This week the U.S. Congress has been considering new policies and investments to keep America’s forests healthy, holding hearings against the dramatic backdrop of a devastating fire season and other forest challenges across America. Given that caring for our forests has bipartisan appeal and broad public support, do we need to inject the controversial issue of climate change into these kinds of discussions on future forest management?
The answer is an unequivocal, “Yes.” Climate change is an existential threat to everything we love about our trees and forests, from city streets to soaring mountain landscapes. Accepting this reality will fundamentally change the way we take care of our forests, and increase our chance of success.
We know that climate change will shift the composition of tree species in our forests and amplify forest threats like fire, drought, pests, and disease in novel ways. If we want to make forest health investments that will last, we must use climate science to prepare our forests for a different world. Denying the role of climate change will to lead to forest management and restoration strategies for the future built with data and forestry techniques that are stuck in the past.
Why is climate change so significant for forests? Different kinds of forests grow in different places due to many different factors, but one of the most important is the prevailing local climate. When that climate shifts, the composition of trees in a given location begin to shift. If the climate shift is too sudden, this change won’t be orderly—instead we could see widespread mortality in the forests there now, followed by an uncertain and potentially slow transition to a different forest type.
Even worse, dramatic changes in climate can super-charge the stresses that kill our forests, like fire, invasive pests, and tree diseases. California is a perfect example.
In the last few years, more than 102 million trees have died across California, with 88 percent of those trees in the Sierra Nevada. This map viewer lets you see specific locations where this tree death has occurred.
A major driver of these tree deaths has been lack of water due to California’s long-term drought—a clear signal of long-term climate shifts that are expected to intensify in the future. But in many cases, the drought has not killed trees directly, but rather opened the door for these trees to be infested by pests in their drought-weakened state. Those dead trees have then become tinder for yet another driver of long-term forest degradation—catastrophic “super fires” that can devastate forest soils and hinder long-term forest recovery.
Speaking of forest pests, many are directly aided by climate change. Cold temperatures can limit the breeding cycles of certain pests and even kill them. That means the warming of northern areas and higher elevation forests can amplify pest outbreaks and facilitate spread into previously inhospitable areas. Here are studies describing the impact of a warming climate on the spread of the mountain pine beetle and hemlock woolly adelgid.
Clearly we need to take immediate action to protect the health of America’s forests, but does it matter if we tie our action to climate change? Some leaders in Washington, D.C. and elsewhere have chosen to speak about the forest health challenge ahead without reference to this driving force. The inclination to skirt climate change is understandable, given the conflicting passions on this issue, but also a serious mistake for our forests.
How we respond to the pressures on our forests will be different, and substantially more effective, if we directly acknowledge the role of climate change. Take fire as an example. This week’s congressional debate has been particularly focused on changes to how we plan, fund, and implement a proactive strategy to address wildfire. This is meant to accelerate a range of actions to lessen fire risk in the first place, and to respond more effectively when fires occur.
But how will we plan and design this restoration work, for the forests of today or tomorrow? If we do not utilize readily available science on climate change and how it will alter our forests, our work on fire will be stuck in a defensive, reactive posture. Anticipating future changes will allow us to better project where fires will occur and how to prevent them with pre-disaster forest restoration that accounts for changing forest conditions and composition.
Similar climate questions arise when deciding how we will replant forests after they are lost to events like fire, pest and disease invasions, and extreme weather. What species should we replant, and how should they be spaced on the landscape to address challenges like less water in the future? Do we need to build innovative nurseries that help us grow more disease-resistant seedlings to replant? We cannot simply replace these forest systems as they were and expect long-term health and resilience.
The good news is that we have abundant scientific resources to launch a new era of forest health protection based on climate-informed action. Over the last decade, the U.S. Forest Service, state governments, academic institutions, and non-profit organizations have used applied science to gaze into our forest future and begin testing new ways to manage and restore forests in a changing climate. One of the most successful efforts has been development of the Climate Change Response Frameworks, innovative public-private partnerships led by the U.S. Forest Service that have fostered hundreds of real-world demonstration projects testing new forestry approaches based on climate science.
With so much at stake, it is essential for government and private sector leaders alike to acknowledge the impact of climate change on our forests and to develop future forest health strategies, policies, and actions that are fully climate-informed. This is one case where the words we use really do matter, because those words—“climate change”—will fundamentally change how we act. Will we overcome the ideological divides on climate change in this instance? The fate of America’s forests is at stake.