Analysis of the Effects of Global Change on Human Health and Welfare and Human Systems
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=175644
Projected environmental changes such as increased heatwaves, increased rainfall, droughts, global warming, reduced air quality, and increased precipitation will greatly affect human welfare and health in the future. Climate conditions are a key element to perceived quality of life, and can affect human well being directly (i.e. extreme weather events) as well as indirectly (i.e. spreading of food borne disease). It is predicted that by 2050 the US population that will be 65 years or older will be 86 million or 21% of the total population. This group, along with small children and the poor, will be highly vulnerable to the climate changes and will feel the affects greatly.
One aspect of climate change is increased heat waves; consequently, heat related deaths are expected to increase in the coming decades. Eleven of the last twelve years have ranked the hottest in the record of global surface temperatures since 1850. In the past 50 years, there has been a steady increase of record extreme temperatures and heatwaves. The West and Southwest have felt the greatest effects of increased temperatures. Those 65 or older have the highest heatwave death rates. One study looked at 44 US cities in the summer and winter to analyze the effects of extreme weather conditions. They looked at the years 2020 and 2050 under a no-control scenario; in 2020 the increase in heat related deaths was from 1,840 up to a range between 1,981-4,100. In 2050 the excess summer deaths were between 3,190-4,748.
The ocean temperatures absorb 80% of the heat, which have increased temperatures to depths of 3000 m. With increased temperatures, the ocean water levels are increasing annually. In fact, in just the past century the level has increased 5-8 inches. It is predicted that by 2100 the temperature will increase by 1.1 to 6.4 degrees C, and the level is estimated to increase anywhere from 7-23 inches.
There is also a recent trend of increased perception in some parts of the US. In the Pacific NW and California, the increase in summer time rainfall has increased 20% to 80%. El Nino events are associated with the increase of precipitation. Another explanation for the increase in precipitation is the rising temperatures which turn snowfall into rainfall. The snow pack is melting faster and earlier, which in some parts has been up to 4 weeks sooner than normal.
Due to these current and furture consistent climate changes, illnesses and diseases will likely increase and affect human health. A recent trend is the increase of the transmissions of blood-feeding insects or tick species, as well as rodent species. Due to ecosystem changes and warmer temperatures, there has been an increase of Lyme disease, ehrlichioses, and West Nile Virus which is expanding the range of people who are affected. Waterborne and food-borne diseases are also on the rise. In 2002 there were 1,300 outbreaks due to food-related diseases. Climate changes that have provided conditions for growth and survival for bacterial which has lead to an increase in outbreaks.
Another cause is increased storm events and flooding which contaminates crops from near by livestock. There is also a direct link between salmonella and increased temperatures. Yearly peaks in salmonella cases occurred within 1-6 weeks of the highest temperatures.
Other diseases that are on the rise due to warmer temperatures include: Leptospirosis (which is the most widespread zoonotic disease in the world), Vibrio (shellfish-related illnesses), cryptosporidium and giardia (waterborne illnesses), and Naegleria fowleri (free-living amboeboflagellate found in lakes at warm temperatures). There are also epidemics of food and water exposure viruses such as enteroviruses, rotaviruses, hepatitis A, and nororvirus. These viruses account for 67% of food-borne illnesses. Between 1948 and 1994, 51% of waterborne illnesses occurred after a 90th percentile precipitation event and 68% after an 80th percentile event. It has also been noted that there is a direct correlation between major rainfall and waterborne diseases.
In seasons of strong precipitation, often resulting in flooding, there have been studies that show that this helps determine the severity of the influenza season in regards to length and intensity. Another illness that is greatly affected by the climate is valley fever, which is caused by the inhalation of spores of a fungus that thrives during wet periods after a drought has occurred.
Poor air quality is exaggerated when ground level ozone is formed because of air pollutants and increased temperatures. This causes millions of Americans to live in areas that are below the air quality standards. There is a direct correlation between poor air quality and short and long term health effects such as: coughing and breathing problems, lung disease, asthma, chronic bronchitis, heart attack, and arrhythmias. When high levels of CO2 are present, the mortality increases by 1.1% per degree temperature increase over the baseline rate.
