Global warming: how is its impact calculated?

Global warming: how is its impact calculated?

By Jorge Riechmann

The fact that a civilizational collapse is not an implausible possibility, and that therefore it will be possible that, in the not too distant future, instead of arguing about the meters of beach lost in tourist areas, or about the costs marginal to the increase in elderly deaths from heat waves, we find ourselves estimating how many small groups of hunter-gatherers will manage to survive on the steppes of a devastated and impoverished Europe; the fact that such a collapse is possible should be enough to push forward ambitious policies to combat climate change. We cannot keep hiding our heads under the wing and postponing effective action: time is running out.

Some of the major disagreements have to do with the procedures employed by economic analysts in translating biophysical impacts to socioeconomic impacts. In relation to the problem, with vast implications, of global warming, the difficult scientific questions that have fueled lively debates among the orthodox economic establishment on the one hand, and on the other the new perspectives opened up by ecological economics (and partly by the environmental economics) during the last decades. (1) One way of pointing to the underlying problem is suggested by Francisco Javier Rubio de Urquía: “As long as we continue to apply models that limit, almost exclusively, cost analysis to the quantitative field, we will not be able to have a more complete vision that allows us to correctly assess costs and qualitative benefits, such as those derived from the burdens assumed by nature and the services it provides us. The mere fact of thinking that technological progress and the laws of the market are sufficient to alleviate environmental problems shows the undervaluation, if not contempt, that nature has been subjected to. Believing that we can act as if we were self-sufficient and that, thanks to technology, we will be able to supply ourselves with all the goods and services that it provides us, and that are vital for our existence, only reflects a high dose of pride and another no less than ignorance." (2)

The possible halting of the North Atlantic ocean current One of the possible consequences of global warming would be the complete halting of the North Atlantic ocean current (Gulf Stream) that brings heat to Europe, which could cause a “mini-ice age” whose effects, according to many experts, (3) would be important. (4)

However, economists like P. Michael Link and Ricahrd SJ Tol run the FUND 2.8 (Climate Framework for Uncertainty, Negotiation and Distribution) model with the result that, in a world warmed by the "greenhouse effect", a total collapse! thermohaline circulation could even be economically beneficial! (5)

According to these calculations, the collapse of the thermohaline circulation would not entail a cooling in absolute terms of Western Europe (and other regions of the North Atlantic), but only a cooling relative to the baseline scenario, which is quite torrid in itself. The end of the thermohaline circulation would delay warming and therefore reduce the damage of climate change (0.5% of GDP in Western Europe, 0.4% in the US). However, the same calculations by these two authors indicate that “climate change is a real problem, since both the total and marginal impacts are negative [decrease in world GDP], both without collapse of the thermohaline circulation and with it”. (6)

Biased models?

But to what extent is such an estimate of benefits and damages in terms of GDP reliable, relevant and adequate? If we examine more closely the assumptions used by many of the economic models coupled with the climate models that attempt to assess the impacts of global warming on the economy, it must be concluded that many of them are limited or inadequate, which which ultimately translates into biases that probably tend to underestimate the damage that climate change will cause.

Let's see some examples, referring to the FUND model used in Link and Tol.

An important problem refers to the use of market prices to value natural resources and their impacts.

A very important problem, which has caused rivers of ink to flow among ecological and environmental economists, refers to the use of market prices to value natural resources and impacts on them. Thus, in the FUND model “impact categories such as agriculture, forest products, energy, water and ecosystems are directly expressed in monetary values, without a mediating layer of impacts measured in their 'natural' units.” (7 ) This practice is highly questionable: from the deep and long debate on the monetarization of the environment it must be concluded that ultimately such monetarization is impossible (without this meaning that it is in all cases a meaningless activity).

How to value in money, monetize "natural capital" in a non-arbitrary way? The repair cost and offset cost methods used by environmental economists are quite useful in many cases, but will be of no use in the case of irreversible damage. The decision to value natural resources and environmental damage at market prices is fraught with moral implications, since neither future generations nor non-human users of the biosphere (the other living beings with whom we share it) intervene in markets. And when the resource or environmental function in question does not even have a market value and we have to invent some “hypothetical market” to assign it a crematistic value, the arbitrariness of the procedures is triggered until it enters the field of the openly irrational. These methods face great theoretical and empirical difficulties, which have resulted in an abundant literature. (8)

In the FUND model, the loss of one square kilometer of land due to rising sea levels is valued at a maximum of $ 4 million for OECD countries (and $ 2 million for wetlands, for these same countries ), and it is considered that for the other countries this value is proportional to GDP per square kilometer. (9) So large territorial losses in poor countries will count the same as small losses in rich countries! Equal proportionality in the loss of human life (due to heat stress or infectious diseases, for example): this model estimates the value of a life at 200 times its annual per capita income. (10) For this reason, serious demographic losses in very poor countries would count for very little in terms of aggregate economic results. As we know in advance that human losses due to climate change will be greater precisely in the poorest countries due to their greater vulnerability (due to insufficient health systems, poor public services, fragile food production, etc.), we must conclude that the model involves a bias that will underestimate the losses - in human lives, land, ecosystems, etc. - in the poorest and most vulnerable areas.

Another problem has to do with the assumptions of linearity. The FUND model assumes that “the damages associated with climate change are attributed either to the rate of change (referenced to 0'04 ºC / year) or to the level of change (referenced to 1 ºC).

Damages due to changes in temperatures slowly decrease, reflecting adaptation ”. (11) That is, the model assumes a gradual, slow and not too large climate change, to which society (especially wealthy societies) gradually adapts, thus minimizing the damage. However, actual changes are likely to deviate from these relatively comfortable patterns: and the difficulty of adapting to abrupt changes will be much greater, until, in the extreme case, impossible.

Climate refugees

Another case of budget linearity but very difficult to justify has to do with climate refugees. In the FUND model "it is assumed that immigrants immediately and completely assimilate to the population that welcomes them." (12) This may facilitate comfortable operation of the model, but this is certainly a very unrealistic assumption. Today, more than 100 million people live below one meter above sea level, worldwide. (13) We can be sure that rapid and / or abrupt climate change will have the effect of significantly increasing migratory flows (in a world where these have already acquired very important dimensions: almost 200 million international migrants in 2006). (14) Various estimates indicate that, around the year 2000, displaced persons or “environmental refugees” outnumbered those displaced by wars and internal military conflicts by a ratio of ten to one. According to the United Nations, 60% of migratory movements are caused by climate change and natural disasters, such as droughts and floods.

According to the IPCC (Intergovernmental Panel on Climate Change), the sea level, if nothing is done to contain the warming, could rise between 9 and 88 centimeters between now and the year 2100. Many independent studies deduce the displacement figures from this data. forced population.

According to these estimates, climate refugees could be 150 million in the year 2050: 30 in China; 30 in India; 15 in Bangladesh; 14 in Egypt; 1 in the island states and 10 in the rest of deltas and coastal regions; 50 in the rest of the regions. This means, at least, 1.5% of the population that is expected to inhabit the planet in 40 years.

But the IPCC forecasts, valid until a few years ago, run the risk of being far behind reality. If Greenland and Antarctica completely thaw - and they are thawing with chilling rapidity in these first years of the 21st century - the sea level will rise not one meter, but between 12 and 25 meters, perhaps even more. This would mean more than 500 million displaced. (fifteen)

The vast majority of these climate refugees will be poor, inhabitants of the countries of the South, who do not have the means to finance the gigantic infrastructure necessary to protect themselves from the tides and who, therefore, have no influence in the climate negotiations. A "slamming the door in the face" would not only be perverse, but would also result in the worsening of the global social and ecological crisis and another step in the transformation of the planet into a huge barrel of powder. (16)

The experiences of the last few decades clearly show that, even at relatively low levels of emigration from poor to rich countries, the socio-political tensions that arise are high. In general, it can be said that economic models ignore these socio-political dimensions of climate change: but no one can seriously believe that strong socio-political impacts will leave economic life unaltered. (17)

Warming of the climate and war conflicts

There is no sociopolitical impact greater than war. However, for years, important analysts have warned about the increase in international conflict related to progressively scarcer natural resources and environmental functions. (18)

In recent times, the recognition that climate change can become a tremendous destabilizing factor in international relations (including new wars) has reached even the highest levels of political-military leadership.

Thus, UK Defense Minister John Reid, in a speech delivered on February 27, 2006 at the prestigious Chatham House in London, warned that combining the effects of global climate change and depleted natural resources increases the possibility violent conflicts over land, water and energy. Climate change, he said, "will make resources and clean water more scarce, and agricultural land in good condition will be more scarce." This will make “emergencies due to violent conflicts more likely”. (19)

According to Reid, it is easier for these resource conflicts to arise in "developing" countries (to use the usual euphemism), but advanced and wealthy countries will not necessarily be spared from the damaging and destabilizing effects of global climate change. The moment sea level rises, when water and energy become scarcer and scarcer, when fertile but scarce farmlands in some areas become deserted, deadly wars for access to vital resources they can end up being a global phenomenon. (twenty)

As Michael T. Klare points out, before Reid's speech the most significant expression of this change in perspective was the report prepared in October 2003 by a California-based consultancy for the US Department of Defense. Titled A Scenario of Abrupt Climate Change and Its Implications for US National Security (21) the report warns that the chances of this phenomenon generating sudden cataclysmic environmental events above a gradual (and therefore manageable) increase are broad. average temperatures. Such events could include a substantial rise in sea level, intense storms and hurricanes, and regions in drought, with large continental-scale dust gales. This would trigger acute battles between survivors of these effects for access to food, water, habitable land, and sources of energy. "Violence and disruption caused by stresses created by abrupt changes in the climate pose a different kind of threat to national security than we know today," the report says. "Military confrontations can arise due to the imperative need for natural resources such as energy, food or water, and not so much because of ideological, religious or national honor conflicts." (22)

An experienced biologist, such as Miguel Delibes de Castro, stresses that there are those who believe that the risk of “water wars” (or, more generally, wars over natural resources) has been overestimated, since fighting would be more expensive than obtaining water by unconventional but more expensive methods (desalinating seawater). As if political decisions are made routinely after careful cost-benefit analysis! One foot from which many economists limp is their overestimation of the rationally selfish components in human behavior. As Delibes de Castro observes –in dialogue with his father, the Castilian novelist Miguel Delibes–, “it has always seemed too optimistic to me, even naive, because when men decide to wage war they rarely consider its costs. Hearing the argument, I remember the perplexity of your character, Pacífico Pérez, from Las wars of our ancestors, when Bisa tells him that 'we would be fine if the wars needed reasons'. " (2. 3)

It would be a mistake for the discussion of the effects of climate change to focus only on ecological and environmental issues, underestimating the socio-political effects

It would be a mistake for the discussion of the effects of climate change to focus only on ecological and environmental issues, underestimating the socio-political effects, which can be far-reaching. At the limit, the greatest danger does not lie in the degradation of ecosystems (in the long term of geological times, nature recovers even after major catastrophes, reaching new equilibrium situations), but rather in the disintegration of entire societies (due to hunger and sanitary deficiencies, massive migrations and recurrent conflicts over scarce resources). (24)

Nordhaus and Boyer's RICE / DICE model

Another of the models used to estimate the possible socioeconomic impacts of climate change is the family of RICE and DICE models (Regional Integrated Model of Climate and the Economy and Dynamic Integrated Model of Climate and the Economy), developed by William Nordhaus and Joseph Boyer to be able to make such estimates according to an advanced type of cost-benefit analysis. (25)

According to this influential model, each additional ton of carbon dioxide (CO2) emissions will cause long-term damage at a cost of $ 7.5, giving an optimal reduction rate of 4% over 1995 emissions, lower than that of the 5.2% on the 1990 emissions approved in Kyoto. The cost per ton of CO2 and year is arrived at by calculating the years of life lost attributable to global warming, divided by CO2 emissions, after applying a discount rate of 5%.

Nordhaus and Boyer estimate a loss in life years of almost 38 million due to climate change - only a part of which would be anthropogenic in origin - for the period 1990-2020. This measure of "lost health" is reducible to an amount of income, since the cost of one year of life is valued in two years of income per capita. For example, about $ 68,200 in the United States in 2000, multiplied by the average 77-year life of an American, gives us an approximation to the total end-of-life cost of about $ 5.3 million.

Nordhaus and Boyer's RICE model presents some serious difficulties, which - according to the synthesis made by Joaquín Valdivielso - can be summarized as follows: (26)

1) It only models CO2, no other greenhouse gas responsible for the remaining 40% of climate change is taken into account.

2) It projects a fixed cost of each ton at 7.5 dollars, when the logical thing is that the worst consequences of climate change are expressed exponentially as emissions increase.

3) It depends on a discount rate, which is nothing more than an expression of the subjective value attributed to future welfare from the present - the rate is the portion of utility that is deducted from a future that is supposed to be richer.

4) Years of life lost only refer to the expected extent of climate-related diseases, such as malaria or malaria. No other source of mortality is included: heat waves, droughts, diarrhea and respiratory problems, diseases related to torrential rains, malnutrition due to crop failure, hurricanes, etc.

5) It assumes a different value for health and life depending on whether one lives in one or another of the 13 regions of the world contemplated. In fact, 70% of the damages will occur according to the chosen scenario in sub-Saharan Africa, where the cost of a life is around 43,710 dollars, given that income and life expectancy are lower, 940 and 46.5 years respectively. -, less than 1% of the cost of living for an American. The loss of a year of life in a rich country would be equivalent to more than two full lives in a poor one!

6) It does not contemplate other forms of non-monetized damage and in particular some non-monetized ones. The typical counterexamples used in the assessment of climate change abound in cases of irreversible losses without reasonable financial compensation, such as the disappearance of Pacific islands such as Nauru, Tonga, Micronesia or the Marshall Islands. One of them, Tuvalu, with a Polynesian population of about 11,000 people, is paradigmatic: an exemplary society in the respect of human rights, it houses a unique language and culture.

7) Even if we accept the whole model, there is no evidence that there will be mechanisms to transfer the present wealth generated to the future ones affected by climate change. The entire focus of this type of analysis (“tradeoff –functional commitments– between consumption today and consumption in the future”, according to the authors) seems unfocused.

Lohachara, Lateu, Tuvalu: solidarity with the victims?

In December 2006 it was learned that for the first time an inhabited island - Lohachara, in the region of India where the Ganges and Brahmaputra rivers flow into the Bay of Bengal, where some 10,000 people once lived - had disappeared under the sea. (27) A year earlier, at the beginning of December 2005 - according to Daniel Tanuro - the inhabitants of Lateu - a small population of a hundred inhabitants, located on the island of Tegua, in the Polynesian state of Vanuatu - were displaced to escape increasingly frequent floods. The barrier reef no longer protected them from increasingly violent cyclones, and erosion was pushing the coast back at a rate of 2 to 3 meters per year. These hundreds of people have the sad privilege of being the first case of collective transfer due to the rise in the level of the oceans, due to climate change. But the number of climate refugees is already high, especially in the Pacific islands. (28)

Before we mentioned Tuvalu, another Polynesian state: it happens that it already has more than three thousand climate refugees. Located 3,400 km. northeast of Australia and close to Vanuatu, this country (barely 26 km2) is made up of eight atolls, where the maximum height is located 4.5 meters above sea level. Half of the 11,636 inhabitants live at three meters above sea level: and now climate change is causing large tides (up to three meters above its normal level), in progressive increase.

Tuvalu is the first country where people have been forced to leave their land to escape flooding. If no drastic measures are taken, it runs the risk of becoming the first state wiped off the map after the evacuation of its entire population.

Tuvalu is the first country where people have been forced to leave their land to escape flooding. If no drastic measures are taken it could disappear from the map

In 2000, the government of Tuvalu asked Australia and New Zealand to commit to welcoming their 11,636 inhabitants in the event that the oceanic level made evacuation essential. The Canberra government responded negatively; its immigration minister, Philip Ruddock, declared that taking in the "castaways" of Tuvalu would be "discriminatory" with respect to other refugee candidates. In reality, "Australia has hit us with the door in the face," said a Tuvalu official.

New Zealand's response was a bit less brutal, staying within the scope of the PAC group (Pacific Access Category), an agreement on immigration between the government of Auckland, on the one hand, and the governments of Fiji, Tuvalu, on the other. Kiribati and Tonga.

Under this agreement, New Zealand agrees to host 74 people from Tuvalu and Kiribati, and 250 from Fiji and Tonga, for one year, provided that the candidates are between 18 and 45 years old, an “acceptable” job offer in New Zealand ( full-time and indefinite salaried employment), with proven knowledge of English, meet certain health conditions and prove sufficient income if they are dependent on them. (29)

To understand the scope of this political measure, it must be clarified that Australia has just 20 million inhabitants (average of 3 inhabitants / km2), which ranks third among countries according to the United Nations level of human development, and that its GDP per inhabitant is $ 29,632 / year. New Zealand, for its part, is not a country with fewer resources. It should be added that the Australian government, a great ally of G.W. Bush, refused to ratify the Kyoto protocol, being the most intense coal-consuming economy on the planet.

98% of the victims of natural disasters in the last twenty years (1985-2005) lived in countries euphemistically called “developing”, according to data from the United Nations International Strategy for Natural Disaster Reduction from the ONU. This indicates the terrible pattern that could be magnified in the future. Allowing for rapid and uncontrolled climate change could have a lot of genocide of the North against the South.

Criteria on Ecosocial Problems

Applying reductively economistic criteria to ecosocial problems is incorrect. Just as a war - as long as it does not reach catastrophic levels - can have beneficial effects on economic activity and employment, although its general consequences for society and the environment are a real disaster; similarly - and for the same reasons - climate change, provided it does not reach catastrophic levels, can have beneficial effects on economic activity and employment, although its broader consequences for society and the environment are a real disaster.

It is conceivable a world that is increasingly socially and ecologically degraded, less and less capable of providing well-being for human beings, but still “good for business”, where GDP grows and employment increases (certainly not in a sustainable way in the long term, but in the short and medium term). This does not mean that climate change - or war - is therefore more acceptable: it means that applying reductively economistic criteria to ecosocial problems is incorrect.

In general, neither the European socio-political elites, nor the societies as a whole, are paying the attention it deserves to the very serious problem of climate change. And to the limited extent that they do, they focus excessively on issues of technological change and adaptation to warming, rather than on ecosocial change and mitigating global warming. But time is running out: if vigorous measures are not taken to reduce greenhouse gas emissions, their concentration could double pre-industrial levels as early as 2035, making an increase in average temperatures of more than 2ºC with respect to pre-industrial levels (considered by scientists, and also by the EU political establishment, as the level from which the consequences would become uncontrollable and extremely dangerous). (30)

A recent Norwegian study criticized Europe's harmful complacency in terms of its ability to adapt to global warming, pointing out that the indirect effects of it may be much more important than the direct and sectoral effects. (31) As a culture, we are clouded by overconfidence in technology and markets, a belief - ultimately irrational - in our ability to dominate situations and suppress contingency. This overconfidence of Euro-North American culture, which tends to degenerate into technolatry and mercatolatry, can become a death trap.

A civilizational collapse is not implausible

The great underlying question is whether the socio-ecological disturbances induced by rapid and extreme climate change can lead, or not, to a civilizational collapse; and no climate, econometric or mixed model can answer this question. We simply do not know or will not know (although we can be sure that these models are not very useful when analyzing or predicting abrupt and non-linear changes).

Even the “optimists” Link and Tol acknowledge that “one reason to be concerned about the possible collapse of the thermohaline circulation [in the North Atlantic] is that it is a regime change, and the uncertainties surrounding natural systems would be very high. greater than without such a collapse. ”(32) The climate and economic models used do not tell us much in the event of“ catastrophic ”change. (33) The substance of the matter has been sharply brought out by Mike Davis: “Scientific discussions of climate change and global warming have always been in the stubborn presence of non-linearity. Climate models, like econometric models, are easy to construct and understand when they are simple linear extrapolations of well-quantified past behavior; that is, when there is a consistent proportional relationship between causes and effects. But most components of the global climate - air, water, ice and vegetation - actually exhibit non-linear behavior: from certain thresholds they can suddenly jump from one organizational pattern to another, with catastrophic consequences for highly engineered species. adapted to previous ecological conditions.

Until the early 1990s it was believed that such great climate transitions required centuries, if not millennia. Hoy, gracias al procesamiento e interpretación de los registros materiales presentes en los casquetes polares y en los sedimentos de los fondos marinos, sabemos que las temperaturas globales y las corrientes oceánicas pueden, bajo determinadas circunstancias, cambiar muy rápidamente (en una década, o incluso en menos tiempo).” (34)

La cuestión es que existen –tanto en la biosfera en su conjunto como en los ecosistemas singulares, así como en el sistema climático en su conjunto– umbrales críticos más allá de los cuales el cambio lento y “digerible” se convierte en rápidas transformaciones profundas.

En lo que atañe al clima, muchos científicos piensan que podemos haber sobrepasado algunos de esos umbrales críticos, o estar a punto de hacerlo. Así, por ejemplo, el experto en glaciares Lonnie G. Thompson (de la Ohio State University) cree que los datos disponibles sobre el retroceso de los glaciares –especialmente en las montañas más cercanas al trópico: los Andes y el Himalaya— indican que “el sistema del clima ha excedido un umbral crítico” y sugiere que quizá los seres humanos no dispongamos del lujo de adaptarnos a cambios lentos. (35) En una entrevista insiste: “Hay umbrales en el sistema, y cuando se traspasan corremos el riesgo de cambiar el mundo tal y como lo conocemos hacia estados en que un montón de gente en el planeta estará en riesgo.” (36)

Por ejemplo, la mayoría de los estudios sobre impactos económicos de la subida del nivel del mar a causa del cambio climático dan por sentado un escenario de cambios graduales, con subidas de alrededor de 25 cms. en el siglo XXI. Por ejemplo, el informe Impactos en la costa española por efecto del cambio climático encargado por el Ministerio de Medio Ambiente español y hecho público en septiembre de 2006 asume subidas de 35 cm. en el Cantábrico, 20 en el Mediterráneo y 10 en el Golfo de Cádiz (advirtiendo, eso sí, que incluso estas subidas modestas y graduales tendrían consecuencias importantes: la línea de costa retrocederá hasta 15 metros en promedio, dañando playas, viviendas e infraestructuras, y amenazando zonas tan valiosas como el Coto de Doñana, la Albufera de Valencia, la Costa Brava, la Manga del Mar Menor o el Delta del Ebro). (37) El cuarto informe de evaluación del IPCC (Grupo Intergubernamental sobre Cambio Climático), cuya primera parte se difundió en febrero, prevé una subida del nivel del mar entre 19 y 58 cm en 2100 (suponiendo que no haya pérdidas masivas de hielo en los polos). (38) Pero la cuestión es que si se funden los hielos de Groenlandia, el nivel del mar subiría no unos centímetros, sino probablemente siete metros (y si se funden los hielos de la Antártida el panorama aún sería mucho peor, con subidas de varias decenas de metros). (39)

Por desgracia hay indicios de que el campo de hielo de Ross en la Antártida –algo más grande que España— está comenzando a fundirse. Y Groenlandia se está fundiendo rápidamente: la velocidad a que lo hace casi se ha triplicado entre 2000 y 2005, y ahora vierte 250 km3 de agua dulce al mar cada año (¡cada kilómetro cúbico equivale al derogado trasvase del Ebro en España!). (40) Científicos expertos en glaciares creen que “bastante antes del final del siglo XXI podemos atravesar un umbral que desencadene una subida de muchos metros del nivel del mar”.41 Desde 1975 el casquete polar se ha ido derritiendo a un ritmo lento pero constante: hasta hace pocos años las previsiones científicas aseguraban que no se deshelaría del todo hasta 2200. Ahora los hielos del Ártico se están derritiendo al ritmo acelerado de 9% por decenio, y los veranos de 2005 y 2006 han sido tan catastróficos que, de seguir esa tendencia, ¡antes de quince años se habrían fundido por completo! (42) En un reciente editorial de Science se decía: “Nada en los registros sugiere que un modelo climático de ‘equilibrio’ sea el término adecuado de comparación.

Estamos dentro de un sistema altamente cinético, y en el pasado, cambios climáticos dramáticos tuvieron lugar en el lapso de sólo algunas décadas. Nuestro confort durante el Holoceno [los últimos diez mil años] puede haber fortalecido nuestro sentimiento de seguridad, pero la expectativa de que los cambios son improbables no constituye una posición razonable. […] Una fusión glacial acelerada y cambios de gran calado en el nivel del mar (por ejemplo) no deberían considerarse posibilidades hipotéticas, sino acontecimientos probables.” (43)

Hoy los niveles de emisión de dióxido de carbono y metano son similares a los que se dieron durante el “infierno del Eoceno”, hace 55 millones de años, cuando la temperatura subió unos 5ºC en promedio en los trópicos, y 8ºC en las latitudes templadas, y el planeta tardó más de 200.000 años en recuperar cierto equilibrio climático. James Lovelock sostiene que hemos pasado ya el punto sin retorno en lo que se refiere a cambio climático, y que resulta improbable que nuestra civilización sobreviva. Su perspectiva no puede ser más sombría: para él, antes de que acabe el siglo XXI miles de millones de personas habrán muerto, y las pocas parejas reproductoras que sobrevivan estarán en el Ártico, donde el clima aún resulte soportable. “Hoy sabemos que la Tierra se autorregula, pero (…) hemos descubierto demasiado tarde que esa regulación está fallando [debido al desarreglo climático antropogénico] y que el sistema de la Tierra avanza rápidamente hacia un estado crítico que pondrá en peligro la vida que alberga”. (44) Pueden debatirse estas predicciones de un científico de talla internacional, experto en el “sistema Tierra” –que él bautizó Gaia hace decenios— y sus múltiples mecanismos de autorregulación: pero lo que no está en cuestión es que un calentamiento climático rápido y fuerte pone en entredicho la habitabilidad de extensas zonas de la Tierra para los seres humanos, y tampoco que el calentamiento en curso se está haciendo cada vez más fuerte y rápido, año tras año. (45)

El hecho de que un colapso civilizatorio resulte una posibilidad nada inverosímil, (46) y que por lo tanto quepa que, en un futuro no muy lejano, en lugar de estar discutiendo acerca de los metros de playa perdida en las zonas turísticas, o acerca de los costes marginales del incremento de muertes de ancianos por olas de calor, nos encontremos estimando cuántos pequeños grupos de cazadores-recolectores se las apañarán para sobrevivir en las estepas de una Europa devastada y empobrecida; el hecho de que semejante colapso sea posible debería bastar para impulsar políticas ambiciosas de lucha contra el cambio climático.

El gran poeta chino Wang Wei (701-761), uno de los clásicos de la literatura universal, tituló uno de sus poemas “Insufrible canícula”. En él se leen los siguientes versos: “Un sol de brasas envuelve cielos y tierra,/ nubes de fuego se acumulan como montañas.// Árboles y hierbas se queman./ Ríos y estanques se han secado.// La ropa delgada se siente pesada;/ el denso follaje apenas da sombra.// (…) ¡Ay, si pudiera salir de este universo/ y sentirme libre en la vasta inmensidad!…”

El mundo de “efecto invernadero” reforzado donde estamos ingresando puede dejar chiquitas a todas las canículas anteriores que han experimentado nuestros antepasados; y aunque lo deseemos, no hay forma de “salir de este universo”. No podemos seguir escondiendo la cabeza bajo el ala y posponiendo la acción eficaz: el tiempo se nos está acabando.

Jorge Riechmann es investigador sobre cuestiones socioecológicas en el Instituto Sindical de Trabajo, Ambiente y Salud (ISTAS), profesor titular de Filosofía Moral en la Universidad de Barcelona y vicepresidente de Científicos por el Medio Ambiente (CiMA). Ha sido coordinador de Vivir (bien) con menos (Icaria, CIP-FUHEM, Barcelona, 2007) – Publicacion 2009:


(1) Ver Jorge Riechmann, et. al., De la economía a la ecología, Trotta, Madrid, 1995; José Manuel Naredo, Raíces económicas del deterioro ecológico y social. Más allá de los dogmas, Siglo XXI, Madrid, 2006.

(2) Francisco Javier Rubio de Urquía, El cambio climático más allá de Kyoto. Elementos para el debate, Ministerio de Medio Ambiente, Madrid, 2006, p. 34.

(3) Por mencionar uno de ellos, paleobotánicos como Polychronis Tzedakis, de la Universidad de Leeds, dan por supuesto que desaparecerían casi todos los árboles de Europa. Entrevista en El País, 29 de marzo de 2006, p. 41.

(4) El funcionamiento de la “cinta transportadora” de agua oceánica –en términos técnicos: la circulación termohalina– depende de pequeñas diferencias en la densidad y salinidad de las aguas; la interrupción de esta enorme corriente, que ha ocurrido algunas veces en los últimos 100.000 años, altera de manera súbita el clima del planeta entero (grosso modo, enfriando más el Norte y calentando más el Sur). Se teme que el incremento de flujos de agua dulce en el Ártico –por hielo derretido, más precipitaciones, etc.– podría ocasionar este efecto, apagando un “interruptor climático” que sumiría de golpe a Europa en una mini-era glacial, incluso dentro de un mundo globalmente más cálido.

(5) P. Michael Link y Richard S. Tol, “Possible economic impacts of a shutdown of the thermohaline circulation: an application of FUND”, Portuguese Economic Journal, 2004, Nº 3, pp. 99-114.

(6) Ibídem, p. 110.

(7) Por otra parte, otros graves impactos que sin duda tendrían lugar no aparecen en el modelo: así los cambios ecosistémicos en el Atlántico Norte, que sin duda entrañarían daños para la biodiversidad y las pesquerías. Ibídem, p. 104.

(8) Para una síntesis de los argumentos relevantes ver Jorge Riechmann, “¿Sabemos sumar dos y dos? Propuestas de reforma ecológica de la Contabilidad Nacional”, en Francisco Fernández Buey y Jorge Riechmann, Ni tribunos. Ideas y materiales para un programa ecosocialista, Siglo XXI, Madrid, 1996; Michael Jacobs, La economía verde, Icaria, FUHEM, Barcelona, 1996, cap. 6, 16, 17 y 18; Herman E. Daly y John B. Cobb, Para el bien común. Reorientando la economía hacia la comunidad, el ambiente y un futuro sostenible, Fondo de Cultura Económica, México DF, 1993; Joan Martínez Alier, La economía ecológica como ecología humana, Fundación César Manrique, Lanzarote, 1998; Óscar Carpintero, Entre la economía y la naturaleza. La controversia sobre la valoración monetaria del medio ambiente y la sustentabilidad del sistema económico, Los Libros de la Catarata, Madrid, 1999, cap. 2 y 4; Joan Martínez Alier y Jordi Roca, Economía ecológica y política ambiental, Fondo de Cultura Económica, México DF, 2000, cap. 2 y 4; Roberto Bermejo, Economía sostenible. Principios, conceptos e instrumentos, Bakeaz, Bilbao, 2001, cap. 2; Diego Azqueta, Introducción a la economía ambiental, McGraw-Hill, Madrid, 2002; José Manuel Naredo, La economía en evolución, Siglo XXI, Madrid, 2003; José Manuel Naredo, 2006, op. cit..

(9) Link y Tol, 2004, op. cit., p. 104.

(10) Ibídem.

(11) Ibídem.

(12) Ibídem, p. 102.

(13) Miguel Delibes y Miguel Delibes de Castro, La Tierra herida, Destino, Barcelona, 2005, p. 98.

(14) “En los últimos 50 años, el número de migrantes internacionales se ha más que duplicado, hasta alcanzar la cifra de casi 200 millones. Actualmente hay más gente viviendo fuera de su país natal que en ningún momento anterior de la historia humana. Este movimiento masivo de población está cambiando no sólo la forma en que vivimos, sino también cómo nos percibimos a nosotros mismos y al ‘otro’.” Thoraya Ahmed Obaid, “International migration: human rights and dialogue”, comunicado del 3 de abril de 2006 en

(15) Tim Flannery, La amenaza del cambio climático. Historia y futuro, Taurus, Madrid, 2006; Ana Martínez, “Tim Flannery: el cambio climático provocará 500 millones de desplazados”, Expansión, 29 de septiembre de 2006.

(16) Daniel Tanuro, “La barbarie climática está en marcha”, Sin permiso, 21 de mayo de 2006, en

(17) Tampoco cabe hoy negar que, en un “mundo lleno” o saturado ecológicamente, los graves daños ambientales afectan de forma cada vez más directa a los resultados económicos y los conflictos sociales. Así, por ejemplo, la comunidad científica está hoy convencida de que hay “una relación directa y estrecha entre los procesos de desertificación (que producen hambrunas) y los alzamientos y revueltas populares en el mundo en desarrollo.” Delibes y Delibes, 2005, op. 69.

(18) Michael T. Klare, Resource Wars: The New Landscape of Global Conflict, Owl Books, 2002; Blood and Oil: The Dangers and Consequences of America’s Growing Dependency on Imported Petroleum, Metropolitan Books, 2004.

(19) John Reid, “Transatlantic defense partnerships: managing divergence”, discurso en Chatham House (Londres), 27 de febrero de 2006.

(20) Michael T. Klare, “Se avecinan guerras por recursos”, Sin permiso, 19 de marzo de 2006, en

(21) Peter Schwartz y Doug Randall, “An abrupt climate change scenario and its implications for US national security”, octubre 2003, en

(22) Citado en Michael T. Klare, 2006, op. cit. Previendo un numeroso flujo de refugiados climáticos, este cínico documento prevé que Europa sucumbiría, mientras que EEUU y Australia “se mantendrían fuertes porque tienen los recursos y las reservas que les permiten la autosuficiencia”. Los autores escriben con frialdad: “los muertos causados por las guerras, al igual que por el hambre y las enfermedades, disminuirían la cantidad de población, que con el tiempo se reajustaría a la
capacidad de carga del planeta”. Peter Schwartz y Doug Randall, 2003, op. cit.

(23) Delibes y Delibes, 2005, op. 83.

(24) Para una amplia perspectiva sobre estas cuestiones ver Jared Diamond, Colapso. Por qué unas sociedades perduran y otras desaparecen. Debate, Barcelona, 2006. Vale la pena atender igualmente a la reflexión de Michael T. Klare: “Podemos responder a estas predicciones en dos formas: confiando en las fortificaciones y la fuerza militar para contar con cierto grado de ventaja en la lucha global por los recursos, o dando los pasos significativos para reducir el riesgo de un cambio climático cataclísmico. Sin duda habrá muchos políticos y expertos —especialmente en EEUU— preocupados en impulsar la superioridad de la opción militar, enfatizando la preponderancia de la fuerza con que cuenta ese país. Argumentarán que fortificando las fronteras y costas para frenar la entrada de migrantes indeseables y luchando por las fuentes de crudo necesarias, podremos mantener nuestro privilegiado nivel de vida durante más tiempo que otros países menos dotados de instrumentos de poder. Tal vez así sea. Pero la penosa guerra en Irak, que no parece concluir, y la fallida respuesta ante el huracán Katrina muestran lo ineficientes que son estos instrumentos cuando se confrontan con la dura realidad de un mundo que no perdona. Y como nos recuerda el informe del Pentágono, ‘las batallas constantes por recursos menguantes reducirán los recursos todavía más de lo que se reduzcan por los efectos climáticos’. La superioridad militar puede darnos una ilusión de ventaja en las luchas venideras, pero no puede protegernos de los estragos del cambio climático. Aunque estemos mejor que Haití o México, también sufriremos las tormentas, las sequías y las inundaciones. Conforme los socios comerciales se sumerjan en el caos, nuestras importaciones de alimentos, materia prima y energía desaparecerán también. Es cierto, podemos establecer puestos militares en algunos sitios para garantizar el flujo de materiales críticos, pero el precio siempre irá en aumento en sangre y recursos necesarios para pagar esta empresa y eventualmente nos rebasará y destruirá. En última instancia, nuestra única esperanza para un futuro seguro y garantizado yace en una sustancial reducción de las emisiones de gases de efecto invernadero y en trabajar con el mundo para frenar el ritmo del cambio climático global.” Michael T. cit.

(25) William D. Nordhaus, Managing the Global Commons: the Economics of Climate Change, MIT Press, Cambridge, 1994; William D. Nordhaus y Joseph, Boyer, “Requiem for Kioto: an economic análisis of the Kioto Protocol”, The Energy Journal, 1999, pp. 93-130; Roll the DICE Again: Economic Models of Global Warming, MIT Press, Cambridge, 2000, en

(26) Joaquín Valdivielso, “Neutralidad e integridad científica en el caso Lomborg: trasfondo normativo y paradigma científico”, en Jorge Riechmann (coord.), Perdurar en un planeta habitable. Ciencia, tecnología y sostenibilidad, Icaria, Barcelona, 2006, pp. 304-306.

(27) Geoffrey Lean, “Disappearing world: Global warming claims tropical island”, The Independent, 24 de diciembre de 2006.

(28) Daniel Tanuro, 2006, op. cit.

(29) Friends of the Earth Australia, A Citizen’s Guide to Climate Refugees, 2005.

(30) Según la UE, este objetivo –fijado en su Sexto programa de acción en materia de medio ambiente— exige que la concentración global de dióxido de carbono no supere las 550 partes por millón (ppm). Otros estudios recientes sugieren que el nivel de estabilización debería ser más bajo, de 450 ppm, a fin de no superar el máximo de 2ºC de ascenso térmico. Ello exigiría reducir las emisiones mundiales de dióxido de carbono entre un 45% y un 60% hasta el año 2050 (con respecto a los niveles de 1990) (AEMA 2006). Tengamos presente que en el último millón de años la concentración de CO2 en la atmósfera nunca superó, hasta 1960, las 310 ppm. Hoy estamos en 390 ppm camino de las 400 y las 600 durante este siglo XXI, si no dejamos de emitir estos gases. 600 ppm no se han alcanzado en el planeta desde hace 18 millones de años.

(31) K. Brien, et al., “Questioning complacency: climate change impacts, vulnerability, and adaptation in Norway”, AMBIO: a journal of the human environment, 2006, 35 (2), pp. 50-56.

(32) Link y Tol, 2004, op. 110

(33) Hasta ahora, la llamada de atención más seria desde círculos gubernamentales se debe al gobierno británico, que ha encargado y difundido el “informe Stern” (Stern 2006, elaborado por Nicholas Stern, asesor económico de la Administración británica y ex economista del Banco Mundial). Este estudio advierte que, de no actuar ahora contra el cambio climático, el coste será equivalente a perder entre un 5 y un 20% del Producto Interno Bruto (PIB) global. El cambio climático puede afectar el acceso al agua potable, la producción de alimentos, la sanidad y el medio ambiente, mientras que millones de personas pasarán hambruna, subraya el documento. Anticipa que el calentamiento de la Tierra puede tener consecuencias “desastrosas” para la economía, a un nivel superior a la Gran Depresión de 1929-30, y puede crear más de 200 millones de refugiados. Según el “informe Stern” sería necesario invertir aproximadamente un 1% del Producto Interno Bruto (PBI) global para hacer frente al problema. En la presentación del informe —que es considerado el más importante que encarga el Gobierno laborista— el 30 de octubre de 2006 el primer ministro británico, Tony Blair, aseguró que el mundo no se puede permitir dejar que pase el tiempo. Las cifras de inversiones necesarias para mitigar el cambio climático coinciden con las que proporcionó la Agencia de Medio Ambiente alemana en 2006: un 1% del PIB anualmente (contrastable con pérdidas de PIB del 10% anual, en un futuro no tan lejano, si la inacción se prolonga).

(34) Mike Davis, “¿Hemos entrado ya en la era del caos?”, Sin permiso, 19 de marzo de 2006, en

(35) Lonnie G. Thompson, et. al., “Abrupt tropical climate change: Past and present”, Proceedings of the National Academy of Sciences, 11 de julio de 2006, Vol. 103, Nº 28, en

(36) Doug Struck, “Earth’s climate warming abruptly, scientist says”, The Washington Post, 27 de junio de 2006.

(37) Raúl Medina, et. al., Impactos en la costa española por el efecto del cambio climático, Ministerio de Medio Ambiente, Universidad de Cantabria, Madrid, 2006.

(38) Los tres informes anteriores se divulgaron en 1990, 1996 y 2001. Según el Grupo Intergubernamental de Expertos sobre el Cambio Climático (IPCC) –en su Cuarto Informe de Evaluación, febrero de 2007—, la temperatura global se incrementará entre 1,8 y 6,4 grados centígrados hasta el año 2100, con la mejor estimación en torno a 3 grados, lo que es enorme. (La diferencia entre el promedio de temperaturas en el último milenio, y la edad del hielo que finalizó hace unos 12.000 años, es sólo de 3ºC.)

(39) R. Kerr, “A worrying trend of less ice, higher seas”, Science, 24 de marzo de 2006, Vol. 311, p. 1698-1701; Flannery, 2006, op. Con precisión: la fusión de los hielos de la Antártida occidental elevaría el nivel del mar 6 metros adicionales, y la fusión completa de la Antártida oriental –que hoy por hoy no se considera previsible— añadiría 70 metros.

(40) Tavi Murray, “Climate change: Greenland’s ice on the scales”, Nature, 21 de septiembre de 2006, Vol. 443, Nº 7109, pp. 277-278.

(41) J. Overpeck, et. al., “Paleoclimatic evidence for future ice-sheet instability and rapid sea-level rise”, Science, 24 de marzo de 2006, Vol. 311, pp. 1747-1750.

(42) Martínez, 2006, op. cit.

(43) D. Kennedy y B. Hanson, “Ice and history”, Science, 24 de marzo de 2006, Vol. 1673.

(44) James Lovelock, La venganza de la Tierra, Planeta, Barcelona, 2007, p. 23.

(45) Las malas noticias han llegado ya incluso a los editoriales de la gran prensa. Así, El País, 1 de abril de 2007, comenta el Cuarto Informe de Evaluación del IPCC en los siguientes términos: “Será difícil reconocer este planeta dentro de 100 años. Aun en el mejor de los casos, con una política inteligente de control de emisiones, el 20% de la superficie de la Tierra habrá sufrido tal cambio de temperaturas y de régimen de lluvias que tendrá un clima enteramente nuevo. Las selvas del África ecuatorial, la Amazonia y el sureste asiático irán pereciendo, y otras selvas irán devorando los trópicos mientras los desiertos del Sáhara, el Gobi, Nuevo México y Kalahari colonizan las actuales zonas templadas. El Tíbet, los Andes y los Himalayas verán fundirse sus nieves perpetuas, como ya le empieza a ocurrir al Kilimanjaro, y treparán por sus laderas la flora y la fauna de los terrenos inferiores, empujando a los habitantes de las cimas. Tanto en los polos como en las alturas, las especies adaptadas a los climas más fríos desaparecerán con ellos. Otros nuevos climas surgirán por primera vez en el siglo XXI con unas cualidades impredecibles para la ciencia actual. Ésta es una de las primeras aplicaciones de los modelos de calentamiento aprobados en la última reunión del Panel Intergubernamental sobre el Cambio Climático de la ONU, celebrada en París en febrero. Esos resultados, muy superiores a los del pasado, ya sirvieron entonces para despejar toda duda sobre la realidad del calentamiento global y su atribución a las emisiones de dióxido de carbono. Los científicos los usan ahora para proyectar unas predicciones sobre el clima futuro que son mucho más precisas y fiables. La conclusión general es que casi todas las predicciones se habían quedado cortas. Todo lo anterior asume una política inteligente de contención de emisiones. En su ausencia -es decir, de seguir como hasta ahora- las zonas con un clima enteramente nuevo no supondrán el 20% -lo que sirve de llamada a la preparación de políticas paliativas.

(46) Flannery, 2006, op. cit.

Video: Global Warming 101. National Geographic (June 2021).