Human
In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. About 36 million humans die every year from causes directly or indirectly related to starvation. Childhood malnutrition is also common and contributes to the global burden of disease. However global food distribution is not even, and obesity among some human populations has increased rapidly, leading to health complications and increased mortality in some developed, and a few developing countries. Worldwide over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an "obesity epidemic." Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet.
Effects of global warming on human health
Fifty percent of the world's fresh water consumption is dependent glacial runoff. Earth's glaciers are expected to melt within the next forty years, greatly decreasing fresh water flow in the hotter times of the year, causing everyone to depend on rainwater, resulting in large shortages and fluctuations in fresh water availability which largely effects agriculture, power supply, and human health and well-being. Many power sources and a large portion of agriculture rely on glacial runoff in the late summer. “In many parts of the world, disappearing mountain glaciers and droughts will make fresh, clean water for drinking, bathing, and other necessary human (and livestock) uses scarce" and a valuable commodity.