Strong winds blew across mountain slopes after a record-setting warm, dry summer. Small fires began to blow up into huge conflagrations. Towns in crisis scrambled to escape as fires bore down.

This could describe any number of recent events, in places as disparate as Colorado, California, Canada and Hawaii. But this fire disaster happened over 110 years ago in the Northern Rocky Mountains of Idaho and Montana.

The “Big Burn” of 1910 still holds the record for the largest fire season in the Northern Rockies. Hundreds of fires burned over 3 million acres – roughly the size of Connecticut – most in just two days. The fires destroyed towns, killed 86 people and galvanized public policies committed to putting out every fire.

Today, as the climate warms, fire seasons like in 1910 are becoming more likely. The 2020 fire season was an example. But are extreme fire seasons like these really that unusual in the context of history? And, when fire activity begins to surpass anything experienced in thousands of years – as research suggests is happening in the Southern Rockies – what will happen to the forests?

As paleoecologists, we study how and why ecosystems changed in the past. In a multiyear project, highlighted in two new publications, we tracked how often forest fires occurred in high-elevation forests in the Rocky Mountains over the past 2,500 years, how those fires varied with the climate and how they affected ecosystems. This long view provides both hopeful and concerning lessons for making sense of today’s extreme fire events and impacts on forests.

Lakes record history going back millennia

When a high-elevation forest burns, fires consume tree needles and small branches, killing most trees and lofting charcoal in the air. Some of that charcoal lands on lakes and sinks to the bottom, where it is preserved in layers as sediment accumulates.

After the fire, trees regrow and also leave evidence of their existence in the form of pollen grains that fall on the lake and sink to the bottom.

By extracting a tube of those lake sediments, like a straw pushed into a layer cake from above, we were able to measure the amounts of charcoal and pollen in each layer and reconstruct the history of fire and forest recovery around a dozen lakes across the footprint of the 1910 fires.

Lessons from Rockies’ long history with fire

The lake sediments revealed that high-elevation, or subalpine, forests in the Northern Rockies in Montana and Idaho have consistently bounced back after fires, even during periods of drier climate and more frequent burning than we saw in the 20th century.

High-elevation forests only burn about once every 100 to 250 or more years on average. We found that the amount of burning in subalpine forests of the Northern Rockies over the 20th and 21st centuries remained within the bounds of what those forests experienced over the previous 2,500 years. Even today, the Northern Rockies show resilience to wildfires, including early signs of recovery after extensive fires in 2017.

But similar research in high-elevation forests of the Southern Rockies in Colorado and Wyoming tells a different story.

The record-setting 2020 fire season, with three of Colorado’s largest fires, helped push the rate of burning in high-elevation forests in Colorado and Wyoming into uncharted territory relative to the past 2,000 years.

Climate change is also having bigger impacts on whether and how forests recover after wildfires in warmer, drier regions of the West, including the Southern Rockies, the Southwest and California. When fires are followed by especially warm, dry summers, seedlings can’t establish and forests struggle to regenerate. In some places, shrubby or grassy vegetation replace trees altogether.

Changes happening now in the Southern Rockies could serve as an early warning for what to expect further down the road in the Northern Rockies.

Warmer climate, greater fire activity, higher risks

Looking back thousands of years, it’s hard to ignore the consistent links between the climate and the prevalence of wildfires.

Warmer, drier springs and summers load the dice to make extensive fire seasons more likely. This was the case in 1910 in the Northern Rockies and in 2020 in the Southern Rockies.

When, where and how climate change will push the rate of burning in the rest of the Rockies into uncharted territory is harder to anticipate. The difference between 1910 and 2020 was that 1910 was followed by decades with low fire activity, whereas 2020 was part of an overall trend of increasing fire activity linked with global warming. Just one fire like 1910’s Big Burn in the coming decades, in the context of 21st-century fire activity, would push the Northern Rockies beyond any known records.

Lessons from the long view

The clock is ticking.

Extreme wildfires will become more and more likely as the climate warms, and it will be harder for forests to recover. Human activity is also raising the risk of fires starting.

The Big Burn of 1910 left a lasting impression because of the devastating impacts on lives and homes and, as in the 2020 fire season and many other recent fire disasters, because of the role humans played in igniting them.

Accidental ignitions – from downed power lines, escaped campfires, dragging chains, railroads – expand when and where fires occur, and they lead to the majority of homes lost to fires. The fire that destroyed Lahaina, Hawaii, is the most recent example.

So what can we do?

Curbing greenhouse gas emissions from vehicles, power plants and other sources can help slow warming and the impacts of climate change on wildfires, ecosystems and communities. Forest thinning and prescribed burns can alter how forests burn, protecting humans and minimizing the most severe ecological impacts.

Reframing the challenge of living with wildfire – building with fire-resistant materials, reducing accidental ignitions and increasing preparedness for extreme events – can help minimize damage while maintaining the critical role that fires have played in forests across the Rocky Mountains for millennia.

Kyra Clark-Wolf has received funding from the National Science Foundation and the Joint Fire Science Program

Philip Higuera receives funding from the National Science Foundation, United States Geological Survey, and Joint Fire Science Program.

After nearly two decades of stagnation, U.S. electricity demand is surging, driven by growing numbers of electric cars, data centers and air conditioners in a warming climate. But traditional power plants that generate electricity from coal, natural gas or nuclear energy are retiring faster than new ones are being built in this country. Most new supply is coming from wind and solar farms, whose output varies with the weather.

That’s left power companies seeking new ways to balance supply and demand. One option they’re turning to is virtual power plants.

These aren’t massive facilities generating electricity at a single site. Rather, they are aggregations of electricity producers, consumers and storers – collectively known as distributed energy resources – that grid managers can call on as needed.

Some of these sources, such as batteries, may deliver stored electric power. Others may be big electricity consumers, such as factories, whose owners have agreed to cut back their power use when demand is high, freeing up energy for other customers. Virtual power sources typically are quicker to site and build, and can be cleaner and cheaper to operate, than new power plants.

A growing resource

Virtual power plants aren’t new. The U.S. Department of Energy estimates that there are already 30 to 60 gigawatts of them in operation today. A gigawatt is 1 billion watts – roughly the output of 2.5 million solar photovoltaic panels or one large nuclear reactor.

Most of these virtual power plants are industrial customers that have agreed to reduce demand when conditions are tight. But as growing numbers of homes and small businesses add rooftop solar panels, batteries and electric cars, these energy customers can become not only consumers but also suppliers of power to the grid.

For example, homeowners can charge up their batteries with rooftop solar when it’s sunny, and discharge power back to the grid in the evening when demand is high and prices sometimes spike.

As smart thermostats and water heaters, rooftop solar panels and batteries enable more customers to participate in them, DOE estimates that virtual power plants could triple in scale by 2030. That could cover roughly half of the new capacity that the U.S. will need to cover growing demand and replace retiring older power plants. This growth would help to limit the cost of building new wind and solar farms and gas plants.

And because virtual power plants are located where electricity is consumed, they’ll ease the burden on aging transmission systems that have struggled to add new lines.

New roles for power customers

Virtual power plants scramble the roles of electricity producers and consumers. Traditional power plants generate electricity at central locations and transmit it along power lines to consumers. For the grid to function, supply and demand must be precisely balanced at all times.

Customer demand is typically assumed to be a given that fluctuates with the weather but follows a fairly predictable pattern over the course of a day. To satisfy it, grid operators dispatch a mix of baseload sources that operate continuously, such as coal and nuclear plants, and more flexible sources such as gas and hydropower that can modulate their output quickly as needed.

Output from wind and solar farms rises and falls during the day, so other sources must operate more flexibly to keep supply and demand balanced. Still, the basic idea is that massive facilities produce power for millions of passive consumers.

Virtual power plants upend this model by embracing the fact that consumers can control their electricity demand. Industrial consumers have long found ways to flex their operations, limiting demand when power supplies are tight in return for incentives or discounted rates.

Now, thermostats and water heaters that communicate with the grid can let households modulate their demand too. For example, smart electric water heaters can heat water mostly when power is abundant and cheap, and limit demand when power is scarce.

In Vermont, Green Mountain Power is offering its customers incentives to install batteries that will provide power back to the grid when it’s needed most. In Texas, where I live, deadly blackouts in 2021 highlighted the importance of bolstering our isolated power grid. Now, utilities here are using Tesla Powerwalls to help turn homes into virtual power sources. South Australia aims to connect 50,000 homes with solar and batteries to build that country’s largest virtual power plant.

Virtual power, real challenges

Virtual power plants aren’t a panacea. Many customers are reluctant to give up even temporary control of their thermostats, or have a delay when charging their electric car. Some consumers are also concerned about the security and privacy of smart meters. It remains to be seen how many customers will sign up for these emerging programs and how effectively their operators will modulate supply and demand.

There also are challenges at the business end. It’s a lot harder to manage millions of consumers than dozens of power plants. Virtual power plant operators can overcome that challenge by rewarding customers for allowing them to flex their supply and demand in a coordinated fashion.

As electricity demand rises to meet the needs of growing economies and replace fossil fuel-burning cars and furnaces, and reliance on renewable resources increases, grid managers will need all the flexibility they can get to balance the variable output of wind and solar generation. Virtual power plants could help reshape electric power into an industry that’s more nimble, efficient and responsive to changing conditions and customers’ needs.

Daniel Cohan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Strong winds blew across mountain slopes after a record-setting warm, dry summer. Small fires began to blow up into huge conflagrations. Towns in crisis scrambled to escape as fires bore down.

This could describe any number of recent events, in places as disparate as Colorado, California, Canada and Hawaii. But this fire disaster happened over 110 years ago in the Northern Rocky Mountains of Idaho and Montana.

The “Big Burn” of 1910 still holds the record for the largest fire season in the Northern Rockies. Hundreds of fires burned over 3 million acres – roughly the size of Connecticut – most in just two days. The fires destroyed towns, killed 86 people and galvanized public policies committed to putting out every fire.

Today, as the climate warms, fire seasons like in 1910 are becoming more likely. The 2020 fire season was an example. But are extreme fire seasons like these really that unusual in the context of history? And, when fire activity begins to surpass anything experienced in thousands of years – as research suggests is happening in the Southern Rockies – what will happen to the forests?

As paleoecologists, we study how and why ecosystems changed in the past. In a multiyear project, highlighted in two new publications, we tracked how often forest fires occurred in high-elevation forests in the Rocky Mountains over the past 2,500 years, how those fires varied with the climate and how they affected ecosystems. This long view provides both hopeful and concerning lessons for making sense of today’s extreme fire events and impacts on forests.

Lakes record history going back millennia

When a high-elevation forest burns, fires consume tree needles and small branches, killing most trees and lofting charcoal in the air. Some of that charcoal lands on lakes and sinks to the bottom, where it is preserved in layers as sediment accumulates.

After the fire, trees regrow and also leave evidence of their existence in the form of pollen grains that fall on the lake and sink to the bottom.

By extracting a tube of those lake sediments, like a straw pushed into a layer cake from above, we were able to measure the amounts of charcoal and pollen in each layer and reconstruct the history of fire and forest recovery around a dozen lakes across the footprint of the 1910 fires.

Lessons from Rockies’ long history with fire

The lake sediments revealed that high-elevation, or subalpine, forests in the Northern Rockies in Montana and Idaho have consistently bounced back after fires, even during periods of drier climate and more frequent burning than we saw in the 20th century.

High-elevation forests only burn about once every 100 to 250 or more years on average. We found that the amount of burning in subalpine forests of the Northern Rockies over the 20th and 21st centuries remained within the bounds of what those forests experienced over the previous 2,500 years. Even today, the Northern Rockies show resilience to wildfires, including early signs of recovery after extensive fires in 2017.

But similar research in high-elevation forests of the Southern Rockies in Colorado and Wyoming tells a different story.

The record-setting 2020 fire season, with three of Colorado’s largest fires, helped push the rate of burning in high-elevation forests in Colorado and Wyoming into uncharted territory relative to the past 2,000 years.

Climate change is also having bigger impacts on whether and how forests recover after wildfires in warmer, drier regions of the West, including the Southern Rockies, the Southwest and California. When fires are followed by especially warm, dry summers, seedlings can’t establish and forests struggle to regenerate. In some places, shrubby or grassy vegetation replace trees altogether.

Changes happening now in the Southern Rockies could serve as an early warning for what to expect further down the road in the Northern Rockies.

Warmer climate, greater fire activity, higher risks

Looking back thousands of years, it’s hard to ignore the consistent links between the climate and the prevalence of wildfires.

Warmer, drier springs and summers load the dice to make extensive fire seasons more likely. This was the case in 1910 in the Northern Rockies and in 2020 in the Southern Rockies.

When, where and how climate change will push the rate of burning in the rest of the Rockies into uncharted territory is harder to anticipate. The difference between 1910 and 2020 was that 1910 was followed by decades with low fire activity, whereas 2020 was part of an overall trend of increasing fire activity linked with global warming. Just one fire like 1910’s Big Burn in the coming decades, in the context of 21st-century fire activity, would push the Northern Rockies beyond any known records.

Lessons from the long view

The clock is ticking.

Extreme wildfires will become more and more likely as the climate warms, and it will be harder for forests to recover. Human activity is also raising the risk of fires starting.

The Big Burn of 1910 left a lasting impression because of the devastating impacts on lives and homes and, as in the 2020 fire season and many other recent fire disasters, because of the role humans played in igniting them.

Accidental ignitions – from downed power lines, escaped campfires, dragging chains, railroads – expand when and where fires occur, and they lead to the majority of homes lost to fires. The fire that destroyed Lahaina, Hawaii, is the most recent example.

So what can we do?

Curbing greenhouse gas emissions from vehicles, power plants and other sources can help slow warming and the impacts of climate change on wildfires, ecosystems and communities. Forest thinning and prescribed burns can alter how forests burn, protecting humans and minimizing the most severe ecological impacts.

Reframing the challenge of living with wildfire – building with fire-resistant materials, reducing accidental ignitions and increasing preparedness for extreme events – can help minimize damage while maintaining the critical role that fires have played in forests across the Rocky Mountains for millennia.

Kyra Clark-Wolf has received funding from the National Science Foundation and the Joint Fire Science Program

Philip Higuera receives funding from the National Science Foundation, United States Geological Survey, and Joint Fire Science Program.