When we talk of global health in the 21st Century, one of the most important things that comes up is climate change and what its impact on global health is going to be and how can we actually respond to this major challenge, which is not merely environmental or ecological, but also threatens global health in very many ways. When we look at the temperature changes that have happened over a long period of human existence, over the last 20,000 years there have been some fluctuations in temperature, mostly because of changes in the way the earth has a planet has changed its ecology. However over the last 10,000 years we have had fairly stable temperature patterns which have helped humanity to thrive and progress. But towards the end of the 20th Century we have seen human interventions change the nature of the environment to the detriment of the climate, by raising temperatures high and at a very rapid pace so that the planet really is not prepared for this level of change. And this inevitably has an impact on health and nutrition. There is unequivocal evidence on climate change. We recognize that there are rising sea levels and global temperatures, retreating glaciers, extreme weather events. And despite some climate change deniers, there is absolute global consensus that climate change needs to be recognized as an important threat to humanity and that we need to collectively do something about it. Since the Industrial Revolution, atmospheric carbon dioxide has increased by a third. And the International Panel on Climate Change projects an increase in global temperatures by at least 1.8 degrees centigrade by 2100, by the end of this century, as the best case scenario. But there are other scenarios, if we do really nothing, of a doomsday scenario where the temperature can actually rise to up by about 5.8 degrees centigrade. And an increase in sea levels between 9 and 88 centimeters is very much possible in the next century, depending upon how much the temperature rises. Most of this change is related to human activity. That means it is anthropogenic. It is not mediated by natural changes in the earth’s environment or its geology, but it’s contributed entirely by humans. We recognize that there are very many scenarios possible with a wide range of temperature changes that are likely to occur based upon the International Panel on Climate Change modeling. But we do recognize that even in the best guess scenario we are likely to have a two-degree temperature rise or more if we do not do anything. Apart from the natural variability that occurs in the earth’s own environment, anthropogenic climate change will contribute substantially. And the kind of hazards that occur because of a variety of environmental distortions can actually accentuate global health challenges depending upon the amount of exposure that different population groups have, how vulnerable they are to these effects, and the impacts will automatically vary according to that. But there are also appropriate responses in terms of socioeconomic actions that we can undertake for mitigation as well as adaptation and how we can actually insure that there is a concerted global response to reduce some of the mediators of climate change. And they all will impact upon global health ultimately. In terms of human exposures there can be fairly acute events like heat waves or extreme weather events, also more steady rises in temperature as well as alterations in precipitation which can play out their effects over the longer period of time. Quite often the skeptics say, where is climate change because of global warming when we see sometimes extreme cold weather? That’s because global warming itself can disrupt weather patterns substantially resulting in what we can call freaky weather. Beyond global warming we are actually seeing global harming in very many ways. Based upon what the contamination pathways are, what the transmission dynamics are, and what’s the nature of changes in agro-economic systems and ecological systems and hydrology as well as the degree of socioeconomic and demographic disruption that takes place as a result of some of these exposures, you can have a variety of health effects. These will be temperature related illness and death, extreme weather related health effects, air pollution related health effects, water and food borne diseases, vector borne and rodent borne diseases. Effects of food and water shortages, particularly when agriculture and water supply are substantially affected. Mental, nutritional, infectious, and other health effects. Cumulatively, climate change can play havoc with human health over a period of time. There are direct effects of climate change, mainly from extreme weather events. Like for example, temperature extremes. In 2003, we had the major European heat wave. And most deaths were in the vulnerable populations, especially elderly with preexisting diseases. France particularly experienced this. And over 70,000 people were estimated to have died in the hottest summer that the world experienced since 1540. But there are also indirect effects of climate change which act via changing patterns of disease. Vector borne diseases, for example those due to mosquitoes or rodents. As the weather warms up, mosquitoes will start breeding at higher latitudes and at higher altitudes. And therefore you’ll see the spread of malaria to places which did not experience it before. Water, sanitation and hygiene related diseases are also going to be a major public health challenge. Reduced crop yields at lower latitudes will result in food shortages, accentuating food insecurity. At the same time, there will be migration compelled by climate change and related extreme weather events. So you’ll have climate refugees and population change will occur also as a result of that. We also recognize from the IPCC’s report that there will be negative impacts on crop yields. But while the whole world is going to be threatened, there will be some vulnerable populations within countries who are likely to suffer particularly more severe effects of climate change. The very old and the very young and the very poor and those who are socially and culturally marginalized are likely to suffer most, particularly you can imagine the plight of the homeless who have to live in very hot climates in the outdoor, exposed to extreme heat. Vulnerable cities. There are about 16 of the 23 global mega cities which are located in coastal areas. And they will have greater exposure to extreme weather events and storm surges. We’ll also see that climate change will accentuate conflict. It has been recorded that deviations from temperature and precipitation patterns correspond to significantly marked rise in conflict. And these are statistically significant rises. One degree increase in temperature, a rise in temperature increase the frequency of interpersonal conflict by 2.4% and inter-group conflict by 11.3%. So when we talk of hot weather, we must also recognize that people become hot tempered as a result. And the effect of rainfall on inter-group conflict is also interesting. As climate change reduces the amount of rainfall and accentuates water shortages, it has been noted that there is likely to be a greater possibility of inter-group conflict where they’re vying for scarce water resources. There is also a big challenge of how to adapt and how to mitigate. Mitigation is reducing the possibility of global warming through effective action. Adaptation is trying to adjust to some of the effects of climate change as it occurs and trying to improve our opportunities for survival despite some of the changes that we could not prevent. So the IPCC again suggests that the adaptive capacity is intimately linked to economic and social development. But this is unevenly distributed across countries and within countries, across population groups. Adaptation plans must be place and context specific. Like for example, heat action plans for different cities or looking at disaster response for different coastal cities. Action is needed at all levels, from individuals to governments. And the first step towards adaptation is reducing vulnerability and exposure. In terms of climate change, the mitigation strategies of course are very important to reduce the projected rise of temperature, even to limit the temperature rise to 2% or less is going to be a major challenge. And for this, we need to act in the main domains that are contributing to climate change. Food and agriculture. Our food and agriculture systems are now causing environmental disruption. And they themselves will again in turn suffer because of the effects of climate change. So this mutual degradation is something that we must stop because our food and agricultural systems are becoming water intensive, they’re also resulting in a lot of deforestation and all of this is something that we must take into account when we plan mitigation strategies. The use of household fuels, the increasing use of vehicular transport, and the way we generate power through coal plants, all of these are going to be important elements that we must look at as we design strategies to reduce the kind of forces that accelerate climate change and thereby we plan effective mitigation. When we look at some of the health co-benefits of climate change mitigation, we must recognize that the determinants are fairly common and the benefits are likely to be also complimentary. For example, when we talk about public transport and we promote cycling in cities, or more safe pedestrian pathways and reduce the dependence on vehicular transport, obviously in addition to reduced carbon emissions there is improved physical activity. There is also reduced air pollution with benefits for prevention of respiratory illnesses. And the improved physical activity itself will reduce the risk of diabetes, heart disease and other non-communicable diseases, including some cancers. Similarly, reduced meat consumption is something that we must look at, because livestock breeding is now responsible for 50% of global methane emissions, so it’s important that we address that even from the point of view of the environment. The WHO has come up with a work plan. It suggests that we must act, actively engag in advocacy to try and mitigate climate change but also promote appropriate plans for adaptation across the world, especially country level plans. It also suggests that we must promote partnerships to insure that health is well-represented in the climate change agenda. Climate change is not merely a matter for meteorologists or environmental experts or energy experts. After all, the consequences are going to be felt in terms of human health and nutrition. So the health community has to be there at the table when climate change agenda is being discussed. The WHO also says that we must coordinate reviews of links between climate change and health to develop a very strong research agenda which can inform and influence these debates on climate change from the health perspective. It also calls for strengthening of the health systems in countries and would like to assist countries in addressing their health system deficiencies and build capacity to reduce health vulnerability to climate change, the whole plan for adaptation. There are also main research areas in the climate change and health area. Firstly we need to establish baseline relationships between climate change and health. We must gather evidence for early effects of climate change. We must develop predictive modeling techniques and try and anticipate what are the likely consequences of positive or negative changes in the weather and the environment. And in terms of looking at the adaptive options and evaluating their comparative cost effectiveness in different country contexts, we must also estimate the benefits and costs of mitigation and adaptation overall. It is not far-fetched to think that if we do not control the forces that are accelerating climate change, human health would not only be degraded over the century that we live in, but in future centuries it may actually result in elimination of humanity itself. So it is from the public health perspective, from a global health platform that we must now engage in the debates on climate change and demand that climate change must not occur to the extent that humanity’s life would be threatened and also plan for mitigation and adaptation in the most effective manner possible in every country on earth.