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Posted on Monday, February 13, 2017 at 2:51 PM
  • Author: Pamela Kan-Rice

Fire History is Human History

Reposted with permission from the Fire Adapted Communities Learning Network

I recently found myself venting about the idea of “nature.” The concept has always bothered me. There's an inherent separatism in it—an implicit line in the sand between humans and nature, where we can and should appreciate it, but we think we aren't really part of it.

I struggle with these ideas often in my work. I've had people question the naturalness of frequently burned landscapes if they know that humans had a role in ignitions—even if human ignitions extend thousands of years into the past. The dichotomy runs deep.

So it's always refreshing to see 

Credit: Lenya Quinn-Davidson, Fire Adapted Communities Learning Network

scientific reinforcement of what I know in my heart to be true: people are a part of the landscape—a very powerful part.

This is the theme of a recent paper by Alan Taylor, Valerie Trouet, Carl Skinner and Scott Stephens in the Proceedings of the National Academy of Sciences (PNAS). The paper looks at California's Sierra Nevada over the last 400 years, and it finds that socioecological change—human activity—has been the primary driver of changes in the region's fire regimes, more so even than climate.

The paper, which came out late last year, incorporates a unique blend of fire history and human history. The authors were able to reconstruct a 415-year fire record for the region using a combination of tree ring studies and 20th century data on annual area burned. From there, they calculated a “fire index” for every year since 1600—basically a metric that combines fire occurrence and extent, and tells us how much fire activity was going on during that time. Those indices were used to identify large-scale shifts in regional fire regimes, which the authors compared with patterns of human settlement and management, and with climate.

The authors identified four major fire regime periods since 1600, which they were able to link to patterns of human activity. The first regime shift occurred in 1776, triggering a 90-year period of enhanced fire activity. During that period, the mean fire index was almost twice what it had been before 1775. The paper shows that this regime shift was coincident with the timing of Native American contact with Spanish missionaries in the region, which occurred in 1769. It's not exactly intuitive, but the authors explain that the decimation of Native Americans—and a subsequent reduction in light burning—allowed for an increase in fuel continuity and wildfire activity during that period. This connection is further evidenced by the increased sensitivity of fire activity to climate—a relationship that was relatively weak when Native Americans were conducting widespread burning.

The second regime shift occurred in 1866, at which point fire activity dropped back to pre-1776 levels. The authors attribute this shift to major land use changes across the region—mostly associated with intensive livestock grazing, which denuded herbaceous vegetation and had notable effects on fuel continuity and fire spread. During this period, fire activity was also less sensitive to climate than it had been during the previous period because of a lack of fuels.

Credit: Lenya Quinn-Davidson, Fire Adapted Communities Learning Network. Hayfork, where Lenya grew up, has been an epicenter of fire activity in recent decades. It's also been the focus of fire history studies by Alan Taylor and Carl Skinner, who co-authored this new paper.

Credit: Lenya Quinn-Davidson, Fire Adapted Communities Learning Network. Hayfork, where Lenya grew up, has been an epicenter of fire activity in recent decades. It's also been the focus of fire history studies by Alan Taylor and Carl Skinner, who co-authored this new paper.

The third shift is the one we're all most familiar with: the beginning of the fire suppression era in the early 1900s. During the fire suppression period, in which we're still operating today, fire activity has been 4–8 times less than in any other period in recent history. Likewise, the fire-climate relationship has been weak for most of this period; the 20th century has shown increased warming trends, yet fire activity has largely been squelched by human activity. Only in recent decades have we seen a strengthening of that relationship, as a perfect storm of high fuel accumulations, longer fire seasons and drier conditions enables fires of unprecedented severity and size, appearing to override the moderating effects of human management.

My last statement should give us pause. Are we entering an era—perhaps a new fire regime period—where changes in climate are overwhelming our human capacity to influence our landscape? The work of Westerling and others (check out my first Science Tuesday blog from last February) would indicate that we're headed in that direction.

A graph of the fire history described above

Figure 2 from Taylor et al., 2016: “Regime shifts in time series (1600-2015 CE) of Sierra Nevada fire index, summer moisture (i.e., PDSI), and summer temperature (i.e., WANT). A switch to new regime (fire or climate) is shown by a vertical line … The number of tree-ring sites recording fires in each year for the 1600-1907 CE period shown by a dashed line. The fire regime periods are indicated by color shading: 1600-1775 CE (green), 1776-1865 CE (orange), 1866-1903 CE (blue), and 1904 CE to present (pink).”

But the really valuable thing about this new paper by Taylor et al. is that it gives us a larger context to work within. Yes, recent decades have had increased fire activity and increased sensitivity to climate—we've all seen it. But let's remember that our collective frame of reference is relatively short; for most of us, our vision of what's natural or normal in terms of fire comes from the mid to late 20thcentury—the height of our fire disconnect. This paper allows us to look back and see that the human relationship to fire is enduring and powerful, and that our biggest mistake in the last century has been to deny ourselves that intimacy—to value “nature” over nurture. History tells us that we should be able to buffer climate effects, but only if we actively engage at a grand scale. I think we're ready.

Reference:

Taylor, A. H., Trouet, V., Skinner, C. N., & Stephens, S. (2016). Socioecological transitions trigger fire regime shifts and modulate fire–climate interactions in the Sierra Nevada, USA, 1600–2015 CE. Proceedings of the National Academy of Sciences, 201609775.

Posted on Tuesday, February 7, 2017 at 9:22 AM
  • Author: Lenya Quinn-Davidson

Scott Stephens Speaks at California Forest Management Hearing

Reposted from UC Berkeley's Department of Environmental Science, Policy and Management

In response to California's growing tree mortality crisis, the Little Hoover Commission held a public hearing on California Forest Management yesterday (January 26) at the state capital in Sacramento.

Professor Scott Stephens, a fire scientist in the department of environmental science, policy, and management, delivered the opening remarks. He provided background on the causes and magnitude of tree losses happening across the state. "Our forests are not in a resilient condition," he said. "Past management actions, including fire suppression and logging focused on large trees have produced forests today that are much more vulnerable to fire and drought-related mortality." Stephens made suggestions for legislation, policy, and forest management techniques that could help restore resilience to California's forest ecosystems and prevent future mortality crises. He also offered ideas on how the state could better work with private landowners as well as the federal government to promote healthier forests. 

Read Professor Stephens' complete testimony, as well as the those of others who spoke at the meeting, on the Little Hoover Commission's website

Posted on Sunday, January 29, 2017 at 3:49 PM
  • Author: ESPM News

Global warming hiatus disproved — again

Reposted from UC Berkeley News 

A controversial paper published two years ago that concluded there was no detectable slowdown in ocean warming over the previous 15 years — widely known as the “global warming hiatus” — has now been confirmed using independent data in research led by researchers from UC Berkeley and Berkeley Earth, a non-profit research institute focused on climate change.

an Argo float

A NEMO float, part of the global Argo array of ocean sensing stations, deployed in the Arctic from the German icebreaker Polarstern Bremerhaven. (Photo courtesy of Argo)

The 2015 analysis showed that the modern buoys now used to measure ocean temperatures tend to report slightly cooler temperatures than older ship-based systems, even when measuring the same part of the ocean at the same time. As buoy measurements have replaced ship measurements, this had hidden some of the real-world warming.

After correcting for this “cold bias,” researchers with the National Oceanic and Atmospheric Administration concluded in the journal Science that the oceans have actually warmed 0.12 degrees Celsius (0.22 degrees Fahrenheit) per decade since 2000, nearly twice as fast as earlier estimates of 0.07 degrees Celsius per decade. This brought the rate of ocean temperature rise in line with estimates for the previous 30 years, between 1970 and 1999.

This eliminated much of the global warming hiatus, an apparent slowdown in rising surface temperatures between 1998 and 2012. Many scientists, including the International Panel on Climate Change, acknowledged the puzzling hiatus, while those dubious about global warming pointed to it as evidence that climate change is a hoax.

Climate change skeptics attacked the NOAA researchers and a House of Representatives committee subpoenaed the scientists' emails. NOAA agreed to provide data and respond to any scientific questions but refused to comply with the subpoena, a decision supported by scientists who feared the “chilling effect” of political inquisitions.

The new study, which uses independent data from satellites and robotic floats as well as buoys, concludes that the NOAA results were correct. The paper will be published Jan. 4 in the online, open-access journal Science Advances.

“Our results mean that essentially NOAA got it right, that they were not cooking the books,” said lead author Zeke Hausfather, a graduate student in UC Berkeley's Energy and Resources Group.

Long-term climate records

Hausfather said that years ago, mariners measured the ocean temperature by scooping up a bucket of water from the ocean and sticking a thermometer in it. In the 1950s, however, ships began to automatically measure water piped through the engine room, which typically is warm. Nowadays, buoys cover much of the ocean and that data is beginning to supplant ship data. But the buoys report slightly cooler temperatures because they measure water directly from the ocean instead of after a trip through a warm engine room.

rising ocean temperatures

A new UC Berkeley analysis of ocean buoy (green) and satellite data (orange) show that ocean temperatures have increased steadily since 1999, as NOAA concluded in 2015 (red) after adjusting for a cold bias in buoy temperature measurements. NOAA's earlier assessment (blue) underestimated sea surface temperature changes, falsely suggesting a hiatus in global warming. The lines show the general upward trend in ocean temperatures. (Zeke Hausfather graphic)

NOAA is one of three organizations that keep historical records of ocean temperatures – some going back to the 1850s – widely used by climate modelers. The agency's paper was an attempt to accurately combine the old ship measurements and the newer buoy data.

Hausfather and colleague Kevin Cowtan of the University of York in the UK extended that study to include the newer satellite and Argo float data in addition to the buoy data.

“Only a small fraction of the ocean measurement data is being used by climate monitoring groups, and they are trying to smush together data from different instruments, which leads to a lot of judgment calls about how you weight one versus the other, and how you adjust for the transition from one to another,” Hausfather said. “So we said, ‘What if we create a temperature record just from the buoys, or just from the satellites, or just from the Argo floats, so there is no mixing and matching of instruments?'”

In each case, using data from only one instrument type – either satellites, buoys or Argo floats – the results matched those of the NOAA group, supporting the case that the oceans warmed 0.12 degrees Celsius per decade over the past two decades, nearly twice the previous estimate. In other words, the upward trend seen in the last half of the 20th century continued through the first 15 years of the 21st: there was no hiatus.

“In the grand scheme of things, the main implication of our study is on the hiatus, which many people have focused on, claiming that global warming has slowed greatly or even stopped,” Hausfather said. “Based on our analysis, a good portion of that apparent slowdown in warming was due to biases in the ship records.”

Correcting other biases in ship records

In the same publication last year, NOAA scientists also accounted for changing shipping routes and measurement techniques. Their correction – giving greater weight to buoy measurements than to ship measurements in warming calculations – is also valid, Hausfather said, and a good way to correct for this second bias, short of throwing out the ship data altogether and relying only on buoys.

hadley data

Berkeley's analysis of ocean buoy (green) and satellite data (orange) and NOAA's 2015 adjustment (red) are compared to the Hadley data (purple), which have not been adjusted to account for some sources of cold bias. The Hadley data still underestimate sea surface temperature changes. (Zeke Hausfather graphic)

Another repository of ocean temperature data, the Hadley Climatic Research Unit in the United Kingdom, corrected their data for the switch from ships to buoys, but not for this second factor, which means that the Hadley data produce a slightly lower rate of warming than do the NOAA data or the new UC Berkeley study.

“In the last seven years or so, you have buoys warming faster than ships are, independently of the ship offset, which produces a significant cool bias in the Hadley record,” Hausfather said. The new study, he said, argues that the Hadley center should introduce another correction to its data.

“People don't get much credit for doing studies that replicate or independently validate other people's work. But, particularly when things become so political, we feel it is really important to show that, if you look at all these other records, it seems these researchers did a good job with their corrections,” Hausfather said.

Co-author Mark Richardson of NASA‘s Jet Propulsion Laboratory and the California Institute of Technology in Pasadena added, “Satellites and automated floats are completely independent witnesses of recent ocean warming, and their testimony matches the NOAA results. It looks like the NOAA researchers were right all along.“

Other co-authors of the paper are David C. Clarke, an independent researcher from Montreal, Canada, Peter Jacobs of George Mason University in Fairfax, Virginia, and Robert Rohde of Berkeley Earth. The research was funded by Berkeley Earth.

 

Posted on Tuesday, January 24, 2017 at 9:50 AM
  • Author: Robert Sanders

UC Research Forest Lands Expand with Donation

Reposted from UC Berkeley College of Natural Resources news

BERKELEY - The first of three large land donations from Pacific Gas and Electric Company (PG&E) to the University of California has been officially transferred, expanding UC's research forest lands by 1,459 acres.

Named the “Grouse Ridge Forest” after the dominant feature of the property, the land is located on three parcels in the headwaters of the Yuba River in Nevada County. In conjunction with the land donation to UC, a conservation easement was conveyed to the Bear Yuba Land Trust (BYLT), ensuring the permanent protection of the forest land and important wildlife habitat there.

“As California's forests experience increased stresses from droughts, beetles, fires, and climate change, we need more “living laboratories” to learn how we can increase the resiliency of these critical watersheds over the next century,” said Bill Stewart, forestry specialist and co-director of the UC Berkeley Center for Forestry (CFF). “This new addition of  research forest land is valuable as another site along a north-south transect of the Sierra Nevada that ensures that research results are broadly applicable and not just valid in one specific location.”   

The University of California now has 6,452 acres of research forests, which are managed by the Center for Forestry. Through research, education and public service, the CFF continues to improve scientific understanding of the interconnected role of California's forests and state watersheds, renewable wood products, fish and wildlife habitat, scenic and recreational opportunities, and climate benefits. 

These new lands will allow for increased research on the effects of climate change on forest ecosystems, expanded experimentation of forest-management techniques, and broadened outreach efforts to students of all levels, researchers, and the interested public. 

“The importance of research forests as a space for studies on both mitigation of and adaptation to climate change was highlighted again this week with the announcement that we had just had the hottest year on record, for the third year in a row,” said J. Keith Gilless, CNR dean and professor of forest economics.

This is the first time UC has owned a forest property while another entity holds the conservation easement. “The Land Trust is excited for the opportunity to be a partner with the University of California in this endeavor,” said BYLT Executive Director Marty Coleman Hunt in an announcement made by the organization in December. “The forest has been a habitat for wildlife like mountain lion, deer and coyote and will remain so for as long as the forest can support them. As the forest changes over time, the University of California will study how nature adapts, and how the impact of humans can harm or benefit the natural processes.”

The land donation became official with the close of escrow in December 2016. It was originally approved by the Pacific Forest and Watershed Lands Stewardship Council in 2004 as part of PG&E's bankruptcy settlement, with the goal of ensuring that over 140,000 acres of California's lakes and watershed lands are conserved for the public good and to serve California's young people.

Two more forests have also been pledged to UC by PG&E and are expected to be officially transferred over the next few years: one along Marble Creek in eastern Shasta County and another near along the Bear River that is the dividing line between Placer County and Nevada County. 

Once complete, these three donations will more than double the number of acres of UC research forest lands.  

More information about the Grouse Ridge Forest Conservation Easement can be found on the Bear Yuba Land Trust Website.

Posted on Monday, January 23, 2017 at 10:16 AM
  • Author: Julie Van Scoy

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