Climate change is the variations in the mean state and other statistics of climate on temporal and spatial scales beyond individual weather events for decades (usually up to three decades). Climate change is causes by accumulation of greenhouse gases in the atmosphere mainly from anthropogenic activities. The World Health Organization (WHO) describes climate change as the biggest threat to human health in the 21 st century ( Butler, 2016) . Climate change affects health directly and indirectly. The direct effects are manifest through increased frequency and intensity of extreme weather events like heatwaves, bushfires, droughts, floods, pests, and diseases. Indirectly, climate change affects health determinants such as sufficient food, clean air, safe drinking water, secure shelter, and changes in spread of infectious illnesses ( Leyva et al., 2017) . This paper discusses the impacts of climate change on global health with a focus on health effects of temperature change, climate-sensitive infectious diseases, and food security and undernutrition.
Health effects of temperature change
Extremely high air temperature poses a threat to global health as it contributes to direct deaths from heat strokes, cardiovascular diseases, cerebrovascular diseases, and respiratory diseases. In addition, high temperatures are linked with rise in ozone levels and other air pollutants that aggravate respiratory and cardiovascular diseases ( Leyva et al., 2017) . The concentration of pollen and other aeroallergens in the air tend to increase in extreme heat. These allergens can trigger asthma, which affects nearly 300 million people globally. Climate projections show that the frequency and intensity of extreme summer heat events will continue to increase in coming decades, and this is expected to exacerbate the situation. Owing to better forecasting, increased access to air conditioning, and reliable heat-health early warning systems in the recent decades, heat-related illness and consequent deaths are diminishing. Nonetheless, extreme high temperature remains a cause of avertible demises across the world. The warming climate has resulted in milder winters reducing deaths, injuries, and diseases associated with snow and cold. While climate change is projected to reduce the health impacts of extremely cold events, such drops are not are not anticipated to recompense the increase in extreme heat-related health effects ( Leyva et al., 2017) .
Delegate your assignment to our experts and they will do the rest.
Climate-sensitive infectious diseases
Climatic change is projected to increase water-borne diseases and infections transmitted through insects, snails or other cold-blooded animals. The increase could be caused by possible increase in the length of seasons during which vectors transmit diseases, or expansion in the geographical range where the diseases occur ( Baylis, 2017) . For instance, the United States could be at risk of insect borne and water borne diseases as well as new diseases that were not in the region previously. Also, it is anticipated that climate change will expand substantially the part of China where schistosomiasis- a snail borne disease, occurs. Particularly, deviations in rainfall patterns could increase infectious diseases that cause diarrhoea. In addition, climate change is likely to influence malaria through increased global exposure to dengue mosquito vector, which is highly sensitive to changes in climatic conditions ( Baylis, 2017) .
Food security and under nutrition
Climate change has significantly affected global food production and the threat is expected to continue affecting various aspects of food quality, distribution systems, and food prices. The combines effects of climate change related changes in rainfall patterns, crop diseases, competition from weed and pests, and severe weather events are projected to continue causing crop failure and consequently, decline in crop yields ( Baylis, 2017) . Fish and livestock production are also on the decline due to adverse climate change effects on water resources, sources of livestock feeds, and increase in livestock pests and diseases. With the decline in food production, prices are expected to rise and people are likely to endure hunger, or turn to calorie-rich poor nutrition and suffer consequences such as malnutrition and obesity. Increased concentration of Carbon IV Oxide in the air decreases nitrogen content in plants and this lowers protein in crop like soy, sorghum, and barley. Besides, with increase in crop pests and diseases, farmers will be exposed to pesticides and herbicides, which could be a threat to their health ( Baylis, 2017) .
Conclusion
Climate change describes change in global weather systems observed over a minimum of three decades. Human activities are the number one cause of recent changes in climate. Climate change affects the global health directly through extreme weather events like heatwaves, bushfires, droughts, floods, pests, and diseases. Indirectly, climate change adversely affects health through impacts on air quality, water quality and quantity, threat to food security, and increase in spread of infectious diseases, waterborne diseases, and insect-transmitted infections.
References
Baylis, M. (2017). Potential impact of climate change on emerging vector-borne and other infections in the UK. Environmental Health , 16 (1), 45-51.
Butler, C. (Ed.). (2016). Climate change and global health . CABI.
Leyva, E. W. A., Beaman, A., & Davidson, P. M. (2017). Health impact of climate change: An integrative review and implications for nursing. Journal of Nursing Scholarship , 49 (6), 670-678.
