Quantitative Disease Ecology and Conservation Lab
Aedes Maps
Aedes Mosquitoes and Climate Change
The maps and data on this page are based on a study called "Global expansion and redistribution of Aedes-borne virus transmission risk with climate change" by Ryan et al. 2019.
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Ryan and her team created models of Aedes aegypti and Aedes albopictus risk based on different climate change scenarios. Risk was defined as the number of months that Aedes mosquitoes would be active in a given area and could therefore transmit diseases.
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The researchers found that climate change will exacerbate risk for mosquito transmitted diseases like dengue, chikungunya, Zika. In the following sections we will walk through some of these findings and visualize them through maps.
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Ryan et al. 2019, Figure 2
Finding #1: Mosquito Heat Tolerance
Researchers found that Aedes aegypti mosquitoes are able to live and transmit diseases in hotter climates than Ae. albopictus. This means that as temperatures increase, year-round transmission potential for Ae. aegypti is likely to increase overall, especially near the north and south poles, while Ae. albopictus transmission is likely to decline overall, especially in central South America and Africa in the most extreme cases.
Lets visualize this with the maps below.
Both maps are in reference to Aedes aegypti. The map on the left is the current risk. The map on the right is for the year 2080 with an RCP of 8.5 and uses the HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes albopictus. The map on the left is the current risk. The map on the right is for the year 2080 with an RCP of 8.5 and uses the HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
A Closer Look:
Analysis:
The areas with the greatest increase in risk are projected to be Europe, high altitude regions in the tropics, the Unites States, and Canada. Aedes aegypti mosquitoes are projected to have longer seasons of activity throughout the year. As for Aedes albopictus, due to its lower preferred temperature range, it will decrease in transmission risk for the world as a whole. This will have specific impacts for the types of diseases that will become most prevalent in a region.
Let's look at this in greater detail below.
Ae. aegypti transmission risk in North America for the year 2080 with an 8.5 RCP and HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
Ae. albopictus transmission risk in North America for the year 2080 with an 8.5 RCP and HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
Ae. aegypti transmission risk in the Southeastern US for the year 2080 with an 8.5 RCP and HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
Ae. albopictus transmission risk in the Southeastern US for the year 2080 with an 8.5 RCP and HadGEM2-ES GCM. R0 > 0 is greater or equal to 97.5%
Finding #2: Ae. aegypti Spread
Researchers found that currently, 6.01 billion people live in at-risk areas suitable for Aedes aegypti transmission for at least one month of the year. By 2050, it is expected that Ae. aegypti will see major expansions in 1 to 2 months of transmission risk. However, by 2080, Ae. aegypti will begin to lose areas of year-round suitability, particularly in the areas of north-central South America.
Let's visualize this with the maps below.
2050
2080
Both maps are in reference to Aedes aegypti for the year 2050 using the HadGEM2-ES GCM. The map on the left has an RCP of 2.6. The map on the right has an RCP of 4.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2050 using the HadGEM2-ES GCM. The map on the left has an RCP of 6.0. The map on the right has an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2080 using the HadGEM2-ES GCM. The map on the left has an RCP of 2.6. The map on the right has an RCP of 4.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2080 using the HadGEM2-ES GCM. The map on the left has an RCP of 6.0. The map on the right has an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
A Closer Look:
The images below are of Ae. aegypti range for the year 2080 with an RCP of 8.5. However they each represent a different GCM. From right to left, the models are: Hadley HadGEM2-ES, Hadley HadGEM2-AO, Beijing Climate Center Climate System Model (BCC-CSM1.1), and National Center for Atmospheric Research’s Community Climate System Model (CCSM4).
Aedes aegypti range for the year 2080 using the HadGEM2-ES GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the HadGEM2-AO GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the BCC-CSM1.1 GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the CCSM4 GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Analysis:
These maps show how with increasing temperatures, Aedes aegypti mosquitoes will see an increase in suitable environments, especially at high elevations and northern and southern latitudes. Also it demonstrates the differences in risk between the years 2050 and 2080. It is consistent that 2080 will experience more suitable area than in 2050. Lastly, it appears that the BCC-CSM1.1 model predicts the smallest increase in Ae. aegypti range while the HadGEM2-ES model predicts the most increase in range.
Finding #3: Ae. albopictus Spread
Researchers found that 6.33 billion people live in areas suitable for Ae. albopictus transmission. Ae. albopictus has a lower heat tolerance than Ae. aegypti, meaning that it cannot survive in as hot of climates as Ae. aegypti can. As a result, researchers found that Ae. albopictus mosquitoes will lose suitability for the tropics in extreme temperature increase scenarios. Instead, it will increase in suitability at higher elevations and at more northern and southern latitudes.
Let's view this below.
2050
2080
Both maps are in reference to Aedes aegypti for the year 2050 using the HadGEM2-ES GCM. The map on the left has an RCP of 2.6. The map on the right has an RCP of 4.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2050 using the HadGEM2-ES GCM. The map on the left has an RCP of 6.0. The map on the right has an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2080 using the HadGEM2-ES GCM. The map on the left has an RCP of 2.6. The map on the right has an RCP of 4.5. R0 > 0 is greater or equal to 97.5%
Both maps are in reference to Aedes aegypti for the year 2080 using the HadGEM2-ES GCM. The map on the left has an RCP of 6.0. The map on the right has an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
A Closer Look:
The images below are of Ae. aegypti range for the year 2080 with an RCP of 8.5. However they each represent a different GCM. From right to left, the models are: Hadley HadGEM2-ES, Hadley HadGEM2-AO, Beijing Climate Center Climate System Model (BCC-CSM1.1), and National Center for Atmospheric Research’s Community Climate System Model (CCSM4).
Aedes aegypti range for the year 2080 using the HadGEM2-ES GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the HadGEM2-AO GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the BCC-CSM1.1 GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Aedes aegypti range for the year 2080 using the CCSM4 GCM with an RCP of 8.5. R0 > 0 is greater or equal to 97.5%
Analysis:
Researchers found that RCP 8.5 will have a greater reduction in Ae. albopictus risk than would moderate RCPs 4.5 and 6.0. This is somewhat counterintuitive, as it has been shown that temperatures generally increases mosquito risk. However, in the case of RCP 8.5, climate change has been left to increase without restraint, meaning that some areas will become too hot for mosquitoes to survive. Thus there will be overall less risk in the RCP 8.5 scenario than compared to partial climate change reduction strategies like RCP 6.0.
