Are scientists overestimating -- or underestimating -- climate change? Part III

On the climate change 'point of no return'

Posted by Joseph Romm (Guest Contributor) at 11:29 PM on 23 Aug 2007

Read more about: climate | climate science

I've argued that scientists are not overestimating climate change, and in fact are underestimating it because they are omitting crucial amplifying feedbacks from their models. In this post, I'll show how these omissions suggest the climate has a "point of no return" that severely constrains the safe level of human-generated emissions.

A major 2005 study [$ub. req'd] led by NCAR climate researcher David Lawrence, found that virtually the entire top 11 feet of permafrost around the globe could disappear by the end of this century. Using the first "fully interactive climate system model" applied to study permafrost, the researchers found that if we somehow stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million. If concentrations hit 690 ppm, permafrost would shrink to just 800,000 square miles.

While these projections were done with one of the world's most sophisticated climate system models, the calculations do not include the feedback effect of the released carbon from the permafrost, which has locked in it more carbon than the atmosphere (and much of that is in the form of methane, a potent greenhouse gas).

That is to say, the CO2 concentrations in the model rise only as a result of direct emissions from humans, with no extra emissions counted from soils or tundra. Thus they are conservative numbers -- or overestimates-- of how much CO2 concentrations have to rise to trigger irreversible melting.

How do carbon cycle feedbacks constrain future safe levels of CO2 emissions? There's really only one major climate model that can answer that crucial question.

The United Kingdom's Hadley Centre for Climate Prediction and Research has one of the few climate models that incorporates a significant number of carbon cycle feedbacks, particularly in soils and tropical forests. In a 2003 study, ($ub. req'd), they found that a typical fossil-fuel emissions scenario for this century, which would have led to carbon dioxide concentrations in 2100 of about 700 ppm without feedbacks, led instead to concentrations of 980 ppm with feedbacks -- a huge increase. Even ignoring feedbacks, keeping concentrations below 700 ppm requires the United States and the world to start slowing carbon dioxide emissions from coal, oil, and natural gas significantly by 2015 and to stop the growth almost entirely after 2025.

In 2006, the Hadley Centre, working with other British researchers, published an important study, "Impact of Climate-Carbon Cycle Feedbacks on Emissions Scenarios to Achieve Stabilisation," that included both ocean and terrestrial carbon cycle feedbacks (though they do not specifically model carbon emissions from defrosting tundra). The study found that such feedbacks reduce the amount of fossil fuel emissions we can release by 21 percent to 33 percent.

We have no room for error. Buried in the IPCC's Fourth Assessment Report (Working Group 1) is a stunning paragraph, which shows that the consensus is finally shifting on this issue:

Climate-carbon cycle coupling is expected to add carbon dioxide to the atmosphere as the climate system warms, but the magnitude of this feedback is uncertain. This increases the uncertainty in the trajectory of carbon dioxide emissions required to achieve a particular stabilization level of atmospheric carbon dioxide concentration. Based on current understanding of climate carbon cycle feedbacks, model studies suggest that to stabilize at 450 ppm carbon dioxide, code required the cumulative emissions over the 21st-century be reduced from an average of approximately 670 gigatons carbon to approximately 490 GtC.

Ouch. We need to average 5 billion tons of carbon this century to avoid catastrophic warming. We're already at 8 billion and rising fast.

There thus appears to be a threshold beyond which it becomes more and more difficult for us to fight the feedbacks of the carbon cycle with strong energy policies that reduce fossil-fuel emissions into the air. While the threshold is not known today precisely, it appears to be somewhere between 450 ppm and 650 ppm (and probably between 450 and 550). If we cross that point of no return, we'll probably shoot to 1000 ppm, and maybe much more -- ruining this planet for centuries, if not millennia.

By 2025, we'll know much better where the point of no return is. Unfortunately, on our current path, the world's emissions and concentrations will be so high by 2025 that the "easy" technology-based strategy will not be able to stop us from crossing the very high end of the threshold range

That's why, in my book, I call the 2025-2050 period Planetary Purgatory. Barring a major reversal in U.S. and world policies in the very next decade, come the 2020s, most everyone will know the grim fate that awaits the next 50 generations. But the only plausible way to avoid it will be a desperate effort to cut global emissions by 75 percent in under three decades -- a massive, sustained government intervention into every aspect of our lives on a scale that far surpasses what this country did during World War II.

That would indeed be punishment for our sins of inaction. It would also be a great irony if conservative Deniers -- who are blocking serious mitigation today because they don't like (a certain kind of) government intervention in our lives -- ended up forcing the country into far more government intervention in the near future.

Failing that desperate effort, we would end up at mid-century with carbon emissions far above current levels, and concentrations at 500 ppm, rising 3 to 4 ppm a year -- or even faster if the vicious cycles of the climate system have kicked in. That would propel us to the point of no return in the third quarter of this century.

This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.

For story: Are scientists overestimating -- or underestimating -- climate change? Part III
9 Comments | Post a Comment

I'm sure I'm not alone

As an engineer, I fully understand what a tipping point is. I vacillate between depression and hope. I've made a game out of it and play for entertainment. Who knows, maybe we will pull it off. The capacity for self-deception is the most frightening propensity of our species. I avoid reading posts like this because I'm already convinced and have enough to worry about. But keep it up. It has to be done.

In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world

by biodiversivist at 11:43 PM on 23 Aug 2007

New Species Name in Order

"The capacity for self-deception is the most frightening propensity of our species."

This is my lie and I deny I ever said it.
Yes, we live based on deception and delusion.

The rocket culture may be entering its spore stage before it can jettison its manifest destiny, before it can become native. Aliens from around the world flock to an alien culture, adrift without roots.

by justlou at 4:24 AM on 24 Aug 2007

1000 ppm is an extinction level event

Reaching 1000 ppm is not simply uncontrolled global warming, it is the point at which the Earth becomes hostile to multicellular life.

Here is a link to a relevant Scientific American article.

by shaej at 5:03 AM on 24 Aug 2007

UNDERestimating the Symptom, Ignoring the Problem

Many thanks, Joe Romm,

Perhaps climate change is not more than a recognizable symptom of the unbridled and skyrocketing growth of absolute global human population numbers as well as the seemingly endless, soon to become patently unsustainable expansion of the globalization of big business activities now over spreading the Earth.

Each culture presents its membership with much that is real and also much less that is illusory. From the standpoint of a psychologist, because humans are shaped early and pervasively by cultural transmissions in our perception of reality, it looks like an evolutionary challenge for humankind to see the world as it is. Whatsoever is is, is it not?

According to Russell P. Hopfenberg and David I. Pimentel, culture may at times mesmerize human beings in that it gives rise to illusions of the world as it is. This research, like some evidence before it, seems to fundamentally disturb (because it comes into conflict with) certain culturally derived notions held by members of a culture about what it means to be human and about the "place" of Homo sapiens in the natural order of living things. Scientific facts of this particular kind are uniformly difficult for people to see, I suppose, because such data have a way of undercutting the pedestal from which we prefer to look upon our fellow creatures, nature itself and the universe. We humans may introject culturally biased and scientifically unsupported transmissions (i.e., memes) that confuse human reasoning and promote a certain cortical conceitedness which is not helpful when trying to see what is real or to recognize certain requirements of practical reality. For a very long time mistaken cultural transmissions or memes appear occasionally to permeate interpersonal communications and to be passed from generation to generation, distorting human perceptions and making it difficult for us to see a scientific fact for what it is real about it.

When a psychological practitioner like myself thinks a patient is suffering from a mental illness, that determination is a matter of evidence-based clinical judgment. However, general standards of what is normal are not clinical judgments (and sometimes do not objectively correlate with reality), but are often unverified understandings based upon cultural norms and social conventions that are full of scientifically validated perceptions of reality alongside some misperceptions of what is real. Because some misperceptions are valued by those who share them, these memes get passed along and shared pervasively AS IF THEY REPRESENTED REALITY.

In the cases of deeply disturbed mental patients, they are inclined to distort reality so drastically that their distortions are not widely shared and held by other people. Instead, these mistaken impressions are labeled as examples of `craziness'. By contrast, governments, social organizations and cultures appear not to misperceive reality so sharply, yet distortions of what people in a culture perceive do remain.

A term of art in psychology is useful here, folie a deux. The term means that two people share an identical distortion of reality. This understanding leads to other terms, folie a deux million for a social order or folie a deux billion for a culture. These terms refer to misperceived aspects of reality commonly shared and held by many people of a government, a society, a culture. One way to define the highest standard of what is normal for the individual and for people in a particular socio-cultural aggregate is in terms of being able to see what is free of illusion, what is in scientific fact real. Hence, in taking note of the process of humankind becoming evermore aware of reality by means of the acquisition of valid scientific data through time, Homo sapiens can track the evolution of science.

From this perspective, the natural world God blesses us to inhabit is a perfected, self-regulating and self-sustaining system that has worked for millions of years, without human presence or input, and will likely continue for millions of years with or without human activities. Ancestors of Homo sapiens survived successfully on Earth for the past few hundred thousand years, and then some more. In all that time humankind presumably did not endanger itself, nor did we oddly expunge other creatures, massively degrade the environment or recklessly dissipate its limited resources upon which our lives, other forms of life and even the global economy depend for their very existence.

In this context it is worth noting that something happened several thousand years ago. At some point not long after the end of the Ice Age, Homo sapiens appear to have turned to growing and storing food and treating it as a commodity. As humans produced more food than the population needed for its immediate survival, our population numbers began going up, up, up and not up and down as do the population numbers of other species on Earth. Instead of continuing to exist as hunter-gatherers and collect food necessary for survival, Homo sapiens produced, stored and sold more and more food. This (agri)culture economy, that appears to have grown over the last 8,000 to 11,000 years, is forthrightly man-made, ever expanding, seemingly limitless and, just now, soon to become patently unsustainable at its current huge scale and its fully anticipated growth rate, and, therefore, in its present form. As this artificially designed economy has grown, human population numbers appear to have stopped fluctuating in a natural cycle as they likely did through unrecorded time. During the past few thousand years human numbers began to increase in an ultimately unhealthful, nearly exponential manner. For the past several hundred years global human population numbers have skyrocketed.

The longstanding and generally accepted theory of the "demographic transition" is descriptive not deterministic. The widely shared and consensually validated current evidence related to the automatic occurrence of a so-called demographic transition at 9.2 billion people around 2050 appears to be preternatural, culturally skewed and, therefore, scientifically unsound.

Looking only at regions where population is increasing at a decreasing rate or at a country like Italy and with its decreasing population numbers may be distracting us -- and need not necessarily blind us -- from the apparently unforeseen knowledge of our continuously increasing absolute global human numbers and their potentially profound implications. We wish to look at trees, but need to see the forest.

According to the unchallenged and virtually irrefutable research from Hopfenberg and Pimentel, human population numbers are continuing to increase worldwide as a result of the production of food in greater and greater quantities. These food resources are then made ever more available by sale and delivery into areas on the planet with low human carrying capacity, where human life in large numbers and other life cannot simultaneously be sustained.

Could it be that we are not making hunger go away by means of maximally expanding the food supply, but instead giving rise to billions of hungry people, extirpating biodiversity, and undermining the integrity of global ecosystems?

Please note that 3.7 billion people exist these days in our planetary home on resources valued at less than $2 per day. That number of people is greater than the total number of people on Earth in the year 1950!

Certainly human beings have sophisticated, forward-planning cultures and a progressive world economy. And for all the wonders of our pyramid-like global economic scheme, still there is apparently not a scientific basis for concluding human beings have broken the bonds of our placement among the creatures of the world. Nor have the conditions of the natural world likely been suspended somehow for human benefit. No, the Hopfenberg/Pimentel evidence indicate that certain biological and physical laws of nature likely apply to all creatures of Earth, including human ones.

by stevenearlsalmony at 6:50 AM on 24 Aug 2007

We Need Many Points of Entry

People have to be given things they can do, and things they will do, to save this planet home. I find that a lot of people are willing to do the right things - they just aren't willing or able to invent them, or to work very very hard to figure out what they are. And it's a lot more tempting to look at the Big Out-there for solutions. But about 30% of our impact on the planet is due to our housing practices. I'm working with www.livegreenlivesmart.org to get people to understand how easily, basically, or even comprehensively they can change their shelters into something that is greener, more sustainable and more comfortable and healthier for themselves and the world.

If we could get 50,000 Americans to do SOMETHING to make their homes more sustainable, it would make a huge difference - and then a half-million homes would follow, because Americans like to get with trends and especially with virtuous trends.

Consider joining the 50,000 Green Homes project at www.livegreenlivesmart.org

Miscetal

by Miscetal at 9:02 AM on 24 Aug 2007

Not Very Aptly Named

The only problem here were the short sighted people who called it "perma-" frost.

If it were called tempafrost then people wouldn't have their knickers in a bunch.

It also shows that CO2 production could entirely be a result of the force feedback mechanism of Naturo-genic global warming as described by Henrik Svensmark, which is why it lags the temperature rise.

by jabailo at 9:23 AM on 24 Aug 2007

Derrida was full of it

Yep, jabailo, I'm sure global warming is just a semantic misunderstanding. What a good Deconstructionist you are! The world as text.

As for the OP, this was an interesting insight:

"It would also be a great irony if conservative Deniers -- who are blocking serious mitigation today because they don't like (a certain kind of) government intervention in our lives -- ended up forcing the country into far more government intervention in the near future."

Indeed.

by Coyote369 at 8:16 PM on 24 Aug 2007

Well said, with a minor caveat

I don't know that scientists underestimate the risk. I think that to some extent we tend to understate it in public communication rather than underestimate it in our own assessments.

This ties into Hansen's argument about scientific reticence. See:

http://environmentalresearchweb.org/cws/article/research/ ...

There is a flip side to the denialist argument that we do what we do for selfish interests. Yes, we are human and can be influenced to say things in the way people funding us want to hear it. The question is which way those pressures act.

In fact, we are mostly funded by governments, and governments do not like big new risks. Our careers are safest if we avoid sticking our necks out.

Some of us, at least, are aware that the sensitivity usually quoted does not include carbon feedbacks, and carbon feedbacks offer a whole new plethora of underconstrained risks.

I expand a bit on the science of the missing feedback on my blog here:

http://initforthegold.blogspot.com/2007/08/missing-feedba ...

mt

by Michael Tobis at 10:11 AM on 25 Aug 2007

Not hopeless even after runaway global warming

While I agree with the above article that carbon feedbacks (i.e. carbon sinks becoming carbon emitters faster as their emissions warm the planet) will dramatically increase greenhouse gas levels, I disagree that once runaway global warming begins all hope ends.

Dr Hansen of NASA says that even now, any feasible planetary rescue strategy must include a method of removing the CO2 from the air.

I suggest biosequestion, a low cost, highly scalable, and technically feasible method of removing the excess CO2 from the air.

Removing the CO2 from the air mechanically would be very energy consuming, hard to do on a large enough scale, and would be very expensive to build and maintain enough machines.

I suggest engineering a GMO and seed it into the ocean. In my opinion, just operating our current energy infrastructure until it wears out would make us cross the tipping point into runaway global warming. The vast expense of completely rebuilding our energy infrastructure is causing political gridlock, delaying emission reductions.

Biosequestration could save billions of lives, and trillions of dollars. I predict that it will be used, but I don't know if it will be too late to prevent our current mild climate from abruptly switching to a hot state with our eco-systems going into death spirals.

by dobermanmacleod at 4:19 AM on 27 Aug 2007

ADVERTISING POLICY

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