The Vicious Climate-Wildfire Cycle
By Carly Phillips
With little fanfare and scant news coverage, fire season 2019 has arrived. Firefighters are already containing blazes in several states, including Colorado, Florida and Oklahoma, and seasonal outlooks suggest that significant wildfires are likely in parts of Alaska, Hawaii and the West Coast.
While forest management and human development have increased wildfire incidence and risk, climate change has exacerbated the trend of large fires and contributed to the lengthening of the fire season, in some cases making wildfires a year-round phenomenon. In the Western U.S., climate change is a major driver behind the near doubling in burned area that we've experienced over the past 35 years, and has contributed to an increase in the frequency and severity of fires, while lengthening the fire season in some regions.
Fires also simultaneously aggravate the impact of climate change by releasing huge quantities of carbon dioxide and other global warming gases into our atmosphere.
As the first act of this new fire season begins to unfold, we have a renewed opportunity and obligation to address the connections between wildfires, climate change and human activity, and take steps to interrupt this vicious cycle.
Climate Change Worsens Fires
Climate change is priming ecosystems in the Western U.S., Southeastern U.S. and Alaska to burn, while climate disasters like drought, rising temperatures and hurricanes compound wildfire risk and spread.
Drought and Rising Temperatures Change How Water Enters and Leaves Ecosystems
Drought is a natural occurrence. However, now we have a greater risk of hotter droughts. Rising temperatures dry out soils and trees. While drought means that less water is entering the ecosystem, rising temperatures mean that water is leaving more quickly. As temperatures rise, plants lose more water per unit of carbon dioxide, exacerbating the already dry and dangerous conditions produced by drought.
With less water coming into the ecosystem, plants become water stressed, which can kill huge numbers of plants if drought conditions persist. In extreme cases, drought itself can kill trees. Plants lose water when they perform photosynthesis, the process where plants use sunlight and carbon dioxide to make food, because they open their pores (aka stomata) to take in carbon dioxide, and water evaporates out in the process.
(This is such a big deal for plants that some have evolved special processes so they can avoid this water loss. In the desert, many plants only do gas exchange at night, when temperatures are lower and water-loss risk is the lowest.) #CAMLife #DinnerPartyFactoid
So in periods of extreme water stress like drought, they close those same pores to conserve what water they have. However, since plants aren't able to photosynthesize with their stomata closed, they then use up their carbon reserves and literally starve, known as carbon starvation.
Hydraulic failure is another way drought can lead to plant death: where air bubbles in the xylem (water transporting plant tissue) block water transport and the plant dies. When droughts are longer and more severe, the risk of hydraulic failure increases.
Alternatively, trees can also die from complications associated with drought, like an insect infestation that a healthy tree could usually defend against. Climate change has magnified the negative impacts of insects, as in the case of California's bark beetle. Cold temperatures have historically regulated the populations of these insects, but as climate change continues to shrink the temperature range that any one given ecosystem experiences, these cold temperatures just aren't happening anymore. These insects also grow and reproduce more quickly in warmer temperatures, which may further enhance their spread. While these outbreaks and subsequent tree deaths are changing the overall composition and structure of the ecosystem, they also can lead to a build-up of dry forest kindling. As a result, we can expect that forests in the West, Southeast and Alaska will continue to be full of dried out, ready-to-burn material.
Hurricanes Can Increase Fuel Loads in Landfall Areas
When hurricanes make landfall, violent winds can bring down huge amounts of timber. While landfalling hurricanes are rare, these natural disasters bring down huge amounts of timber that can easily become create fuel for wildfires. In 1989, Hurricane Hugo damaged approximately 4.39 million acres of forested land in South Carolina alone and generated widespread concerns about increased fire risk from larger fuel loads and higher wind speeds. In the past month, we've seen a similar phenomenon play out in Florida, where downed trees from Hurricane Michael aggravated a small debris fire and inhibited firefighters as they worked to access and contain the blaze. The risk this year, however, is not isolated to Florida, and threatens large portions of the southeastern U.S.
Fires Worsen Climate Change
On the flip side, the burning of trees, dead biomass and soil sends huge pulses of carbon to the atmosphere. Carbon enters an ecosystem when plants take carbon dioxide out of the atmosphere and incorporate it into their tissues. Over time, that carbon becomes integrated into soil, the largest land carbon pool, via plant roots and as dead plants decompose. These processes take time and the buildup of carbon stores is gradual. However, when fire roars through, all that carbon literally goes up in smoke.
In carbon-rich areas like boreal forests, arctic tundra and peatlands, the impact of fire on climate change is further amplified. The carbon in these ecosystems accounts for about 50 percent of global soil organic carbon or twice what is currently in the atmosphere as CO2. These ecosystems have built up carbon in their soil over MILLENNIA and a single fire can devastate these stocks.
In addition, fires release particulate black carbon that can magnify the effects of climate change in two ways. When suspended in the atmosphere, the particles trap heat, magnifying the warming of Earth's surface. Once these same particles disperse and settle on ice or snowy surfaces, they can decrease the reflectivity and melt ice in areas like Greenland, further warming the world.
We Worsen Both
Due to our prolonged and ever-growing addiction to fossil fuels, we're exacerbating climate change which feeds back to catastrophic wildfires. Our continued spewing of global warming gases to the atmosphere has caused many of the climatic complications discussed above. As a result, we're continuing to worsen a problem that we ourselves created.
Beyond fossil fuels, humans have aggravated wildfires by suppressing most fires, moving into wild areas, and simply igniting the fires ourselves. Total suppression has been the primary strategy of the U.S. federal government on nearly all conterminous U.S. land for decades, despite indigenous knowledge and practices that preceded this policy. Unlike homes, restaurants and businesses, our national forests have evolved with fire, requiring it for seed germination, competition reduction and general ecosystem maintenance. The absence of fire means that material (branches, logs and understory shrubs) that would normally burn off in regularly returning fires, has accumulated in these forests over time, creating fuel-rich conditions that drive these devastating wildfires. This suppression has also increased forest density creating greater competition for resources (especially in drought) and allowing fires to spread more easily through the forest.
Interrupting the Cycle
This vicious feedback loop where warming begets fire begets warming begets fire will continue without targeted, science-based intervention.
To interrupt the climate side of this cycle, we NEED to reduce our overall global warming emissions. This is achievable through a number of channels, including reducing our dependence on fossil fuels and moving to cleaner energy sources. We can also remove carbon from the atmosphere and protect the large stores of carbon that already exist. Regardless of the mechanism, addressing our current wildfire predicament and guarding against future disasters requires that we also address climate change and global warming emissions.
To interrupt the cycle from the fire side, we need to codify information from fire science into proactive fire management policy. Research demonstrates that prescribed burns, reduction of fuel loads, reestablishing historic fire return intervals (the frequency with which an ecosystem experiences a fire event), reducing expansion into the wildland urban interface and strategic preventative planning at the can all decrease the prevalence and intensity of the mega fires we've seen in recent years. On a more local and regional scale, fuel treatments and prescribed burns can be an effective strategy to reduce wildfire risk.
While science has revealed how we can work to resolve our current predicament, we are slow to follow through. Democrats, Republicans and bipartisan coalitions in the Senate have drafted legislation to address our nation's wildfire problem in the past 3 years, but none of these bills made it into law. In March 2018, we made progress with a budget that included a major restructuring of funds for fire fighting efforts, including a disaster fund for wildfires. However, President Trump's most recent budget proposal slashes funds for forestry in both the USDA and DOI, suggesting the progress made in 2018 may not be sustained.
Prescribed fires, where managers intentionally set and monitor fires towards ecological ends, are already used as a tool across the country to reduce fuel loads and mimic natural fire return intervals. The risks of this strategy, such as fire escape and increases in air pollution, often discourages decision makers from using this management option. While nearly 99 percent of prescribed fires are successful, those that escape are often the ones we hear about, like the Cerro Grande fire in 2000. As an alternative, manual removal of fuels (mechanical thinning) can reduce burn intensity and speed of fire spread while maintaining the ecological integrity of the ecosystem. In situations where prescribed fire is untenable, like following Hurricane Hugo, alternative strategies like fuel breaks and strategic build-up of suppression capacity can more effectively reduce risks of catastrophic wildfires.
Despite the bleakness of our current situation and the dangers that wildfires pose, we have the knowledge and skills to break this vicious cycle. 2019 seems as good a time as any to start.
Carly Phillips is the Kendall Fellow for Protecting Carbon in Alaska's Boreal Forests with the Climate & Energy program at the Union of Concerned Scientists.
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What Is PTSD?<p><a href="https://theconversation.com/veterans-refugees-and-victims-of-war-crimes-are-all-vulnerable-to-ptsd-130144" target="_blank">PTSD</a> can occur when someone is exposed to extreme exposure traumatic experience. Typically, the trauma involves a threat of death, serious injury, or sexual violence. Along with war veterans, it happens to refugees; to victims of gun violence, rape and other physical assaults; and to survivors of car accidents and natural disasters like earthquakes or tornadoes.</p><p>PTSD can also happen by witnessing trauma or its aftermath, often the case with <a href="https://www.psychiatry.org/patients-families/ptsd/what-is-ptsd" target="_blank">first responders</a> and <a href="https://www.psychologytoday.com/us/blog/the-many-faces-anxiety-and-trauma/202006/invisible-wounds-the-frontline-heroes" target="_blank">front-line workers</a>.</p><p>All this adds up to tens of millions of Americans. Up to 30% of combat veterans and first responders, and 8% of civilians, <a href="https://www.ptsd.va.gov/professional/treat/essentials/epidemiology.asp" target="_blank">fulfill the diagnostic criteria for PTSD</a>. And that criteria is not easily met: symptoms of PTSD include nightmares, flashbacks, intrusive trauma memories, difficulty sleeping, avoidance of reminders of trauma, negative emotions, and what we call "hyperarousal symptoms."</p>
Fireworks Can Trigger Flashbacks<p>Hyperarousal, a core component of PTSD, occurs when a person is hyper-alert to any sign of threat – constantly on edge, easily startled and continuously screening the environment.</p><p>Imagine, for instance, stepping down the stairs in the dark after hearing a noise; you're worried an intruder might be downstairs. Then a totally unpredictable loud sound explodes right outside your window.</p><p>For people with PTSD, that sound – reminiscent of gunfire, a thunderstorm or a car crash – <a href="https://theconversation.com/veterans-refugees-and-victims-of-war-crimes-are-all-vulnerable-to-ptsd-130144" target="_blank">can cause</a> a panic attack or trigger flashbacks, a sensory experience that makes it seem as if the old trauma is happening here and now. Flashbacks can be so severe that combat veterans may suddenly drop to the ground, the same way they would when an explosion took place in combat. Later, the experience can trigger nightmares, insomnia or worsening of other PTSD symptoms.</p><p>Those of us who set off fireworks need to ask ourselves: Are those few minutes of fun worth the hours, days, or weeks of torment that will begin for some of our friends and neighbors – including many who put their lives on the line to protect us?</p>
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By Jeff Berardelli
For the past year, some of the most up-to-date computer models from the world's top climate modeling groups have been "running hot" – projecting that global warming may be even more extreme than earlier thought. Data from some of the model runs has been confounding scientists because it challenges decades of consistent projections.
International Effort to Evaluate Climate Models<p>For the past 25 years the international community has been evaluating and comparing the world's most sophisticated climate models produced by various teams at universities, research centers, and government agencies. The effort is organized by the World Climate Research Programme under the United Nations World Meteorological Organization.</p><p>Climate models are complicated computer programs composed of millions of lines of code that calculate the physical properties and interactions between the main climate forces like the atmosphere, oceans, and solar input. But models also go a lot further, incorporating other systems like ice sheets, forests, and the biosphere, to name a few. The models are then used to simulate the real-world climate system and project how certain changes, like added pollution or land-use changes, will alter the climate.</p><p>Every few years there is a new comprehensive international evaluation called the Coupled Model Intercomparison Project (CMIP). In the sixth such effort, known as CMIP6 and now under way, experts are reviewing about 100 models.</p><p>Information gleaned from this effort will act as a scientific foundation for the U.N.'s Intergovernmental Panel on Climate Change (IPCC) next major assessment report, scheduled for release in 2021. The goal of the report – the sixth in 30 years – is to inform the international community about how much the climate has changed, and, importantly, how much change can be expected in coming decades.</p>
A Conundrum Emerges<p>Over the past year, the CMIP6 collection of models being reviewed threw researchers an unexpected curveball: a significant number of the climate model runs showed substantially more global warming than previous model versions had projected. If accurate, the international climate goals would be nearly impossible to achieve, and there would be significantly more extreme impacts worldwide.</p><p>A foundational experiment in every report addresses "sensitivity": If you double levels of carbon dioxide (CO2) that were in the air before the Industrial Revolution, how much warming do the models show? This doubling is not expected for a few more decades, but it is a quick way to communicate the critical role of greenhouse gases in changing the climate.</p><p>The amount of CO2 in the atmosphere has increased by 35% since the 1800s because of the burning of fossil fuels. As a result, global temperatures have already increased by more than 2 degrees Fahrenheit.</p><p>In the first IPCC assessment report, published in 1990, the answer to that question about the impact of doubling carbon dioxide gave a fairly wide range of results – between 2.7-8 degrees F of global warming. Since then, four more assessments issued six to seven years apart reached nearly the exact same conclusion on sensitivity.</p><p>But that sensitivity may, for the first time, change significantly in next year's assessment. Why? Because starting last year, numerous models in the CMIP6 collection displayed even bigger spikes in temperature upon doubling of CO2 concentrations. We're in serious trouble if the climate sensitivity falls in the mid or upper range of the previous assessments. But if the new, higher estimates are correct, the impacts on civilization would be catastrophic.</p>
In the above CarbonBrief interactive visualization, the bars offer a comparison in the range of sensitivity in the CMIP5 models (gray) and CMIP6 models (blue).
New and Encouraging Evidence Is Emerging<p>At first, scientists were uncertain whether the new model runs were on to something, so the international modeling community dug in to produce multiple studies. The results are not yet conclusive, but a gradual collective sigh of relief seems to be materializing.</p><p>"Evidence is emerging from multiple directions that the models which show the greatest warming in the CMIP6 ensemble are likely too warm," explains Dr. Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.</p><p>For example, <a href="https://www.earth-syst-dynam-discuss.net/esd-2020-23/" target="_blank">a study</a> released April 28 evaluated the past performance of the models making up the CMIP6 ensemble. The team assigned weights to each model based upon historical performance of their warming projections, weighing the poorer performing models less. By doing so, both the mean warming and the range of warming scenarios in the CMIP6 ensemble decreased, meaning the warmest models were the ones with weaker historical performance. This result supports a finding that a subset of the models are too warm.</p><p>That conclusion is supported by another new study evaluating one particular model – the Community Earth System Model (CESM2) – that showed greater warming. Using that model, the researchers simulated the climate in the early Eocene era, about 50 million years ago, when rainforests thrived in the Arctic and Antarctic. The CESM2 simulated a historical climate that seems way too warm compared with what is known about that era from geological data, indicating that the model is likely also too warm in its future projections.</p><p>Two other recent studies of the CMIP6 models being evaluated use clever analysis methods to <a href="https://www.google.com/url?q=https://www.earth-syst-dynam-discuss.net/esd-2019-86/&sa=D&ust=1589209938203000&usg=AFQjCNHYwFB-1KqndGfJ4sXdrrm9DpbLaQ" target="_blank">narrow the range</a> of future warming projections and also <a href="https://www.google.com/url?q=https://advances.sciencemag.org/content/6/12/eaaz9549&sa=D&ust=1589209938203000&usg=AFQjCNEhKY1YZ19qgjSZ_hJM14JmzqXOXw" target="_blank">reduce the projected warming</a> of the CMIP6 models by 10 to 15%.</p><p>Through the intensive research spurred by the CMIP6 climate-sensitivity curveball, scientists have been able to turn a confounding challenge into a confidence builder, providing even greater certainty than they had before in both the abilities of the climate science community and in the computer models used. Moreover, the experience has helped unearth uncertainties remaining in the modeling process.</p><p>Experts conclude much of this uncertainty probably lies in the complexity of clouds. "We have been looking as a community at why the models with greater warming are doing what they are doing – and it's tied to cloud feedbacks in the southern mid-latitudes mostly," explains Schmidt.</p><p>In fact, <a href="https://advances.sciencemag.org/content/6/26/eaba1981" target="_blank">a new study</a> addressing the increased sensitivity was published in Science Advances stating, "Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS [sensitivity] in CMIP6."</p>
Understanding the Complexity of Clouds<p>It's long been known in climate modeling circles that cloud processes and interactions are a potential weak link for climate modeling. That reality has been brought front and center by the urgent challenges posed during this CMIP6 evaluation period, but the current evaluation of models also provides an opportunity for discovery and improvement.</p><p>Cloud complexity comes from the reality that clouds have a multitude of sizes, altitudes, and textures. Some clouds cool Earth by providing shade, reflecting sunlight back into space. Others act like a blanket, trapping heat and warming the world.</p><p>Given that about <a href="https://www.nasa.gov/vision/earth/lookingatearth/icesat_light.html" target="_blank">70% of the globe</a> is covered by clouds at any given time, it's no surprise that they play an integral role in regulating the climate. The challenge is to figure out which types of clouds will increase, which will decrease, and what the net effect will be on cooling or warming as the climate changes.</p><p><a href="https://www.nature.com/articles/s41561-019-0310-1" target="_blank">One study</a> last year reached an alarming conclusion: Left unchecked, the release of CO2 into the atmosphere may lead to a tipping point where shallow low clouds disappear – leading to runaway, catastrophic warming of nearly 15 degrees F. While scientists see that outcome as only a remote possibility, it drives home the urgent need to better understand clouds.</p><p>"We have a saying at NOAA: It isn't rocket science – it's much, much harder than that," quips Dr. Chris Fairall, ATOMIC's lead investigator. "One of the major problems for modeling is there is not clean separation of scales." The photo below is one that Fairall took from the NOAA P-3 aircraft.</p>
Investigating the Secrets of Clouds<p>To address the urgent question about the dynamics and role of clouds in a warming world, NOAA and European partners launched their ongoing research effort unprecedented in scale. The U.S. contribution, ATOMIC – short for Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign – is an international science mission that was featured recently on "<a href="https://www.cbsnews.com/video/study-aims-to-examine-links-between-climate-change-and-clouds/" target="_blank">CBS This Morning: Saturday</a>."</p>
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