Few realistic scenarios left to limit global warming to 1.5°C

https://phys.org/news/2021-05-realistic-scenarios-left-limit-global.html

by pseudolus • 5 years ago

66 82 5 years ago

GhostVII2• 5 years ago

What are the actual consequences of the globe warming by 2 degrees instead of 1.5 degrees? I feel like I never see it quantified. Like is that the difference between Miami being underwater or not? Is that difference going to cause an extra couple cyclones a year?

I'm totally on board with reducing carbon emissions and whatnot, but I don't actually have any idea of the impact.

And maybe it is impossible to quantify. I see some people say it is going to make earth uninhabitable, which intuitively seems wrong. But we do see some effects already, so clearly it's not harmless.

pantalaimon• 5 years ago

My main worry is increasing droughts that will jeopardize our food supply.

eplanit2• 5 years ago

Prepare now... pressure your state to build reservoirs.

missedthecue4• 5 years ago

Climate change has been shown in many studies to increase food production, because carbon is an input to photosynthesis.

stevep98• 5 years ago

My understanding is that 2 degrees is not that harmful in itself, but it would lead to further uncontrollable runaway increases due to release of methane locked in frozen tundra.

cableshaft3• 5 years ago

That, and also we would be reflecting less heat from the sun without the ice, as ice reflects back 90% of the sunlight that hits it, so no ice would lead to even more warming.

ajross• 5 years ago

The antarctic ice seems already to be melting, so Miami (also the port regions of most cities -- Shanghai has like 15M people living in likely flood zones!) is going under at this stage no matter what we do. Likewise the deep ocean circulation has already begun to collapse, so an anoxic ocean floor seems inevitable. The mass extinction event seems under way already.

But the modelling is noisy, so no one can give you serious answers to "how will this affect people" that will meet your demand for precision. But the worst cases are all disastrous. Things like "we can't grow food in south asia to feed the 2-3 billion people there" are very much on the table.

hackeraccount3• 5 years ago

How much would a sea wall around Miami or Shanghai cost?

jjcon6• 5 years ago

Miami isn’t going anywhere for at least a few hundred years, by which point they will have plenty of time/tech to keep things above water. The most likely models show 1 to 4.3 feet of rise by 2100 compared to 2000 [0] which has relatively low impact on miami other than the miami beach [1] which is already making plans for keeping/getting flood and rain waters out.

[0]https://www.climate.gov/news-features/understanding-climate/...

[1]https://coast.noaa.gov/slr/#/layer/slr/3/-8927718.607502826/...

GhostVII2• 5 years ago

I don't think I have that much need for precision. But it would be good to have at least some analysis of the costs of an additional 0.5 degree increase, given that limiting climate change is one of the biggest global efforts right now, and the costs of that effort. And maybe that analysis exists, but if so I haven't seen it. We shouldn't be having these big global efforts without clearly explaining to the public exactly why it is worth the investment over other things we could be investing in to improve global health.

If there is a good chance food production will drop significantly with the additional 0.5 degree, it probably makes sense to invest a lot to meet the goal of 1.5 vs 2.0. If the main concern is flooding and a smaller drop in food production, it might make more sense to invest in more intensive farming (we are certainly nowhere near the ceiling of easy gains here) and better infrastructure.

fallingfrog3• 5 years ago

My ballpark guess: climate regions will shift north by a few hundred miles. In some places that will mean tundra turns to forest, in other places farmland will turn to desert. Sea levels will also rise by a few feet.

But then there will be a couple billion people living in the wrong place; they will have to move across national borders in huge numbers. This is historically linked to political instability and sometimes war.

The worst part will be what we do to each other as a result of climate change, rather than the change itself, imho.

kaybe4• 5 years ago

This is an interesting paper in this regard:

Bastin et al, Understanding climate change from a global analysis of city analogues:

https://journals.plos.org/plosone/article?id=10.1371/journal...

"Even under an optimistic climate scenario (RCP 4.5), we found that 77% of future cities are very likely to experience a climate that is closer to that of another existing city than to its own current climate. In addition, 22% of cities will experience climate conditions that are not currently experienced by any existing major cities. "

"We notably predict that Madrid’s climate in 2050 will resemble Marrakech’s climate today, Stockholm will resemble Budapest, London to Barcelona, Moscow to Sofia, Seattle to San Francisco, Tokyo to Changsha."

The information might not be new, but the way it is presented is quite tangible, since many people have an understanding of today's conditions in different cities.

jjcon6• 5 years ago

I see some people say it is going to make earth uninhabitable

Not even the worst case scenarios from the IPCC show anything even remotely close to ‘uninhabitable earth’ - the people saying that are being even more disingenuous and pseudoscientific than climate deniers. Some fringe regions of the planet may become a lot harder to live in (note that climate change is not uniform, it will affect some places a lot more than others) and of course some coastal areas may experience more flooding but by and large day to day living in the first world will be similar to what it is today even with 2C of warming.

lotsofpulp2• 5 years ago

Some fringe regions of the planet may become a lot harder to live in (note that climate change is not uniform, it will affect some places a lot more than others) and of course some coastal areas may experience more flooding but by and large day to day living in the first world will be similar to what it is today even with 2C of warming.

How can this be known at this point? I can certainly imagine changing weather patterns such as monsoon, drought, heat waves, cold snaps, etc not being limited to fringe regions.

RupertEisenhart2• 5 years ago

I have a citation[0] that disagrees with your characterization, suggesting (the obvious) that while it may technically be possible for humans to live in harsh environments, they tend not to, they tend to live in a small subset of all places, and climate change will move those places everywhere, even in the first world.

"We show that for thousands of years, humans have concentrated in a surprisingly narrow subset of Earth’s available climates, characterized by mean annual temperatures around ∼13 °C. This distribution likely reflects a human temperature niche related to fundamental constraints. We demonstrate that depending on scenarios of population growth and warming, over the coming 50 y, 1 to 3 billion people are projected to be left outside the climate conditions that have served humanity well over the past 6,000 y."

Unless you are cheating by saying 'first world' without noting that the places constituting the first world will likely migrate rapidly in the coming century.

[0] https://www.pnas.org/content/117/21/11350

hluska2• 5 years ago

The planet will be stable under our models, but what about the humans? There are mass migration scenarios in the models and mass migration always leads to instability. Our species is capable of unspeakable violence.

legulere• 5 years ago

Humans’ ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979.

https://advances.sciencemag.org/content/6/19/eaaw1838.full

fringe regions

I wouldn't call India a fringe region and typically cities are hardest hit.

missedthecue4• 5 years ago

In addition, while global warming makes some places harder to live, it makes others more habitable.

mariusor• 5 years ago

I'm just making assumptions here, but if an average increases by 2 degrees, that could mean that the outlier maximum temperature can reach 4-5 degrees. For areas where this temperature is already in the 45-50(Celsius), that's probably uninhabitable (at least for poor people).

This will probably mean that there will be a wave of ecological emigration moving towards the more temperate areas of the globe.

So, it's not an uninhabitable earth unless you are poor and live around the dry tropical/ecuatorial areas. And there are a lot of people there.

sm0ss117• 5 years ago

Parts of India might get uninhabitable in the summer in some of the worse case scenarios. Given the population there and the fact they're a nuclear armed state that's a geopolitical powder keg.

hackeraccount3• 5 years ago

In a dynamic system anyone who says they know the consequences with a high degree of certitude is blowing smoke.

Oddly the most reasonable course of action is to always paint the worst possible future but it will presumably spur people to greater action. If it turns out to be incorrect there's no harm is there? It's not like we can overreact to climate change.

Unless of course we can.

Aerroon• 5 years ago

If it turns out to be incorrect there's no harm is there? It's not like we can overreact to climate change.

We can. Human life is still resource constrained. While we live better lives than ever before, it's something that can always improve. The resources we spend on dealing with climate change could've been used to improve the lives of people instead. An investment in the economy today can have (positive) compounding effects in the future.

We could live like people lived in the middle ages, but that would cause more human suffering than it would help. The same point goes for the future though - if we stop technological advancement, then how many people will suffer from issues of the modern day that would be solved in the future?

Ultimately, it's a balancing act on what will help more people more in the long run.

uh_uh• 5 years ago

The harm in being incorrect is that more and more people will use the past incorrect statements as grounds to dismiss future potentially correct statements.

GuB-42• 5 years ago

Of course we can, ban fossil fuels overnight and nuke everyone who doesn't comply, nuclear winters are good against global warming. Reducing carbon emissions is tame as far as possible responses go, there are some extreme solutions involving geoengineering.

It won't happen because there are more incentives for underreacting than overreacting but yes, definitely possible.

carlosf• 5 years ago

We can't predict shit like whether is gonna be sunny tomorrow, truth is the consequences of climate change are unknown, as the earth is a terribly complex system.

Just like Covid, economics, politics... my only prediction is that most predictions will sound stupid after we start feeling the effects of climate change (for good or bad reasons, who knows).

My personal philosophy is not to mess with complex systems if that can have fatal consequences, but I guess we are way past this point.

zidel• 5 years ago

What are the actual consequences of the globe warming by 2 degrees instead of 1.5 degrees?

IPCC SR1.5 [0] deals with this question. Figure SPM.2 [1] is probably a good place to start for a quick look, and the summary for policymakers has 4 pages (part B) that all seem directly related to your question.

[0] https://www.ipcc.ch/sr15/

[1] https://www.ipcc.ch/sr15/chapter/spm/b/spm2/

fallingfrog3• 5 years ago

I don’t think 1.5 degrees is likely at all to happen.

We’re already at 1 degree, and because of lags in the climate system we’ve already put enough CO2 in the atmosphere to bring us to 1.25 even if we stopped all emissions right now. If we were to turn around on a dime and emissions fell just as fast as they went up, that would mean we would be at the halfway point now, in terms of co2. Then the final value would be 540 ppm; almost one doubling. So, 2.75 degrees of warming or so.

Even that feels like a pretty optimistic scenario to me though. It’s more likely that it plateaus for a while before declining. So then we might end up 670ppm. That’s 1.25 doublings. That’s about 3.75 degrees.

I’d guess that we’ll land somewhere between those two, closer to the 3.75 degrees side.

Edit: corrected a math error

dwheeler• 5 years ago

I agree, stopping at 1.5 C is extremely unlikely. You have to get worldwide agreement to do very hard things. I see little appetite for that. I also don't see any way to make it less hard, though if there is any hope that's where it lies.

benjohnson• 5 years ago

There's a lot of room for hope - I don't really care* global warming, and I'm getting solar on the house in five years because it's disturbingly cheap and will be driving an electric car because they're less maintenance.

There's going to be a lot of moving away from oil - because refining sludge from the ground and transporting is expensive compared to the competition.

Also... there's a heck of a lot of Nuclear Fusion research going on where I live. I wish them well!

*I do care, but it's in the abstract. I kinda like not living in an ice-age. Normally, the land where my house sits is under 1.5 miles of ice.

cableshaft3• 5 years ago

Plus there's the positive feedback loops, so even if that's the natural course we're on, it will lead to changes that will result in even further warming, i.e. no ice to reflect the suns heat, so we absorb more heat, and the methane released by the melting gas, amongst others (there's quite a few of them).

From what I've been reading, it seems like if we get up to 2 degrees, the positive feedback loops would probably keep us going up to at least 4-5 degrees.

fallingfrog3• 5 years ago

That might be, but as far as I can tell that’s not considered a certain conclusion and I don’t consider myself qualified to judge how likely it is.

yread• 5 years ago

There are also lots of negative feedback loops - photosynthesis, cloud albedo, radiation, oceans, at some point human population might start shrinking...

willmadden4• 5 years ago

We are heading into a grand solar minimum. My prediction is that the earth will be cooler in ten years. Check back in 2031 to see if I’m right.

I’m far more worried about the magnetic pole shift and what that could mean about our sun.

kelp• 5 years ago

Was trying to find evidence for this and it doesn’t seem like NASA agrees with you: https://www.nasa.gov/feature/goddard/2020/what-will-solar-cy...

refurb• 5 years ago

My understanding is even if we stop all CO2 emission tomorrow, we’re still looking at catastrophic warming. Anything else is just rearranging the chairs on the Titanic.

Honestly people should just be enjoying the world prior to it falling into chaos. It’s going to be very ugly. It’ll make Covid look like a tea party.

kaybe4• 5 years ago

Global warming is not binary. We still get to choose the degree of chaos.

The last-ditch effort of carbon capture is still a possibility. And a lot of work in preparation remains as well. The more resilient we can become the less suffering there will be. And some of these things are not even complicated, such as large monocultures being much more susceptible to crop failures for example.

cableshaft3• 5 years ago

Yeah, we can choose the degree of chaos, and right now the degree that's being chosen is total fucking chaos (while pretending there's going to be zero chaos). Maybe we can tone it down to "quite a bit of chaos", though.

corty• 5 years ago

Problem is, we are mostly not preparing for chaos, we are still trying to prevent it. We should stop trying to prevent global warming because that is a futile endavour anyways. Instead we should start building water reservoirs, dams, begin resettlements, etc.

hackeraccount3• 5 years ago

This is probably the wrong way to look at it or at least an incomplete way. It's not just how much but how quickly the change happens. Everyday that goes by there's more money which gives everyone greater room to act - both in terms of adaptation and mitigation.

cbmuser• 5 years ago

Stop shutting down nuclear power plants, seriously.

Compare France and Germany on electricitymap.org and ourworldindata.org to understand why volatile renewables don’t help while nuclear massively helps to reduce CO2 emissions!

foepys• 5 years ago

France relies on German gas and coal to stabilize their grid. You cannot power down or up a nuclear plant quickly and in the summer some rivers get too hot for cooling unless you want to kill all wildlife in it.

Germany is also importing a lot of nuclear power from France.

I'm not saying that Germany is in a better position than France but France couldn't live off of pure nuclear either. Both countries need each other (plus the rest of the European grids) to support their local grids. France is delivering a lot of the baseline power and Germany can help out in times of shortages and overproduction.

huffmsa• 5 years ago

German is also shutting down most of it's nukes (post Fukushima) and importing Russian gas. Nordstream 2

throw0101a• 5 years ago

You cannot power down or up a nuclear plant quickly and in the summer some rivers get too hot for cooling unless you want to kill all wildlife in it.

While you cannot efficiently adjust the thermal output of a nuclear plant on short notice, you can redirect the steam generated so that generators don't produce electricity. This is down somewhat regularly in Ontario; see the first group (Bruce, Darlington, Pickering):

* https://www.sygration.com/gendata/today.html

Sometimes they're at 100% (numbers don't change), other times they go up and down depending on what the rest of the grid is doing. Nuclear delivers most of Ontario's caseload (see "Supply"), and while mostly steady there are fluctuations:

* https://www.ieso.ca/power-data

cconroy2• 5 years ago

Is it known what are, perhaps narrow, the climate conditions for humans? Humans evolved during the Pliocene which was 2-3 degrees warmer than today.

My gut feeling is not good, especially on geologic time, of which most spans humans would most certainly not survive. It feels like we are tossing 100s of thousands of years of stable climate and pushing Earth to points in its history were fauna/flora were very different from today.

RupertEisenhart2• 5 years ago

See my post below, but here is one paper: https://www.pnas.org/content/117/21/11350

shalmanese• 5 years ago

Are you asking about humans or civilization? If you look at the habitable range of humans today, obviously a change in a few degrees is not going to do much, some previously habitable land will become uninhabitable and vice versa but large swathes will remain.

Civilization is a lot more fragile and dependant on the pace of change, not the absolute magnitude. The problem with civilization is it's like a Jenga tower, you can continue building higher and higher up the complexity ladder and gradually knocking out supporting pegs for a little bit of time and things will seem fine, but keep knocking out just a few of the wrong pegs and there's no halfway state of falling, it's either intact or severely collapsed.

cconroy2• 5 years ago

Humans, on time scale of 100s of thousands of years. You wouldn't expect Earth to be too dissimilar from today, if not for fossil fuel consumption.

tzs• 5 years ago

A few degrees either way would not change whether or not humans can survive in most places. What it would change for many places is (1) how much effort it requires to live there, and (2) how many people can live there.

E.g., if climate change greatly reduces the water supply in a region, that can be address with effort (transporting water in from somewhere else) or by cutting the population in the region down to what the reduced supply can support.

The problem is finding a way to fund that effort in such areas or to reduce their populations without it degenerating into wars and terrorism.

As an example, consider India and Pakistan. They both greatly depend on water from Himalayan glaciers that are rapidly shrinking. It is not at all hard to imagine them going to war with each other over how to allocate that water between them.

They both have nukes. You might think a nuclear war between them would not be a threat to the rest of the world because neither of them have big nukes. But it is not the nukes that would hurt the rest of the world. It is the firestorms.

Here's a paper [1] and article [2] that looks at a hypothetical nuclear war between them involving about 100 nukes the size of the Hiroshima bomb from WW II, directed at the major population centers. That's about 1/3 of the nukes they have available.

Based on the amount of combustible material in the target areas, they estimate 1.5 Tg of soot aerosol would end up in the upper atmosphere. They then use climate models to predict what that would do to temperature and precipitation, and applied that to crop models.

What they get is several years of temperature reduction and precipitation reduction. The strongest effects would be in the temperate regions of the US, Europe, and China, and last 10-15 years. That should result in serious worldwide food shortages for quite a while.

Note that the shortages would not just be in the poor, undeveloped countries. This would be food shortages even in the rich, developed world. It is not unlikely that this would lead to more wars.

[1] https://www.pnas.org/content/117/13/7071

[2] https://blogs.ei.columbia.edu/2020/03/16/even-limited-india-...

willmadden4• 5 years ago

The predictions from the 2000 decade using the major models was so far off the mark, as a layperson (who is not working for the oil and gas industries, by the way), why should I take these new predictions at face value?

Bluntly, I think it is high time we take a deeper look at the funding behind this body of research and identify any financial conflicts of interest, both in terms of grant money given to academics, and entities and individuals who would benefit from a global carbon tax.

Does anyone else follow suspicious0bservers.org? It’s a great resource for alternative views around climate change.

boxed2• 5 years ago

The past predictions were widely wrong because they predicted TOO LITTLE warming. You're clearly off your rocker.

willmadden4• 5 years ago

Using the "adjusted" data? Give me a break.

If you look at unadjusted station data you'll see the temperature isn't rising at all.

https://wattsupwiththat.com/2012/08/01/a-comparison-of-adjus...

magicalhippo• 5 years ago

Here's[1] the IPCC report from 2001. Which predictions do you consider "far off the mark"?

I only checked a few like

- CO2 level, predicted 490-1250 by 2100, 420 in 2020[2].

- Glacier ice loss, projected widespread retreat, recent measurements seems to agree[3]

- Temperature rise, predicted increase of 0.4C-1.1C for 1990-2025, measurements for 2001-2010[4] was +0.56C and 2011-2020[5] shows +0.82C.

- Sea level rise, predicted rise in period 1990-2025 of 0.03-0.14m, status as of 2020 is 0.09m above 1990 levels[6].

These seems to hold up pretty good as far as I can see, maybe even conservative, unless I'm missing something?

[1] https://www.ipcc.ch/report/ar3/syr/

[2] https://www.climate.gov/news-features/understanding-climate/...

[3] https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019...

[4] https://www.ncdc.noaa.gov/sotc/global/201013

[5] https://www.ncdc.noaa.gov/sotc/global/202013

[6] https://podaac.jpl.nasa.gov/DataAction-2020-11-19-Globally-a...

rekabis• 5 years ago

There is only one relatively easy, safe, cheap and responsive way of reducing atmospheric CO2 left to us: oceanic seeding with iron.

Phytoplankton represent 80% of the carbon cycle, in terms of converting CO2 to O2. Problem is, they are resource-constrained via a lack of iron in the water.

Seeding the oceans with iron is easy and cheap - we already have all the tools to do so, and almost all are last century’s tech. It would be as simple as flying slightly-modified retired airliners a hundred meters over the ocean, out and back again, while releasing the dust.

Seeding the oceans with iron is safe - it has been done before, and the only known knock-down effect has been a massive increase in the health and fecundity of the entire oceanic food chain (salmon runs for the following three years were the largest in the prior half century).

Seeding the oceans with iron is responsive - unlike almost any other form of terraforming, iron seeding needs to be done constantly, as the life cycle of phytoplankton is so darn short. The iron either gets recycled very quickly, or ends up descending into the benthic layer when the phytoplankton die without getting eaten. Any seeding program can literally stop on a dime and go back to zero effects in less than three years - a blink of an eye, geologically speaking - if something negatively unexpected starts happening as a direct response to the seeding.

No other terraforming method has this level of ease, safety or responsiveness, making it the most appropriate method to use on our home directly.

And with 80% of all oxygen transpiration is done by phytoplankton in the oceans, we ALREADY have the largest oxygen-sequestration machine at our fingertips. We don’t have to build it. Why are we not maximizing its effectiveness?

bradlys• 5 years ago

https://youtu.be/8ZO9M1_CJD0 This video seems to indicate that it wouldn’t have a sizable enough effect and likely would require extensive mining to get done. (Which is done with fossil fuels)

Glench• 5 years ago

Reports like this always make me worry but I feel better knowing there are actually realistic (if ambitious) plans to limit warming helps a lot.

The plan I like the most is by the people at https://www.rewiringamerica.org/ which starts at 1.5C warming limit and works backward through the energy system to figure out what physical machines needs to change on what timeframe. They basically found that one of the most effective ways is electrify everything (cars, stoves, heating/cooling, etc) and switch over to mostly or all renewable electricity. We'll meet the carbon target as fast as possible, save everyday people money with the right financing, and create a lot of jobs all without changing our lifestyles significantly. It's going to be a lot of work but it can be done.

Gravityloss2• 5 years ago

1.5 C was lost decades ago. George W Bush did a lot of harm.

slx26• 5 years ago

We have already normalized that governments can't properly manage threats like the current pandemic even when they are part of our present. What do we expect for stuff like global warming that doesn't even have the same level of immediacy? Governments, our best bet towards coordination, have abundantly demonstrated their inability to handle these situations. Science can't push harder than economy. They all provide facts, but those of subsistence are always more immediate and have much more weight.

Whether we keep complaining or remain positive and hopeful it's all the same, just learned helplessness. I don't want to incite madness, but the only true coordinators for humanity seem to be fear, disaster and death. You can only get people to run in the same direction if they are running away from something. We aren't feeling the heat enough yet.

We have to find better ways than "regulation" to convert long-term threats into immediate threats. Human rationality does not exist at scale. Adjust reality to compensate the bias or face the consequences.

robomartin2• 5 years ago

No. No. No.

What are we doing?

I want to try to be kind, yet I have to admit I am growing increasingly frustrated with the nonsense being floated on a constant basis with regards to this matter.

Reality is never covered well by a single variable, so I won't ascribe this to political effects. I can't even begin to list all the factors. There are, for example, people and companies who are positioned to make a lot of money if the fear-mongering evolves into extreme action. Like I said, hard to evaluate all the players and their motivations.

The truth about this issue is so ridiculously simple to explain and demonstrate that a high school kid with a ruler and some coaching could arrive at the inevitable conclusion:

We cannot affect significant change in anything that approximates a human time scale.

Prove it!

OK. No problem. Easy.

Don't reply to my comment unless you have done the following:

Disclaimer: Global warming is very real. Deniers are delusional. And so are zealots. I feel like I have to proclaim this every time this is discussed because climate change has become a religion at both ends of the scale.

Step 1: Go to this website...

https://cdiac.ess-dive.lbl.gov/trends/co2/ice_core_co2.html

...and study this graph:

https://cdiac.ess-dive.lbl.gov/images/air_bubbles_historical...

Focus on atmospheric CO2 and ignore the rest for now.

Step 2: Print the graph or open it with an image editing program of your choice.

Step 3: Fit lines to the down slopes on the graph; the periods of time of descending atmospheric CO2 concentration

Like this:

https://i.imgur.com/SW4tLGe.png

Step 4: Draw vertical lines so we can estimate how long each descent phase took, like this:

https://i.imgur.com/37AKa8L.png

Step 5: Estimate how long each phase took. This is what I get:

[80000, 25000, 33000, 40000, 50000, 60000, 50000, 100000] years

Step 6: Do a little math:

MIN: 25K years

MAX: 100K years

AVERAGE: 55K years

Step 6: Think!

What does this mean?

Well, let's start from the basis that this is highly accurate atmospheric data going back 800K years. You can --as I did years ago-- dive into learning about why it is so accurate. Google is your friend.

What does this data represent?

No, not the most obvious (atmospheric CO2 concentration across a very long span of time). No, there's something far more important and significant in there:

This shows us what the atmosphere and the planet did, how it behaved, WHEN HUMANS WERE NOT AROUND. Or, if you want to be more accurate, when we were insignificant in the context of our contribution to the problem. This is truly valuable and relevant insight.

What does it say?

It says that if humanity left the planet --if we all beamed-up to Mars and shut down all of our tech--, if we evaporated from earth tomorrow, it would take, on average, about 55000 years for atmospheric CO2 concentration to be reduced by about 100ppm.

Worst case: 100K years. Best case: 25K years.

It also says something far more powerful: WE CANNOT FIX THIS PROBLEM BY SUBTRACTION.

What do I mean by "subtraction". Shutting things down. Not ever using petroleum for anything (which is impossible). Going solar. Going to wind power. Going to 100% nuclear power. Voluntarily destroying half the cities in the world and having half the population of the planet voluntarily commit suicide in the name of climate change.

Nothing --singularly or collectively-- compares favorably to the extreme case of all of humanity disappearing tomorrow. Ergo, none of these proposals --singularly or collectively-- can perform better than the baseline case, or about 55K years for a 100ppm reduction of CO2.

We. Cannot. Fix. This.

If we left the planet it would take tens of thousands of years.

Anyone proposing a solution that could fix the problem faster has to explain how it is they are going to improve from the no-humans-on-earth baseline while seven billion of us (and our cities, tech, etc.) are still on the planet.

It is pure hubris to think we can take a planetary scale process that takes tens of thousands of years and accelerate it to such a degree that the results would come in on a human time scale. 25 years? Crazy! 50 years? Nonsense. 100 years? Please stop. Even a thousand years sounds insane.

There's another principle here which everyone is glossing over. And that's the energy equation. Without doing any math we can say that you cannot fix a problem like this with LESS energy than what it took to create it in the first place. Impossible. And, at a planetary scale, the mere suggestion of such a thing should have someone laughed off the stage.

What is far more likely to happen if we are not careful is that the zealots will push for ridiculous ideas and we are going to succeed at killing everything on the surface of this planet rather than fixing it. Humanity's history is full of examples of catastrophic unintended consequences such as the introduction of species A to erradicare species B from an ecosystem only to cause an even larger problem. And we think we can engineer a rapid change of atmospheric CO2 at 1000x the natural rate? Never mind mass extinction, I am not sure the energy and resources something like this would required is even available on earth on that time scale.

What to do then?

Start discussing this reality and have our brightest minds work on how humanity will deal with it. In other words, work on solutions to the real problem rather than pushing religious belief in some superman-like solution.

This chart holds other secrets as well. There are two very obvious questions one should ask:

1- What caused the increase in CO2 levels when humans were not around or insignificant?

2- How did CO2 decrease without human intervention?

The answer to the first question is easy: Massive continental-scale fires. While not the only contributor, it is easy to see this is just-about the only way this could have happened multiple times in 800,000 years.

The answer to the second question is equally simple: Weather. Storms. Hurricanes. Rain. And the regrowth of vegetation. These are natural carbon capture mechanism. And, yes, they take a lot of time. And energy. You can't fix a problem faster than it was created without expending more energy. Since the energy per unit time available on earth is limited to what the sun provides, the reduction phases took longer.

This information is valuable because it helps us understand what we are seeing. The planet has been reacting to atmospheric CO2 through weather. And, in 50K to 100K years it will get things back down about 100ppm.

Yes, we made it worse. We burned energy-dense materials that took millions of years to produce while consuming planetary-scale amounts of material (trees, animals, etc.) and energy from the sun. We, effectively, released hundreds of thousands of years of CO2 in a short period of time, something that would not have happened naturally. We now have to live with it. We can't fix it.

The earth will do what it does and we are along for the ride.

We need to focus on making that ride as benign to humanity as possible. I can't see how we can do anything else. We are wasting valuable pretending we can fix this on a human time scale.

RhysU• 5 years ago

We need to focus on making that ride as benign to humanity as possible.

I like the idea of planning to accommodate the upcoming changes (climate, geopolitical, behavioral, etc) with defense-in-depth approaches. That is, reliability engineering aiming to put a backstop behind as much of modern civilization as possible.

robomartin2• 5 years ago

I don't have a list of what we could and should do. If I had to guess I think my top priority would be energy generation. It is clear that anything we might do will require lots more energy than we generate today.

True global leadership would find ways to communicate understanding of what we are facing and seek to unite humanity behind the common goal of survival. Imagine if people got the same sense of survival that this pandemic created around the globe.

Coming generations are clearly in for some challenges. We are not going to fix anything in the next 50 to 100 years. This is tough. Humanity does not do well with the idea of making decisions or sacrificing for the benefit of those who might come two or three generations after us. Imagine the world making changes that will be absolutely meaningless to us and likely several generations after us.

It's hard to imagine humanity uniting behind such objectives. This is where my analysis results in a shrug. I truly don't have an idea of how we go from the current insanity between deniers and those who are pushing the idea that we can fix this a thousand times faster than if we left the planet, and the concept of "We can't fix it. Let's unite to ensure future generations can survive it". No clue.

Few realistic scenarios left to limit global warming to 1.5°C

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