This makes no sense. How exactly an abundance of CO2 will "kill all plants" given that they are thriving on it? Let's say temperature rises further, like +10C rise. Desertification may kill some plants, sure. In the meantime, huge swaths of Siberia and Canada will stop being permafrost and transform back into thriving bogs, marshes and forests.
Moreover, there were times on Earth with widely higher temperatures. We are talking thousands of ppm of CO2 in the air and tropical flora on Antarctica. This didn't "end all life on Earth" at all.
A 3C rise will kill a lot of plants. A 5C rise will kill most of the plants, and if they can survive the change in biodiversity, the release of methane and CO2 from everything rotting, starving predators, and extreme weather and fire, life on earth might survive and eventually recover after a few hundred thousand or million years.
A 7-10C change over 300 years would, most likely, kill every single thing on the planet that was not transplanted by humans. There are only two ways to survive that without human intervention.
1: Be wide-ranging enough to spread very quickly to areas that become habitable as they open up. A few times a century the entire ecosphere will have to pack up and move to live in the changing climate as floods and deserts move things around. These plants would find it impossible to thrive over the long term and have very little chance of surviving.
2: Literally just tank the entire thing start to finish. For most plants, they will not be able to significantly change their range over this time. In ideal conditions yes, under the massively destabilized climate -disappearing coasts, halting ocean circulation, temperature swings from freezing to sweltering- no way.
The plants in northern Canada would have to be able to survive in tropical heat as well as they currently do in ice and snow. Plants in the tropics would have to survive 100 meters underwater. As the permafrost melts, plants will spread northerly- but the climate will catch up. Ironically it would be better if we killed 99% of plants right now so they could beat the climate. As it stands in a hundred years tropical vines will not be winding their way between New England evergreens- they will be dust in a desert. The pines outside my window will be choking in 40C weather. Boabab trees wouldn't survive in the soil here and Redwoods won't survive in Greenland.
NB: I don't mean to say I think the total collapse of life on earth is likely at this point in time. I think at present even humans are pretty likely to survive what's coming even if we stay our current course for 30 years. However I would give it better than 50% odds that a 7C+ warming would kill multicellular life. Most of the assumptions that you have to make to lead to warming that high necessarily kills everything, eg ice melting, circulation stopping, humans not giving a fuck, etc.
It's like setting up a bomb, and it has multiple stages. You load co2 into the air until the bomb goes off, causing enough temperature change to cause large desertification. That releases even more stored carbon. That triggers the polar melt feedback, which triggers the permafrost melts, which triggers even more deforestation, which triggers wildfires and weather, which trigger even more polar melting, which wrecks ocean circulation, which fires the clathrate gun, and suddenly there are a handful of species in an earth that is set to random and they will inevitably die out.
But plant life? Are you thinking phytoplankton?
If you instead pumped a toxin into the air, you would kill a great deal of things right away but as the concentration of poison rose they would develop a resistance. Thats the slow, traumatic burn, which is global but survivable with enough biodiversity.
If you nuked everything, that would kill almost everything on earth but after a couple decades it'll be relatively survivable again. Life only has to stick around a little bit- spores and seeds is safe places, that by some freak coincidence managed to survive the radiation. Also survivable.
With CO2, nothing happens until suddenly it does. There is a massive change in temperature that kills off biodiversity at a rate higher than ever before- we haven't even hit significant changes and we're experiencing this already. Then, once the biosphere is vulnerable, it gets hit with millenia of instability and extreme problems. There might be pockets that are shielded from this- if they sustained large, diverse populations through the massive initial changes.
It's like the KT extinction on steroids. KT was ~10,000 years- a CO2 bomb would happen even faster and last even longer.
But killing off plants? Can you cite something for that?
It seems to me that preventing collapse of human civilization is the thing to focus on. It's what most people will care about, right? And it's far more likely than total global ecosystem collapse. I mean, we may see the first signs within a few years. The "end of all life on this planet" is something that humanity will never get near, because it'll be long gone before it happens.
The short term problem is probably ocean acidification, although 3+ degrees will directly kill a ton of food production and plant species. Ocean acidification is usually thought of in terms of corals and shellfish but it can also lead to a collapse of the ocean food chain when nearly all zooplankton die. Oceanic plants can survive acidic conditions and will thrive without predators or competition, but that leaves out the fact that the ocean will now be full of dead, rotting things. There are an incredible number of ways that scenario can become a nightmare. Poison by toxins, infection caused by too-rapid growth, explosion of predators as they feed on detritus, etc. A healthy population is required to survive a huge climate change, and there are a million ways for that to go wrong.
The major catastrophe would be 5+ degree warming, which has the potential to collapse current ocean circulation patterns including the nino cycle. That would cause major devastation to biodiversity, deoxygenation of the ocean, and kill most life by land area and ocean volume. Then the isolated patches of life would have to deal with extreme weather, air quality, acidity changes, water and temperature changes. The survivors would have to stabilize the biosphere and live for millions of years with an unprecedented lack of biodiversity, until they could evolve. Species die spontaneously all the time. Tasmanian devils developed contagious cancer.
The Sahara used to be a jungle. The wind changed a little bit, and converted everything to sand. As the climate changes, areas will be destroyed- even if they stay green, biodiversity will be massively reduced and those places will no longer be sustainable long term. Even if rain starts falling in the Sahara, it will be decades or centuries before it grows.
In a normal extinction event growth is moderated over tens or thousands of years, in a smooth transition to other species. We have a century until we reach the same changes.
Say you have a field with grass, moss and cows. Geological warming kills the grass over a hundred years, and the moss slowly grows in it's place, and all is good. If anthropogenic warming kills all the grass overnight, The cows eat all the moss except for a little hidden under a rock, which is killed when a cow dies on top of it and blocks the sun.
>It seems to me that preventing collapse of human civilization is the thing to focus on. It's what most people will care about, right? And it's far more likely than total global ecosystem collapse. I mean, we may see the first signs within a few years. The "end of all life on this planet" is something that humanity will never get near, because it'll be long gone before it happens.
Wow, that may actually change my feelings on reading this sentiment. It's still a little horrifying that we have to wait until humans are affected, but I do understand how someone could look around and say "Yep, still looks alive to me!". If focusing on the threat to humanity engenders the threat as a whole, I'm all for it.
Of course, the breakneck speed of extinction is still horrifying. Each day means hundreds of species that I will never see, and I'm already pissed about missing giant sloths. We only killed those 10,000 years ago.
With luck, we'll only get part way into 2, and it won't be too bad. But those positive feedbacks are frightening.
From wikipedia, Holocene extinction. By what other metric could you possibly define "killing the planet" than killing the life on it?
I hate this argument because it feels like moving goalposts. For one thing, I don't think its hyperbolic to say that an uninhabitable planet is dead. It's dead as far as it matters to us. Moreover its so hard to read something like that and not feel like the message is "Don't worry, it'll be okay". If life is reduced back to single cells, is that okay? Will the planet still not be dead? If there is still water and organic molecules, so that life may evolve in the coming millions of years, is the planet still alive?
Due directly to human actions, species are dying faster than they ever have. Global warming has the potential to erase more species than ever before. Given the speed it's happening at, it may be a very real possibility that plants will not be able to adapt to changing conditions. Given that, it may be a very real possibility that the overwhelming death will cause runaway greenhouses faster than new plant and ocean life can reverse it, which would end all life on earth.
Life on earth would probably survive a nuclear holocaust. If you wanted to have the beast chance of permanently killing all life on this planet, this isn't far off from how you would do it. Push as much co2 as possible into the air as quickly as possible to change global conditions enough to kill all plants at the same time. If you just try to nuke everything, you'll leave a niche that other organisms will expand into. It's like antibiotics- you can't take just one huge pill, you need to keep taking them to make sure absolutely nothing survives.
Saying we aren't killing the earth is like watching someone that is getting stabbed repeatedly and saying he still has blood left.