Life on a Warming Planet

Endless Summer

What’s really causing all this year’s extreme weather? Rachel Cleetus on rising temperatures, billions in damages, and the climate’s uncertain future.
Shashank Sahay
June, July, and August were the hottest three-month span in human history. By the end of summer in the northern hemisphere, more than 110 million people in the United States alone were still living under governmental excessive-heat warnings, as temperatures hit record highs in the country’s Southeast and Southwest. To the north, Canadian wildfires had burned more than 20 million acres, forcing many to evacuate their homes and sending thick, hazardous smoke down through the U.S. Northeast and Midwest.

In the meantime, unprecedented flooding hit India and China. Flooding also killed dozens in Haiti, Pakistan, Nepal, South Korea, Colombia, and the U.S. state of Vermont. A cyclone killed more than 400 in Burma and Bangladesh. And this year marked the first time two tropical storms formed in the Atlantic during the month of June—an early and ominous start to a hurricane season that led recently to devastation from Idalia across Cuba, Mexico, and the U.S. Southeast. Now, with Tropical Storm Daniel making landfall in eastern Libya, thousands are already feared dead. Where is this all going?

Rachel Cleetus is a researcher and the policy director in the Climate and Energy program at the Union of Concerned Scientists, a nonprofit science-advocacy organization founded in 1969 at the Massachusetts Institute of Technology. According to Cleetus, while there’s some natural variation in weather patterns behind this year’s extremes, they’re mostly among the effects of anthropogenic climate change—climate change caused by us. These effects are in the extreme weather taking place all around the world—and also in less visible but no less significant environmental changes, as in rising ocean temperatures, melting ice sheets, and withering rainforests. The increased adoption of renewable-energy sources is encouraging, Cleetus says—but for now, they’re still competing with heavy, sustained investment in fossil fuels; the world is far from meeting the targets its leaders have set for emission reductions; and uncertainty about the extent of “irreversible changes in natural systems” remains high.

Michael Bluhm: How do you understand all this devastating weather?

Rachel Cleetus: We know it’s been amplified this year by the El Niño effect—a regular warming of ocean currents that increases air temperatures and rainfall levels. But the fundamental climate trend the El Niño effect is amplifying is very clear—and very in keeping with what a global scientific consensus has predicted for years now: As heat-trapping emissions increase, mainly from fossil fuels, average temperatures are rising around the world, and a range of transformative effects are accompanying them.

We’re seeing extreme heat waves—not just a high-temperature day here and there but multiple days of extreme heat in a row—and then heat wave after heat wave. And because warmer air holds more moisture, we’re also seeing extreme precipitation events, like all the extensive, deadly flooding now happening in Libya. At the same time, some parts of the world are experiencing hotter and drier conditions—as in the American West, as well as eastern and western Canada, this year—making it more likely that wildfires would turn into mega-fires releasing tons of carbon dioxide into the atmosphere. These conditions have also led to mega-droughts, with water scarcity and severely negative effects on livestock, crops, and plants.

Now, climate change caused by human actions is never going to account entirely for any given weather event, but we know it’s either mainly causing or significantly worsening many of them. Our own research shows that 82 percent of the extreme-heat alerts in the U.S. this year have shown clear signals of human-caused climate change. At this point, climate change is the background condition.

Bluhm: What’s the pattern of extreme weather events looked like globally?

Cleetus: It’s striking how much we’ve seen them across nearly every region of the planet: Europe’s been hit by massive heat waves and flooding, for example—as have China, India, South America, sub-Saharan Africa, and now North Africa, in Libya. But it’s important to recognize that these extremes capture headlines precisely because they’re so striking. There are other effects happening—like rising sea levels, ocean acidification, and marine heat waves—that don’t tend to get the same attention but are at least as consequential.

We’ve seen ocean temperatures, for instance, reach extraordinary levels around the world this summer. Off the coast of Florida, the ocean has been repeatedly warmer than 100 degrees Fahrenheit. That’s brutal for coasts, marine ecosystems, and marine life—and of course for all the different ways we humans depend on the oceans.

Meanwhile, the extent of sea ice hit record lows this year, especially in the Antarctic, which has a profound influence on climatic and weather patterns. What happens in the Arctic and the Antarctic doesn’t stay there; it affects the climate everywhere.

Bluhm: How would you describe the human cost of these events?

Cleetus: As of this week, the U.S. National Oceanic and Atmospheric Administration has confirmed at 23 extreme weather and climate-related events—many of them bearing the mark of climate change—each with a cost at or above US$1 billion.

Beyond the economic impact, there’ve been major implications for human health and well-being. In extended heat waves, temperatures stay for multiple days at levels that are dangerous to the human body. Many cities—such as Phoenix, in the U.S.—have urban heat-island effects, where all the concrete absorbs heat and amplifies it. Wildfires have meanwhile meant acute densities of smoke—as we’ve seen in the U.S. Northeast and Midwest from the fires in Canada—which is very damaging to people’s lungs. In these conditions, we see a lot of related exhaustion, illness, and sometimes death—particularly among the elderly, the very young, people with pre-existing medical conditions, and those who work outdoors, like construction workers or farmworkers.

Marcus Kauffman
More from Rachel Cleetus at The Signal:

Livelihoods have also been affected, where they depend on natural systems like ranching and farming. These sectors are tremendously vulnerable to weather extremes—either in temperature or rainfall. Infrastructure—like roads, bridges, and power lines—are highly exposed to climate risks, as well, including wildfires, flooding, and intensified storms. At the same time, the U.S. coastal floodplain has a lot of valuable property and critical ecosystems, and in an extreme event—like an extreme storm at a time of sea-level rise—there tend to be much more damaging storm surges in these areas. It’s important to remember, too, that extreme weather events like this are often most devastating for people with low incomes. Electricity prices, for example, will shoot up during extreme heat waves, and people with low incomes or fixed incomes, or those who simply can’t afford air conditioning, will be among those hardest hit.”

The world’s emissions trajectory is way off track from the goals the signatory countries to the Paris Agreement set in 2015, when they pledged to try limiting the rise of global temperatures and the worst effects of climate change. Emissions have risen every year since, except during the Covid pandemic. Still, there’s been some very good news: The costs of producing and storing cleaner forms of energy, such as wind and solar, have been dropping every year—by more than 10 percent in some years. So the adoption of renewable-energy sources is accelerating, often because, in many places, they’re simply the cheapest forms of energy now. Even though we’re seeing the use of renewables accelerate, we’re not seeing any sharp turn away from fossil fuels, which is ultimately crucial to getting emissions under control.”

Global average temperatures have increased more than 1.1 degrees Celsius above pre-industrial levels, and we’re already seeing very significant climate impacts from that. We’re already in a world of dangerous climate change. The Paris Agreement of 2015 aimed to keep the temperature increase as close to 1.5 degrees Celsius as possible. Right now, we’re not close to meeting that goal. The latest IPCC report says there’s a very high likelihood that we’ll breach the 1.5-degree mark in the next 10 to 15 years. The question is, what happens after that? Do we hurtle past it and keep going? Or do we do everything in our ability to make sure that breach is as small as possible and then try to bring temperatures back down later in the century?”

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Categories: Environment

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