The title of this year’s report points to the risk that, due to climate change, children born today may have to live their lives in a world harshly different from what previous generations have experienced.
The team behind the Lancet Countdown uses a set of indicators to track progress and failures across five key domains, spanning from the physical impacts of increasing temperatures and other extreme events, via adaptation and mitigation efforts, to the economic losses of damage and, finally, to the public and political engagement and responses to the challenges ahead.
Human populations are concentrated in areas most exposed to warming
Several of the indicators that are being monitored by the Lancet Countdown are highly relevant to the topics covered in EXHAUSTION. Especially, the very first indicators, related to heat and health, are directly in line with our research. The 2019 report finds that the population-weighted temperatures on Earth, i.e. the average temperatures weighted by the number of people experiencing the different levels, are growing at a substantially faster pace that the global average temperature rise. In fact, the increase in population-weighted mean summer temperature over the period 1986–2015 was four times higher than the global average change, 0.8⁰C versus 0.2⁰C. This is related to the unfortunate fact that human populations are concentrated in the areas most exposed to warming. In EXHAUSTION we are adding new evidence on the health risks to warming, by projecting how a range of indices of human exposure to hot temperatures may develop under alternative climate scenarios (Schwingshackl et al. (work in progress).
Increasing heatwave exposure among older populations
The issue of vulnerable populations is a core element in the Lancet Countdown. Regarding heat stress, older adults are among the groups that are particularly vulnerable. Older adults, defined as people >65 years of age, suffer disproportionally more than younger people during extreme temperature events due to a number of factors including lower efficiency of their thermoregulatory mechanisms, enhanced prevalence of chronic diseases, potential side effects of medications, cognitive impairment, and limited mobility (Astrom et al., 2011; Basu, 2009; Vicedo-Cabrera et al., 2016). Along with global warming, the populations of many countries are ageing. Thus, the Lancet Countdown has defined a separate indicator to track the change in heatwave exposure among older populations. A heatwave exposure event is defined as one heatwave experienced by one person older than age 65 years. The report finds that in 2018 the number of such events was seven times higher than the average number of events during 1986–2015. This increase is due to heatwaves hitting densely inhabited regions like India, Northern China, Japan, the Korean peninsula, and central and northern parts of Europe. In EXHAUSTION, we use a broad range of health data, including time-series death counts and long-term cohort data, to further dig into the question what are the most vulnerable groups in a European context, and what factors make some individuals more sensitive to hot temperatures.
New indicators on wildfires and air pollution co-benefits
In addition to previous indicators, the Lancet Countdown 2019 report introduces some new indicators. Two of these are related to, respectively, the health effects of wildfires and the economic cost of change in mortality associated with air pollution, both being core topics of the EXHAUSTION project as well. The risk of wildland fires increases during periods of extreme heat and decreasing precipitation (Kovats et al., 2014). In addition to the direct, sometimes deadly, effects of thermal injury from wildfires, these fires cause intense air pollution (Baker et al., 2016). Hence, these two indicators are interrelated. The unit applied to monitor wildfire exposure in Lancet Countdown is a wildfire event, defined as one person experiencing one day of wildfire. The report finds that the annual mean number of person-days of wildfire exposure is increasing, and that the increase in some countries is far greater that the global mean increase. The largest increase in wildfire person-days was reported for India, China, the Democratic Republic of Congo, Iraq, and Mexico – thus across different regions of the world. A positive development, with substantial reductions, was also reported, including for Spain and Russia. So far, the Lancet indicator for wildfires does not include the health risks of wildfire smoke. In the EXHAUSTION project, we aim at quantifying potential future changes in cardiopulmonary mortality in Europe from changes in wildfire emissions. While difficult to disentangle, we also aim at investigating whether air pollution from wildfires may be particularly harmful, which has been indicated in previous studies (Analitis et al., 2012; Faustini et al., 2015; Wu et al., 2018).
As of today, air pollution is the largest environmental health risk factor globally, with an estimated 2.9 million premature deaths due to ambient air pollution alone. In addition comes the health burden for those who are still without access to clean household fuels for their daily cooking and heating, in total almost 3 billion people. Improved air quality reduces mortality and diseases, and thus leads to reduced costs for the society that can substantially counterbalance climate policy costs (Aunan et al., 2007; Markandya et al., 2018).
Adaptation and mitigation – hand in hand?
The world is not on track to reaching the goals of the Paris Agreement. Thus, careful planning of adaptation measures is required. The Lancet Countdown tracks progress in adaptation planning and local risk assessment efforts, reporting a small, but steady, increase in such activities. The challenge is to develop adaptation measures that have multiple benefits and do not counteract GHG mitigation as such. A new indicator introduced in the 2019 report focuses on air conditioning (AC) as an adaptive measure to heat mortality. On the positive side, AC was found to have reduced heatwave-related mortality by nearly a quarter compared to a hypothetical absence of AC. However, AC and the energy needed to run the installations (unless being renewable energy), contribute to GHG emissions, air pollutants, and enhance the urban heat island effect. In EXHAUSTION, we are investigating how alternative measures that do not counteract GHG mitigation, e.g., expansion of green and blue spaces and urban architectural design may contribute to reducing heat exposure in European cities (Burkart et al., 2015; Monteiro et al., 2012). Sustainable solutions, both in terms of mitigation and adaptation, must be found to ensure that children born today can enjoy a healthy environment.
The full report can be read here.
References
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