What are the effects of climate change on health?

A new study evaluating health data over the past 20 years finds that a spectrum of health conditions are adversely affected by climate change.

Consensus states that fossil fuel combustion and tropical deforestation contribute to climate change, which is "inextricably linked" to health.

Both the extent and cause of climate change remains a controversial area of debate.

According to polling over the past 2 decades, two thirds of Americans believe that climate change is occurring, with about 40% of these believing that humans are the cause, and about half believing climate change will pose a serious threat in their lifetimes.

But the authors of the new study - from the Global Health Institute, University of Wisconsin-Madison - say the consensus is that fossil fuel combustion and tropical deforestation contribute to climate change. Health, the researchers add, is inextricably linked to climate change.

The authors gathered data from 56 medical journal articles investigating the health impact of climate change and looked at air temperature data from the National Oceanic and Atmospheric Administration NATIONAL CLIMATE DATA CENTER. The researchers averaged data over 13 climate models.

The researchers say their results show that many American cities will experience more frequent extreme heat days by 2050. This means that cities such as New York and Milwaukee may have, on average, three times as many days hotter than 90°F.

What health conditions may be affected by climate change?

More frequent days of extreme heat means that many health concerns will be exacerbated, such as:

• Respiratory disorders, including those made worse by fine particular pollutants (such as asthma and allergic diseases)
• Infectious diseases, including insect-transmitted diseases and water-borne diseases (such as childhood GASTROINTESTINAL diseases)
• Food insecurity, including reduced crop yields and an increase in plant diseases
• Mental health disorders, such as post-traumatic stress disorder and depression, that are associated with natural disasters.

In the study, the authors argue that substantial health and economic benefits may be associated with reduced combustion of fossil fuel:

"Accounting for co-benefits may document that reducing greenhouse emission yields net economic benefits, that labor productivity increases, and that health system costs are reduced. Co-benefits can provide policymakers with additional incentives, beyond those of curtailing climate change, to reduce the emissions of both carbon dioxide and short-lived climate pollutants."

The authors add that because climate change may have important implications for the health of the world's population, it is important that high-quality research "and responsible, informed debate needs to CONTINUE. 

However, given that evidence over the past 20 years suggests that climate change can be associated with adverse health outcomes, strategies to reduce climate change and avert the related adverse effects are necessary."

In a linked editorial, JAMA's editor-in-chief Dr. Howard Bauchner and executive editor Dr. Phil B. Fontanarosa write that the gains in well-being in the 20th century occurred because of large efforts to improve public health.

Today, in the early part of the 21st century, it is critical to recognize that climate change poses the same threat to health as the lack of sanitation, clean water, and pollution did in the early 20th century. 

Understanding and characterizing this threat and educating the medical community, public, and policy makers are crucial if the health of the world's population is to CONTINUE to improve during the latter half of the 21st century.