Urban Heat Islands and Record Heat in Las Vegas: Unpacking the Causes Beyond Climate Change
Las Vegas has recently experienced a record-breaking heatwave, with temperatures reaching unprecedented highs spurring absolutely ridiculous headlines like this from The San Francisco Chronicle…
This event has reignited discussions about the causes of such extreme heat, with arguments focusing on urban expansion, population growth, and the Urban Heat Island Effect (UHIE), rather than solely attributing it to increased greenhouse gas (GHG) emissions. By examining the ten hottest days in Las Vegas history and the context of urban development, we can better understand the primary factors contributing to these extreme temperatures.
On July 6, 2024, Las Vegas recorded its highest temperature ever, reaching 120°F (48.8°C). This surpasses previous records and prompts a closer examination of historical temperature trends and the contributing factors to such extreme heat.
To understand the trends, we can look at the ten hottest days in Las Vegas history:
- 120°F (48.8°C) on July 6, 2024
- 117°F (47.2°C) on June 30, 2013
- 117°F (47.2°C) on July 19, 2005
- 116°F (46.7°C) on July 24, 1942
- 116°F (46.7°C) on July 17, 2005
- 116°F (46.7°C) on July 15, 2023
- 115°F (46.1°C) on June 20, 2017
- 115°F (46.1°C) on July 15, 2020
- 114°F (45.6°C) on July 8, 2002
- 114°F (45.6°C) on July 19, 2006
Notably, several of these records were set decades ago, with some dating back over 80 years. This longevity of high-temperature records suggests that factors other than increases in GHGs are significantly influencing these temperatures.
The Urban Heat Island Effect (UHIE) is a phenomenon where urban areas experience higher temperatures than their rural surroundings due to human activities and infrastructure.
The following factors contribute to UHIE:
Concrete and Asphalt: Urban surfaces like roads and buildings absorb and retain heat, increasing local temperatures.
Lack of Vegetation: Green spaces and trees cool the air through evapotranspiration, a process significantly reduced in densely built environments.
Human Activities: Energy consumption for air conditioning, vehicles, and industrial processes generates additional heat.
Las Vegas has undergone rapid urban expansion and population growth over the past few decades. The city’s population has increased from around 273,000 in 1980 to over 2.3 million in 2020. This urban sprawl has replaced natural desert landscapes with heat-absorbing infrastructure, significantly contributing to local temperature rises.
The temperature record in Las Vegas was set at McCarran International Airport (now Harry Reid International Airport), which has seen substantial growth over the decades. Initially a modest regional facility, the airport has expanded significantly alongside the city’s population boom and tourism industry.
The airport handled nearly 1 million passengers annually in the 1950s, a number that surged to over 50 million passengers by 2019, making it one of the busiest airports in the United States.
This expansion has included multiple runway extensions, terminal upgrades, and increased tarmac area, all contributing to the Urban Heat Island Effect by replacing the natural desert landscape with heat-absorbing infrastructure.
The proximity of temperature monitoring stations to these developments likely amplifies recorded temperatures, further underscoring the impact of urbanization on local climate conditions
While GHG emissions likely play a role in global climate change, the localized effect of UHIE in cities like Las Vegas is significantly more pronounced.
The slow pace at which new temperature records are set, despite accelerating global CO2 levels, suggests that urban factors are significant contributors to extreme heat events.
The assertion that GHGs, particularly CO2, are solely responsible for the record temperatures in Las Vegas is overly simplistic and ignores significant local factors.
Despite the continuous rise in global CO2 levels, which have accelerated over the past decades, temperature records in Las Vegas are not broken annually.
If CO2 were the primary driver of extreme heat, we would expect a more consistent upward trend in temperature records, correlating directly with rising CO2 levels. Instead, several of Las Vegas’s highest temperatures were recorded decades ago, such as 116°F in 1942.
This indicates that other factors, such as urbanization and the UHIE, play a more crucial role in these temperature extremes. Rapid urban expansion and increased heat-retaining infrastructure, like concrete and asphalt, have significantly contributed to localized heating.
Therefore, attributing these record temperatures primarily to GHG emissions overlooks the substantial impact of local environmental changes and urban development.
See more here Substack
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Urbanization is the sole cause of the new highs . . .
We know that no gas molecule of the open system, as our atmosphere is, can possibly control temperature.
We know that there are two very different mechanisms that drive dynamics of CO2 exchange between air–water and air-biomass and therefore there is no such thing as global levels of CO2. Levels of CO2 above the water mass, covering 70% of the Earth surface is controlled by solubility of CO2 in water which is solely driven by temperature; while levels of CO2 above the biomass that covers most of the land surfaces is solely driven and controlled by photosynthesis.
We know that all the knowledge about the physical world comes from experiments that can be validated and not from calculations that cannot be validated. And yet, everything about man-made global warming is about calculations and NOTHING about measurements.
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