Heating Up The Issue

How Global Warming Impacts Human Health

This month, Sailors for the Sea presents a four part blog series based upon the recently issued 3rd National Climate Assessment. Read parts one, two and three.

More often than not, when we talk about the threats global warming poses to the environment, we discuss property damage from increased frequency of storms or coastal erosion. However climate change affects human health just as seriously as it does the environment and our property’s economic value. In the coming years, most impacts on human health will come from extreme weather events including:

  • Wildfires and decreased air quality
  • Increased risk of heat stroke and related conditions
  • Threats to mental health
  • Illnesses transmitted by food, water, and disease carrying insects

Many of these threats can already be measured in the United States. And on top of other health concerns the United States already faces, climate change is predicted to amplify these issues. Those most at risk include children, the elderly, the sick, the poor, and some underserved communities.

Hot & Dry – A bad combination

As human-induced climate change causes temperatures to rise, the chances of extreme summer heat events will increase in the United States. Extreme heat events are the leading weather-related cause of death in the United States, particularly in cities such as St. Louis, Philadelphia, Chicago, and Cincinnati. These cities have suffered dramatic spikes in death rates during heat waves. As a rule of thumb, the longer the heat lasts, the greater risk the risk to human health. 

Projected temperature change of hottest days
These maps show projected increases in the average temperature on the hottest days by 2081-2100 relative to 1986-2005. The left map assumes a rapid reduction in heat-trapping gases and the right map, a scenario that assumes continued increases in these gases. 

Air Quality

Warmer and drier conditions have already contributed to increasing wildfire extent across the western United States. The impact of air quality from wildfires reach far and wide, such as the 2002 wildfires in Quebec that resulted in a 30-fold increase in airborne fine particle concentrations in Baltimore, nearly a thousand miles away. Wildfire smoke contains particulate matter, carbon monoxide, and other compounds, which can significantly reduce air quality. Exposure to smoke increases respiratory and cardiovascular hospitalizations, emergency room visits and medication for asthma, bronchitis, chest pain, and other ailments.

More frost-free days and warmer seasonal air temperatures, contribute to shifts in flowering time and pollen initiation from plants that commonly cause allergies.

Flood & Waterborne Illness

Air and water temperatures, precipitation patterns, extreme rainfall events, and seasonal variations are all known to affect disease transmission. Diarrheal disease is a major public health issue in developing countries, and while not generally increasing in the United States, remains a persistent concern nonetheless.

Diarrheal disease poses problems after heavy downpours, floods and storm surges that create standing water along with septic and sewage overflow. In particular, risks of waterborne illness, and beach closures resulting from heavy rain and rising water temperatures are expected to increase in the Great Lakes region due to projected climate change.

Heavy Downpours are increasing exposure to disease
Heavy downpours, which are increasing in the United States, contribute to increases in flood events. The figure above illustrates how people can become exposed to waterborne diseases, including drinking water and recreational uses such as boating.

Disease carrying insects

Mosquitoes, fleas and ticks – just the mention of these insects can make you have an itch! (In fact, writing this section has been rather difficult.) However as temperatures rise, and frost-free days increase, these bugs - and many other disease carriers - will have a larger habitat to reproduce.

“Large-scale changes in the environment due to climate change and extreme weather events are increasing the risk of the emergence or reemergence of health threats that are currently uncommon in the United States, such as dengue fever.” National Climate Assessment, 2014

Climate change is also spreading the expansion of ticks that carry Lyme disease, as visualized on the map below. 

Projected changes in tick habitat

Seafood at risk for disease as well

Warmer surface waters can stimulate blooms of harmful algae in both lakes and coastal oceans, which may include toxic cyanobacteria. As water temperatures rise, algal blooms will occur more frequently in different regions. Additionally, diseases that are typically found in tropical regions will shift north. For example, ciguatera fish poisoning, a common problem in the Caribbean, could start to spread north as the algae that causes this food-borne illness will occur in warmer waters. Warmer waters in coastal areas and regional estuaries will expose shellfish to more species of bacteria and for longer periods of time.

Infections from Gulf Coast shellfish are now frequently reported both earlier and later by one month than traditionally observed. Harmful blooms of algae, more likely to occur in warmer water may contribute to more cases of paralytic shellfish poisoning.

Increase in algae blooms can come in multiple forms including increase in water temperatures, additional runoff of fertilizer due to large downpours and ocean acidification. National Climate Assessment, 2014

Mental Health Issues

Extreme weather events are traumatic and often lead to mental health issues such as anxiety and post-traumatic stress disorder. Anyone who has experienced a mandatory evacuation can attest to the stress levels created by these events.

Yikes! You have my attention

The good news is the risks to human health are manageable and the earlier they are addressed, the less costly and damaging they will be. Advanced warning systems and weather monitoring abilities for extreme weather will aid in the mitigation efforts.

Responding to climate change provides opportunities to improve human health and well being across many sectors, including energy, agriculture, and transportation. Many of these strategies offer a variety of benefits, protecting people while combating climate change and providing other societal benefits. National Climate Assessment, 2014

There are actions you can take at home to dampen your impact on the environment – and your impact will be even stronger if you convince ten friends to change their habits too.

  • Many algae blooms are caused by fertilizer run-off. Switch to organic fertilizer at home and use minimal amounts.
  • Biking and walking has an immediate benefit to personal health, and reduces your carbon footprint.
  • Choosing renewable electrical power generation reduces CO2 emissions and air pollutants like particles and sulfur dioxide, which can help reduce asthma.

What is the National Climate Assessment?

The assessment, which has now been published in its third edition, focuses on our changing climate, highlighting current and future impacts of a warming world. This blog series will focus on topics that will most greatly affect the boating community and response strategies that can help diminish these trends and prepare for change. All graphs and images are from the National Climate Assessment website, unless otherwise noted. To read the full report visit: nca2014.globalchange.gov