The debate concerning the effects of climate change on human activity has intensified in recent years. It is well recognized that climate change has increased global temperatures over the past few decades, but only recently have meteorologists explored whether temperature variability - fluctuations over the long-term local temperature mean -  has also increased over time (Thompson et al. 2013; Thornton et al. 2014; Wang and Dillon 2014). These enquiries, though, are in their very early stages and an accurate picture of how temperature variability can affect human activity remains unclear.

Institutions all over the world are becoming more interested in the potential effects of temperature variability on health. For instance, the European Research Framework Programme states that exploring these effects “[…] is particularly important for low income countries, where the influence of climate variability on health is widely recognized and where economic development is severely affected by disease in humans and animals.” There is, however, limited evidence on how climate variability can affect human activity and, in particular, human health.

Motivated by this lack of evidence, in a recent study we examine whether and how exposure to a higher temperature variability while in utero affect the health status of newborns. Attempting to understand the effect of temperature variability on the health status of vulnerable populations, such as newborns, is important for re-directing and prioritizing public resources aimed at preventing and treating climate change induced diseases. A more accurate assessment of such impacts could improve the reliability of predictions of future health burdens caused by climate change, which would allow health stakeholders to make cost-effective decisions regarding long-term health policies.

Recent studies have documented a negative impact of in utero exposure to high temperature levels on fetal health (Dêschenes et al. 2009; Andalón et al. 2014). Rainfall shocks (Pereda et al. 2014; Rabassa et al. 2014; Rocha and Soares 2015), natural disasters (Simeonova 2011; Currie and Rosin-Slater 2013), and vector borne diseases (Barreca 2010), all consequences of climate change and increasing temperature levels, have also been found to impair the health status at birth.

When examining the effects of temperature variability on the health status of newborns in the Andean region, we find that exposure to a temperate one standard deviation relative to the municipality’s long-term temperature mean during pregnancy reduces birth weight by 20 grams and increases the incidence of low birth weight (birth weight being less than 2,500 grams as defined by the World Health Organization) by 10 percent. We also find that children exposed to a higher temperature variability during pregnancy were more likely to be small when compared to other newborns, based on the report of their mothers.

Another interesting result is that fetal health is only affected by positive (and not by negative) distributional changes in the air temperature during pregnancy. Figure 1 depicts this result. We find that birth weight is reduced by 20 grams when the average temperature during pregnancy was observed to be between 0.5 and 1.5 standard deviations above the municipality’s historical temperature mean, and is reduced by 70 grams when the average temperature level during pregnancy was above 1.5 standard deviations relative to the municipality’s historical temperature mean. 

Further results also indicate an increase in food insecurity and a decrease in prenatal health care when a high temperature variability is observed. These results may explain some of the channels through which fetal health is affected by climate variability.

But beyond the actual effects of temperature variability on fetal health, our results resemble only a partial picture of the true consequences of climate change. If the current forecasts of future temperature levels are met, the health burden of climate change induced diseases will be carried out by future generations. As Figure 2 shows, current estimates predict that over 40 percent of children born in the next decades will be exposed to temperatures over 1.5 standard deviations relative to the normal local temperature levels, assuming the same geographical and seasonal distribution of births as well as a constant natality rate.

Based on these predictions, it is not unreasonable to think that the prevalence of low birth weight in the Andean region will increase by 2050, with climate change being its leading cause. The consequences of low birth weight have been well documented in the literature (see, for example, Black et al. 2007): poor health status in adulthood, lower educational attainment, and lower earnings to name only a few. That being said, it is not only expected that climate change will affect future generations via adverse health status at birth, but will also affect the economy through its effects on human capital accumulation.

We doubt that the effects of climate change on human health can be fully explained by changes in local average temperatures across time. A growing stream of literature in the environmental sciences is becoming more interested about the unpredictability of future weather conditions brought about by climate change; namely, climate variability. However, there is not a clear picture on how climate variability can affect human activity and, in particular, human health. Regardless of the advancement of these studies, we believe that designing mitigation plans and adaptation strategies for current populations in response to climate change will be one of the greatest challenges of the first half of this century.

References

1. Andalón, M., Azevedo, J. P., Rodriguez-Castelán, C., Sanfelice, V. and Valderrana, D. (2014). “Weather Shocks and Health at Birth in Colombia”. IDB, Policy Research Working Paper 7081.

2. Barreca, A. I. (2010). “The long-term economic impact of in utero and postnatal exposure to malaria”. Journal of Human Resources, Vol. 45(4), p. 865-892.

3. Black, S., Devereux, P. J. and Salvanes, K.G. (2007). “From the Cradle to the Labor Market? The Effect of Birth Weight on Adult Outcomes”. Quarterly Journal of Economics, Vol. 122(1), p. 409-439.

4. Currie, J. and Rossin-Slater, M. (2013). “Weathering the storm: Hurricanes and birth outcomes”. Journal of Health Economics, Vol. 32(3), p. 487-503.

5. Deschênes, O., Greenstone, M. and Guryan, J. (2009). “Climate change and birth weight”. American Economic Review, Vol. 99(2), p. 211-217.

6. Molina, O. and Saldarriaga, V. (2016). “The Perils of Climate Change: In Utero Exposure to Temperature Variability and Birth Outcomes in the Andean Region”, Mimeo.

7. Pereda, P. C., de Menezes, T. A. and Alves, D. (2014). “Climate Change Impacts on Birth Outcomes in Brazil”. IDB, Working Papers Series No. IDB-WP-495.

8. Rabassa, M., Skoufias, E., and Jacoby, H. (2014). “Weather and child health in rural Nigeria”. Journal of African Economies, Vol. 23(4), p. 464-492.

9. Rocha, R. and Soares, R. R. (2015). “Water scarcity and birth outcomes in the Brazilian semiarid”. Journal of Development Economics, Vol. 112, p. 72-91.

10. Simeonova, E. (2011). “Out of sight, out of mind? Natural disasters and pregnancy outcomes in the USA”. CESifo Economic Studies, Vol. 57(3), p. 403-431.

11. Thompson, R. M., Beardall, J., Beringer, J., Grace, M., and Sardina, P. (2013). “Means and extremes: building variability into community‐level climate change experiments”. Ecology letters, Vol. 16(6),p. 799-806.

12. Thornton, P. K., Ericksen, P. J., Herrero, M., and Challinor, A. J. (2014). “Climate variability and vulnerability to climate change: a review”. Global change biology, Vol. 20(11), p. 3313-3328.

13. Wang, G., and Dillon, M. E. (2014) “Recent geographic convergence in diurnal and annual temperature cycling flattens global thermal profiles” Nature Climate change 4, p. 998-992.