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As the world experiences long heatwaves, data shows that many cities already live in a world that's much hotter than 50 years ago 

A new analysis by the Daniels Family Sustainable Energy Foundation shows that many cities already experience living conditions feared for most of the world in a few decades. Scientists and sustainability experts refer to it as a "two-degree world," where average temperatures rise by 2º (C). 

One of the reasons cities experience more extreme temperature is the "heat island effect." This is an excessive warming of urban areas due to the lack of forest or green spaces. Cement, asphalt, metal and glass absorb and retain heat much longer than natural environments. If you touch black pavement in the middle of a sunny day, it will be much hotter than if you touched a field of grass. That's due to color (darker colors absorb more heat) and the inability of most building materials to reflect heat effectively (see below for our innovations in this field).

Summer temperature anomaly—how much hotter it is, in degrees ºC, compared to normal summer average—in cities of the world estimated to have a severe "heat island effect." Data from Climate Reanalyzer, Climate Change Institute, University of Maine. Temperatures were selected for summer or hot season in each city (months abbreviated in legend), then compared to a 30-year average (1951-81) with 10-pt binomial smoothing. 

As the graph shows, cities such as Madrid, Spain, and even Denver, Colorado, already reach 2ºC above normal in summer months, on average. Madrid stands above most cities as one of the worst heat islands in the world, on track to set new records with current heat waves. Understanding what "average" means is key. Anyone who's ever received a bad grade in college knows how an extreme event such as a C or a D can move a grade point average, forcing the student to have to balance out the bad grade with a straight As to return to a respectable GPA. In other words, to move an average 2º many extreme events are needed—days that go well beyond 2º hotter than average.

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Graphic representation of the "heat island effect:" how cities and urban areas are hotter than forested or rural areas, due to building materials absorbing heat at a much higher rate than natural environments. Illustration: EPA and USGS.

Those temperature extremes are the heatwaves we've been hearing about in the news so often, recently. Cities in the developed world, such as Denver and Madrid, have the luxury of air conditioning and a power grid that, so far, can support the ever increasing energy demand. However, many cities in the graph above—such as Manila, Karachi, Mumbai, Kuala Lumpur, Lagos, together home to more than 54 million—do not have the energy grid or air conditioning resources to keep the population safe from extreme heatwaves. Unfortunately, air conditioners—while cooling indoor spaces of the lucky few—also heat up outdoor areas with their exhausts, while consuming energy that is produced mostly by fossil fuels.

The only solution to such a crisis is to reduce energy demand, not by shutting off air conditioners, but by needing them less, thanks to improved heat management made possible next-generation heat abatement technology that can be implemented quickly and economically in regions of the world that are not equipped with air conditioners or power grids necessary to sustain them. This is the only feasible bridge solution to mitigate climate change in the short term and save the lives of those exposed to extreme heat, who are, by and large, socioeconomically disadvantage, as is often the case with the majority of the victims of climate change.

temp anomalies ref 1951-1981 copy.jpg
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