Escalating Heat Waves and Their Causes
Summary:
- Heat waves are intensifying and becoming more prolonged.
- High-pressure systems are a primary cause of heat waves.
- Climate change exacerbates these conditions.
- The US Southwest is particularly affected.
- Elevated nighttime temperatures pose serious health risks.
Heat waves are now more intense and extended. This week, an examination of temperature maps revealed a bright red swath stretching from Baja California to Canada’s Northwest Territories. For an entire week, scorching temperatures blanketed the West Coast. Palm Springs hit an all-time high of 124 degrees, and Death Valley saw thermometers read 128 degrees for consecutive days. This extreme heat came just a month after a prior heat wave pushed Central Valley temperatures into the triple digits before the official start of summer. These patterns prompt questions about the root causes of such extreme heat.
High-Pressure Systems and Heat Domes
The main driver of heat waves is a high-pressure system in the upper atmosphere, leading to two primary outcomes:
- Cloud Suppression: High pressure restricts cloud formation, allowing the midsummer sun to heat the ground swiftly.
- Blocked Convection: This pressure acts like a lid, preventing the hot air from rising and contributing to surface heating.
This phenomenon, often referred to as a “heat dome,” traps hot air at the surface. Occasionally, as seen across the entire West Coast, heat domes get stuck due to interactions with nearby pressure systems, extending heat waves and worsening their impact on health.
Climate Change Impact
Climate change partially underpins every heat wave. Clear skies that once allowed for nighttime cooling now trap more heat.
Over the last century, human-emitted gasses have acted like a secondary heat dome, suppressing heat radiation and resulting in even higher temperatures.
The danger of heat waves varies by region, with the Southwestern U.S. experiencing a rapid increase in both intensity and frequency. Moreover, nighttime temperatures are rising faster than daytime highs. Over the past 50 years, summer low temperatures have escalated more than twice as quickly as highs. This pattern raises the alarm since nighttime temperatures above 80 degrees severely impact human health by disrupting the natural cooling process during sleep.
Understanding the roles of high-pressure systems and climate change is critical as heat waves grow more severe and frequent. The escalating temperatures, particularly in the US Southwest, and the increasing nighttime warmth pose significant health risks. Addressing these contributing factors is essential for mitigating the impact on human health and well-being.