A home is engulfed in flames as the Dixie Fire rages on in Greenville, California

A home is engulfed in flames as the Dixie Fire rages on in Greenville, California on August 5, 2021.

(Photo: Josh Edelson/AFP via Getty Images)

Summer in the US Is Now 'Danger Season'

Climate change has transformed summer into our country's Danger Season, and we'd best start seeing it as such so that we can adequately prepare.


Every year, as the calendar flips from May to June, I feel a sense of dread sink into my chest. By June 1 each year, the West's rainy season is long over, hurricane season is likely to have kicked off, and the grim annual parade of heatwaves has begun. While summer is still summer and we on the climate team at UCS look forward to ice cream and late sunsets as much as anyone, there's something we need to tell you: Climate change has transformed summer into our country's Danger Season, and we'd best start seeing it as such so that we can adequately prepare.

Summer? Dangerous?! Really?! Yes. Really.

Aside from the annual exposure to wildfire smoke that all Californians endure, I haven't been directly affected by climate-related disasters. But part of my job--especially part of my job during the summer--is remembering disasters past and communicating about those that unfold over the course of the season.

Facts show that Danger Season is the season in which we experience most of our heat waves, hurricanes and tropical storms (and their attendant floods), and wildfires in the US, and it's the season when droughts get exacerbated by hot conditions.

There's a long list of disasters in my brain that serve as constant reminders of why I'm fighting for climate action.

I remember that Superstorm Sandy struck the New York City region in 2012 and know that the home buyout programs may not have reduced the vulnerability of buyout recipients to hazards. I remember that this September will mark the five-year anniversary of Hurricane Maria and know that the extreme inadequacy of our nation's response to the hurricane means that the island is still plagued by major power outages and that the health of Puerto Ricans has suffered. I remember that federal relief funds went disproportionately to white victims of Hurricane Harvey's massive flooding in Houston in 2017 while Black and Hispanic communities were largely excluded.

Then there's the heat--Phoenix endured 53 days of 110deg temperatures in 2020 and logged more than 300 heat-related deaths that year; the 2021 Pacific Northwest heatwave would have been virtually impossible without the "help" of climate change. And, of course, the fires. They grow ever larger and affect everything from majestic sequoias to tiny babies. Aspects of many of these events reflect broader trends in how extreme events are changing as our climate warms.

Sometimes this remembering is oppressive and the litany of disasters I feel rising in my throat as I talk to colleagues, reporters, and policymakers becomes a knot of ache that renders me silent. This summer, like many of my fellow climate scientists, I'll try to recount the facts I remember and those I've been disciplined enough to write down for all the reporters who work tirelessly to tell the story of how we got here and where we should go from here.

But this summer, we also have a clear and critical message for those reporters, as well as our policymakers, and, really, everyone in the US:

Because of climate change, the months of May through October amount to Danger Season in the US and around the world. We need to understand it as such and bring our best efforts to reducing the climate-related risks we already shoulder as well as the worsening risks that lie ahead.

Summer is Danger Season. What does that mean?

Facts show that Danger Season is the season in which we experience most of our heat waves, hurricanes and tropical storms (and their attendant floods), and wildfires in the US, and it's the season when droughts get exacerbated by hot conditions. Each of these types of climate-related extremes brings with it danger. Just as a grim sampling to paint the picture, exposure to extreme heat can bring on heat stress or heat stroke, the latter of which can be fatal; storm surge and floods associated with hurricanes can also be fatal, and long-term exposure to mold in flood-damaged homes can cause respiratory issues; and even short-term exposure to the poor air quality associated with wildfire smoke increases the risk of mortality.

During Danger Season these threats also compound one another and cause cascading chains of hazards. For example, the ongoing megadrought in the US Southwest compounds wildfire risks by drying out vegetation that then serves as wildfire fuel, and by making fires more difficult to contain. That very situation is playing out right now in New Mexico, where the Hermits Peak and Calf Canyon fire--the state's largest fire on record--is currently burning.

And the risks from extreme events can cascade as they affect critical infrastructure. During 2021's one-two punch of the massive heatwave that followed on the heels of Hurricane Ida in Louisiana in 2021, for instance, residents of the state were left without water or power for weeks. During a pandemic. In Louisiana, the inability to cool off in the wake of the storm ultimately led to more deaths due to heat after the storm than to the storm itself even as the storm travelled northward, wreaking havoc and claiming dozens of lives from Mississippi to New York.

How is climate change creating Danger Season?

Hurricanes, wildfires, droughts, and heatwaves have occurred throughout history, but global warming is changing the likelihood and severity of extreme events such that they pose greater risks to people. While it's important to bear in mind that not every extreme event is attributable to climate change and that some aspects of these events are changing while others are not, there are some clear patterns that have emerged from recent research. Here are just a few:

  • The proportion of Atlantic tropical cyclones undergoing rapid intensification has roughly tripled and the number of hurricanes globally reaching the strongest categories has increased over the last four decades.
  • Since the mid-1980s, human-caused climate change changing is responsible for a doubling in the areas burned by forest fires in the western US and is increasing the likelihood of autumn wildfires in the region.
  • Human-caused climate change is increasing hot extremes around the world, including across much of North America.

If you'd like to dive deeper into the topic of whether and how extreme events relate to climate change, you can read more in our 2018 fact sheet or in a recent roundup of studies evaluating the extent to which extreme events in 2020 were attributable to climate change.

What can we do to reduce climate risks?

Understanding the warm months in the US as Danger Season is important so that we can limit the severity and impacts of future Danger Seasons. First and foremost, we must reduce emissions alongside other nations because the greater our emissions in the future, the greater the impacts will be. And we can also be acting on several fronts to adapt and build our resilience to Danger Season. We can and must:

  • Learn from what we've experienced so far. On this front, there's a wealth of information we can be drawing from. For instance, we know that recovery from climate-related disasters is highly inequitable and that longstanding policies have exacerbated these inequities. We know that certain groups of people are more at risk during climate extremes--elderly adults and people living within urban heat islands during heat waves, for example. And we see over and over again that our energy systems are fragile. Addressing our Danger Season risks will mean distilling what we know from countless studies and turning that knowledge into more robust and equitable means of preparing for climate extremes and recovering from them after they've occurred.
  • Learn from models of what is working. Despite the increasingly heavy toll exacted by extreme events, there are many clear examples of systems and places that are successfully prioritizing risk reduction. Improved storm-tracking capabilities are enabling greater community-level preparedness; Communities such as Philadelphia are working with local health departments to make sure data on heat-health outcomes are incorporated into local heat warning systems. Maricopa County, Arizona, is tracking and reporting heat-related deaths--making accessible data that researchers normally have to hunt down. And in California, since the passage of heat-protection standards for outdoor workers in 2006, heat-related injuries among those workers have declined by about 30%.
  • Develop a national resilience strategy that addresses the risks of Danger Season. While there are existing programs within many federal agencies that aim to build climate resilience, there is currently no national strategy to build that resilience in an equitable and proactive way. A national resilience strategy that encouraged households, communities, and states to prepare for disasters ahead of time--rather than primarily responding to them reactively--would help tremendously. Also needed is a recognition that people and communities often require support for years as they recover from a disaster such as a hurricane or wildfire. We need policy makers who would champion efforts to develop a cohesive plan for building climate resilience nationwide. As candidates head out on the campaign trail in advance of elections in November, we can all pay attention to what candidates are saying about climate resilience and use our voices and votes to demand attention to these issues.
  • Recognize that we're far from the only ones suffering, then help. Danger Season is far from a US phenomenon, as my colleague, Rachel Cleetus, explains in her latest blog post. People in poorer nations around the world disproportionately suffer the impacts of climate extremes made more likely, in large part, due to the heat-trapping emissions from wealthier nations. We cannot simply stand by and let this happen.

Summer is changing. Waking up and recognizing Danger Season for what it is now--and what it could be in the future--is a critical first step to building our resilience to it.

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