hot summer

Hydroclimate whiplash

January 30, 2025 By EarthWise Leave a Comment

Hydroclimate whiplash is a term that describes rapid swings between intensely wet and dangerously dry weather. Global weather records show that the occurrence of hydroclimate whiplash has increased by 31% or as much as 66% since the mid-20th century.

California’s experience is a prime example of this phenomenon. After years of severe drought, dozens of atmospheric rivers subjected the state to record-breaking amounts of precipitation in the winter of 2022-23. A second extremely wet winter in the southern parts of the state the following year resulted in the growth of abundant amounts of grass and brush. 2024 saw a record-hot summer which was then followed by a record-dry start to the 2025 rainy season. The result was the catastrophic wildfires in the Los Angeles area in January.

Research by UCLA climate scientists explains that the primary driver for the increasing occurrence of hydroclimate whiplash is the expansion of the atmospheric sponge – that is, the growing ability of the atmosphere to evaporate, absorb and release water. Every degree Celsius that the planet warms increases this ability by 7%.

The global consequences of hydroclimate whiplash include not only floods and droughts but also the increased danger of whipsawing between the two, leading to the bloom and burn cycle that California recently faced. The risk of wildfire is twofold: first by increasing the growth of flammable grass and brush in the months before the fire season, and then by drying it out to dangerous levels with extremely warm and dry weather.

**********

Web Links

Floods, droughts, then fires: Hydroclimate whiplash is speeding up globally

Photo, posted January 13, 2025, courtesy of Victor Guillen / USDA Forest Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Heatwaves And Bird Populations | Earth Wise

July 28, 2022 By EarthWise Leave a Comment

The increased occurrence and intensity of heatwaves around the world is affecting most living things. Heatwaves can be lethal for warm-blooded animals – including people – but the behavioral and physiological effects of sub-lethal heat have not been extensively studied. Heat that doesn’t kill animals can still impact their ability to adapt and thrive as the climate changes.

Researchers at the University of Tennessee in Knoxville recently published a new study that examined how heat impacts the behavior and physiology of Zebra finches. They exposed the birds to a four-hour heat challenge, similar to what wild birds might experience during a hot summer afternoon. They used Zebra finches because these songbirds experience extreme temperature fluctuations in their native Australia.

The team measured heat effects on thermoregulatory behavior, how heat alters gene activity in tissues critical to reproduction, and how heat affects the area of the brain that controls singing. The evidence showed that even sub-lethal heat can change a bird’s ability to reproduce both from the functioning of its reproductive system and its motivational circuits for mating behavior.

The researchers found that some individual birds were better able to minimize the physiological effect of heat, for example by adjusting their behavior to dissipate heat. Some individuals and even some species are likely to be able to adapt to increasingly extreme temperatures.

Global bird populations have been dramatically declining over the past few decades. Previous studies have shown that birds sing less during heatwaves. Based on the new study, it appears that increasing heatwaves may be a potential underlying mechanism for the decline in bird populations.

**********

Web Links

New Research Suggests Heat Waves Could Lead to Avian Population Decline

Photo, posted August 22, 2017, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Antarctica’s Hot Summer | Earth Wise

May 1, 2020 By EarthWise Leave a Comment

The Southern Hemisphere’s recent summer brought drought, heatwaves and bush-fires that ravaged Australia. At the same time, Antarctica experienced a summer of extreme weather.

In East Antarctica, the Casey research station in the Australian Antarctic Territory had its first heatwave event, recording extreme maximum and minimum temperatures over three consecutive days in January. Record high temperatures were also reported at bases on the Antarctic Peninsula.

The Casey station recorded a record high maximum temperature of 49 degrees Fahrenheit and a record overnight low of 36 degrees. In February, Brazilian scientists reported a high temperature of 69 degrees at Marambio, an all-time record for Antarctica.

Ecologists say that the hot summer would most likely lead to long-term disruption of local populations, communities, and the broader ecosystem. That disruption could be both positive and negative.

Most life in Antarctica exists in small ice-free oases and depends on melting snow and ice for a water supply. Melt water from the warming temperatures will lead to increased growth and reproduction of mosses, lichens, microbes and invertebrates.

However, excessive flooding can dislodge plants and alter the composition of communities of invertebrates and microbial mats. If the ice completely melts early in the season, then ecosystems will suffer drought for the rest of the season.

Extreme events often have impacts for years after the event. There will be long-term studies of the areas affected by the recent Antarctic heat wave. Such extreme events associated with global climate change are predicted to increase in frequency and impact, and even the most remote areas of the planet are not immune to them.

**********

Web Links

Antarctica’s summer of extreme heat

Photo, posted January 30, 2014, courtesy of Andreas Kambanis via Flickr

Earth Wise is a production of WAMC Northeast Public Radio.