it is doing right now, the oceans turn into a mild acid. Mild, that is, except for corals and shellfish whose shells dissolve. And anything that depends on them. Which, given how ecosystems connect, is pretty much everything in the ocean. Already, 3/4 of coral reefs in the world have experienced bleaching event. Similarly mass die-offs of shellfish have been widely reported in fisheries. Future projections are..bleak. All of this from a level of change that would have been fine if it was spread over 10,000 years rather than 100.
- floatrock 6y agoTo expand on the coral example: before fish get large enough to catch and eat, they start off as little hatchlings. Coral reefs are fish nurseries that offer protected environments before setting off for the deep blue seas, where the fishing boats find them. Something like 40% of humans worldwide rely on fish as their primary source of protein. What happens when there's no habitat to support that food source? Mass disruptions and migrations. So yes, the earth was warmer before, but that warming happened over geologic timeframes that allowed ecosystems to adapt and change. 100 years is long on human timescales, but it's an instantaneous disruption on geologic timescales. And despite the convenience of your neighborhood supermarket, we are not that detached from our ecosystems. The empty shelves at the start of covid should have been a wakeup call that our supply systems are still interconnected.
- TeMPOraL 6y agoBack then we didn't have 8 billion people and nuclear weapons. Consider the impact of ecosystem-related consequences others mentioned on habitability and food production. Once mass migrations and food shortages start, and starving migrants show up at the borders of higher-latitude/elevation countries in amounts orders of magnitude larger than before, what do you think will happen? Will these countries, worrying about how to feed their own citizens as crops fail due to weather anomalies, open up the borders and accept doubling their population? Will the migrants just accept being refused to enter? In the meantime, powers will be jockeying for mining rights of newly-unfrozen, but still not habitable lands. With all that pressure mounting, how long it'll take until someone starts shooting, someone else shoots back, and we'll have a WW3 on our hands? If climate situation degrades fast enough, we'll wipe ourselves out way before the changing weather does.
- lovecg 6y agoAre there actually historical examples of mass migration due to food shortages? My understanding is that most migrants are relatively young, healthy, and resourceful. It’s hard to travel thousands of miles while literally starving.
- rufus_foreman 6y agoIreland: https://en.wikipedia.org/wiki/Great_Famine_(Ireland)#Reaction_in_Ireland https://en.wikipedia.org/wiki/Great_Famine_(Ireland)#Reactio... 1.5 million people emigrated out of a population of around 8 million. "Of the more than 100,000 Irish that sailed to Canada in 1847, an estimated one out of five died from disease and malnutrition, including over 5,000 at Grosse Isle, Quebec, an island in the Saint Lawrence River used to quarantine ships near Quebec City. Overcrowded, poorly maintained, and badly provisioned vessels known as coffin ships sailed from small, unregulated harbours in the West of Ireland in contravention of British safety requirements, and mortality rates were high." So some of them travelled thousands of miles while literally starving.
- peterashford 6y agoThe Irish Famine. One million people emigrated.
- peterashford 6y agoThe globe has been hotter, but not with humans on it