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Climate Change: An Overview
Climate change is considered to be any statistically significant changes in the average state of a climate and its highs/lows. For it to be significant changes, they must persist for an extended period of time, typically decades or longer.
The terms climate change and global warming are often used interchangeably. However, the term global warming suggests that climate change only results in an increase in temperature. In reality, it composes a broader range of changes, which can include increasing humidity, extreme weather events, and, of course, warmer summers.
Global warming is a very gradual process, but despite how slight the increase has been, its impact is of great significance.
Some areas which are currently affected by the Earth’s rising temperature include:
- rising sea levels
- flooding
- changes in rain patterns
- changes in food production
One area which is suspected to be significantly impacted by climate change, though, is the transmission of vector-borne diseases, such as malaria.
What Is Malaria?
Malaria is a mosquito-borne disease transmitted by the female Anopheles mosquitos. These mosquitos prefer warm, wet and humid climates. The location most affected by malaria is Africa, accounting for 94% of all malaria cases in 2020.
However, climate change is causing more areas of the world to experience the ideal climate for malaria transmission for longer periods of time.
The Impact of Climate Change on Malaria
Many advances have been made to protect individuals in high-risk malaria regions. However, climate change is threatening these advances. Essentially, the changes in temperature, rainfall and humidity are creating an environment that mosquitos thrive in.
To put into perspective these rising temperatures, NASA has reported that nineteen of the warmest days ever recorded have occurred in the years since 2000. Additionally, 2020 and 2016 combined have been the warmest years since record-keeping began in 1880. So, when you feel as though this summer is warmer than usual, you are probably right!
Changing Geographical Areas of Risk
The rising temperatures and other changes in climate are benefiting mosquitos. Not only does this increase the cases of transmission, but it is also causing a change in geographical areas affected by malaria.
Places without malaria risk are now seeing increasing cases as their climate becomes one that is appealing to mosquitos. This is especially true in locations of higher altitudes, which are seeing increases in temperature, rainfall, and humidity.
Faster Parasite Growth Cycles
The growth cycle of the parasite causing malaria is also changing in lower altitude areas experiencing higher temperatures. Scientists are seeing that mosquitos are developing malaria faster, meaning they’re able to spread it to humans faster as well.
Reemerging Malaria Cases
Some studies have reported the reemergence of malaria in locations that had previously controlled it. This is causing these populations to, once again, be vulnerable to malaria transmission.
While areas such as Africa currently see the greatest malaria risk, Europe itself once had a malaria endemic. However, it was eliminated in 1975 because of improved irrigation and drainage, better socio-economic conditions, behavioral changes, adoption of new farming methods, and access to better health care.
Recently, though, there have been some reported cases of malaria in Europe. These cases suggest a malaria reintroduction to this country.
In 2020, researchers at the University of Zurich compiled a systemic review on malaria incidence in Europe due to rising temperatures. The ten studies included in this review predict that the increasing temperatures will cause the Anopheles mosquitos to spread northward. Additionally, they predict that malaria’s high-risk season will extend to six months.
The Indirect Impact of Climate Change
In addition to the direct way in which climate impacts malaria (through rising temperatures and rain), there is also an indirect impact. These indirect effects include the many socio-economic factors that affect malaria risk. However, these indirect factors are highly unpredictable, and are thus understudied.
One of these suspected factors is extreme weather, such as tropical cyclones, storm surges, heavy rainfall, and flooding. These extreme weather events can significantly disrupt everyday life by impacting someone’s ability to access diagnostics, drugs, or vaccines. Extreme weather events could also cause roads or other transport lines to be out of service. This can then complicate the transport of these supplies, especially to those in remote rural areas.
Yet another indirect effect of climate change on malaria transmission has to do with a willingness to follow preventative steps. Two of the most recommended actions include wearing long clothes (e.g., long sleeves and long pants) and sleeping under mosquito netting at night. However, rising temperatures can make these things much less appealing. For those who forego long sleeves, long pants, and mosquito netting, the risk of a bite becomes much higher.
Additionally, risk mapping uses historical patterns to determine risk and let you know when you are traveling to a location with a high malaria risk. However, it may become less effective as seasonal changes continue to deviate from historical patterns.
Final Remarks
There are many ways in which the increasing temperature can impact us, beyond making us hesitant to go outside into the higher heat. The rising temperature of the Earth is causing climate changes such as increased rainfall and high humidity, which are favorable conditions for the mosquito that transmits malaria.
The extreme weather events that occur with climate change can also affect someone’s ability to access the tools created to diagnose, treat, and prevent malaria. Additionally, climate change may lead to a reemergence of malaria in areas which had previously eradicated it, such as Europe.
The truth is that we cannot predict just how much climate change will impact malaria. Because of this uncertainty, it is important for everyone to be aware of the possible changes in malaria transmission risk areas and prepare accordingly before traveling.
References
- Climate Change and Malaria - A Complex Relationship | United Nations. (2022). Retrieved 11 July 2022, from https://www.un.org/en/chronicle/article/climate-change-and-malaria-complex-relationship
- Nissan, H., Ukawuba, I., & Thomson, M. (2021). Climate-proofing a malaria eradication strategy. Malaria Journal, 20(1). doi: 10.1186/s12936-021-03718-x
- 2020 Tied for Warmest Year on Record, NASA Analysis Shows. (2022). Retrieved 11 July 2022, from https://www.nasa.gov/press-release/2020-tied-for-warmest-year-on-record-nasa-analysis-shows
- Nabi, S., & Qader, S. (2009). Is Global Warming Likely to Cause an Increased Incidence of Malaria?. Libyan Journal Of Medicine, 4(2). doi: 10.4176/090105
- Fischer, L., Gültekin, N., Kaelin, M., Fehr, J., & Schlagenhauf, P. (2020). Rising temperature and its impact on receptivity to malaria transmission in Europe: A systematic review. Travel Medicine And Infectious Disease, 36, 101815. doi: 10.1016/j.tmaid.2020.101815
- The "World malaria report 2020" at a glance. (2019). Retrieved 11 July 2022, from https://www.who.int/publications/i/item/9789240015791