2020 stands out as a year of staggering political turbulence in the United States. With over 340,000 deaths from COVID-19 in 2020 alone, widespread Black Lives Matter protests and a monumental presidential election, it may seem easy to forget the series of unprecedented natural disasters experienced over the year. Intense heatwaves were recorded nationally, major wildfires spread across the West Coast and a record-breaking hurricane season ravaged southern and western states. These natural disasters should not be treated as threats separate from the year’s political events; hazards such as heatwaves are also intrinsically political as patterns of vulnerability are strongly influenced by economic inequalities and legacies of racism. As the effects of climate change alter the frequency and intensity of extreme weather events, these climate injustices will be further exacerbated unless the unequal effects of natural hazards are addressed.
Although the effects of climate change are complex and spatially variable, extreme heat is a simple and deadly consequence of anthropogenic warming, accounting for around a fifth of deaths from natural hazards in the United States. Reports suggest that more deaths may be caused by extreme heat in the country than previously estimated, accounting for an estimated average of 5,600 per year. This is a growing public health concern, as human-induced climate change is expected to drastically increase the prevalence of extreme heat across the country. If no action is taken to reduce anthropogenic greenhouse gas emissions, it is predicted that there will be four times the number of days with temperatures greater than 40oC by mid-century, increasing in the number of people experiencing more than 30 days of the year at 40oC from around 900,000 to 90 million — nearly a third of the U.S. population. By the end of the century, this could result in more than 60% of urban areas experiencing at least 30 days where temperatures exceed 40oC. These extreme temperatures will increase the overall risk of mortality and burden health services, energy systems and water provision.
Although heatwaves are related to temperature extremes, there are both local and regional inequalities that place people of colour at greater risk of extreme heat due to legacies of slavery on settlement patterns and the effect of discriminatory housing policies. At a regional scale, counties with greater proportions of Black residents (above 25%) experience 18 more days above 38oC annually in comparison to counties with fewer than 25% Black residents, largely due to the influence of slavery on historic settlement patterns. In addition to regional patterns, heatwaves can be intensified by heating effects at local scales due to the presence of heat-retaining materials and a lack of shade and vegetation — a phenomenon known as the urban heat island effect. A study using a land cover data set including tree canopy and impervious land surfaces found that people of colour were more likely to live in areas of increased land cover-related heat risk, with non-Hispanic Black residents experiencing the greatest risk — 52% greater compared with non-Hispanic white residents.
Much of the disparity in local heating effects can be attributed to ‘redlining’: a practice common in the 1930s, whereby federal officials diverted investment from urban areas with Black residents by marking them as hazardous areas, preventing housing loans and investment in green space. A report in the journal Climate last year studied over 100 urban areas in the US and found that 94% showed greater temperatures in neighbourhoods that were formerly redlined. The average temperature difference was 2.6oC but in some areas the difference between redlined and non-redlined neighbourhoods was as much as 7oC, highlighting just how stark these inequalities can be.
These extreme temperatures place Black and minority communities at greater risk of heat-related mortality. They also exacerbate existing economic equalities, since individuals more at risk are those without air conditioning or with greater occupational exposure to extreme heat, such as agricultural workers. The effects of these inequalities are not insignificant: in 1995, the Chicago heatwave killed over 700 people, with African American deaths constituting a disproportionate contribution to the total. Events like these are set to become increasingly frequent due to anthropogenic climate change, and the predicted increased frequency of other extreme weather events, such as hurricanes, may exacerbate the effects of extreme heat events. For example, in 2017 hurricane Irma in Florida coincided with temperatures around 40oC, causing heat-related deaths because of the lack of air-conditioning due to the power outages associated with the hurricane.
So how can these inequalities be addressed? Confronting the legacy of structural racism within embedded patterns of settlement and housing standards may seem like a tough feat. Nevertheless, investment in heat-smart infrastructure, public housing improvements, warning systems, more robust power systems and local heat adaptation and emergency response plans could effectively develop the climate resilience of communities at risk of extreme heat. In conjunction with adaptation-based responses, rapidly reducing emissions by addressing energy consumption, vehicle emissions and efficiency standards are essential to mitigate the magnitude and frequency of future heatwaves.
Although the practice of redlining is specific to the U.S., the urban heat island effect disproportionately impacts low-income communities around the world, highlighting the global importance of climate justice on a local scale. Often climate justice is evoked as a concept to explain global inequalities relating to climate refugees and the impact of climate change on economically developing countries. Of course, this is an essential part of the debate, but intraregional inequalities like those in the US demonstrate the importance of addressing climate justice issues at national and regional scales if we are to tackle climate justice effectively at all levels.