Archive for the ‘environment’ Category

Nidaros Cathedral

I had the chance this week to attend to a lecture given by a lecturer in Industrial Ecology, that is currently member of an NGO, as well as a member of the City Council of Trondheim. Prior to this job, she took a degree in Industrial Ecology and spend time both in research within this field and applying this knowledge. The political aspects of this subject and the implementation of measures have therefore been addressed. In this post, I will comment on a more philosophical aspect our generation and behavior as a group of 6,7 billions (and still growing) individuals.

Education is a key point in succeeding to change this society and our system based on endless consumption of non-renewable resources, ecosystem destruction and purely monetary values. Our lecturer was trying to expose us the dilemma politicians have to face. In a first step, let us try to conceive politicians motivated by the common good, not by greed or power alone. Admit this is feasible for a while. As a matter of fact, politicians are only humans, and their vision of life is as restricted as ours to a limited amount of decades; therefore, their conception of success is based on personal achievements, impact on their communities, recognition by their peers. But most importantly, and due to their limited time in a position of leadership, they are inclined to secure their reelection at whatever cost. And to win elections, one has to suggest socially, morally and ethically accepted proposals (although these concepts and values can evolve with time. Take slavery for example, which was completely accepted a couple of hundred years back in time).

A direct consequence is that the one willing to act for the good of society as a whole, maybe the one thinking further than a couple of years, the one advocating changes that will secure next generations well-being at the cost of some (relative) sacrifices of ours; this one has little or no chance to see his wishes fulfilled. Implementing them, passing laws can be done, even if the majority of the population is against the measures, since the bills are not passed based on a democratic vote, but on the vote of representatives of the population, which are, once again, only humans and not robots, acting according to their beliefs and values. I have never seen any politician asking to his voters advice prior to a voting session. Incidentally, the only times I have seen politicians speaking to common persons were during the election periods.

But let’s go back to our core discussion: laws can be passed. If they are not accepted by the majority of voters, then the following elections will be bound to throw away the enlightened leader who had chosen to act for the good of the human species and not for the satisfaction of his community (notice the difference, which is fundamental in the following). This way, laws can be voted and later rejected. This is the principle of democracy, representing only a certain fraction of the population (spatial dimension) living in certain economical and sociological conditions (time dimension).

So the enlightened politician has to face this hard dilemma: “should I pass a law which I know will never be accepted, or should I give up and forsake the coming generations because of my fellows’ blindness?” The solution found was to call for help those who would share these ideas but are politically neutral: NGOs. Of course this solution cannot be always chosen; actually this option might only seldom be taken. But in the case of education, then it can be relevant. Because NGOs can simply teach a message that would never be accepted if coming from the political sphere. Let us consider the Global Warming issue, and the non-popular actions that must be undertaken in order to effectively affect our GHG emissions. These include radical changes in our consumption patterns; for a simplicity purpose I will consider here only two of them: car driving and vegetarianism.

Which politician would forbid the use of private cars in a city? Which one would put a ban on meat? Even though we all know that these are two steps to take, no one is ready to accept these bans. Simply because it would be considered as a violation of our “freedom” to choose, our freedom to act as we want, staying within the framework set up by law. Our lives would not be deeply affected though: it is just a question of re-learning what to eat, and a question of efficient public transportation networks. In spite of these extra efforts which would require maybe a couple of years to be integrated in our daily lives, nobody or so few are willing to act when it comes to effective measures for climate change mitigation, although recognizing that something has to change. And we are reluctant to upheaval, we resist changes that imply less “freedom”. Take the case of oil prices for example. A growing number of scientists now acknowledge that world production has peaked; therefore oil prices can only increase, the demand continuing to rise while the offer diminishes. We will have to accept higher oil prices, or change technologies; despite this reality we still keep on burning fuel for no reason. Recently, fishers in France went on strike because they could not afford any longer high fuel prices, and were hereby asking for subsidies. This is useless; subsidies will never suffice on a long time scale, deeper and more radical changes will be required. But we still keep on burning oil instead of wondering on how to save it.

These unpopular measures have then to be implemented through another way. This has to be education. Everything goes back to it. Education shapes us. It makes us the way we behave, enhances curiosity or passiveness, ethics or disrespect, altruism or individualism. And as Joel Bakan has depicted so well in his book, the Corporation, we have become more individualists because we have to be in order to consume more. The less we care about our fellows, about what happens in the world, the better it is because the less we see the effects of our actions. And the less we care about the consequences of our actions. So living in bubbles is exactly what corporations would like to see. Communities are a danger to those who decide to rob local resources. And as one must admit, they have remarkably succeeded in this goal. Today, few care about how our clothes are made, be it in sweatshops or in ethically acceptable conditions. Nobody knows how our food is produced, with which chemicals; what the impacts on the global environment our purchases have. And obviously, the one willing to break from this state of ignorance rapidly realizes the extent of the inflicted damages. Because our education has been supplemented by an omnipresence of corporations and other actors that have, little by little, turned us into passive, consuming individuals.

So here we are: we have never been so many on this planet; but paradoxically, we have never been so far from our neighbor, from our fellows. We do not care about the one dying down in our street, we do not know our neighbors, seldom speak to them, except when there is a problem requiring help or special cases. The time of the central plazza where people were meeting to speak and discuss; these times of public debates, of knowledge sharing; this agora that was the core of the ancient Greek daily life has disappeared from our lives.

Could we gather and act as one, forget our individualist lives, our selfishness, and achieve something that we could do before? Could we build another cathedral? Could we dedicate our life to the construction of a single project, explicitly knowing that we will never see its achievement? It took sometimes centuries to complete the construction of such edifices. Could we build something for generations to come? Could we spend our lifetime to one cause, the reconstruction of a salvaged world? Could we understand that we are, because of our limited sight and our numbers, each one of us destroying unconsciously the world we live in? Could we accept constraining measures that would require us to loose a bit of this “freedom”, for the sake of our children? I would like to believe it. But the truth is different. Everything goes back to education.

Picture: Nidaros Cathedral, Trondheim. Its first construction began in 1070 and finished in 1300. Photo: Jesús Rojo Martinez, 2007

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Today seems to be the right day for publication of another synthesis of what has been available online in the newspapers this week.

For those interested in an even better review, covering the recent times and looking at different issues, I would recommend this post from Trinifar. Impressive but true.

I was astonished to discover three significant articles on the homepage of the Guardian Environment and Le Monde (in French): first, that a new report has acknowledged that the world oil production peaked recently, and that increasing gap between offer and demand will inevitably lead to catastrophic social and economical consequences (English version available there); then, that the UK was trying to withdraw from its commitment to reach 20% renewables by 2020 (an information confirmed the day after); finally, (see also here for a French version) that scientists have observed an increased rate of CO2 emissions since 2000, leading to faster and tougher environmental consequences. And today a new report reveals that our civilization and the world it lives in are in danger of disappearance. In a couple of number, it gives this (quoting from the Guardian)

· 45 thousand square miles of forest are lost across the world each year

· 60% of the world’s major rivers have been dammed or diverted

· 34%: the amount by which the world’s population has grown in the last 20 years

· 75 thousand people a year are killed by natural disasters

· 50%: The percentage by which populations of fresh fish have declined in 20 years

· 20%: How much the energy requirements of developed countries such as the United States have increased in the period

And in the meantime, when companies study new technologies, people are expressing their refusal to see large wind turbines developed and sold, on the excuse that it is visually disturbing. Well, one has to choose: whether we try to shift from fossil to renewable power, thus attempting to limit our greenhouse gases emissions (and accept a visual “insult”, which is to me acceptable given the other option), or we go on burning coal and gas and go to hell within a century. Fortunately, politics are beginning to address the question and locally things are changing. In France, this week after the “Grenelle of environment” talks, the government has agreed in partnership with environmental organizations to vote new laws aiming at setting the path to a more environmental-friendly society; although there is a lot left to do in order to actually achieve sustainability. It is too early to judge how these new measures will be implemented, but the example of UK is not a good one to be inspired.

Well, time for some synthesis: the news are accumulating, as they have always done, although at a higher rate now, and show that it is no longer merely our climate which is at stake. It is our whole civilization, and the majority of the biosphere on this planet (see here and there for examples) that are now threatened. And even though we thougt we would have 1-15 years to react and change the slope we have taken, it appears that all the scenarios imagined before have systematically been wrong, even the most pessimistic ones (here, concerning the Stern report), and see the above mentioned articles for the rising GHG emissions.

Unfortunately, as I often witness, people have two behaviors when confronted to the problem:

  • They do not know and prefer not to know about it. After all, we live in developed countries and it is far better to shift the problems to the other side of the globe rather than questioning our lifestyles
  • They deeply reckon that technology can solve everything. “Put your faith in humanity and in science”. Being a scientist, I totally disagree with this claim. It is not like switching off the light: finding new solutions or establishing new theories takes a lot of time. Implementing them worldwide takes even longer time. We are running out of time. Everything goes exponentially and we cannot afford to wait a couple of years more, because we will already have reached the tipping point. Or have we already?
  • As discussed previously on GIM, solving the carbon-rich energy might not be enough. Our problems lie much deeper in our society and our culture. Those who put their faith on science rather than considering the wider problem are only accepting to solve one factor, that might be overwhelmed by the others (like absolute consumption growth, population growth, and the associated resource depletion issues).

On Wednesday I attended a conference on the investments in renewable energies worldwide. A striking figure was the increase in investments the last 3 years: here is a graph of the amounts:

Investments in renewable technologies

The leading countries, depending on the origin of the fundings, are USA, Germany, Japan, and… China. Despite the gloomy award of being the largest GHG emitter worldwide, catching up the US at an incredible pace, they invest a lot in renewable technologies. The backside is that in spite of huge amounts invested, they still represent 10% of the total investments in energy. Meaning the rest goes to fossil energies. It is like buying tons of cigarettes although one would be in the final stage of a lung cancer… No hope to survive with it but still money flows. And as the following graph shows, it seems like too much faith is put on biofuels, while these are in their current version not adequate to solve both energy and food supply problems. Interestingly, the US and Brazil are among the largest investors in biofuels, seen from the Venture Capital/Private Funds source of investments (34 %).

Percentage of investments per energy source

So things are moving. We do not see it often because it happens locally; the US is the typical example. Things are moving but it might appear not to be enough, or maybe it’s already too late. But let’s hope and believe we can all wake up and gather.

One last comment about the articles above mentioned, dealing with the energy crisis bound to rise up in the coming decades. The one I read on Le Monde did not last very long on the web; after less than 24 hours published online it was moved into the archives, accessible only to paying customers; normally articles stay a couple of days or more online… I find it a pity that important articles like this one are not left at the forefront longer than that. In the meanwhile, I receive “last minute” exclusive mail to let me know that… Brazil will organize the soccer world cup.

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We are just another animal species, unfortunately given the ability to master fire and technique. I write unfortunately, because it is this gift that is going to cost us our disappearance. And not satisfied enough to put an end to our short period of existence on this world, we will also bring with us to the abyss some thousands of species which never hurt us, never asked anything from us, never attempted to steal us our “territory”. Maybe we will destroy so much this planet that no life as we know it today will be left after our era.

Deforestation by fire (Wikipedia)

We are burning our lungs. Today the Guardian environment publishes an article about the Amazon rainforest being once again burned and chopped down. After reading, a feeling between hate, despair and revolt fills up my mind, and these feelings for my fellow humans is bound to leak here. We are destroying our world, for the sake of growing soy, for the sake of making money. And this soy will, ironically, not feed us humans, but the chicken farms of Europe. What is the effect of eating meat? Here you have the answer: in each piece of chicken you buy, you could see some tropical trees. And if we could hear them, I guess they would cry of hate, despair and revolt. I am myself a criminal: I eat meat.

Why are we burning and chopping this forest? Because, as the article relates, we need to feed ourselves, we need to earn money to survive. And because we are endlessly more on this planet, we will have to feed even more impoverished people. And because rainforest is located in developing countries, where the governments do not have enough will or strength to enforce laws, it is easy for locals to break or violate these laws, set fire to the forest, and plant crops instead. Our thirst for development will lead us to the point where no turning back will be allowed, when we will be left witnessing, powerless, nature taking its rights again, destroying what our civilization has built. Indeed, when there will be no plants left on this planet to produce the oxygen we breathe, nobody will be left claiming “put your faith in the market, it will solve our problems by itself”.

When I read such articles, I realize that my generation will experience something none has lived before. We will witness climate change, resource depletion, while the world population will reach its higher levels ever, thereby requiring even more resources. Get me right: my generation will live what we could call an environmental nightmare. And I am not speaking about the wars that will inevitably follow. Do our children have some hope? I would really like to say so. I would like to believe in Humanity, in our ability to gather and act as one. But I know this is a dream, an utopia. Because there is too much selfishness in human beings. In order to save us all, we would need more than worldwide unity; we would have to sacrifice something. Give up our comfort and grasp on nature. Who would accept this? A couple of individuals who realize what the reality is? Would we accept to give our lives to the reconstruction of a world? No. Would we accept to forget any concept of “the one who works the harder earns the most”? No. Because this concept is based solely on monetary rewards. This is the American Dream: through hard work, sweat and personal involvement, anyone can succeed in life. Unfortunately, to make it brief, the American Dream has two flaws: first, we are no longer in the early industrial age, when corporations were left to create. Second, this dream is based on a materialist and monetary description of what a successful life is. Both points are outdated. The American Dream is virtually dead, but still alive in many people’s mind. We live in a dream.

Human kind has no altruism. That is what makes us different from the other species: our egoism leads us to our self-destruction.

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In the context of a series of conferences organized by the department of Industrial Ecology at NTNU, Norway, we had the honor and pleasure to welcome Mr. Leo Meyer on the 2nd of October, for a speech on the work of the working group III of the IPCC in its 4th assessment report. Mr. Meyer is the head of the technical support unit of this working group. In this article, I will comment on the functioning principles of the IPCC and address critically the different solutions proposed by the group, with respect to the IPAT equation.

At first was explained the principle of the IPCC; what his missions were and how governments would act in collaboration with the scientists working in this panel. I will stop at this point and pinpoint the fact that governments have an influence on what is finally published, but only when it comes to the Summary for Policymakers (SPM), a 30-pages long document offering a synthesis of the work otherwise published both in the final report and in the technical summary. This report has to be approved by all the 180 participating countries word by word, graph by graph, etc… A direct consequence is that this report might be a light version of the thicker ones, only presenting facts that do not clash against policies or mentalities of various governments. If you do not have time to read the longer reports, then go for the SPM ones, but be aware that they are diluted versions of the truth available elsewhere. Their content is nonetheless accepted by scientists chairing the working group.

It is often heard that the IPCC does not represent all the scientific community; that it does not give space to alternative theories. To understand this fact, one has to keep in mind what the ultimate goal of the panel is, and how it proceeds to achieve it. How are authors selected?

  1. Governments and institutes of the 180 member countries submit CVs
  2. the IPCC Bureau matches CVs against chosen subjects. Here a first “filter” is applied, so as to choose people from different geographical origins, and from different “schools”. This in order to avoid a unique view of the issues.
    1. The concept of different schools might be for example relevant when it comes to economy.
    2. The chosen ones are not only academics, but also experts from the industry, NGOs, etc
  3. 15 lead authors are chosen per chapter
  4. The co chairs, as well as the lead authors, can also invite authors

The IPCC is so to say summarizing the current scientific knowledge on the evolution of the climate and the science therein. Its goal is not to produce new papers, explain new facts. It is an assembly of experts whose task is to read a lot of peer-reviewed papers (meaning read and corrected by other scientists) and write a report on the state-of-the-art. All the results published by the IPCC are therefore already published in the literature; the sole purpose of the IPCC is to gather the data and make it available, and in a certain extent, more comprehensible to a larger public.

The working group III has the task of describing the strategies to adopt to mitigate climate change, based on the impacts published by the working group II. Although the latter are regional, the strategies to adopt are inherently to be applied worldwide. Some differences of strategy might appear, depending on the current state of economic development of the considered country; but in the end one striking pattern comes out from the report: what we have to fix is technology, and change our consumption patterns. These two points, and particularly the former, are recurrent in the report. To summarize, technologies exist, but have to be implemented. The group does not expect any technological breakthrough to happen in the form of the discovery of a new energy source; what can be done is improvement of the existing technologies.

An “economic fix” is required in order to boost the shift from fossil to renewables, through the establishment of a worldwide price on carbon. And in spite of the apparently opposite mentalities of “bottom-up” (techno-economic analysis) and “top-down” (integrated assessment analysis), it appears that each way to address the problem can lead to substantial reductions in CO2 emissions. The following two graphs represent the possible reductions in CO2 emissions achievable through the implementation of a worldwide carbon trading system, using each of the two above-mentioned approaches. Of course the reductions will depend on the price set on eq-CO2. Due to uncertainties, a low- and high end-of-range are shown in each case.

Effects of a tax on CO2 (Top Down case)

Effects of a tax on CO2 (Top Down case)

What is frightening is to realize that the maximum emission reduction that can be achieved through technological shift, helped economically by a price on carbon, is roughly 30 GtCO2-equivalent per year, in the best case envisioned by the projections. Looking a couple of pages further in the report, one realizes that in order to stabilize our atmosphere at CO2-eq concentrations between 450 and 500 ppm, the limit for containing the temperature rise below 2 degrees, we need to peak our emissions by 2015. Let’s say that is impossible. With China and India growing, as well as the other countries still desperately looking for extensive economic growth based on over-exploitation of resources, nobody will accept such a sudden shift in mentalities. Although the solution for mitigation is within reach, we prefer not to take it and go on the same path as before.

I recently commented on Growth is Madness! that the IPCC was not addressing the population growth problem, although it recognizes it as one of the main drivers of increasing GHG emissions:

the effect on global emissions of the decrease in global energy intensity (-33%) during 1970 to 2004 has been smaller than the combined effect of global per capita income growth (77%) and global population growth (69%); both drivers of increasing energy-related CO2 emissions.

Of course, this conference was the ideal occasion to ask the right person the right question. Unfortunately, someone else asked our lecturer about population before I could, and turned it in such a way that it sounded too extreme (one-birht policy was given as an example). Here follows the question that I would have asked:

The IPCC Working group III addresses only the two last terms in the famous equation I=PAT (Environmental Impact = Population*Consumption*Technology), dismissing the first one, namely population growth, although recognizing it as one of the main drivers of increased GHG emissions. The predictions summarized in limits to Growth thirty years ago are even more valid today than when the book was initially written. Indeed, the neo‐Malthusian movement is pushing towards addressing the first term of the equation. Recently, China stated that by controlling population growth, 300 million births had been avoided by 2005, leading to direct savings of 1,3 billion tones of emitted CO2 in 2005 alone. Why is the IPCC WG III not emphasizing more strongly this fact and does not introduce policies required to curb population growth, policies which could include aid to development, access to family planning, and women empowerment in developing countries? And if it is not considered as relevant by the group, then why?

In my question, I nevertheless made one error, which was also the key to the answer provided by Mr. Meyer: I implied that the IPCC was introducing policies. It is not its role. The IPCC has been created in order to give the political leaders some ideas about how to deal with the problem. The IPCC has to be “Policy relevant, not policy prescriptive”. That means that it cannot suggest new, radically different ways of solving the global warming issue rather than by choosing to solve the problem with the political, economical and technological tools that we use or have today. Indeed, population control, through the use of whichever policy, is not accepted by most of the countries member of the panel.

So the answer of our guest lecturer was the following: when it comes to such issues directly touching the population and the human beings, cultural, religious and political problems rise up and block any further discussion of the subject. If the IPCC report does not address the population issue, that is because it is not politically correct, or because it would be too provocative to certain cultures. This concern is thus left to others to address.

By avoiding such sensitive subjects, and despite the full acceptance of their importance, the experts are not even in the position to suggest policies or strategies that could help us to take care of the P factor. By leaving this aspect as an external variable nobody can do anything about, we are actually refusing to fully open our eyes, and make the inevitable crash even harder to support.

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An introduction to Industrial Ecology (two terms which, in my opinion, are hard to put together) will certainly expose this equation, which describes easily the current problems our civilization has to face:


I is the total impact on the environment. P is the population, in capita. A is the affluence, or consumption level per capita, expressed in unit GDP per capita. Finally, T is the technological factor, expressed in impact on the environment per unit GDP. This formula has been expressed by Ehrlich and Holdren, and one could of course object its simplicity; but I find it gives us a good starting point from which we can develop.

To minimize our impact on the environment, there are thus three ways to proceed, according to this equation:

  • reduce population
  • reduce our consumption
  • improve technology so as to increase materials and resource efficiency

Of course this equation has some flaws. For example, what stroke me first was that the notion of “impact” is totally subjective. What does it mean? Impact on which time scale? Indeed, by taking the example of CO2, what we emit today will have effect in some time; so the impact right now is zero, but delayed. And impact on what? Can we reduce the environment to one single system, without distinguishing different sub-systems? And how can we pretend that the technological factor is only function of money? Can’t we change our impact without relying on new technologies, just by developing the existing ones?

Well, of course this model is ultra simple. But it has the merit to be easy, and some of the questions above can find answers. Life Cycle Analysis theory uses also the notion of “impacts”, to make the results more comprehensive to the reader. In fact, the impacts come from different “stressors”, or “emissions”: for example, emissions of CO2, CH4, CFC, SO2, volume of natural gas burned, etc… A typical LCA can include several thousands of different stressors. Nobody could sort them out and get a grasp of what these stressors mean; so they are grouped into impact categories, such as Global Warming Potential, Acidification Potential, etc… So in the end, only a dozen of impacts can be considered. This might be a way to solve one question. The other ones can find similar answers, which are in fact just methods to model a complex system.

What is striking is that we are nowadays only concentrating ourselves on the last parameter, T. We are speaking of “fuel efficiency”, electricity savings, etc… “Change your light bulbs!” is a typical example. And the business sphere obviously puts this factor on the forefront of its communication plans. Energy and materials efficiency is their leitmotiv. But well, in fact we have two other factors which are more important to address.

Some others are trying to take into consideration some changes in their lifestyle: drive less, take the public transportation instead of your car, buy organic; but these are really small changes that are not bound to reverse the global trend: GDP grows faster than population in our OCDE countries, meaning that the A factor increases as well. And as long as our policies will be based on achievement of an exponential growth of GDP, we will not be able to change A. To achieve such a goal, we would need to consume otherwise, but most of all, consume less.

Finally comes the big taboo, P. We have a tendency to consider it as fixed, an external variable that nothing and nobody can change. Indeed, I believe this is the major factor that we actually can do something about, besides A. Simple measures are education, empowerment of women, family planning, etc… World population has doubled those last 40 years, and plotting the world population vs. the time on a large scale has something frightening.

World population evolution those last 12000 years

And a closer look at the population evolution during last century gives this:

World population evolution during the XXth century

A look at the scale shows that our numbers have been growing at an unprecedented rate.

So here we are, the three factors have been introduced… What is weird is that we see a shift from the right hand side to the left one. We are now trying to convince us that some technological fixes will help us to reduce our impact on the environment. With the aspirations of 80% of the world population to reach a western standard of living, “efficiencies”, and even a shift to greener technologies will not be enough. Some are understanding that reducing our consumption of goods is critical to sustainability, but these individuals are still considered as marginals and dismissed by the capitalist system, whose philosophy is based on an infinite growth of consumption. And too few are understanding the remaining factor, which is perhaps the one we should all be concerned about.

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This post will be the first of a series, aiming at giving you a fair idea of what would be needed to effectively mitigate climate change. Let me first emphasize our core belief: global warming and the resultant climate change are anthropogenic, meaning human-induced. Some might argue that no, everything is a question of natural cycles, cosmic rays, God’s hand and who knows. For those, I’d advise some easy reading: the “Start here” page on a blog written by climatologists. But I’ll try to give you a brief description of the phenomena. The sources I use are wikipedia and the IPCC working group I report, 2007.

Sun radiates electromagnetic waves in a variety of wavelengths. For example, it radiates visible light, but also infrared and ultraviolet. Quantum mechanics predict that the exact distribution of the emitted radiation is given according to the sun’s temperature (5800 K), following a mathematical formula called Planck’s law. In reality, the black-body is just a model and the real spectra is slightly different. The figure on the left shows the solar radiation spectrum as seen from space (in yellow) and from the surface of the Earth (in red). The black body approximation is also shown, and one can notice that it fits well to the yellow curve.
Spectrum of the sunlight above the atmosphere and after its transmission

So when the sunlight arrives on Earth, some of the energy is reflected to space because the albedo of the Earth (albedo is comprised between 1 -total reflection of the incoming light- and 0 -complete absorption. Earth’s is now 0.31, but bound to decrease because of the polar caps melting), while some is transmitted through the atmosphere. The different components of our atmosphere fill absorb some energy in different frequencies, which explains that when you look at the red spectrum, measured at sea level, you do not have the same pattern as before.

The light then hits the ground and gives some energy to it, thereby decreasing its frequency (an electromagnetic wave with high energy has a high frequency, ie a short wavelength). It is then reflected to the atmosphere. A fraction will be emitted in space, but the major part of this reflected energy will be trapped and absorbed by the atmosphere and converted in heat. You will ask why this did not occur earlier, when the light went through the atmosphere the first time: that is because then it had a high energy content, with high frequencies! And molecules like CO2 are really effective at absorbing electromagnetic waves of low frequencies, rather than high ones.

So you get what is called the greenhouse effect. Without atmosphere, the temperature on Earth would be around -19 degrees Celsius, and of course no life could ever have developed in these conditions…

The concentration of CO2 in the atmosphere has increased during the last 150 years, because of human activity. Of course, the CO2 concentration follows cycles; sometimes it goes up, sometimes it goes down. The following figure shows the evolution of temperature and CO2 concentration during the last 450,000 years.

Evolution of CO2 concentration and temperature

What is striking is that temperature is strongly correlated to the concentration of CO2. Moreover, an increase in CO2 leads to an increase in temperature through radiative forcing, and a feedback exists: an increase in temperature leads for example to higher evaporation of water, which is by far the largest greenhouse gas present in the atmosphere, so in turn higher temperature, etc… Until a new equilibrium is reached.

There are several such positive feedbacks, although for us living species their effects might be considered as negative. Since it takes some time for the CO2 recently released in the atmosphere to have an effect, the worst is yet to come. The global atmospheric concentration of carbon dioxide has increased from a pre-industrial value of about 280 ppm to 379 ppm in 2005. Indeed, and as can be seen on the graph, the atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice cores. There is not only CO2 as greenhouse gas; the most common ones, besides carbon dioxide, are CH4 and N2O. Scientists have tried to put some “equivalent global warming potentials” (GWP) on these other molecules, compared to CO2. For example, CH4 has a GWP of 21, meaning that it is potentially 21 times more effective than CO2. And guess how much is GWP of N2O? 310.

Now, you mqybe wonder why the global atmospheric concentration of CO2 has increased recently. But you know the answer. Our society is based on the consumption of fossil fuels. Fossil fuels (coal, oil, gas) are remainings from carbon wastes such as plants and living organisms like animals, which died millions of years ago and progressively decayed and decomposed in the soil. Under certain temperature and pressure conditions, time helping, these wastes are transformed into fossil fuels. Indeed, they are composed of molecules based of carbon. Burning them in presence of oxygen leads to formation of CO2 and water (H2O), among other substances. And that’s where the extra atmospheric CO2 comes from.

This introduction was just a short explanation of the basic physical principles behind the greenhouse effect and its extension to anthropogenic global warming (AGW). My next post will expose the solutions the scientific community recommends for an “effective” mitigation of climate change. I put it between brackets, because it is not possible to stop AGW so easily. CO2 has a half-life of 12 years in the atmosphere, N2O of 120; that means that it will take maybe centuries for natural processes to come back to our original situation, just 150 years ago. Yeah, isn’t it powerful, destroy a 12,000 years long climatic equilibrium in 150 years?

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