The possible impact of climate change on transmission of vector borne diseases is the subject of considerable scientific debate. It has important policy implications and attracts a lot of attention from the public and various interest groups.
Part of the reason it’s controversial derives from the very divergent predictions of different scientific studies. Some studies present doom and gloom scenarios, suggesting many millions of people will be at increased risk of malaria in the coming decades. Others predict no real change, or even net reductions in disease as the impact of various control measures is expected to outweigh any possible influence of climate.
So what will happen?
Our aim is to address this question by improving mechanistic understanding of exactly how environmental factors (and our primary interest is in temperature) influence the essential components of mosquito and parasite biology that combine to determine transmission intensity. By better understanding the biology we hope to gain novel insights into the factors that contribute to the current disease burdens, and how the dynamics and distribution of disease might change in the future.
One of our most significant findings to date is the demonstration that daily temperature fluctuation can substantially alter the various parasite and mosquito traits that influence transmission rates. We found that diurnal temperature variation around cool temperatures acts to speed up rate processes relative to the baseline mean temperature, while variation around warmer temperatures acts to slow rate processes down. Consequently, models that ignore diurnal variation overestimate malaria risk in warmer environments and underestimate risk in cooler environments. This effect of temperature fluctuation also reduces the impact of increases in mean temperature overall. The research shows that the use of simple degree-day models and mean ambient temperature alone are insufficient to capture the effects of temperature on transmission , yet few (if any) climate change and/or malaria transmission models have considered daily temperature dynamics or how daily temperature ranges will shift under future scenarios in addition to any impact on mean conditions.
This research is currently funded by grants from the NSF and NIH. We have various publications in recent years and these are set to grow as the research progresses so watch this space.
Key recent papers (accessible from our publications page) include:
- Paaijmans, K.P., Blanford, S., Chan, B.K. & Thomas, M.B. (in press). Warmer temperatures reduce the vectorial capacity of malaria mosquitoes. Biology Letters.
- Paaijmans, K.P. & Thomas, M.B. (2011). Health: Wealth versus warming. Nature Climate Change 1: 349-350.
- Paaijmans, K.P. & Thomas, M.B. (2011). The influence of mosquito resting behaviour and associated microclimate for malaria risk. Malaria Journal 10:183.
- Lambrechts, L., Paaijmans, K.P., Fansiri, T., Carrington, L.B., Kramer, L.D., Thomas, M.B. & Scott, T.W. (2011). Impact of daily temperature fluctuations on dengue virus transmission by Aedes aegypti. Proceedings of the National Academy of Sciences 108: 7460-7465.
- Rohr, J.R., Dobson, A.P., Johnson, P.T.J., Kilpatrick, A.M., Paull, S.H., Raffel, T.R., Ruiz-Moreno, D. & Thomas, M.B. (2011). Frontiers in climate change-disease research. Trends in Ecology and Evolution 26: 270-277.
- Paaijmans, K.P., Blanford, S., Bell, A.S., Blanford, J.I., Read, A.F. & Thomas, M.B. (2010). Influence of climate on malaria transmission depends on daily temperature variation. Proceedings of the National Academy of Sciences 107: 15135–15139.
- Paaijmans, K.P., Imbahale, S.S., Thomas, M.B. & Takken, W. (2010). Relevant microclimate for determining the development rate of malaria mosquitoes and possible implications of climate change. Malaria Journal 9:196.
- Paaijmans, K.P., Read, A.F. & Thomas, M.B. (2009). Understanding the link between malaria risk and climate. Proceedings of the National Academy of Sciences 106: 13844–13849.
As indicated, this research attracts the attention of the media and various blogs. Some of this is good coverage that contributes to the science and policy debate sensibly. Some of it, however, is outrageous. We attach a few links below…..you can be the judge!