What are the impacts of climate on human health?

Main conclusions from research on the impact of climate change on human health. Global climate change often leads to drastic changes in local climate and weather, which has a wide range of impacts on human health, including both positive and negative impacts. However, overall, the negative impacts outweigh the positive impacts.

(1) The direct impact of climate change on human health is the thermal effect caused by extreme high temperatures. Global warming appears to be accompanied by an increase in the frequency and intensity of heat waves, making summers hotter and winters milder. Increased humidity exacerbates the impact of extreme summer heat on human health. In temperate regions, daily deaths increase during periods of high temperatures. For example, during the 1995 heat wave in Chicago, the United States, more than 500 people died, with the highest death rate among the elderly. As heat waves increase in frequency and intensity in the future, the number of deaths and serious illnesses caused by extreme heat events will increase.

The impact of heat waves on health is greater in urban areas than in suburbs and rural areas. Due to the "heat island effect", high temperatures in urban areas are not only high but also last for a long time. Research shows that prolonged heat has a greater impact on mortality than transient high temperatures. Air pollution levels are also higher in urban areas, and heat waves are often associated with high pollution levels. During the 1995 U.S. heat wave, more than half of the deaths were estimated to be caused by increased air pollution at the time.

(2) There are obvious seasonal changes in mortality in many temperate countries. The mortality rate in winter is 10% to 25% higher than in summer. Some studies have pointed out that the increase in heat-related mortality will be greater than the decrease in cold-related mortality. Some studies have also pointed out that under climate warming, the reduction in mortality in winter may be greater than the increase in mortality in summer. Due to climate warming, it is estimated that the number of annual cold-related deaths will decrease by 20,000 by 2050. Across Europe, the percentage increase in deaths for a 1°C change in temperature when temperatures drop below 18°C ??is greater in warmer countries than in colder countries. In North America, increased mortality in winter is associated with snowfall and blizzards.

(3) The impact of climate change on human health is related to changes in the frequency and intensity of extreme events caused by climate change. Many studies have shown that the impact of flooding on human health can be divided into short-term, medium-term and long-term impacts. The short-term impact is mainly casualties, the medium-term impact is mainly an increase in infectious diseases, and the long-term impact is mental depression due to economic difficulties and loss of life and property caused by floods. Drought affects human health by reducing food production, exacerbating the original malnutrition situation, inducing famine. Health impacts of drought also include diseases caused by water scarcity. During droughts when water is scarce, water can only be used for cooking and not for hygiene, so the risk of disease increases and epidemic outbreaks can occur.

3． Uncertainty analysis in studies of the impacts of climate change on human health. There are currently many scientific uncertainties in assessing the impacts of climate change on human health. The reasons are:

(1) Climate change is usually accompanied by various other environmental changes, and most diseases are caused by multiple reasons. The pathogenic effects of climate factors are derived from other factors. It is difficult to distinguish among the combined effects.

(2) It is also difficult to determine the sensitivity of human health to climate change. The response of human health can be caused by endogenous human characteristics or can be caused by factors that affect the sensitivity of human response to climate change. caused by the relevant environment.

(3) When predicting the possible impact of climate change on health, it is difficult to accurately predict the changes that may occur in society, economy, population, technology, health, and health care when the climate changes in the next few decades.

(4) There are three main uncertainties when simulating the impact of climate change on health. One is the statistical variation of the "normal value" itself; the other is the approximate selection of key parameter values ??in the model. ; The third is the imperfection of model structure relationships that inevitably occurs due to incomplete knowledge.