Roosevelt Institute | Cornell University

How Global Warming Set the Stage for the Zika Outbreak

By Anna KambhampatyPublished March 2, 2016

Zika is not a new virus. In fact, it has been around since the late 1940s. However, 2015's Zika outbreak has been the most widespread and severe thus far; the World Health Organization has even called the outbreak a Global Health Emergency, a label they've only had to give to three crises in the past. 2015 also happened to be the hottest year in historical record; it's fairly obvious that these two events are more than just mere coincidence.
By Anna Kambhampaty, 03/02/16

There are many factors that contributed to  the outbreak and rapid spread of the Zika virus . Several  of these factors can be attributed to and are direct causes of global warming.  It's important to note that
Zika is not a new virus. There have been minor outbreaks of the virus in Africa, Southeast Asia, and the Pacific Islands after it was first discovered in 1947. Because  this virus has existed  for decades and stayed relatively contained, its recent, rapid spread can be linked to the changes prevalent in the earth's climate.

Zika is primarily a mosquito-borne disease, spread via the Aedes species of mosquito. This species has been around in North and South America prior to the current outbreak, but has been thriving recently as a result of heavy rains and high temperatures in Brazil and Uruguay. The heavy rains in these regions makes for still-standing water pools and puddles, creating and fostering mosquito breeding havens. Increased temperatures in South American regions have also been cause for people to spend more time outside and have more exposed skin, while giving mosquitos the ability to incubate the virus. For the virus to be transmitted to a person, there must be a period for it to reproduce within the mosquito. Higher air temperatures speed up this process. Charles B. Beard, head of a unit in Fort Collins, Colorado, studying insect-borne diseases for the Centers for Disease Control and Prevention claims, "you get larger populations, with more generations of mosquitoes, in a warmer, wetter climate. You have this kind of amplification of the risk." Moreover, this latest Zika outbreak started in 2015, the hottest year in the historical record. The relationship between climate and the spread of the disease is especially concerning. Additionally, climate change has been suspected to be a contributing factor to disease outbreaks in the past; the spread of malaria in eastern Africa and the rising cases of Lyme disease in North america have been linked to changes in climate.
Global warming is predicted to increase both the life span  and speed of the life cycle of disease carrying mosquitoes. As it is, the North American mainland is home to the Aedes species of mosquito, but increasing temperatures and erratic weather patterns make for deeper and more dangerous spreads of mosquito-borne diseases into previously temperate countries and regions.
Experts have said that the main reason for disease outbreaks is the increasing number  of people at risk. Urbanization and population growth have made for quick, easy routes over which the disease can spread. However, climate change is a crucial factor contributing to Zika's spread. Clearly, climate change is no longer a distant issue. It is a factor directly causing the spread of the Zika virus, a situation the World Health Organization has called a Global Health Emergency, a title they've only given to three other crises before in the past. We must ask ourselves, if global warming contributed this greatly to the spread of one of the greatest global health issues in history, what else has it contributed to?