Author Archives | Sara O'Brien

Climate change and Greater Yellowstone fire regimes

Last week’s issue of the Proceedings of the National Academy of Sciences  included a compelling article by western fire researcher Tony Westerling and colleagues. The title, “Continued warming could transform Greater Yellowstone fire regimes by mid-21st century,” caught the attention of a lot of blogs and other media outlets.

Westerling and his co-authors modeled changing fire regimes in the Greater Yellowstone ecosystem  by looking at past correlations between climate data and the size and occurrence of large fires, then projecting those trends forward to see how often fire could be expected to burn a given area under likely future climate conditions. Today the Greater Yellowstone area is dominated by conifer forests that are characterized by infrequent but severe fires. Every 100-300 years or so, major fires sweep through these ecosystems, killing a large proportion of trees in the affected area and starting the succession process over by providing shade-sensitive species with access to sunlight.

However, this new research suggests that an increase in temperatures of just a few degrees by mid-century could have profound effects both on patterns of fire in the Yellowstone area and on the ecosystems and species found there. All of the modeling results pointed to a more rapid fire cycle, with a given area burning every 30 years or less by 2050. As Westerling et al. point out, this kind of fire regime would also indicate a significant shift from the current mixed conifer forest type to something much different, something more like a dry woodland or unforested ecosystem. Such a complete shift in vegetation would obviously have dire impacts on many of the species that currently inhabit that area.

When we talk about helping ecosystems adapt to climate change, we often tend to imagine – and plan for – a gradual, almost imperceptible shift in conditions over long periods of time. But many scientists have shown that ecological systems can contain hidden transition points, thresholds beyond which rapid, extreme changes  in ecosystem structure and function may be unavoidable and virtually irreversible. Westerling’s paper shows us is in quite vivid terms what ecological thresholds might look like on the ground, and it gives us a frightening glimpse of how soon climate change might start pushing us across these thresholds. How would we go about managing the transition to an unforested Yellowstone?

Posted in Climate Change, Imperiled Wildlife, National Forests, Northern Rockies, Public Lands, Uncategorized0 Comments

A wetland in South Slough National Estuarine Research Reserve, near Charleston, Oregon.

Can coastal wetlands adapt to climate change?

A wetland in South Slough National Estuarine Research Reserve, near Charleston, Oregon.

A wetland in South Slough National Estuarine Research Reserve, near Charleston, Oregon. Photo by Bruce Taylor.

Based on evidence of past changes , we know that coastal wetlands can be surprisingly adaptable to changes in sea level. Rising sea levels can actually cause higher rates of sediment deposition in many types of estuaries, so that the floor of the wetland increases in elevation along with the rising sea. This process helps explain the persistence of these unique and highly productive ecosystems through times of much higher and much lower sea levels than today. But despite this inherent adaptability, a number of important coastal marshes, including those in Chesapeake Bay and parts of the Mississippi River Delta, are currently experiencing submersion and erosion and are expected to be heavily impacted by future sea-level rise .

A recent article in the journal Geophysical Research Letters  looks more closely at these feedbacks and what they mean for coastal wetlands in the future. The authors found that the response of coastal marshes to sea-level rise depended both on the rate of rise and the amount of sediment found in the marsh water. Their model showed that marshes with very little suspended sediment could not keep up with even a very slow rise in sea-level, while those with more sediment could adapt to a rise of several centimeters per year. (Tidal range, the difference between high and low tide, also affected the response.) At the higher rates of sea-level rise projected by more recent studies, however, only marshes with very high sediment concentrations and very large tidal ranges could be expected to survive beyond the end of the 21st century. Others would fail to keep up and would eventually be inundated with water.

This article is an interesting example of the importance of feedbacks and ecosystem responses in modeling climate change impacts. More than that, though, it offers at least two compelling lessons for those of us interested in managing ecosystems for climate change adaptation.

First, we can see that a lot of the impacts we’ve had on natural systems over the past few centuries will greatly limit their ability to adapt to climate change. While some coastal marshes are naturally low in sediment, others have been so affected by flood control and other changes that they are submerging even under current sea levels. In some cases, we can restore some of the adaptive capacity of these systems by reversing past damage. 

But the case of the coastal marshes also highlights the importance of reducing greenhouse gas emissions as quickly and as dramatically as possible. Many ecosystems can adapt to climate change up to a certain point, and we may be able to give them an additional boost by improving management practices. However, for many ecological systems abrupt changes may occur once thresholds or tipping point are reached–beyond which the system can no longer absorb change and shifts to a new state.  In the case of coastal wetlands such a threshold would occur when the rate of sea level rise outpaces the ability of the system to generate new marsh.  Once these wetlands are finally submerged and converted to open water it is very unlikely that they will be able to return to their former state. Unless we greatly limit the rate and magnitude of climate change, there will be very little we can do to help ecosystems adapt to the rapid, extreme changes in climate to which we are now committing ourselves. 

Kirwan, M.L. et al. Limits on the adaptability of coastal marshes to rising sea level. Geophysical Research Letters 37, L23401 (2010).

Posted in Climate Change, Pacific Northwest0 Comments

Planning for Climate Change Across Sectors

Over the last several months, Oregon’s state land use planning agency has been leading an interagency effort to develop a cross-sectoral framework for climate change adaptation planning. The final document (including a separate executive summary) was released last week. This report was requested by Governor Ted Kulongoski and was intended to be a first assessment of how the different agencies can help Oregon’s communities and ecosystems respond adaptively to future climate change. The result was a joint effort of the state’s natural resource, energy, transportation, and public health agencies.

This new state adaptation framework is in many ways a first crack at a very difficult nut. The process was limited somewhat by a short timeframe and severe limitations in the state budget, but it was also a valuable opportunity for representatives from a diverse set of state agencies to sit down at the same table and talk about their plans for preparing for climate change. Perhaps most importantly, it helped identify adaptation strategies that would benefit multiple sectors – for example, rehabilitating riparian areas to improve natural water storage on the landscape, which can benefit cities, agriculture, and wildlife – and to look for areas where adaptation strategies in once sector might unintentionally undermine efforts in another sectors. The process really highlighted the importance of coordinating adaptation planning to avoid duplicative or counterproductive efforts.

I participated in developing this framework as part of an ongoing contract with the Oregon Department of Fish and Wildlife, and I was impressed with the willingness of the diverse set of agencies at the table to think about the challenges and opportunities of climate change in an ecological context. Everyone around the table clearly recognized the interconnectedness of human and natural systems and was eager to find solutions that had multiple benefits across multiple sectors. Likewise, everyone recognized that technologies that benefited one sector at the expense of others were likely to fail in the long run.

At the same time, our conversations made it increasingly clear that there are not a lot of easy answers when it comes to climate change. The goal was to identify inexpensive actions for short-term implementation – the low-hanging fruit, as it’s often called – but in a world where climate conditions are changing rapidly and both humans and wildlife are already struggling to keep up with those changes, these kinds of solutions are hard to come by. I think this highlights the importance of making significant early investments in both mitigation and adaptation efforts, even at a time when budgets are tight. This problem will only become more intractable and more expensive the longer we put those investments off., and climate change itself will soon start having significant negative impacts on local, national, and global economies. Kudos to Oregon for being one of the first states to start having these difficult conversations and mapping out the best way forward.

Posted in Climate Change0 Comments

A photo of an estuary

At the front lines of climate change

A photo of an estuaryEstuaries, the ecosystems that exist where rivers and oceans meet, are at the front lines of climate change. Rising sea levels threaten to inundate coastal wetlands, increasing their salinity and causing a shift in vegetation communities. Air and water temperatures, precipitation patterns, and ocean chemistry are also changing. All of these processes likely add up to a loss many of the values these systems provide, including providing habitat for fish, migratory birds, and other species, filtering water, stabilizing shorelines, and buffering coastal communities from storm damage.

On November 18-19th, a group of researchers and managers got together in Newport, Oregon, to mull over what to do about this situation. We asked ourselves:  How can we best manage these sensitive ecosystems so that they continue to provide fish and wildlife habitat and other important values as the climate changes?

The question is a particularly tough one, because relatively simple physical changes in climate and water chemistry will create complex effects in biological systems. For example, we know that air temperatures here in the Pacific Northwest are likely to rise some 2-5°F over the next several decades and that we can expect on the order of 3-4 feet of sea-level rise globally by the end of the century (although the magnitude of sea-level rise remains much debated).  These changes are likely to affect factors that are critical to estuary function like water salinity, sediment deposition, and vegetation type, but we know relatively little about exactly how these cascading effects will play out on the ground. As a result, many managers feel that climate change projections are still too uncertain to inform management decisions

One of the conclusions from the group was that many of the conservation tools we already have will be useful in responding to climate change. For example, many estuaries can effectively migrate inland as sea levels rise. Where they are hemmed in by development, though, they are unable to shift and some of their function and value as wildlife habitat is almost certain to be lost, so protecting coastal lands from development through conservation easements and purchase is vitally important. We also discussed some creative strategies for managing estuaries and the riparian areas that feed them, such as reintroducing beavers into streams and rivers improve water storage on the landscape and help moderate water flows.

Many of these strategies are robust to uncertainty, in the sense that they are very likely to be beneficial even if we are wrong about the magnitude or effects of future changes in the climate. Developing more of these robust strategies will help keep conservationists from becoming paralyzed by the uncertainty inherent in climate prediction and modeling. In Oregon, the next step is to delve deeper into some of the solutions we identified and start thinking critically about what tools to use, where, and why. We’ll also be working to spread the word so that that general public is more aware of likely climate change impacts and our options for managing it.

Posted in Climate Change, Pacific Northwest0 Comments

Biodiversity as an ecosystem service: what to measure, how, and why?

The G8+5 recently released a report titled “Mainstreaming the Economics of Nature” that argues that the current financial system is fundamentally flawed – not because of the recent meltdowns, but because it does not account for the provision, use, or loss of ecosystem services such as clean air and water, flood mitigation, and natural pollination. It predicts that failing to address this problem will continue to harm not only ecological but also economic and social systems. The emerging ideas of ecosystem services and ecosystem markets represent interesting new thinking about the benefits provided by natural systems, how those benefits are represented in economic systems, and what kinds of policies and economic tools might be used to make sure they persist into the future.

One of the first and most significant challenges in this area lies in quantifying the services being provided. The sub-field of environmental economics has produced some innovative approaches to valuing ecological services, but assessing the value conservation land adds to local economies through property values or spending on recreation falls far short of describing what we lose when a natural area is degraded or destroyed. Emerging markets in water quality and carbon have helped to pave the way, but quantifying the value of biodiversity and other unregulated resources lags far behind.

As a result, a small cottage industry has sprung up recently around the creation of environmental metrics, tools for quantifying the ecological values provided by a particular area of land. We have participated in a few of these efforts, including the Stewardship Index for Specialty Crops, which aims to develop environmental and social metrics for agriculture and food processing and distribution systems. We are also working on an effort to create metrics that efficiently and effectively quantify the biodiversity outcomes of conservation lands. These metrics should be useful in efforts to integrate ecosystem services into market values, but it may also be used more immediately to describe the impact of conservation incentive programs or to measure the biodiversity value of lands being placed in conservation or affected by development.

Developing metrics for ecosystem services is a small step toward the fundamental shifts in economic systems that are described in the G8+5 report, but it may prove to be a significant step in improving the outcomes of conservation efforts on the ground. The ability to reliably measure the impacts of development and the outcomes of conservation actions can help make sure we gain the best results from every dollar spent on conservation, whether that dollar comes from government incentive programs, mitigation for development, or private investment.

Posted in Paying for Conservation0 Comments