INTRODUCTION
The 19th and 20th centuries were times of intense economic and social globalization, as well as unprecedented application of scientific knowledge. This resulted in today’s proliferation and widespread use of advanced technology that permeates societies worldwide.

In recent decades human activities, particularly fossil fuel combustion, have released ever-greater volumes of greenhouse gases into earth’s atmosphere, sufficient to affect global climate. Concentration of atmospheric CO2 now exceeds 390 parts per million—almost 40% higher than preindustrial levels.[1]

Multiple scientific reports highlight the impact of climate change on natural and human systems on all continents. For example, since the 1980s, increased numbers of floods and droughts have been classified as disasters, with accompanying increases in the total area and number of persons affected as well as the magnitude of the damage caused.[2] Alterations in water systems can also be observed in many regions, with negative effects on the quantity and quality of water resources.[3]

The impact of climate change on human health is also related to people’s living conditions, environmental quality and, more generally, the organization and functioning of the societies in which they live. Communities and persons who are marginalized (due to social, economic, cultural, political, institutional or any other reason) are especially vulnerable to climate change, and even to the implications of some adaptive and mitigative responses.[3]

For a small island nation such as Cuba, it is particularly important to identify as precisely as possible the most probable impacts of climate change, and thus determine scientifically-based actions to prevent or reduce their adverse consequences and formulate the necessary adaptive measures. Five decades of social transformations have laid the basis for relatively high resilience and created capacities to undertake the needed measures. Even so, the challenges ahead are great and will require consistent political will, leadership and involvement of all sectors of society to prepare adequately for the onslaught of climate change.

A GLOBAL OVERVIEW
Current evidence suggests that climate change weighs less on human health–disease processes than other major factors, and its effects are not as yet well quantified. Nonetheless, it has already been proven that global warming has contributed to increased mortality from heat and reduced mortality from cold in various regions around the world. It has also been documented that local changes in temperature and rainfall volume have altered distribution of a number of water- and vector-borne diseases.[3] In fact, WHO has been issuing advisories concerning global warming, and the consequent health risks and repercussions already observed. The organization points to examples including the aforementioned increase in disasters associated with extreme weather events, such as floods, and the short- and long-term effects of these and climate variability in general; more deaths related to heat waves; and shifting distribution of infectious diseases, or emerging diseases, related to changes in ecosystems—particularly potentially fatal vector-borne diseases such as malaria.[4]

Increased incidence of natural catastrophes will lead to higher numbers of direct victims as well as indirect victims due to psychological or somatic effects such as cardiovascular conditions, plus damages to housing, potable water and food supply. These last factors in turn will have repercussions on the health status of affected populations.

Relative increases in atmospheric CO2 could favor growth of many plants but does not necessarily mean a greater abundance of food. Quite the contrary: climate variability will be accompanied by increased agricultural risks, greater water stress and higher peak temperatures, eventually damaging crops. Increased malnutrition and accompanying diseases can be expected if agricultural practices fail to adapt to higher temperatures and shifting patterns of humidity and precipitation. To this scenario should be added obvious adverse effects of violent conflicts likely to arise over basic natural resources such as water, as well as emerging mental health problems associated with these conflicts and other situations of environmental stress.

As a result of steadily rising temperatures, significant increases are expected in the annual number of days with humidex >37.77 °C (humidex: an indicator combining temperature with relative humidity to estimate perceived ambient temperature),[1] particularly dangerous for health of older populations, as has already been observed.

Disruption of the natural balance in many ecosystems by multiple factors will promote vector proliferation, and this will be compounded by increased human migration and resulting gaps in epidemiological control. Respiratory problems and allergies are also predicted to rise as a result of increased urban pollution. The latter serves as a reminder that as the world confronts climate change, it is important to deploy adaptive strategies that promote clean, pollution-free environments:[5] WHO estimates that 25% of all diseases have their roots in environmental factors.[6]

Consideration of social conditions is vital in confronting climate change, since these are associated with virtually all health and disease processes—from the classic examples of infectious diseases to the more complex and multifactoral chronic non-communicable diseases. Such social determinants were described by WHO’s Commission on Social Determinants of Health as “the circumstances in which people grow, live, work, and age, […] in turn, shaped by political, social, and economic forces.” The report also stressed the importance of bringing together the health equity and climate change agendas.[5] This is particularly relevant, given that a number of studies have concluded that environmental injustice, poverty and lack of individual empowerment are key factors in increasing people’s vulnerability, especially that of women and children.[6] Thus, any strategic assessment of the health effects of climate change must also address health’s social determinants, as well as the possibilities of actively influencing them, to obtain and sustain the best possible population health indicators. In general, climate change makes actions on social determinants of health more urgent, especially to protect vulnerable populations and communities.[6]

The UK’s chief scientist, John Beddington, alerted the world to an alarming global “perfect storm” of problems by 2030, by which time he predicted demand for food will grow by 50%, water 30% and energy 50%.[7] Each of these problems will be compounded by the impact of climate change.

Analysis of all these factors and their interrelation points to essential principles for action on the social determinants of health while confronting challenges presented by climate change: adoption of values incorporating social justice, sustainability and health equity; political commitment at the highest levels of government; development of working intersectoral partnerships; empowerment of individuals and families; community participation; and continuous monitoring of progress.[8] In this complex context, health must be accorded its full value—its outcomes and the ways it is achieved recognized as indicators of society’s wellbeing. Health inequities cannot be resolved without concerted political, economic and social effort on all fronts.

While the well-known maxim think globally, act locally does not absolve developed countries of their responsibility for creating global-scale problems or their moral obligation to help solve them, it does point to the need to analyze the particular conditions of each geographic area. The global challenges to health inherent in the environmental predicament are manifest in specific issues, requiring national and local approaches and solutions. This is also true for Cuba, where geographic, demographic and social features combine to create a unique scenario.

THE CASE OF CUBA
Cuba has certain social policies and achievements, as well as coordinated scientific research capacities, which place it on a better footing than some developing countries when it comes to facing the health and related challenges presented by climate change.

The 2014 UNDP Human Development Report ranks Cuba as a high human-development country, its human development index 44th, one of the highest in Latin America and the Caribbean.[9] In 2013, Cuba had one physician for every 137 inhabitants; its infant mortality rate was 4.2 per 1000 live births and its under-five mortality rate 5,7 per 1000 live births.[9] The Constitution and Public Health Law have provided the basis for a single, government-run public health system that provides services that are universal, accessible and free of charge. Education is also public and free, in line with policies that explicitly aim to improve social as well as economic development, eliminate inequities and defend equal rights for all citizens to basic food, health, education and adequate income.[10]

The public health system aims to promote healthy living, prevent and treat diseases, and provide rehabilitation. Health-related social policy aims to reduce inequities and ensure universal access to all health programs, with particular attention to the needs of population groups identified as vulnerable. Between 1959 and 2009 life expectancy rose by 15 years[11] and has continued to rise, reaching 79.3 years in 2013.[9] Chronic non-communicable diseases are responsible for 84% of deaths, while 8% are due to infectious diseases, maternal causes, perinatal complications and nutritional conditions.[10]

In 2006–2010, total health spending rose from 7.7% to 11.9% of GDP.[10] A substantial portion of annual public spending is also allocated to environmental protection, rising from 390.8 million pesos in 2009 to 517.3 million pesos in 2013. Of this, 230.4 million pesos were allocated to water management, 44% of the total environmental budget.[12]

In recent periods, the country has already had to address important environmental and climatic problems. For example, extreme weather events have become a primary concern. In 2008, successive lashings by four hurricanes (Fay, Gustav, Ike and Paloma) damaged 647,111 dwellings, 84,737 of which were completely destroyed. Economic losses were estimated at 9.76 billion pesos.[13] The country has also suffered extreme drought, with effects on croplands and availability of water, as well as increased danger from fires. In 2013, 388 forest fires were reported, destroying a total of 4279 hectares of forest. It is noteworthy that loss of human life from these extreme events has been low, in part due to effective warning and protection systems adopted by Civil Defense, informed by scientists at various centers, including the National Meteorology Institute.

As we move forward, integrated research projects from dozens of scientific centers become even more essential to protecting lives and developing coherent strategies to improve the environment and address adverse effects of climate change in general. A 2009 study identified important environmental factors already suffering in Cuba:

• erosion, impoverishment, compaction, salinization, contamination and changes in use of soils
• diminished quality and quantity of inland surface and groundwater and quality of marine and coastal waters
• changes in biological diversity, fragmentation or loss of habitats/ecosystems
• increased air acidity, particulate quantity and N2O and SO2 concentrations.[14]

Cuba is also not exempt from the rising global trend in acute diarrheal and respiratory infections, as well as variations in their seasonal and interseasonal patterns, which in our case corresponds to climate variations also associated with increases and differing patterns observed in foci of Aedes aegypti mosquitoes that transmit dengue.[15]

CUBAN PROSPECTS AND PROPOSALS FOR CONFRONTING CLIMATE CHANGE 
Environmental problems arising from climate change are urgent and call for immediate action; they present a major challenge for developing countries, especially island nations such as Cuba, which approaches the issues of climate change mitigation and adaptation from the perspective of an archipelago. A collaborative study involving more than 130 Cuban experts in different disciplines and from different scientific centers has resulted in a seminal report that contends that climate variability, changes in climate, and effects on human health can only be understood by examining interactions among various environmental components, which in turn affect epidemiological patterns. It offers evidence-based prediction of medium- and long-term climate change impact in Cuba and recommendations for adaptive measures.[15] As a result, several scenarios have been created for specific time horizons and combinations of principal factors considered (including, for example, estimated sea level in 2050 and in 2100 and its likely impact on coastal areas, especially heavily populated ones).

The research contained in this report is the basis for the most recent edition of the National Climate Change Program. Several years ago the program was approved at the highest level of government and has been systematically reviewed and updated since then, based on results noted and changing conditions. The main national-level impacts expected and corresponding adaptive measures are identified. Priority factors include land degradation, access to potable drinking water and varying effects on biodiversity, as well as environmental pollution from mining and industrial activity in some regions. In addition, data from multiple studies have been evaluated and integrated to estimate municipal-level danger, vulnerability and risk related to phenomena such as strong winds, intense rain, and inland incursion of seawater.

The recent research also reveals that climate variations are associated with ecological and socio-economic changes that promote epidemiological shifts affecting the health system, its planning for prevention and services, and which can result in different patterns of vulnerability than those observed thus far.[16] Evidence also indicates there may be an increase in incidence of water- and food-borne diseases (acute diarrheal, viral hepatitis); as well as acute respiratory diseases, meningitis, and vector-borne diseases (dengue, malaria and others), as a result of changing vector populations, with the associated threat of outbreaks and epidemics.[15]

We must confront the effects of climate change at the same time as we must predict and take maximum preventive measures to minimize the danger of air, soil, and water pollution invariably linked to the country’s expanding industrial and production capacities. Maintaining Cuba’s hitherto favorable health indicators will demand concerted and consistent management of such environmental impacts of economic growth, growth in turn needed to sustain and extend advances in health and education—essential components of wellbeing and comprehensive human development. Many adaptive measures recommended for Cuba have already been implemented or are about to be launched, although they may require adjustments, synchronization or more detailed projections (see box).[16] The evidence base must be continually updated and our scientific and technological capacity augmented in order to systematically add to it—and, when necessary, to introduce new environmentally sound approaches into production facilities being built or developed.

Finally, our ultimate success in protecting our people and environment in the face of climate change will depend on the vital role the public is called upon to play, contributing actively to the urgent preventive and corrective measures needed to address these challenges.