In the western United States, fear of another hellish summer

Cracked soils as far as the eye can see, dry rivers, vegetation reduced to nothing and the thermometer that exceeds 50 ° C. The western United States, primarily California, is experiencing a new episode of drought aggravated by an intense heat wave. While summer didn’t start until Monday, the California governor has already issued emergency measures in 41 of the state’s 58 counties.

On Wednesday 23 June, AFP unveiled the conclusions of the new report of the Intergovernmental Panel on Climate Change (IPCC). According to them, whatever the rate of reduction of greenhouse gas emissions, the devastating impacts of global warming on nature and humanity will accelerate by 2050. However, faced with the situation in the West America, the scientific community is unanimous: the impacts of climate change are already painfully palpable there with concrete consequences for the populations.

A drought “exacerbated by global warming”

Composed of immense dry and desert plains, “drought is a normal phenomenon in California”, points out Philippe Ciais, researcher at the Laboratory of Climate and Environmental Sciences, contacted by France 24. “We also know that the region experienced a period of drought in the 1400s, which is believed to have played a role in the demise of some Indian civilizations. “

“But all the studies agree that climate change exacerbates the phenomenon. It makes drought episodes more intense, but also longer,” he continues. A study published in 2020 in the journal Science estimated that the human activity responsible for climate change had accentuated the impact of drought in the region by 46% between 2000 and 2018.

And this year, the episode promises to be particularly intense. According to the latest data posted on June 17 by the Drought Observatory, 97.5% of the territory of the great West is in a state of drought, against 65% in 2020. Even more worrying, 55% of the region is in a state of “extreme” drought and 27% in an “exceptional” situation. By way of comparison, only 2.3% of this territory was concerned by this last category in 2020.

In particular, not very abundant snowfall during the winter. At 1^er April, which traditionally marks the end of snowfall, supplies in the neighboring Sierra Nevada – the source of about a third of the water used in California – were only about 60% of the average.

50.5 ° C in Palm Springs, 47.7 ° C in Phoenix

Another source of concern: since the beginning of June, the 40 million Americans in the region have been living in suffocating heat.

Several cities have broke temperature records in recent days. In Palm Springs, California, the thermometer climbed to 50.5 ° C. No less than 47.7 ° C were recorded in Phoenix, Arizona, 42.2 ° C in Sacramento, or 46.6 ° C in Las Vegas in neighboring Nevada, and 53.3 ° C in the Valley of Death, temperatures around 11 degrees higher than seasonal averages. Never seen so early in the year.

“This heat wave is unprecedented, both because of the period in which it occurs, for its intensity and for its geographical extent”, worries with the Washington Post, Deepti Singh, climatologist at the University of Washington.

“And this heat still contributes to accentuating the drought”, continues Philippe Ciais. “For good reason, it increases the transpiration of plants which therefore draw even more water from the soil, until they can no longer.”

Water shortages

This drought now raises fears of a water shortage in the coming weeks. All eyes are on Lake Mead, the country’s largest water reserve located on the Colorado River, on the border of Nevada and Arizona. It has now reached its lowest level since its construction in the 1930s.

The same goes for northern California, at Lake Oroville, which provides drinking water to 27 million inhabitants. Its level is currently 50 meters lower than in 2019. In total, the 1,500 reservoirs in the State are only 50% full on average.

Several governments have adopted water restriction measures. An extremely rare decision which is not without consequences for farmers, who depend for the majority on irrigation and who provide a large part of the country’s fruit and vegetables.

In New Mexico, for example, farmers living along the Rio Grande River have been banned from planting new crops in 2021. Others have decided to uproot their almond trees, which represent 80% of world production, for limit their water consumption.

>> To review: “United States: California lacks water for its crops”

“In addition to the shortages, we risk seeing power cuts”, adds Philippe Ciais. “With this heat, the consumption of electricity, in particular to use the air conditioning systems, increases drastically and, very often, the electrical installations do not hold”, he explains.

In 2020, California had indeed narrowly escaped a total cut-off of its electricity network. The latter was particularly overloaded by the demand of the population, but also weakened by the strong heat. The California Independent System Operator, which manages the majority of the network, had declared a state of emergency and asked residents and businesses to reduce their electricity consumption as much as possible.

Already dozens of forest fires

“Finally, we must not forget that these climatic conditions are perfectly conducive to forest fires”, continues the scientist. These, which have become systematic every summer in the region, have already resumed. At the end of May in California, the fires had already consumed five times more vegetation than last year at the same time.

In 2020, more than 1.6 million hectares of forest (4% of the state) went up in smoke and some 10% of the world’s sequoias were devastated by fire. “They destroy thousands of trees, sometimes entire sections of forests. However, trees play a major role in cooling the atmosphere, it is a vicious circle”, laments the scientist.

“Not to mention that they greatly degrade air quality, with harmful consequences on the health of populations,” he continues. Each summer, some Californian municipalities record some of the worst air quality levels on the planet, equaling some Asian megalopolises like New Delhi or Bangkok. According to the Woods Institute for the Environment, around 3,000 people died in the summer of 2020, due to deteriorating air quality.

For Philippe Ciais, California is thus an example of the need to reduce greenhouse gas emissions, a sine qua non for “limiting the damage”. And to recall: “The State is committed to reducing to 80% its CO emissions₂ by focusing on renewable energies “.