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'If the world ends in 2100, we’re probably OK'

Posted on 29 January 2016 by howardlee

There’s a myopia in the climate discourse today.

“Everyone is focused on what happens by 2100. But that’s only 2 generations from today. It’s like: If the world ends in 2100 we’re probably OK!” says Professor Richard Zeebe of the University of Hawai’i. “But It’s very clear that over a longer timescale there will be much bigger changes.”

If the next century seems impossibly far off, bear in mind that if you have a young child now, we’re talking about the world her or his grandchildren will be trying to raise their kids in.

Scientists who take the long view on climate change see parallels between global warming today and mass extinctions in Earth’s past: “Apart from the stupid space rock hitting the Earth, most mass extinctions were CO2-driven global warming things,” says Professor Andy Ridgwell of Bristol University in the UK.

It has been a consistent pattern throughout geological time: “If you screw with the climate enough, you have huge extinctions,” says Ridgwell.

So much of what you read and hear about climate change is heavily based on instrument records that only go back 160 years or so. But Richard Zeebe and Andy Ridgwell are among a few scientists who look millions of years into Earth’s past to learn how the Earth responded to big additions of CO2 into the atmosphere before. I had the opportunity to chat with each of them about their work during the American Geophysical Union conference in San Francisco at the end of last year.

Beyond the ice ages

It’s true that scientists can learn about the ice age climate going back 800,000 years from bubbles of air trapped in ancient ice drilled from Greenland and Antarctica. They reveal many swings from warm to cold to warm again, in a low-CO2 world mostly cooler than today. “We went from very cold and low sea level to a mild climate with normal sea level,” says Ridgwell. But it was a very different scenario than today - those cycles were mainly driven by Earth’s wobbles as it circles the Sun, and those same orbital wobbles mean we should be cooling, not warming, today.

So both Ridgwell and Zeebe have been studying the best equivalent to modern climate change they have found so far, a relatively rapid global warming event that occurred 56 million years ago, called the “Paleocene-Eocene Thermal Maximum,” mercifully shortened to “PETM.” For Ridgwell, it’s a better analog for the future: 

This is why I like the PETM, at least it’s a warming event. It had a peak global warming of about 5º or 6ºC, which is a little bit beyond the end-of-the-century worst case scenario.

For Zeebe it’s also about data quality: 

We are focusing on the PETM is because we have relatively good sediment records. We are able to constrain timescales and ages relatively accurately. If you go further back in time, these constrains become very, very difficult.

Unprecedented in 66 million years

Scientists use a wide variety of data from rocks exposed and drilled at various locations around the globe. They look at geology, fossils, and the chemical makeup of sediments, particularly chemical isotopes - different atoms of the same element that differ minutely in their mass. As Zeebe says,

We have two isotope systems that we can look at. One of those are oxygen isotopes and they are essentially a thermometer, they tell us about climate change. And the other isotope system we’re looking at is carbon isotopes and they tell us something about carbon release.

Zeebe and colleagues compared isotope samples with computer models of the climate system. They stretched the models’ carbon emission timescale until they got a match with the isotope measurements. This showed that the carbon emissions which caused the PETM took about 4,000 years - remarkably similar to an estimate of about 3,000 years just published by Ridgwell and his colleague Sandy Kirtland Turner. They used a completely different approach from Zeebe, focusing on the differences in the carbon signal between marine and land sediments.

Narrowing the PETM emissions timeframe to around 3,000 to 4,000 years shows that, like today, the global warming back then was caused by geologically-fast carbon emissions. But our emissions have taken just a couple of centuries so, as Zeebe points out: 

What we’re doing with our emissions is unprecedented in the past 66 million years!

Even if the PETM isn’t a perfect equivalent of today’s climate (it was slower, and it happened in a world that was already warmer than today), it still tells us how the planet reacts to a sharp excess of carbon in the atmosphere. For example, the2013 Intergovernmental Panel on Climate Change (IPCC) report says we can expect a warming of between 1.5°C and 4.5°C if we double atmospheric CO2levels, but also acknowledges that the longer term warming (over centuries to millennia) “could be significantly higher” than that. The PETM tells us it is. Zeebe notes:

If we just try to explain the PETM with a climate sensitivity of 4.5°C, we only get maybe 60% of the warming. So my conclusion would be that long term sensitivity must be more than 4.5°C.

Mass extinctions

Ridgwell has also investigated global warming events going back deeper in geological time, including the big mass extinction events like the end-Permian and the end-Triassic, as well as so-called “Ocean Anoxic Events” in the Cretaceous. These involved profound and long-lived environmental disruption, with symptoms quite similar to today’s climate change, such as global warming, rainfall changes, and ocean acidification.

“Overall these are relatively slow events, on timescales of tens to hundreds of thousands of years,” says Ridgwell. But recent advances in rock dating, and in tracing Earth’s magnetic field frozen into ancient lava, suggests that within those slow events there may well have been intense, rapid episodes that came closer to today’s human emission rates.

You might have very short pulses of CO2 release within them. Some of these pulses of CO2 could look like what we’re doing now in terms of amount and rate. That’s an area of active research, because the estimates of individual pulses are getting better, but the estimates of how much CO2 would be released associated with an individual pulse are still uncertain.

The change already baked in

Ridgwell is skeptical about ambitions to limit warming to 1.5°C: 

Click here to read the rest

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Comments 1 to 8:

  1. This is a great subject.  Possibly the most important aspect of the entire issue.   Thank you and more please. 

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  2. What a great article. This small minded focus on the current 85 years ahead has been causing me concern for many years.

    Its as if our watch ends at that point and to hell with the future after that.

    When the ice sheet data is added into the mix with sea level rise over the comming many centuries the future looks much more of a concern.

    Why it matters is that the Coal mine policy of the current Australian Government is at complete odds with statements made at the recent Paris talks.

    Wanting to keep warming to 1.5 degrees C means no more new coal mines in Australia and a rapid wind back of current mines. 

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  3. Paul @2

    I agree. Our minds are only focussed on the next 85 years, and struggle even with that time frame. This may  be because our minds are not  wired up to deal with long term problems. We are programmed to deal with short term threats.

    Of course some people may be better at grasping long term issues than others. The article below is an interesting discussion of scientific evidence of how our minds deal with different time frames and the relation to climate change.

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  4. It's the 'baked in' bit that is going to prove most troubling as anything we do now is only going to show any effect some 40/50 years or more down the line and current societies look for an instant response to any action/policy. Baked in lag timing and the absence of an immediate response is also going to generate a series of magic cures and all the dangers they potentially carry. Some of the geo-engineering proposals currently thought up carry a huge potential for catastrophe never mind any future Dr. Strangelove's magic elixir that gets promoted as an instant cure.

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  5. Johnb,

    I share your concern about the merits of geoengineering 'solutions' to the climate change issue. My concern is that they will be 'popular and profitable' rather than be thoroughly understood and legitimately justified.


    I understand that Humans are not 'wired to ignore the future or not care about others'. Lots of marketing research results (and what is presented by Susan Cain in “Quiet: The Power of Introverts in a World That Can't Stop Talking”; and Naomi Oreskes' and Eric M. Conway's “Merchants of Doubt”), clearly show that some humans can easily be impressed and be encouraged to care about personal short term desires to the detriment of others or the future.

    Most aboriginal cultures developed the understanding that they must live as part of nature and limit their actions to ensure they only made things better for future generations (did not make things worse).

    Competition to get more of a limited opportunity for desired personal benefit (not needs, just desires) can obscure or even erase that type of understanding and awareness. It made many aboriginal groups fight each other.

    And the ability to 'win' by deliberately misleading others, or through created authority and the force it can exert when being misleading fails, makes things worse. This was proven by most of what was done by the European conquerors as well as many other horrible examples of abuse of power and authority (including things happening today).

    The detrimental consequences of competition in a game that allows uncaring selfish people who would abuse their freedom to get away with unacceptable actions, including misleading marketing, is repeatedly proven by every successful delay of the research into, and dissemination of better understanding of, how to advance humanity to a lasting better future for all when that better understanding is likely to be contrary to the interests of people who got away with becoming more fortunate, wealthier and more powerful.

    That is the best explanation I am aware of for what can be seen to be going on, not just regarding climate science related to rapid recent global warming and the resulting climate change.

    Human nature is not the problem. The problem is clearly people who understand how to manipulate human nature and abuse that understanding to impede the advancement of humanity to a lasting better future for all. And they do it because that future would have them be perceived as 'comparatively less of a winner' even if they too would be better off in that future.

    This leads many people to desire to not want to understand climate science. And if they must, they prefer to only talk about what things might be like 85 years from now, and deliberately understate the expected future consequences of their personal short-term interests and pursuits.

    This counter-productive way of thinking (counter-productive from the perspective of the advancement of humanity to a lasting better future for all), also leads people to believe they are justified in doing economic assessments of their perceived 'value of lost benefit by the most fortunate in the current generation' for comparison to their 'perceived costs of the consequences on others in the current and future generations (limited to the next 85 years)' and justifying what they want to get away with by claiming the perceived benefit a portion of humanity would need to give up today (as those having to give up the opportunity to benefit figure it) is more than the costs to all others including future generations (as those having to give up the opportunity to benefit figure it and limit it). This way of thinking is totally irrational and clearly inappropriate. It is like a person wanting to do something they personally consider to be a $1000 benefit and justifying it by figuring that the cost to their neighbour is less than $1000. Yet it is the way the US Government and many other powerful groups like to think about this issue.

    So there are far more unacceptable ways of thinking and acting than 'limiting the thoughts to what things may be like 85 years from now'. And they are being exposed by the fight against climate science. It is a very 'enlightening issue'. Hopefully it can help change what has been going on so that humanity has a better chance of advancing (rather than developing a steady stream of ultimately unsustainable and damaging technological changes selected based on popularity and profitability that are incorrectly perceived to be advances).

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  6. While it certainly is seemingly useful to consider things like periods after 2100 it is impractical to consider really 20 years into the future with any reliability for virtually anything.  Prediction is hard.  People in the climate business should be more aware of that than anyone.  Who would have guessed 20 years ago that practically all the energy from the excess CO2 could be stored in the ocean below 300M for 20 years while man poured 57% of all the CO2 ever poured into the atmosphere in.   Certainly none of the climate scientists thought such a thing was possible.  No computer models predicted this.   So, even when considering nature one can be drastically surprised by the way nature works.   If you look 20 years ago in any field you will see a fantastical amount of change that was impossible to predict 20 years ago.  It is hard to believe that it was 2007 when apple introduced the cell phone.   It has been only 8-9 years since and we cannot imagine life without them.  20 years ago we were utterly dependent on middle east oil to run the US economy and suffering trade debt of 800 billion/year to Arab and other oil economies.  Today the US debt related to oil is under $300 billion and falling rapidly.  Arab nations are eating up their surpluses rapidly.

    One of the big problems with estimating something like co2 in 2100 is technological.  The rate of change in cost of solar is fairly constant price decreases which show the price to go below the price of coal/oil in 10-20 years maybe less.  Many developments in progress are very significant.  Other technologies for energy production are in development.  The rate of all technological development is on an exponential curve.   We just discovered the CRISPR virus and the means to use it to modify DNA reliably.  It has already been used in clinical trials.   In 20 years we will see dramatic improvements in medicine as we unlock both the epigenetic code and are able to engineer at the micro level new materials and cheistry of all types including new materials twice as strong as any previously known material, the ability to make computer memories that are terabytes in size and as fast as RAM yet persistent without power like SSDs.  We now have 1152 qubit quantum computers and our AI is able to recognize faces and other objects almost as well as humans can.  We have the first self-driving cars.  Elon Musk landed a rocket ship back on Earth after deploying cargo in space.  In the meantime we have saved animals from extinction, raised the living standard of hundreds of millions of human beings and reduced starvation dramatically.  I could go on.   It is just very difficult to say what will happen in 85 years considering the confluence of all the factors above and all the unknowns.  

    The assumption of CO2 rising to 2100 at an exponential rate is already in question.  Total CO2 production peaked last year and is expected to be flat this year as well.  It may already be that we are on a slowly decelerating trend of CO2 increases.  A prediction of exponential growth in anything is problematic.  It has been the undoing of many predictions.  The fact that is it is near impossible to maintain a systematic growing CO2 output for 85 more years in the face of all this.  So, by 2100 it is unlikely we will have CO2 levels above 500 in my opinion and we will be on a downward trend most likely.  That's my prediction simply based on what seems like what is the most probable evolution of technology.   

    I think there are many things to worry about the future however CO2 is by far the smallest of all worries.  We are producing smart machines, genetic abilities, micro materials, nano materials, huge changes in jobs and livelihood, distribution of wealth and populations.  There is a lot to think about but global warming has to be one of the silliest concerns imaginable.   The simplest argument I have is that temperature is uncorrelated with growing wealth and improved condition of man or animals.  The more wealthy man has been we have been able to take care and care about the environment more.  So, better economic conditions short term are more likely to result in improved conditions for the planet.   The chinese for instance need to be wealthier so they can afford to clean their environment.   if they stay poor they will kill themselves with pollution.  no amount of telling them to clean up the environment will work until they get wealthy enough to afford to clean it up.  They may be at that point right now.   We are learning about the environment in exponential ways.  I am confident we will figure out how to save it but the worst thing to stifle our ability to learn and fix the environment would be to stifle growth or development.  It is a catch-22 in a sense but this is the only way forward.  

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  7. jmath, Apple did not introduce the cell phone. The rest of your screed is just as incorrect.

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  8. jmath & one planet only forever.  I confess that your voluminous dissertations above are over my head.  But, I would like to refer you both to Elizabeth Kolbert's "Sixth Extinction" and maybe David Archer's latest book on climate: "The Long Thaw".  The devil is in the details that almost nobody is paying any attention to....  Like the day soon coming when the oceans move from a pH of 8.08 to 7.9 and drive shell forming organisms off to extinction, causing a catastrophic decline in the base of the ocean food chain...or maybe the methane currently stored in melting permafrost soon to be liberated into an atmosphere already too rich in CO2 and industrial pollutants.  It is unfortunate that humans are an outlaw species living outside the rules of nature...the only living creature on the planet to so behave.  One cannot really believe that too many of the very creatures that have messed up the planet are now going to turn around and fix it?   Elizabeth Kolbert said :  A thousand years from now, ..."Rats will dominate the planet.  They will live in caves and wear the skins of animals they have killed and eaten"   I add, ...they will dig up the bones and "stuff" of humans and then, in admiration for our massive craniums and all our "stuff", seek to be like us.

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