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Climate change: the moment of truth?

Climate change: the moment of truth?

By José Santamarta

After about 20 years of endless international negotiations, 4 IPCC reports, the tortuous development of the Kyoto Protocol, the opposition of the US presidencies of Bush father and son, the verbosity of governments installed in inaction and the disturbing signs of change climate, everything seems to indicate that we are approaching the moment of truth.


Climate change is due to greenhouse gas emissions into the atmosphere caused by the use of fossil fuels and deforestation, where there are no national borders. Today atmospheric concentrations of carbon dioxide are the highest in the last 650,000 years. Human activities (some more than others) have changed the chemical composition of the atmosphere. For tens of thousands of years atmospheric concentrations of carbon dioxide never exceeded 300 parts per million, but in 2007 we reached 382 parts per million and 430 equivalents, if we include the effect of other greenhouse gases. When 550 parts per million are exceeded, climate change can take on catastrophic proportions, a limit that many scientists place at 450 parts per million. Of course, many uncertainties remain, but the most elementary precautionary principle tells us that we know enough to act, reducing emissions and adapting to the inevitable. We have less than 20 years to reverse the trend and reform the energy model.

Stopping and reversing this trend implies increasing efficiency, developing renewable energies, promoting public transport, gradually decarbonizing our energy system and stopping deforestation, creating new activities, companies and jobs. There will be sectors that win, but also some sectors and companies will lose. The cost will be just over 0.1% of world GDP, but nonetheless the cost of inaction can reach 20% of world GDP.

Climate change, due to greenhouse gas emissions, after the fourth IPCC report, is a reality accepted by the entire scientific community, and even by policy makers, at least on paper. It is true that there are still some “dissidents”, always paid by the companies that will be harmed by the measures that will have to be adopted, but the resistance is less and less and today it does not go beyond anecdotes, at least frontally. The real resistance probably comes from those who want to perpetuate the current system and an environmentally and socially unsustainable model, promoting nuclear energy, tar sands, oriemulsion, methane hydrates and other unconventional hydrocarbons, the so-called biofuels (which should be called agrofuels ) and the capture and storage of carbon dioxide, which would allow to continue with a growing and amplified use of coal, oil, natural gas and other unconventional fossil fuels. In other words, continue to increase energy consumption and perpetuate a transport model based on the private car, with small changes that do not touch the root of unsustainability and social inequity.

But this seeming consensus on the severity of climate change and the need for action has not always been the case, and it will happen again and again in the future. Every time concern about an environmental problem has arisen, the responsible multinationals and their conservative political representatives, cheered by numerous media, have launched an intoxication campaign. In 1962 Rachel Carson's book Silent Spring gave the first warning that certain man-made chemicals had spread across the planet, contaminating virtually all living things even in the most remote wilderness. That landmark book, which helped light up the environmental movement, presented evidence of the impact these synthetic substances had on birds and other wildlife, as well as humans. The response from the industry was immediate, and the multinational Monsanto released a brochure titled Shut Up, Mrs. Carson. Even today, the measures adopted to curb the chemical industry are radically insufficient, even in Europe (the Reach, with all its shortcomings, is a clear manifestation of the power of pressure of multinationals), although all countries have already banned the DDT and other organochlorine pesticides, but what is done is always late, little and bad.

The tobacco industry for decades denied the relationship with cancer, and opposed the adoption of the Precautionary Principle, or any measure aimed at reducing the pernicious habit, which has provided so many benefits, at the cost of our health. A similar situation occurred or occurs with the nuclear industry, asbestos, PVC, transgenic crops, fishing overexploitation, forest monocultures, or the scattered and predatory urbanism of the territory.

In 1975 the destruction of the ozone layer was related to CFCs, and the reaction of the chemical industry and governments, especially the Reagan administration in the United States, is the usual: first the problem is denied, then it is ridiculed or minimizes, and the necessary measures are only accepted when the problem is pressing and more than evident, the damage is already considerable and the pressure overcomes any resistance. The same multinational companies that create the problem first resist and only give in when they see new businesses, substituting the products they have created for others, theoretically less harmful, such as substitutes for CFCs.

With climate change the problem is infinitely greater than with CFCs, DDT or transgenics, because it affects the core of the economic system, the energy that drives all economic activity and that causes emissions that contribute to climate change, a consumption 80% of energy comes from fossil fuels, the commercialization of which is controlled by a few multinationals and which allow the United States, with 4.7% of the world's population, to emit 25% of CO2, the main greenhouse gas.

Denialism is in retreat

The United States, its multinationals, its pressure groups and its political class are not willing, for now, to adopt measures appropriate to their historical responsibility for the emissions that are causing climate change, which creates a serious problem, not only environmental, but also ethical and of responsibility towards those who will suffer the most from climate change: the poor of the Earth and future generations. A large well-lubricated conglomerate of "scientists", communicators and public relations companies is in charge of carrying out a permanent work of intoxication of citizens, to protect the interests of companies responsible for environmental degradation, and around "denial" it has created a thriving public relations and lobbying industry.

In Spain, the opposition leader, Mr. Rajoy, timidly joined the denial, putting his cousin in trouble, and cheered by Esperanza Aguirre, Ana Botella and Telemadrid, but a few days later they had to rectify and even proposed a Law of Change Climate in the electoral program approved a few weeks later. Today denialism is reduced to a few far-right press media and to some bizarre and well-paid Toharia-style communicator. Pure folklore.

Concern about global warming due to human emissions of carbon dioxide and other greenhouse gases, such as methane and nitrous oxide, dates back to 1896, the year that Swedish scientist Svante Arrhenius first formulated it. When Arrhenius published his first estimate of global warming due to CO2 emissions, the level of CO2 in the atmosphere was 290 parts per million (ppm). The science of climate change advanced slowly throughout the 20th century, and in 1988, when the Toronto Conference called for a 20% reduction in emissions by 2005 from 1988 levels, the severity was already very evident. of the problem. We know the subsequent milestones: in 1992 the Framework Convention on Climate Change was approved in Rio, and in 1997 the Kyoto Protocol. But so far the air travel of thousands of delegates, officials and journalists from one point to another on the planet have not justified the emissions and cost of so much travel in the era of videoconferencing and the Internet.

Who and why are they opposed? The multinational oil and automobile companies, the coal companies and Australia (the largest coal exporter), some OPEC countries such as Saudi Arabia and, above all, the United States, first with Bush Sr. and above all with Bush Jr. Although the Clinton presidency (and his vice president Al Gore, doing what I say, not what I do) was not very active either, let us say, it managed to reduce the emission reduction targets of the industrialized countries of the Kyoto Protocol , imposed the emission market heir to those implanted by the EPA for sulfur dioxide in the United States, although at least it did not maintain the ultra-reactionary rhetoric of the Republicans. The nucleus that financed the intoxication campaigns was the so-called Global Climate Coalition, in addition to other institutes linked to the hard core of multinationals such as Exxon, and with close relations with US politics, and especially the Republican Party.

But in a few months there will probably be a new President, and after Hurricane Katrina and the increasingly disturbing signs, the United States will have to start acting, under pressure from its citizens. In Australia, the victory of Labor, who are promoting the ratification of the Kyoto Protocol, shows the isolation of the United States. We are also witnessing the development of renewable energies and other technologies, and the emergence of a business sector that has much to gain from more active policies to decarbonize the energy system.

To make an omelette you have to break an egg

The political class does not want to face the unpopularity of not acting in the face of climate change, with the exception of Bush in his already last months of the worst presidency since the independence of the United States, but prefers to settle in the verbiage, to hide the inaction. Because the truth is that real policies do not reflect official speeches. Al Gore is the model, with his royal politics throughout the negotiation that led to the Kyoto Protocol when he could really do more than just give lectures, which is what former Presidents and former Vice Presidents live by, or with their private jet travel , even for tourist visits, while preaching to others to reduce their emissions. To preach, you have to set an example, and that is more than just planting a few trees to try to offset unjustifiable emissions.

When the rulers introduce a new tax on fossil fuels, or auction off emission rights instead of granting them for free, they will gain credibility. Meanwhile, it is better to judge them by what they do, and not by what they say, using objective indicators, such as the evolution of annual greenhouse gas emissions. Acting to stop climate change has its cost, a political and social cost, and also an electoral cost (it hurts there) because it implies making gasoline, diesel, kerosene (and air tickets), natural gas and electricity rates more expensive, internalizing its externalities. It also means drastically reducing coal consumption. But what politician is willing to bear the cost of probably very unpopular measures, or to explain them adequately and seek consensus to apply them? What will have to happen for them to take action? How many alarms do they have to sound, how many Katrina?

The United Nations Intergovernmental Group of Experts on Climate Change (IPCC) has already raised all the alarms, with all the necessary caution and consensus from more than a hundred countries, and its predictions leave little doubt. The rise in temperature at the end of this century will be between 1.8 and 4 degrees, although it could reach up to 6.4 degrees. During the last 100 years, the Earth has warmed by an average of 0.74ºC.

The warming of the last half century is unusual at least compared to the last 1,300 years. For the next two decades the warming rate is expected to be 0.2ºC per decade. Eleven of the last twelve years (1995-2006) are among the twelve warmest since there are records of the land surface (since 1850). The temperature has risen more in the northern hemisphere, more in winter than in summer, more at night than during the day and especially in the Arctic, which is warming at a speed that is twice that of the rest of the planet.

The sea increases in volume due to thermal expansion, its level has risen 3.1 millimeters a year since 1993 and will rise between 18 and 59 centimeters throughout this century. Arctic ice in summer has shrunk by 10% every decade since satellite records began in 1978. Glaciers in the Alps, Pyrenees, Africa, Himalayas and South America are shrinking by the minute, threatening the water supply, not to mention the elite winter sports. The glaciers of the Alps have already lost a third of their surface and half their volume, and the famous snows of Kilimanjaro, at the current rate, will disappear in 2025. The possible contribution of the Greenland thaw could be several meters, and in 20,000 square kilometers of ice have been lost on the Antarctic Peninsula.

Plants bloom earlier, birds do not need to migrate to warmer latitudes in winter, each year the snows take longer to arrive, cover less surface area and melt earlier, heat waves increase, in many areas rainfall increases while in others, Like the Sahel, Australia and the Mediterranean area, the opposite happens and the droughts are accentuated, the corals bleach and die because of the increase in temperatures, and everywhere there are signs that something is happening, and 90% of the Changes observed in more than 29,000 data series from around the world from 75 studies are consistent with climate change. 30% of species could become extinct, droughts and floods will increase, and the consequences could be severe in agriculture, tourism, health, the insurance industry and on the coast, where many of the largest cities are concentrated.

The Fourth Assessment Report (AR4, in its acronym in English) consists of three blocks plus the Synthesis Report. Part I is the contribution of Working Group I, it refers to the scientific bases of climate change and was approved in February 2007 in Paris. Part II, contribution of Working Group II, deals with impacts and adaptation, and was approved in April 2007 in Brussels. Part III of Working Group III on mitigation was approved in May in Bangkok. The Synthesis Report, approved in Valencia in November, was presented at the 13th Conference of the Parties, which was held in Bali from December 3-17, 2007.

Since the Framework Convention on Climate Change (UNFCCC) entered into force, the IPCC has been the scientific and technical institution that collaborates with and supports the Subsidiary Bodies of the Convention. The IPCC carries out its activities through its Working Groups, each of which is dedicated to dealing with different aspects of climate change. Working Group I is in charge of scientific aspects, Working Group II analyzes the vulnerability of natural and social systems to climate change and its possible adaptation strategies, and Working Group III addresses the mitigation of climate change. such as options for reducing greenhouse gas emissions. In addition, there is a group dedicated to Greenhouse Gas Inventories. Since its inception, the IPCC has prepared four major assessment reports.

The greenhouse effect

The Earth receives short-wave solar radiation, part of which is reflected and another reaches the surface, where it is converted into heat (long-wave radiation), which heats the surface and evaporates water, maintaining the hydrological cycle. Long-wave radiation escapes into the atmosphere, where part of it is absorbed by greenhouse gases, which re-emit it to Earth. Without the greenhouse effect, life would be impossible as we know it, as the average temperature would be 18ºC below zero, instead of 15ºC. But too much of a good thing turns out to be bad.

Increasing the concentration of greenhouse gases increases the temperature and causes changes in the climate. Concentrations of carbon dioxide, the main greenhouse gas in the atmosphere after water vapor, have risen from 280 parts per million around 1750, at the start of the industrial revolution, to 382 parts per million in 2007. Carbon dioxide Carbon contributes 53% of the radioactive forcing since the Industrial Revolution, and its average atmospheric life, depending on the complex carbon cycle, can range from 5 to 200 years, that is, that part of the CO2 we emit when electricity is generated with coal or the car consumes gasoline, it will remain in the atmosphere for up to 2 centuries, trapping and re-sending long wave solar radiation and contributing to climate change.

The second most important gas is methane (CH4), which accounts for 17% of radiative forcing, and whose concentrations have increased from 730 ppb (parts per billion or billion) around 1750 to 1,852 ppb today, although its half-life he is only 12 years old. Emissions are due to enteric fermentation of livestock, manure management, landfills, emissions from coal mining, oil and natural gas, sewage and rice crops. One molecule of methane equals 23 CO2.

The third most important gas is nitrous oxide (N2O), which contributes 5% of the radiative forcing, and whose concentrations have increased from 270 ppb (parts per billion or billion) towards 1750 to 319 ppb today, whose half-life is 114 years old. Emissions are due to fertilizers applied to agricultural soils, the energy sector, the chemical industry, manure and wastewater. One molecule of nitrous oxide is equivalent to 296 CO2.

Other greenhouse gases include ozone-depleting CFCs (already banned in industrialized countries), their substitutes such as hydrofluorinated carbides (HFCs), perfluorinated carbides (PFCs), sulfur hexafluoride (SF6), and a pollutant like ground-level ozone. Greenhouse gas emissions should be reduced in 2050 between 50% and 80% in relation to 1990 so that the temperature does not rise more than 2.4 degrees and thus prevent climate change from worsening, according to the IPCC.

To the above factors must be added the changes in albedo, and especially the effect of aerosols, many of them pollutants, but short-lived, and which cause the opposite effect to greenhouse gases, masking warming, therefore that reducing certain pollutants can exacerbate warming. We must also cite the important role of water vapor, aircraft contrails and the so-called global darkening or reduction in the amount of sunlight that reaches the earth's surface, due to the emission of particles such as carbon black (or charcoal). ), issued by thermal power plants, industries and vehicles. The reduction has been in the order of 4%, but has slowed down during the past decade. Global dimming creates a cooling effect that has led to an underestimation of the effects of greenhouse gases, partially masking global warming. Equally noteworthy are the multiple feedback in one direction or another, such as changes in albedo due to the reduction of snowfall, the increase in the amount of water vapor or the emission of methane contained in permafrost, the permanently frozen ice sheet. in the surface levels of the ground of the very cold regions like the tundra.

Atmospheric circulation and ocean currents distribute heat, and could be altered by climate change. In an even more worrisome future is what could happen to the oceanic conveyor belt, or thermohaline circulation, the flow of water that carries heat from the Pacific and the Indian Ocean to the Atlantic, where it continues to receive heat in tropical latitudes, to end up sinking in the North Atlantic, returning at deeper levels. Some ocean currents are due to winds and tides, but others are due to differences in temperatures and salt concentrations. The change in temperatures and salinity, due to the melting of glaciers, could slow down or even eliminate these currents as we know them, something that is still unlikely in this century, but if it occurs it would have serious implications on the climate. the carbon cycle (sinking cold waters carry large amounts of carbon dioxide), nutrients and fisheries. Temperatures in Europe, at the same latitude, are 5ºC to 7ºC warmer than the same latitudes in the Pacific.

Causes of climate change

The causes are greenhouse gas emissions caused by the extraction, production, transformation, transport and consumption of fossil fuels (coal, oil and natural gas), transport that uses petroleum products, deforestation, agriculture and livestock, and certain industrial activities, such as the manufacture of cement.

Behind the emissions, there is an underlying problem of social and generational equity. The poor emit little, but they will be the ones who suffer the most from climate change, as will future generations, who do not participate in consumption, but will suffer the consequences, both from emissions and from resource depletion. In just over a century we have consumed a considerable part of the fossil fuels that nature took millions of years to form, as we have destroyed forests, with the consequent irreversible loss of thousands of species and the functionality of entire ecosystems.

The industrial revolution and the internal combustion engine improved to unsuspected levels the material well-being and mobility of a part of the population (of some more than others), but at the cost of altering the chemical composition of the atmosphere and initiating a change in the climate, which can only be stopped with a profound revolution in the way of producing and consuming the energy that drives the economic machine.

Sustainability is the only possible future, but to set course and curb emissions, fossil fuels will have to be slowly but surely replaced by renewable energies, while improving energy efficiency and, more difficultly, energy efficiency. consumption patterns of a part of the population accustomed to waste.

Sustainability is also an equation with three variables: population, per capita consumption and technology. The trap is to only emphasize the miraculous technologies that will allow to maintain and increase the unsustainable consumption of the privileged, the uncomfortable truth of Al Gore and so many others, that factor that is obviated because the privileged do not want to give up increasingly larger homes, increasingly powerful cars and vacations in the four corners of the world. They give advice that they don't have for themselves.

Nor can the need to accelerate the demographic transition towards population stabilization, which inevitably requires a more equitable distribution of resources and emissions, cannot be ignored.

Emissions and climate change are the historical responsibility of 15% of the world's population, of that part of the population that largely lives in the United States, Europe, Japan and Australia, and of the elites of southern countries. The emissions of China and India are growing rapidly, but their historical responsibility is minimal, because emissions must be related to the population, and take into account the historical emissions of the last century.

Between 1950 and 2000, the United States emitted 27% (with a population that only represents 4.6% of the world total), Canada 2%, Western Europe 24%, the former Soviet Union 15%, Japan 5% and Australia and New Zealand 1%. Latin America only issued 4% and Africa 2.5%. The rest of the world, including China and India, emitted just under 20%. Historical emissions are the basic factor when it comes to distributing responsibilities and assuming obligations, as was partly taken into account in the so-called Berlin mandate and in the Kyoto Protocol, by establishing only obligations to reduce emissions in industrialized countries. Any post-Kyoto agreement will have to consider historical emissions, although the United States intends to put them aside, as reflected in a Senate resolution where it literally says that they will do nothing as long as poor countries do not also assume emission reduction obligations, it is assumed that in similar percentages. The excuse is to prevent the leakage of industries and jobs to countries that, like China, have no obligation to reduce their emissions in the first stage, a kind of carbon dumping, although the United States emits six times more per capita than China, 10 times more than Brazil and 20 times more than India.

Regional analysis is key, but any reduction strategy must analyze the sectors that cause them. Electricity production accounts for 25%, road transport 12%, industry 10%, agriculture and livestock 13%, deforestation 18%, waste 4%, industrial processes other than combustion such as cement manufacturing 3%, air transport 2%, fugitive emissions 4% and the rest corresponds to domestic and tertiary energy consumption.

It is relatively easy to reduce emissions from electricity generation (substituting coal-fired power plants for natural gas combined cycle plants that emit one third per kWh produced, or even better, wind farms that emit nothing), but it is a lot more difficult to act on the transport. The only sensible thing is to reduce demand, promote the dense city with a mix of activities, and the modal shift (travel by public transport or rail instead of cars or airplanes).

Certain alternatives, such as first and second generation biofuels (really agrofuels) create many more problems than they solve, and it will take long before hydrogen can be produced at reasonable costs and from renewable energy. Of course, biofuels allow maintaining an unsustainable model of transport based on the private car, and that is why they are promoted, even at the cost of putting food security at risk, depleting ecosystems, destroying biodiversity and occupying the land necessary to produce food or use them for other, no less essential uses.

Air transport in percentage terms barely reaches 2%, but its emissions have grown by 205% between 1975 and 2003, and growth will accelerate in the coming years, due in large part to low-cost companies and cheaper rates, which do not reflect the environmental cost of their emissions of carbon dioxide, nitrogen oxides and the contrails they leave, in addition to the noise and the enormous impact of airports on neighboring populations. In fact, kerosene from international flights is exempt from tax. Voluntary measures of "donating" small amounts to plant trees that offset emissions do little, except to calm the bad conscience of some, and the only reasonable thing is to penalize air travel and renounce all unnecessary trips in the city. era of the Internet and video conferencing.

Consequences of climate change

In the past, climate changes were due to the cycles of the sun, changes in the Earth's orbit or volcanic eruptions, factors that are still present, but for the first time in Earth's history, human activities (consumption of fuels fossils and deforestation, new chemicals that destroy the ozone layer such as CFCs or that are powerful greenhouse gases) are capable of altering the climate and varying the chemical composition of the atmosphere.

The signs of climate change have hardly been noticed, due to the cooling effect of other pollutants such as aerosols, but we are already witnessing the first signs, such as heat waves, the disappearance of many mountain glaciers and the rise in the level of the sea.

Ecosystems, like agriculture and multiple activities, are adapted to certain conditions, the result of a long evolutionary adaptation. The rise in temperatures, the rise in sea level, the alteration of the rainfall, humidity and wind patterns, in a relatively short period of time, will have serious implications, which we are only beginning to understand. To try this, climate models are becoming more sophisticated and reconstruct with greater precision what may happen, based on the analysis of past climates.

En general, lloverá más, pero dónde, es otra cuestión: en ciertas zonas lloverá mucho más y en otras mucho menos. La región mediterránea, incluida España, muy probablemente sufrirá aún mayores sequías, sobre todo en verano. Pero con toda seguridad aumentarán las temperaturas y es probable que se agraven las olas de calor, tan perjudiciales para la salud, como la que afectó a Europa en el verano de 2003. Es probable, aunque hay menos certidumbres, que aumenten los ciclones y huracanes. Las poblaciones pobres, que no tienen ninguna responsabilidad en las emisiones, serán las más afectadas. Bangladesh, donde los ciclones han matado a medio millón de personas desde 1970, y el Sahel, con sus lacerantes hambrunas y una pobreza extrema, son los paradigmas de esta nueva realidad.


El último informe del Grupo Intergubernamental de Cambio Climático (IPCC) vaticina que hay una gran probabilidad de que el calentamiento provoque que hacia 2020 entre 75 y 250 millones de africanos sufran escasez de agua y, en varios países, las cosechas se reducirán un 50%, agravando la crisis alimentaria. En 2080, las tierras áridas y semiáridas en África aumentarán entre un 5 y un 8%.

En Asia en 2050 se reducirá la disponibilidad de agua dulce, especialmente en las cuencas de los grandes ríos. Las pobladas regiones de los deltas de los ríos en el sur, este y sureste asiático, peligrarán por la subida del nivel del mar. Aumentarán las enfermedades asociadas con las inundaciones.

Australia y Nueva Zelanda sufrirán una pérdida significativa de biodiversidad en la Gran Barrera de Coral. Los problemas hídricos empeorarán en el sur y este de Australia y en Nueva Zelanda, afectando a la producción agrícola, ganadera y forestal. Los incendios forestales aumentarán de virulencia, al igual que las sequías cíclicas.

En Europa el cambio climático acentuará las diferencias regionales en el acceso a los recursos naturales. Aumentará el riesgo de inundaciones en numerosas zonas y crecerá la erosión y la desertificación en el sur de Europa. Igualmente retrocederán los glaciares de los Alpes y los Pirineos. El sur de Europa (España, Italia y Grecia) será la zona más afectada, a causa del aumento de las temperaturas y la sequía, la disminución de los recursos hídricos y los incendios forestales, reduciendo la producción hidráulica y la producción agrícola, afectando negativamente al turismo. Las olas de calor estivales afectarán a la salud de la población más desfavorecida, sobre todo los ancianos y los enfermos crónicos.

En Suramérica hacia mediados de siglo se producirá una gradual sustitución del bosque tropical húmedo por sabanas en la Amazonia oriental, con una gran pérdida de biodiversidad e importantes alteraciones en el ciclo hidrológico del que depende el importante sector agrícola y ganadero. La desaparición de los glaciares andinos afectará al suministro de agua y a la producción hidráulica.

En Norteamérica el calentamiento de las montañas Rocosas provocará inundaciones en invierno y descenso del caudal de los ríos en verano. En las primeras décadas del siglo, un moderado calentamiento será positivo para la agricultura, con aumentos de las cosechas del 5 al 20%, pero con importantes variaciones regionales. Las olas de calor empeorarán los problemas sanitarios, al igual que en el sur de Europa.

Las regiones polares serán de las más afectadas, a causa de la reducción del espesor del hielo, el aumento del nivel del mar y cambios en los ecosistemas, con graves efectos en las aves migratorias, mamíferos y grandes depredadores, y en las poblaciones indígenas que dependen de la pesca y la caza. Los pequeños estados isleños sufrirán el aumento del nivel del mar, la escasez de agua, las inundaciones y los fenómenos meteorológicos extremos.

El cambio climático acelerará la pérdida de biodiversidad en todo el mundo. Pequeñas variaciones en las temperaturas y en las precipitaciones pueden alterar complejos ecosistemas, sustentados sobre la interdependencia de miles de especies. La subida del nivel del mar afectará a manglares, arrecifes de coral, estuarios y sistemas dunares costeros.

Para afrontar el cambio climático se necesitaría una migración sin precedentes de plantas y animales, tanto en altitud como en latitud, una migración hoy imposibilitada por carreteras, campos de cultivo y todo tipo de barreras. La creación de corredores biológicos que conecten los ecosistemas, es una de las medidas de adaptación más apremiantes. Muchas especies podrán emigrar, pero otras muchas, como las situadas en las cumbres de las montañas o en las zonas árticas, no podrán hacerlo. La destrucción o la alteración de ecosistemas tendrán efectos realimentadores, al liberar el carbono acumulado en el suelo o en la vegetación, o el metano del permafrost de la tundra. La pérdida de especies a su vez reducirá las opciones de adaptación a nuevas situaciones. Igualmente proliferarán la invasión de especies alóctonas y oportunistas, así como las plagas. De hecho, el invierno y las bajas temperaturas son el mejor plaguicida y la forma óptima de mantener a raya a multitud de insectos y roedores, que ahora sobrevivirán en mayor número y extenderán su rango de acción a nuevas zonas.

El cambio climático supone una gran amenaza para el abastecimiento del agua, al cambiar el régimen de precipitaciones, acentuar los fenómenos meteorológicos extremos como sequías e inundaciones, al aumentar la evapotranspiración y fundir los glaciares y las nieves que regulan los caudales de los ríos en épocas estivales. Una pequeña reducción de las precipitaciones, junto con el aumento de las temperaturas y la necesidad de mayor dotación hídrica de los regadíos, por el aumento de la evapotranspiración, reduciría de manera drástica la escorrentía y el caudal de los ríos. Los países más afectados serán los más pobres y localizados en las regiones secas.

Los efectos en la agricultura son complejos, y de hecho ésta siempre se ha adaptado a las demandas o a las circunstancias cambiantes. En algunos casos supondrá un aumento de la producción, al permitir cultivar zonas hoy muy frías de Rusia y Canadá, prolongar la época de crecimiento y reducirse las heladas, además del efecto fertilizador en algunas especies de plantas del aumento de las concentraciones de dióxido de carbono. Pero en otras zonas los efectos pueden ser graves, por el estrés térmico, la falta de agua, la erosión al abundar los fenómenos extremos y la extensión de plagas y enfermedades, que sobrevivirán a los fríos del invierno. Los peores efectos se darán en algunas zonas tropicales y subtropicales, donde vive la mayor parte de la población del Tercer Mundo.

El cambio climático puede afectar negativamente a la salud de la población, tanto por las olas de calor, como por ciertas enfermedades, que verán ampliado su radio de acción. El régimen de precipitaciones, la humedad y la temperatura, tienen una influencia determinante en la distribución de los agentes patógenos y transmisores que extienden ciertas enfermedades.

La subida prevista del nivel del mar puede afectar a millones de personas: cerca de cien millones viven a menos de un metro sobre el nivel del mar, y el 40% de la población mundial vive a menos de 100 km de la costa, en el área de influencia de temporales costeros, como la gota fría que afecta muchos años a las regiones mediterráneas, o el huracán Katrina que inundó Nueva Orleáns. La intrusión salina afectará a los ya sobreexplotados acuíferos costeros, reduciendo el abastecimiento de agua. También habrá que realizar enormes inversiones para mantener los puertos y otras costosas infraestructuras. Por cada centímetro que aumente el nivel del mar, desaparecerá un metro de playa, afectando de esta manera a una de las principales atracciones turísticas en países como España o Grecia. Muchas de las mayores ciudades del mundo están en la costa, ciudades como Nueva York, Los Ángeles, Buenos Aires, Río de Janeiro, Barcelona, Valencia, Venecia, Londres, Lisboa, Lagos, Mumbai, Tokio o Shangai.

Cambiar de políticas para evitar el cambio climático

Los desafíos de mitigar (reducir las emisiones) y adaptarse al cambio climático no tienen precedentes en la historia, y no podrá hacerse sin la cooperación y el acuerdo de la mayoría de los países, al ser la atmósfera un recurso común a donde van a parar las emisiones, cualquiera que sea el lugar en donde se hayan producido, afectando a todos.

Ya se ha transitado un buen trecho, desde la Conferencia de Toronto en 1988, el Convenio Marco de Cambio Climático en 1992 en Río, el Protocolo de Kyoto de 1997 y las negociaciones actuales, pero queda un camino aún más largo, hasta lograr reducir las emisiones actuales de un 60% a un 80%, que es lo necesario para evitar las repercusiones más graves del posible cambio climático.

Las diversas administraciones deben establecer planes claros para reducir las emisiones, incluyendo instrumentos fiscales (impuestos sobre las energías no renovables, incentivos a las renovables y a la eficiencia), supresión de las subvenciones a los combustibles fósiles y los presupuestos para llevarlos a cabo. Entre otras medidas se deben reducir los incendios forestales y la emisión de gases de invernadero, como el metano y el óxido nitroso, así como la producción y consumo de cemento, una de las principales fuentes de emisión de CO2, agravada por la construcción de autovías, carreteras y otras infraestructuras.

Una política de repoblaciones forestales con especies autóctonas de árboles y arbustos, en las zonas adecuadas, retiraría de la atmósfera grandes cantidades de CO2, frenaría la erosión, las inundaciones y las sequías, dado el efecto esponja de los bosques. Pero los bosques y los mares, aún actuando como sumideros, son incapaces de retirar la cantidad actual de CO2 emitida anualmente.

La reducción del consumo de carne, del empleo de fertilizantes, de las fugas de metano en la minería de carbón y en la red de gasoductos, o de la cantidad de residuos, es fácil de realizar. La fabricación de nailon y la de ácido nítrico son responsables de parte de las emisiones antropogénicas de óxido nitroso. La eliminación de los HFC no plantea ningún problema, pues hay alternativas viables y baratas, como el butano y propano (tecnología greenfreeze).

Los residuos generan importantes emisiones de metano. La reducción de la producción de residuos, el reciclaje, la prohibición de la incineración, el aprovechamiento de la materia orgánica para producir compost y el aprovechamiento del metano en los vertederos, son algunas de las medidas de una política de residuos adaptada al cambio climático.

El aumento de la eficiencia en los nuevos vehículos, y algunos programas para emplear gas natural y biocombustibles, sólo reducirán en un pequeño porcentaje el aumento previsto de las emisiones en el transporte. La reducción de los consumos unitarios de los vehículos, actuando sobre ellos o sobre la forma de utilizarlos, es necesaria pero insuficiente. Tanto o más importante es la reorientación hacia los modos más eficientes, como el ferrocarril, el transporte público y los modos no motorizados, y las actuaciones encaminadas a la gestión de la demanda y la moderación de la movilidad.

La política municipal debe ir encaminada a reducir la demanda, promoviendo la ciudad mediterránea densa, compacta y con mezcla de actividades, con barrios donde viviendas, trabajo y servicios estén próximos en el espacio, aminorando la segregación espacial y social de las ciudades, y limitando el crecimiento de las grandes áreas metropolitanas. El planeamiento urbanístico y territorial debe ir encaminado a promover la mezcla de actividades, y no la segregación, y a posibilitar la movilidad en transporte público, evitando los crecimientos urbanos y turísticos que consumen gran cantidad de espacio. El ferrocarril debería elevar su participación, pero para ello se requiere una clara voluntad política, materializada en las inversiones necesarias para mejorar el conjunto de la red, la seguridad, la gestión y los servicios, elevando las tarifas en una proporción inferior al del Índice de Precios al Consumo. Una política decidida, clara y bien estructurada, para reducir la necesidad de desplazarse, que no su posibilidad, y para orientar la demanda hacia los modos más eficientes de transporte, significaría una sensible reducción del consumo de energía, de la contaminación atmosférica y del ruido, menor ocupación de espacio, reducción del tiempo empleado en desplazarse, menor número de accidentes, inversiones más reducidas en la infraestructura viaria y una mejora general de la habitabilidad de las ciudades.

La eficiencia energética es la obtención de los mismos bienes y servicios energéticos, pero con mucha menos energía, con la misma o mayor calidad de vida, con menos contaminación, a un precio inferior al actual, alargando la vida de los recursos y con menos conflictos. Al requerirse menos inversiones en nuevas centrales y en aumento de la oferta, la eficiencia ayuda a reducir la deuda externa, el déficit público, los tipos de interés y el déficit comercial. La eficiencia energética debería incrementarse en un 2,5% anual. Las tecnologías eficientes, desde ventanas aislantes o lámparas fluorescentes compactas a vehículos capaces de recorrer 100 kilómetros con tres o menos litros de gasolina, o la cogeneración, permiten ya hoy proporcionar los mismos servicios con la mitad del consumo energético, a un coste menor. La cogeneración (producción simultánea de calor y electricidad), la mejora de los procesos y de los productos, el reciclaje y la reorientación de la producción hacia productos menos intensivos en energía, con mayor valor añadido, menos contaminantes, generadores de empleo y socialmente útiles, deben ser desarrollados. Las tecnologías hoy ya disponibles permitirán a la industria ahorrar entre el 10% y el 27% de su consumo actual de energía, según sectores, con una media del 16%. Los ahorros posibles en los usos domésticos y en los servicios podrían reducir a la mitad los consumos, con medidas como el aislamiento térmico, electrodomésticos más eficientes y las lámparas fluorescentes compactas.

Para aumentar la eficiencia es necesario que los precios energéticos reflejen todos sus costes, lo que no sucede en la actualidad. La reforma ecológica de la fiscalidad es uno de los instrumentos económicos clave para avanza hacia la sostenibilidad y frenar el cambio climático. La implantación de ecotasas, cuya recaudación se destine a mejorar la eficiencia y el empleo de energías renovables, es una necesidad acuciante, pero las ecotasas son sólo un primer paso de lo que debería ser una ambiciosa reforma ecológica de la fiscalidad, finalista o recaudatoria. La imposición de un etiquetado energético obligatorio de los aparatos eléctricos, y la reforma de las normas de edificación para mejorar el aislamiento térmico, pueden reducir el consuno de energía en el sector residencial. Se deben promover los programas de Gestión de la Demanda, encaminados a aumentar la eficiencia y a prestar los mismos servicios con un consumo menor, más megavatios y menos megavatios. La Planificación Integrada de Recursos, o Planificación al Menor Coste, tienen como fin evitar el crecimiento del consumo energético al tiempo que se satisfacen los servicios que precisa la sociedad, y se debe implantar de forma real, especialmente en el sector eléctrico.

Las energías renovables podrían solucionar muchos de los problemas ambientales, como el cambio climático, los residuos radiactivos, las lluvias ácidas y la contaminación atmosférica. Las energías renovables podrían cubrir algo más de un tercio del consumo de electricidad en pocos años, y a largo plazo permitirán reducir las emisiones de dióxido de carbono, avanzando hacia un modelo energético “descarbonizado”.

La producción de hidrógeno es un proceso aún inmaduro tecnológicamente y cuya viabilidad económica es necesario demostrar, lo que requerirá enormes inversiones en investigación; cuando se logre producir hidrógeno comercialmente, a precios competitivos, y a partir de dos factores tan abundantes como son el agua y la energía solar, los problemas energéticos y ambientales quedarían resueltos, pues el hidrógeno, a diferencia de otros combustibles, no es contaminante. En cualquier caso una economía basada en el hidrógeno como combustible secundario es un objetivo aún muy lejano e incierto. El hidrógeno servirá para almacenar la energía solar y eólica cuando no haya sol o no sople el viento, y alimentará a las pilas de combustible hoy en desarrollo, y que en un futuro no muy lejano puede llegar a ser una importante fuente de producción descentralizada de electricidad a pequeña escala, sin apenas impactos ambientales. Las pilas de combustible también sustituirán a los motores de combustión interna de los automóviles.

Pero también existen soluciones duras, y que nos conducen a perpetuar la insostenibilidad ambiental y social, y son quizás las que van a ser promovidas con mayor entusiasmo por los que quieren que el cambio climático no suponga ningún cambio sustancial. Los agrocombustibles, la energía nuclear de fisión y de fusión y la captación y almacenamiento de carbono, para explotar las grandes reservas de carbón y otros hidrocarburos no convencionales, son las opciones preferidas por quienes crearon y alimentaron la insostenibilidad, cuyo mejor ejemplo es el propio cambio climático.

Artículo publicado en la revista World Watch Nº 28
http://www.nodo50.org/worldwatch/

Referencias en Internet


Video: David Attenborough: Climate Change - Britain Under Threat (July 2021).