Record-breaking heatwaves this summer have claimed thousands of lives around the world, highlighting how high temperatures can quickly pose serious health risks.
But it’s not just high or low temperatures that matter: it’s how many degrees the temperature changes over the course of a day, and the daily temperature changes themselves, which pose health risks.
Studies have shown that days with higher than normal temperature fluctuations can lead to more asthma attacks, more hospitalizations for respiratory and cardiovascular diseases, and higher overall mortality rates. One study based on data from 308 cities from 1972 to 2013 estimated that 2.5% of deaths during that period were attributable to high daily temperature fluctuations.
Although humans can live over a wide range of ambient temperatures, rapid changes in temperature place strain on many of the body’s systems, including the immune, musculoskeletal and cardiovascular systems, particularly on young children and the elderly, who are more vulnerable to harsh climates.
To get a better understanding of where temperature fluctuations are greatest and who is most affected, we mapped daily temperature changes at a neighborhood scale across the United States. Our results highlight how a legacy of poverty and discriminatory practices leaves racial minorities and low-income residents in areas with greater temperature variations throughout the day.
What influences temperature change?
Large differences in daytime and nighttime temperatures are common in some areas, such as the southwestern United States, but topography and the urban heat island effect can cause temperatures to vary over short distances.
For example, the ocean can absorb a lot of heat before the water heats up, helping to buffer rapid temperature changes. The Los Angeles metropolitan area is a good example of this: Santa Monica, a coastal area of Los Angeles County, experiences much smaller temperature changes than inland areas of the county, such as Downtown Los Angeles.
Compare maps of tree cover and temperature differences in New York City
It shows the cooling effect of parks and neighborhoods with lots of trees.
NASA/USGS Landsat
Green spaces like forest parks can also help reduce temperature fluctuations: Trees and plants in urban areas keep neighborhoods cooler, reducing temperature fluctuations.
Who will face the biggest temperature changes?
Using NASA satellite data from 2000 to 2017, we matched daily temperature variations in different census tracts with the U.S. Census Bureau’s American Community Survey demographic data to examine how race/ethnicity, income, and age affect exposure to daily temperature variations in all 50 states.
Of the three demographic factors, exposure to daily temperature changes was found to be most unequal by race and ethnicity, followed by income. Age had the least effect.
Racial differences: A map of average daily temperature variation by race in each state. The darker the yellow squares, the greater the inequality. In each state chart, blue represents the white population and red represents the non-white population. Shengjie Liu, CC BY-ND
In Rhode Island, the state with the largest difference, Hispanic and black residents experienced an average daily temperature change of 31.2 degrees (17.3 degrees) in May, while white residents experienced an average daily temperature change of 25.8 degrees (14.3 degrees) — a difference of 5.4 degrees (3 degrees) between the two groups.
The temperature difference between low-income and high-income residents in Rhode Island was 28.6 F (15.9 C) and 24.5 F (13.6 C), a difference of 4.1 F (2.3 C). The difference between age groups was only 1.8 F (1 C).
Income disparities: A map of average daily temperature variation by income level for each state. The darker the yellow box, the greater the disparity. For each state, blue represents high-income groups and red represents low-income groups. Shengjie Liu, CC BY-ND
Of the 50 states, 46 showed significant differences by race and ethnicity, 39 by income, and 15 by age. In general, daily temperature variations were greatest in Western states, especially in late spring and summer.
The fact that ethnic minorities live in areas that experience disproportionately greater temperature changes underscores another dimension of inequality in vulnerability to climate change.
Climate change is increasing temperature fluctuations
There is also evidence that temperature changes will become more dramatic over time. From the 1950s to the 1980s, records show that global temperature changes were decreasing. But since the 1990s, studies have shown that temperature changes have been increasing, with the potential to affect all life on Earth.
The interactive map available at the following link shows the average daily
Temperature changes by race and ethnicity in each state: skrisliu.com/dtvus/map.html, CC BY
Research shows that these temperature fluctuations will continue to grow as greenhouse gas emissions (mainly from burning fossil fuels) continue to increase the planet’s temperature. And with this increase comes more premature deaths. The Intergovernmental Panel on Climate Change’s (IPCC) highest emissions scenario (RCP 8.5), which projects a world that burns increasingly more fossil fuels, predicts future temperature fluctuations of as much as 2.9 degrees Fahrenheit (1.6 degrees Celsius) by the end of the century.
There are ways to mitigate the risks, starting with reducing greenhouse gas emissions from vehicles, power plants, livestock, etc.
Communities can also take steps to reduce the exposure of low-income and minority neighborhoods to temperature changes by planting more trees or using thin coatings on roofs to reflect heat from buildings, and they can provide assistance programs to help people who have difficulty installing heating and cooling systems or accessing electricity.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
