Before we take a look at the maps themselves, we first need to understand how the temperature-based mosquito transmission models are made.
Climate Models are mathematic equations that allow us to understand how Earth's oceans, atmosphere and land interact with one another. They include variables such as the fundamental laws of physics, water's density, the relationship between vapor-pressure and temperature and hundreds more. All these variables are included to achieve the most accurate picture of what Earth's environment is like. Once scientists can distill Earth's systems into a set of equations, they can begin to answer big questions and test solutions
For our purposes, we will look at two components of these models, which are general circulation models (GCMs) and representative concentration pathways (RCPs).
Illustration of the variables added to climate models from 1970 to 2007. As you can see, the models become more complicated yet also more accurate. Source: IPCC
Interactive: Climate Time Machine
Click through this interactive page to understand how some of the climatic variables and systems on Earth have changed over the past decades.
Source: NASA Climate Time Machine
General Circulation Models
General circulation models (GCMs) are mathematical representations of the physical characteristics of the atmosphere and ocean. For our models, they will be used to simulate the conditions of Earth as a result of climate change.
Four of the most commonly used GCMs are the Beijing Climate Center Climate System Model (BCC-CSM1.1); the Hadley GCMs (HadGEM2-AO and HadGEM2-ES); and the National Center for Atmospheric Research’s Community Climate System Model (CCSM4).
Use the sliders on the right to compare these four predictive models. For context, these maps all represent the year 2080 and map Aedes aegypti risk. Notice how each climate model has a slightly different prediction of at-risk areas. This means that predicting disease transmission or climate change solutions will vary slightly based on the models chosen to answer the question.
For all maps, R0 > 0 is greater or equal to 25%. 2080 maps have an RCP of 6.0
Representative Concentration Pathways
Representative Concentration Pathways (RCPs) are greenhouse gas emission predictions as established by the Intergovernmental Panel on Climate Change. They represent different future climate scenarios based on the volume of greenhouse gasses produced.
There are 4 main RCPs: RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5. Think of these values as a range, with RCP 2.6 as the best case scenario and RCP 8.5 as the worst case scenario. RCP 2.6 represents the highest amount of action taken to reverse climate change, including less reliance on fossil fuels and halting deforestation. RCP 8.5 is the nightmare scenario with uncontrolled fossil fuel use and extreme population growth. This means that RCP 2.6 will result in the lowest temperature increase, and RCP 8.5 will cause the highest increase. Some scientists believe that RCP 2.6 is no longer possible to achieve due to a lack of greenhouse gas restrictions.
Look over the document below to learn more about each RCP and some ways to curb greenhouse gas emissions.
Use the sliders below to compare these four RCPs. For context, these maps represent the year 2080 and map Aedes albopictus risk. Notice how each RCP leads to different at-risk areas. Recall the "Mosquitoes and Climate" website page. Mosquitos are highly temperature sensitive so their activity is determined by the climate. Also notice how the hotter temperatures in RCP 8.5 may become too hot for the mosquitoes to survive, and therefor disease risk decreases in some areas.
For all maps, R0 > 0 is greater or equal to 25%, the year is 2080, and the GCM is the National Center for Atmospheric Research’s Community Climate System Model (CCSM4).