Hot in Denver: Heat Waves (1)

In the summer I live in Boulder, Colorado and this summer has been hot and dry. In fact in both Denver and Boulder the record for number of days above 90 degrees F has been broken. This is a sustained heat wave, not a heat wave where daily records fall one right after another.

Heat waves that impact human health are generally listed as the environmental condition which causes the most deaths annually. From a human health point of view, they are primarily an urban problem. From the point of view of the climate scientist, heat waves are expected to increase in intensity, frequency and duration. That is, it will be hotter, more often, and the heat will last longer.

Examination of the problem of heat waves is useful for understanding how climate change fits in. Human health is currently impact by excess environmental heat. Therefore a warming climate is likely to amplify the risk, but the fact that there is heat related health impacts is NOT a consequence of climate change. Heat waves, like many other impacts, represent a class of problem that already exists that is likely to be amplified by climate change.

Also like many other problems if your job was to reduce the deaths associated with excess environmental heat, then your motivation to reduce carbon dioxide emissions would be very low. Any impact on heat waves from reducing CO2 emissions would be realized far in the future. The most effective ways to lessen the health threats associated with heat waves are improved heat-health warning systems, better communication of threat conditions and proper responses to affected communities, and provision of a way to stay cool. Therefore, if your job was to reduce the deaths associates with heat waves, you would concentrate your efforts on developing the societal capabilities to warn, taking action, and protecting vulnerable communities.

Figure 1 provides a schematic for thinking about how to improve our abilities to address heat related health threats. There are three basic types of information. The first type is environmental information that informs that there is the likelihood that heat-related health threats are present. The second type of information is geographical information. An important ingredient of determining where heat is a threat is the built environment, city or country, park or parking lot? Knowing the characteristics of the built environment is important, as is a way to determine, for instance, just how hot it might it be in a particular neighborhood. Then once it is known how hot it is, then the health impact is strongly related to knowing if the population is vulnerable. This is often related to wealth and education. Do people have air conditioners or a way to get to a cooling center? Do people see themselves as vulnerable? Do people get the information that dangerous heat is likely? Are people acclimated to high heat?




Figure 1. A schematic of the types of information needed in order to evaluate and respond to environmental heat threats.


From the perspective of someone concerned about climate change and heat waves, then you anticipate how climate change will impact the margins. Will heat health warnings be needed at more northern cities? Will they need to be initiated earlier in the year? Will more facilities be needed to cool people? Strategies to build resilience follow from urban planning, for instance, the use of parks, and policy such as use of roofing materials to moderate urban warming. These strategies are all called for in the absence of climate change; climate change is an additional increment.

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Some previous heat wave blogs

Letter from India
Heat, Flood, and Fires
Records and Patterns