Pope Francis pleads with nations to act now on climate change


Pope Francis addressed the 70th session of the United Nations General Assembly on Friday, Sept. 25, 2015 at United Nations headquarters. (AP Photo/Seth Wenig)

Pope Francis pleads with nations to act now on climate change

By Michael O’Loughlin National reporter September 25, 2015

NEW YORK — Pope Francis brought his campaign for action on climate change to the United Nations Friday, proclaiming the existence of a “right of the environment” and pleading with countries to stop abusing it.

In remarks to the largest gathering of world leaders in UN history — close to 200 prime ministers, presidents, and potentates — the leader of 1.2 billion Catholics blamed environmental degradation on “a selfish and boundless thirst for power and material prosperity” that causes untold suffering for the poor who “are cast off by society.” But the environment was hardly Francis’ only focus: In a wide-ranging speech, he urged action on drug trafficking, armed conflict, terrorism, education, inequality, and corruption — reminding the UN General Assembly that “solemn commitments” without follow-through could ultimately do more harm than good. Francis is the fourth pope to address the UN (John Paul II visited twice), and he used the opportunity to push his pro-environment message, framing the issue in moral terms and citing his climate change encyclical, Laudato Si’. He was clear that in his mind, environmental protections include an “absolute respect for life in all its stages and dimensions.”

Pope Francis’ remarks to the United Nations (English)
The pope’s speech to the United Nations (Spanish)

Sierra snowpack lowest in 500 years; a wet winter won’t save California





Sierra Nevada snowpack lowest in five centuries

Posted: 14 Sep 2015 08:45 AM PDT

Snowpack in California’s Sierra Nevada in 2015 was at the lowest level in the past 500 years, according to a new report. The research is the first to show how the 2015 snowpack compares with snowpack levels for the previous five centuries.
“Our study really points to the extreme character of the 2014-15 winter. This is not just unprecedented over 80 years — it’s unprecedented over 500 years,” said Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research. “We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” Trouet said. “Anthropogenic warming is making the drought more severe.” California’s current record-setting drought began in 2012, the researchers note in their report.

On April 1 of this year, California Gov. Jerry Brown declared the first-ever mandatory water restrictions throughout the state while standing on dry ground at 6,800-foot elevation in the Sierra Nevada. The historical average snowpack on that site is more than five feet, according to the California Department of Water Resources. The lack of snow in 2015 stems from extremely low winter precipitation combined with record high temperatures in California in January, February and March, Trouet said. About 80 percent of California’s precipitation occurs in the winter months, she said. Snowpack level is generally measured on April 1 each year, a time when the snowpack is at its peak. “Snow is a natural storage system,” she said. “In a summer-dry climate such as California, it’s important that you can store water and access it in the summer when there’s no precipitation.” In past years the snows of the Sierra Nevada slowly melted during the warmer months of the year, and the meltwater replenished streams, lakes, groundwater and reservoirs. In a winter with less snow or with winter precipitation coming as rain rather than snow, there is less water to use during California’s dry summers….


Soumaya Belmecheri, Flurin Babst, Eugene R. Wahl, David W. Stahle, Valerie Trouet. Multi-century evaluation of Sierra Nevada snowpack. Nature Climate Change, 2015; DOI: 10.1038/nclimate2809



National Geographic graphic

A Wet Winter Won’t Save California


Noah S. Diffenbaugh is an associate professor of earth system science at Stanford. Christopher B. Field is director of the department of global ecology at the Carnegie Institution for Science.

STANFORD, Calif. — As wildfires rage, crops are abandoned, wells run dry and cities work to meet mandatory water cuts, drought-weary Californians are counting on a savior in the tropical ocean: El Niño.

This warming of the tropical Pacific occurs about every five years, affecting climate around the globe and bringing heavy winter precipitation to parts of California. The state experienced two of its wettest years during two of the strongest El Niños, in 1982-83 and 1997-98. Now climatologists have confirmed that a powerful El Niño is building, and forecasts suggest a high likelihood that El Niño conditions will persist through the next several months. So we in California expect a rainy winter. But before everyone gets too excited, it is important to understand this: Two physical realities virtually ensure that Californians will still face drought, regardless of how this El Niño unfolds.

  • The first is that California has missed at least a year’s worth of precipitation, meaning that it would take an extraordinarily wet rainy season to single-handedly break the drought. Even if that happened, we would most likely suffer from too much water too fast, as occurred in the early 1980s and late 1990s, when El Niño delivered more rainfall than aquifers could absorb and reservoirs could store.
  • The second is that California is facing a new climate reality, in which extreme drought is more likely. The state’s water rights, infrastructure and management were designed for an old climate, one that no longer exists.

Our research has shown that global warming has doubled the odds of the warm, dry conditions that are intensifying and prolonging this drought, which now holds records not only for lowest precipitation and highest temperature, but also for the lowest spring snowpack in the Sierra Nevada in at least 500 years. These changing odds make it much more likely that similar conditions will occur again, exacerbating other stresses on agriculture, ecosystems and people. At the same time, extreme wet periods may also increase because a warming atmosphere can carry a larger load of water vapor. In a possible preview, persistent El Niño conditions this year could force Californians to face both flooding and drought simultaneously. The more rainfall there is, the more water will be lost as runoff or river flow, increasing the risk of flooding and landslides. Add in the fact that the drought and wildfires have hardened the ground, and a paradox arises wherein the closer El Niño comes to delivering enough precipitation to break the drought this year, the greater the potential for those hazards. In the United States, we experienced more than 80 “billion-dollar” climate and weather disasters in the last decade, and several have cost much more. The regularity of these episodes and the resulting damage shows that we are not prepared for the current climate, let alone a changing one that portends more weather extremes. From these disasters, we can take away two lessons: Increasing resilience now can build protection for the future, and stressed systems are more prone to disasters. For instance, the risk from a period of extremely low water supply in California is far greater when high temperatures, like those we’ve seen here over the last two years, prolong drought. There are also risks when the combined demands of households, manufacturing, farming and ecosystems tax water supplies even in good years, or when forest management practices create conditions that fuel fires. Californians will benefit by reducing these interacting stresses. We are not arguing that the drought has been caused by climate change alone, or that all weather disasters have a link to climate change. However, the evidence is clear that many areas of the globe are experiencing increasing risks from weather and climate hazards. As with the California drought, climate change is an important thumb on the scale, increasing the odds of particular extremes in specific places. In California, we can expect warmer winters and hotter summers, drier dry years and wetter wet years, and less water storage from snowpack in the mountains, which also controls flooding. This means more years with extreme fire danger, critically overdrawn groundwater, legal water rights that exceed the amount of water available and challenges to balancing trade-offs among water storage, flood control and environmental protection. We have opportunities to rethink the fundamental structure of water rights and markets, re-engineer water storage to compensate for decreasing snowpack, update regulations and infrastructure to embrace water reuse and recycling, and regulate end-user pricing to encourage conservation. In short, we benefit from incorporating climate-related risks in planning for California’s future. Fortunately, California has many assets, including historical experience, robust institutions, sophisticated science and engineering expertise and financial flexibility. Capitalizing on these assets can reduce risks today and set a path for a vibrant future. Doing so will begin by acknowledging that we are already living in a rapidly changing climate.

El Nino-fueled coastal erosion


Photo: Paul Chinn, The Chronicle This year’s El Niño may be stronger that the version that hit California in 1997-1998 rainy season.  Here are photos from the 1997-1998 El Niño: A storm-damaged section of the Great Highway south of Sloat Boulevard in March 2012.

Scientists see a future of El Niño-fueled coastal erosion

By David Perlman SF CHRON Updated 7:04 pm, Monday, September 21, 2015

The seacoasts of California and nations on both sides of the Pacific are likely to be battered in coming years by increasingly high waves pushed ashore by ever-stronger weather patterns, leaving them vulnerable to destructive erosion, an international group of experts said Monday. Those intensified weather patterns such as El Niño, when warmer eastern Pacific waters contribute to more intense storms hitting California, will increasingly threaten the coasts irrespective of climate change, said an international team of 17 coastal experts. Severe weather events across the entire Pacific basin have been increasing for more than 30 years and are expected to double in frequency in coming years, the scientists said in a report published in the journal Nature Geoscience. Only five years ago, an unusual weather pattern during an El Niño winter brought extreme wave heights and unprecedented erosion that tore away protective revetments along more than 3 miles of San Francisco’s Ocean Beach and damaged the Great Highway. Patrick Barnard, the leading coastal geologist at the U.S. Geological Survey’s Marine Science Center in Santa Cruz and principal author of the new study, said Ocean Beach has since recovered, and other beaches in the Bay Area “now look in moderately decent shape.” But in the long term, Barnard said, such areas are going to become increasingly vulnerable to erosion brought about by surging storms. And it isn’t only El Niño events that are the problem: Intensified episodes of El Niño’s meteorological opposite, called La Niña, when the eastern and central Pacific becomes abnormally cold, are likely to threaten coastal regions in New Zealand, Australia and elsewhere in the Southern Hemisphere, the report said. The coastal scientists who compiled the new report surveyed 48 beaches bordering the Pacific and analyzed detailed climate events around the Pacific stretching from 1979 to 2012 to reach their forecasts. They also considered forecasts of extreme La Niña and El Niño events published recently by a separate group of international climate and coastal scientists led by Wenju Cai, a climate modeler at Australia’s Scientific and Industrial Research Organization, Barnard said. The Cai group predicted that increased global warming and rising sea levels due to climate change would double the frequency of those severe weather events across the Pacific basin. The result, the group said in a report published this year in the journal Nature Climate Change, would be “more occurrences of devastating weather events and more frequent swings of opposite extremes from one year to the next, with profound socio-economic consequences.”


Coastal vulnerability across the Pacific dominated by El Niño/Southern Oscillation

Barnard et al. Nature Geoscience (2015) doi:10.1038/ngeo2539 Received 29 June 2015 Accepted 17 August 2015 Published online 21 September 2015


To predict future coastal hazards, it is important to quantify any links between climate drivers and spatial patterns of coastal change. However, most studies of future coastal vulnerability do not account for the dynamic components of coastal water levels during storms, notably wave-driven processes, storm surges and seasonal water level anomalies, although these components can add metres to water levels during extreme events. Here we synthesize multi-decadal, co-located data assimilated between 1979 and 2012 that describe wave climate, local water levels and coastal change for 48 beaches throughout the Pacific Ocean basin. We find that observed coastal erosion across the Pacific varies most closely with El Niño/Southern Oscillation, with a smaller influence from the Southern Annular Mode and the Pacific North American pattern. In the northern and southern Pacific Ocean, regional wave and water level anomalies are significantly correlated to a suite of climate indices, particularly during boreal winter; conditions in the northeast Pacific Ocean are often opposite to those in the western and southern Pacific. We conclude that, if projections for an increasing frequency of extreme El Niño and La Niña events over the twenty-first century are confirmed, then populated regions on opposite sides of the Pacific Ocean basin could be alternately exposed to extreme coastal erosion and flooding, independent of sea-level rise.

Why scientists are so worried about drylands — which make up 40 percent of the Earth’s land


Needles District of Canyonlands National Park, with continuous biocrust in the foreground. (Courtesy Bill Bowman, University of Colorado.)

Why scientists are so worried about drylands — which make up 40 percent of the Earth’s land

By Chris Mooney September 14

Virtually every ecosystem of the world — from forests to the oceans — raises concern about the toll that a warming climate will take. There’s one type of landscape, though, that doesn’t get talked about very much in this context — so-called “drylands,” a grouping that includes arid and semi-arid regions ranging from many deserts to grasslands. Drylands are one of the more important ecosystems in the world, comprising fully 40 percent of the Earth’s land surface. And now, an alarming new study in the Proceedings of the National Academy of Sciences says the impact of a warming climate on these ecosystems could be much worse than expected — comparable to humans trampling the landscapes underfoot or driving off-road vehicles across them. “Contrary to our expectations, experimental climate change and physical disturbance had strikingly similar impacts,” wrote the researchers, led by Scott Ferrenberg of the U.S. Geological Survey’s Southwest Biological Science Center in Moab, Utah. Ferrenberg conducted the work with two Geological Survey colleagues….


Climate change and physical disturbance cause similar community shifts in biological soil crusts

Scott Ferrenberg
et al PNAS Sept 2015 doi: 10.1073/pnas.1509150112


In drylands worldwide, where plant cover is sparse, large amounts of the ground surface are covered by specialized organisms that form biological soil crusts (biocrusts). Biocrusts fix carbon and nitrogen, stabilize soils, and influence hydrology. Extensive physical disturbance from livestock/human trampling and off-road vehicles is known to destroy biocrusts and alter ecosystem function. More recent work also indicates that climate change can affect biocrust communities. Contrary to our expectations, experimental climate change and physical disturbance had strikingly similar impacts on biocrust communities, with both promoting a shift to degraded, early successional states.
These results herald ecological state transitions in drylands as temperatures rise, calling for management strategies that consider risks from both physical disturbances and climate change.


As Fires Grow, a New Landscape Appears in the West


Flames from the Valley Fire covered a hillside along Highway 29 in Lower Lake, Calif. on Sept. 13, 2015. Credit Noah Berger/Reuters

As Fires Grow, a New Landscape Appears in the West

Governments’ interference in the natural cycle of fires, along with climate change, has created more brush on forest floors and hotter, drier seasons.

By JOHN SCHWARTZ NY Times Sept 22 2015
NEAR COCHITI CANYON, NEW MEXICO — The hills here are beautiful, a rolling, green landscape of grasses and shrubs under a late-summer sky. But it is starkly different from what was here before: vast forests of ponderosa pine. ….. The result is bad news for forests here, in the West and around the world. A planet with fewer trees is less able to fight climate change, because trees absorb carbon dioxide from the atmosphere as part of photosynthesis. “The future in a lot of places,” Dr. Allen said, “is looking shrubbier.”

The fire season of 2015 in the American West is shaping up as one of the worst in the nation’s history, with more than eight million acres burned nationwide — more than five million acres in Alaska alone. Fierce wildfires this month have destroyed hundreds of homes in California. The Forest Service struggles under an increasingly costly mission: According to a report released last month, firefighting takes up more than 50 percent of its annual budget, up from 16 percent a decade ago. In 10 years, it could consume three quarters of its budget. Climate change has lengthened fire seasons, which are, on average, 78 days longer than they were in 1970, and the six worst fire seasons since 1960 have come since 2000.

The consequences of a century of forest policies to suppress fires are now combining with the hotter and drier seasons to create tinderbox conditions, producing high-severity fires that kill trees and are increasingly hard to bring under control. Dr. Allen and many other researchers have studied how to manage forests so fires are not as destructive. And in the case of the most destructive fires, they are studying what happens to those landscapes in the years after a blaze.

In an increasing number of cases, said Malcolm P. North, a research scientist with the United States Forest Service Pacific Southwest research station in Davis, Calif., “after the satellite trucks leave and everyone goes home, you have a charred condition on the landscape that does not have a historical precedent.” Fire, over eons, has been an essential and cyclical part of forest life; tree-ring records show fires occurring every five or 15 years for ponderosa pine in the Southwest, said Thomas W. Swetnam, a professor emeritus at the University of Arizona and an expert in tree-ring analysis. The fires tended to burn with low intensity, clearing underbrush, grasses and seedlings, leaving an uncluttered forest floor and helping some species of pine spread their seeds.

More than 100 years ago, that pattern of frequent surface fires was disrupted, first by widespread grazing by sheep and cattle, which cleared much of the grass and other undergrowth, and then by a government policy to suppress forest fires wherever possible. Fewer fires caused the forests to grow more densely, and for grasses and dead trees to accumulate on the forest floor. The hotter, longer droughts associated with climate change make the trees and ground cover drier; the result is a greater tendency for fires to “ladder up” to the canopy of leaves or needles above.

Dr. North, the California researcher, said that as much as 80 percent of California’s forests were in the kind of conditions that were likely to lead to the more destructive, tree-killing fires. Without mature trees near the fire-ravaged areas to spread their seeds, brush and grass are likely to grow in place of the conifers. That means forest recovery can be slow, or worse, said Donald A. Falk, a fire expert at the University of Arizona. “That’s a recovery process that could take centuries — and given where climate is going, it might never recover,” he said. Not everyone agrees with this gloomy assessment. William L. Baker, a professor emeritus at the University of Wyoming, has used historical land-survey data to argue in papers that large, severe wildfires are a natural phenomenon and are not necessarily worse than before. Over time, he has argued, the forests can grow back.

But Dr. Swetnam and others disagree with Mr. Baker’s conclusions, arguing that the land-survey records are not as reliable an approach to understanding fire history than the trees’ own rings, among other data sources.

Droughts are certainly not new, nor are large fires or even intense fires, Dr. Swetnam acknowledged. But the greater number of intense and large fires, and the repeated “burns on top of burns” like the ones that cleared the landscape around Cochiti canyon, are part of a pattern of worsening conditions exacerbated by the hotter droughts. He has studied sections of many trees from the former forest near the canyon, which provided 300 years of fire history before the 2011 Las Conchas blaze, which ultimately burned 150,000 acres. “Obviously, the forest had survived many, many, surface fires,” he said. “But this fire — this fire — killed all of the trees in this area. ”

He added, “I’m often pressed to say which is the most important factor in the changing nature of forest fires. I’m more inclined now to point to climate change than I was 10 years ago.” A sweeping recent paper from Mr. Allen and colleagues suggests that wildfires are only part of the damage that climate change is wreaking on the world’s forests. The hotter droughts that are associated with climate change are causing stress for trees, and are likely to grow worse over time, leading to increased tree mortality. By the middle of this century, “If the climate models are at all accurate, what in 2011 were really extraordinary conditions will be typical conditions for June” in the Southwest, he said.

Because dry and wet periods are cyclical, he said, year-by-year variation could lead to brief periods of even more extreme drought along the way. El Niño could bring wetter and cooler weather to this region, reducing the number and severity of fires for a while. But the long-term trends are anything but good. And what is happening in the West is a harbinger for much of the rest of the planet.

The trees in too-dense forests are already competing for water that the historically more sparse stands of trees might have found adequate; as drought increases, the stress will kill many trees outright and weaken others to the point that they become more vulnerable to predators like aggressive bark beetles.

Because of hotter drought, he said, “the future broad-scale vulnerability of forests globally is being widely underestimated, including the vulnerability of forests in wetter regions,” he said. With three trillion trees in the world, of course, there is still a great deal of carbon being stored. But that could change over time. And because forests provide an important natural mechanism for fighting climate change, the stress of hotter drought could become part of a feedback loop of increased warming. Landscapes like the scrubland in New Mexico absorb far less carbon than the forests they are replacing, said Mr. Falk of the University of Arizona. With forest fires and the decay of dead trees, which also puts the carbon they were storing back into the atmosphere, “These forest become carbon sources, where in the past, we’ve relied on them to become carbon sinks.”

A study published in July suggests this has occurred in California, where forests have shifted from net carbon absorbers to carbon emitters, according to Patrick Gonzalez, a forest ecologist with the national park service and the author of the report. An author for the Intergovernmental Panel on Climate Change, Dr. Gonzalez said that wildfires were “tipping the balance” between storage and emission. Even droughts that do not lead to tree death impair the ability of forests to absorb carbon dioxide. A study published in July from William R.L. Anderegg of Princeton University and colleagues has found that forests slow their growth for four years after a drought, and absorb less carbon during that period. Researchers in the past believed that forests recovered quickly, but Dr. Anderegg and his colleagues found that severe drought greatly curtailed the absorption of carbon over a broad range of tree species. “It’s absolutely clear that drought has these manifold and very severe impacts on forests,” Dr. Anderegg said. “Forests are more vulnerable than we thought. Drought has lasting impacts, even when the rain comes back and the soil becomes wet again.” So far, he said, the world’s forests appear to be a net absorber of carbon, but there are “some worrying signs that we could be starting to change that.” He added, “We could be in more danger than we thought, sooner than we thought.” Fire experts have long called for action to meet the challenge of forest fires in a changing climate.

In a paper published last week in the journal Science, Dr. North and colleagues argued for ending the national policy of fighting every fire, and for making more concerted effort to thin forests so more fires might only scorch trees without destroying them. The authors called the traditional policy of trying to suppress every fire “dangerous, expensive, and ill advised.” Thinning involves techniques like selectively cutting down trees in forests and burning sections of forest, carefully and under weather conditions that make fire easier to control. The alternative, Dr. Swetnam said, is more of the severe and repetitive blazes. “If you don’t come in and thin these trees with chain saws or fire,” he said, “you’ve got a bomb.” Tightly packed trees spread fire to other trees faster, noted Paul F. Hessburg, a research ecologist with the United States Fire Service at the Pacific Northwest Research Station. Thinning and prescribed burns, he said, “can break that contagiousness up.” Local citizens complain about smoke from controlled burns, he said, but some kind of fire is inevitable. “I think society is going to have to decide how it wants its fire and how it wants its smoke — whether in large-fire-sized doses, or in smaller-fire-sized doses,” Dr. Hessburg added. “We have it in us to decide what kind of society we want to live in.”

The problem with controlled burning, Mr. Allen said, is that the century of fire suppression has created forests that can readily burn out of control. “We were trapped in this Catch-22,” he said. But such thinning, he said, is nonetheless essential. Restoring forests that have burned is also expensive, Mr. Allen said, and not always effective. After the Los Conchas fire in 2011, the federal government announced a program to plant 5,200 acres of trees – a large number, though still just a fraction of the 150,000 acres of land that were burned. The seedlings, planted during a severe drought, also did not fare well; most died.

And even if the forest service could replant millions of acres of forest land, would those new trees be able adapt to the changing climate of the next 100 years? Those problems have led to high-level discussions about topics like climate adaptation and planting species that might be better suited to emerging environmental conditions — a process that goes by such names as “assisted colonization” and “assisted migration.”

Meg Krawchuk, an assistant professor of geography at Simon Fraser University, noted that such initiatives would be expensive, and contentious as well. Theoretically, she said, it might be attractive to shift species to areas where they might be expected to do well. “Given enough time and limited tinkering from humans,” she said, “one would think an appropriate response to changes in climate and to fire would be proposed by mother nature.”

As the fires in California are showing, conflagrations that threaten people and communities receive the most attention. Better land management can reduce the risk to life and property, but people will always be drawn to the lush beauty of forests, just as they are drawn to risky coastal areas and locations threatened by river flooding. “This is the human condition,” said Dr. Swetnam, standing on his land in the Jemez mountains of New Mexico. While the trees on his hillside property have been thinned, many neighbors have not taken that step — and he knows a major fire would easily race across his handful of acres. It is, however, home, and human beings have long preferred to overlook some obvious risks of natural — and increasingly human-created — disasters “In so many places, we live under the volcano,” he said. “We have a great capacity to set aside the risks we are taking.”

Cold rush: Bird diversity higher in winter than summer in Central Valley- Point Blue Publication


The black-headed grosbeak commonly summers in the Central Valley. A UC Davis study found bird diversity in the area was actually higher in the winter than in summer, highlighting the importance of protecting habitat for birds year-round. Andrew Engilis/UC Davis

Cold rush: Bird diversity higher in winter than summer in Central Valley

During the warmer months, the air surrounding California’s rivers and streams is alive with the flapping of wings and chirping of birds. But once the buzz and breeding of spring and summer are over, these riparian areas grow quiet. Sometimes it seems as though there are hardly any birds there at all. Not so, according to a study from the UC Davis Department of Wildlife, Fish and Conservation Biology. Researchers examined bird diversity in the lower Cosumnes River and lower Putah Creek watersheds in the Central Valley between 2004 and 2012. They found that just as many bird species used the riparian habitats in the winter as in the summer, and genetic diversity was actually higher in the winter than during summer months.

It turns out that while many birds headed south for the winter to tropical habitats, birds that breed in the boreal forest of Canada flew in to take their place.
These “neotemperate migrants,” as the researchers call them, include birds such as the yellow-rumped warbler, white-crowned sparrow, fox sparrow, cedar waxwing, and varied thrush. You might have to look harder, but there are just as many species there,” said lead author Kristen Dybala, a UC Davis postdoctoral student at the time of the study and currently a research ecologist with Point Blue Conservation Science. “We found strong evidence that Central Valley ecosystems are very important in supporting bird populations throughout the year.”….


Kristen E. Dybala, Melanie L. Truan, and Andrew Engilis, Jr. (2015) Summer vs. winter: Examining the temporal distribution of avian biodiversity to inform conservation. The Condor: November 2015, Vol. 117, No. 4, pp. 560-576. doi:

Drought, Land Cover and Waterbirds in California- Point Blue Publication



Spatio-Temporal Patterns of Open Surface Water in the Central Valley of California 2000-2011: Drought, Land Cover, and Waterbirds

Matthew E. Reiter, Nathan Elliott, Sam Veloz, Dennis Jongsomjit, Catherine M. Hickey, Matt Merrifield, Mark D. Reynolds

Article first published online: 18 SEP 2015 DOI: 10.1111/1752-1688.12353 © 2015 American Water Resources Association Paper No. JAWRA-14-0153-P of the Journal of the American Water Resources Association (JAWRA).

View Full Article (HTML)
Enhanced Article (HTML)
Get PDF (662K)


We used Landsat satellite imagery to (1) quantify the distribution of open surface water across the Central Valley of California 2000-2011, (2) summarize spatio-temporal variation in open surface water during this time series, and (3) assess factors influencing open surface water, including drought and land cover type. We also applied the imagery to identify available habitat for waterbirds in agriculture. Our analyses indicated that between 2000 and 2011 open surface water has declined across the Central Valley during the months of July-October. On average, drought had a significant negative effect on open surface water in July, September, and October, though the magnitude and timing of the effect varied spatially. The negative impact of a drought year on open water was experienced immediately in the southern Central Valley; however, there was a one year time-lag effect in the northern Central Valley. The highest proportion of open surface water was on agricultural lands followed by lakes, rivers, and streams, yet the relative proportions varied spatially and across months. Our data were consistent with previous descriptions of waterbird habitat availability in post-harvest rice in the northern Central Valley. Tracking water distribution using satellites enables empirically based assessments of the impacts of changing water policy, land-use, drought, climate, and management on water resources.

Satellite Data Helps Migrating Birds Survive (with Video)- Point Blue, TNC, CLO and other partners


The long-billed curlew is just one of dozens of species of birds that forage for insects on the flooded rice fields, created by the BirdReturns program. Credits: Greg Golet/The Nature Conservancy

Satellite Data Helps Migrating Birds Survive (with Video)

NASA NEWS Sep. 24, 2015 By Kate Ramsayer
NASA Goddard Earth Science

This fall, birds migrating south from the Arctic will find 7,000 acres of new, temporary wetland habitat for their stopovers in California. The wetlands – rice fields shallowly flooded for a couple weeks after the harvest – are courtesy of a project that combines citizen science, conservation groups and imagery from Landsat satellites, a joint NASA and U.S. Geological Survey program. The BirdReturns program, created by The Nature Conservancy, is an effort to provide “pop-up habitats” for some of the millions of shorebirds, such as sandpipers and plovers, that migrate each year from their summer breeding grounds in Alaska and Canada to their winter habitats in California, Mexico, Central and South America.

The route takes the birds along what’s called the Pacific Flyway, where they seek out the increasingly rare wetlands teeming with tasty insects to fuel their long-distance flights. The problem – more than 90 percent of the natural wetlands in the Central Valley of California have been lost to development, agriculture and other land use changes, said Mark Reynolds, lead scientist for The Nature Conservancy California Migratory Bird Program. The organization operates the BirdReturns program, with partners including Point Blue Conservation Science, Audubon California and the Cornell Lab of Ornithology. “The challenge is how do you help wildlife that move around and create habitat in places that may only be important for a few weeks or a few months out of the year?” Reynolds said. “We’d long been searching for spatial data that could help us.”

Pop-up habitat

The solution involves big data, binoculars and rice paddies. The Cornell Lab of Ornithology’s eBird program collects on-the-ground observations, including species and date spotted, from bird watchers nationwide. With a recent NASA grant to Cornell, scientists created computer models to analyze that information and combine it with satellite remote sensing imagery from Landsat and the Moderate Resolution Imaging Spectroradiometer instruments on NASA’s Terra and Aqua satellites. With these models, they could identify areas in the Central Valley where birds flocked to during the spring and fall migrations, as well as estimate the number of birds making the journey. “The challenge then was to better understand the status of the habitat, where the models were predicting we should have birds,” Reynolds said. Some of his colleagues had been using Landsat images to look at where – and when – there was standing water, to assist with surveys of shorebirds. Matthew Reiter, a quantitative ecologist with the conservation science nonprofit Point Blue, based in Petaluma, California, worked on developing models that can classify habitats based on Landsat imagery. For the BirdReturns project, the team analyzed 1,500 Landsat scenes between 2000 and 2011, and then additional images from Landsat 8 after its 2013 launch. For each area not blocked by clouds, they classified whether there was surface water. “We can show patterns of how there’s changing habitat availability through the year, and that the timing may vary year to year,” Reiter said.

Matching the location and timing of surface water from Landsat with the route and timing of migrating shorebirds from eBird, the BirdReturns program looks for those key sites where extra water would make a difference for the birds, which forage for food in the wetland areas. That’s where farmers come in. Rice farmers in California’s Central Valley flood their fields post-harvest, to soften the stubble and make it easier to clear for the next year. Using a reverse-auction, the farmers submit bids to The Nature Conservancy, stating how much money per acre it would take for them to shallowly flood their fields for a few weeks to create these pop-up wetland habitats. The BirdReturns team examines the bids, compares them to the priority habitats, and then makes selections, paying farmers to flood fields for specific two-week periods. This fall, 30 farmers applied water on approximately 7,000 acres of rice fields. It’s the fourth round of auctions; about 30,000 acres of cumulative habitat was created earlier through auctions in Spring 2014, Fall 2014 and Spring 2015. In Spring 2014, the group surveyed the participating fields, as well as control fields where the water wasn’t left on. They found that more than 180,000 birds of over 50 different species used the 10,000 acres of pop-up wetlands – 30 times more than counted on the dry fields. “It’s been a pretty astonishing success,” Reynolds said. “Farmers participated, and we were able to put habitat out there at a fraction of the cost to purchase that land or put an easement on it.”

Mapping water

With an ongoing drought in California, which is drying up some of the state’s wildlife refuges, it’s even more valuable to have a program like this, he said. If farmers have the water to create the habitat, it could compensate for dry areas elsewhere along the route. With Landsat’s free archive of decades of land cover information, the mission has often been used for habitat and biodiversity studies, said Jeff Masek, project scientist for the upcoming Landsat 9 mission. With the currently in orbit Landsat 7 and Landsat 8 capturing more images per day than previous satellites, scientists have more information to draw on to study the timing of the ephemeral lakes, rivers and wetlands that only appear certain times of year. “There’s been more and more work with the water mapping,” Masek said. “You can start to do much more detailed studies of the seasonality of water – when these lakes fill in, and when they dry up.” The freely available satellite imagery from Landsat, and other satellite instruments such as the Moderate Resolution Imaging Spectroradiometer, are invaluable data resources to see how birds and other animals are affected by landscape changes, Reiter said. “With applied conservation programs, we’re using that imagery to say here are the areas that we can prioritize for conservation management, and here are areas that maybe we can let go,” he said. “It’s a very powerful tool for getting conservation to happen.”




Spatio-Temporal Patterns of Open Surface Water in the Central Valley of California 2000-2011: Drought, Land Cover, and Waterbirds

Matthew E. Reiter, Nathan Elliott, Sam Veloz, Dennis Jongsomjit, Catherine M. Hickey, Matt Merrifield, Mark D. Reynolds

Article first published online: 18 SEP 2015 DOI: 10.1111/1752-1688.12353 © 2015 American Water Resources Association Paper No. JAWRA-14-0153-P of the Journal of the American Water Resources Association (JAWRA).

View Full Article (HTML)
Enhanced Article (HTML)
Get PDF (662K)


We used Landsat satellite imagery to (1) quantify the distribution of open surface water across the Central Valley of California 2000-2011, (2) summarize spatio-temporal variation in open surface water during this time series, and (3) assess factors influencing open surface water, including drought and land cover type. We also applied the imagery to identify available habitat for waterbirds in agriculture. Our analyses indicated that between 2000 and 2011 open surface water has declined across the Central Valley during the months of July-October. On average, drought had a significant negative effect on open surface water in July, September, and October, though the magnitude and timing of the effect varied spatially. The negative impact of a drought year on open water was experienced immediately in the southern Central Valley; however, there was a one year time-lag effect in the northern Central Valley. The highest proportion of open surface water was on agricultural lands followed by lakes, rivers, and streams, yet the relative proportions varied spatially and across months. Our data were consistent with previous descriptions of waterbird habitat availability in post-harvest rice in the northern Central Valley. Tracking water distribution using satellites enables empirically based assessments of the impacts of changing water policy, land-use, drought, climate, and management on water resources.

James Hansen on sea level rise, 2 degrees C and more


Predictions Implicit in “Ice Melt” Paper and Global Implications

21 September 2015 James Hansen and Makiko Sato


S.L. Marcus suggests that our paper “Ice Melt, Sea Level Rise & Superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C global warming is highly dangerous” would have greater appeal and impact if it featured some notable, verifiable predictions. In related vein, E. Stabenau asks what observations in the next decade or so would verify our assumptions. Indeed, there are many predictions implicit in our paper, and there is merit in highlighting these. Most revealing, in stark contrast to all IPCC models, is strong cooling of the Southern Ocean surface and in the North Atlantic, as shown in Fig. 1. These coolings are a consequence of fundamental processes induced by injection of meltwater into upper layers of the ocean.
Cooling of the Southern Ocean and North Atlantic results mainly from the stratification effect of freshwater. Lesser density of fresh meltwater, compared to salty ocean water, reduces sinking of surface water to the deep ocean. Reduced Antarctic Bottom Water formation reduces the amount of relatively warm deep water rising to the surface, where it increases heat flux to the atmosphere and space. Instead heat is kept at depth, raising deep water temperature and melting ice shelves (see diagram in Fig. 22 of our paper).


We predict not only that the Southern Ocean surface will cool, rather than warm, but also that the cooling will be largest in the Western Hemisphere. Cooling is larger there because the rate of ice shelf melt is larger there (Fig. 2; note that longitude is shifted 180° in Fig. 2 relative to Fig. 1). Our modeling assumes that warming induced meltwater is three times larger in the Western Hemisphere, stretching from the Ross Sea to the Weddell Sea, than in the other hemisphere. What we have is a push and shove match between global warming, which warms the global ocean surface with amplification at high latitudes, and the freshwater stratification effect, which causes ocean surface cooling in the North Atlantic and Southern Oceans. IPCC simulations for the 21stcentury find a warming Southern Ocean with declining sea ice cover, as freshwater injection is either omitted or small. In contrast, with our assumed rates of freshwater injection, estimated from observations today and extrapolated into the future with several alternative doubling rates, the freshwater cooling effect is already comparable to the greenhouse warming effect in the Southern Ocean, and cooling wins out in our model over the next decade or two. Furthermore, we argue that our model and many ocean models understate the stratification effect because of excessive small scale ocean mixing….We interpret the Southern Ocean cooling and sea ice increase of the past two decades as effects of Antarctic ice shelf melt, i.e., increasing freshwater injection. The sea ice area anomaly decreased sharply in August 2015, back to about the mean value for the base period (1981-2010). We suggest that this sea ice loss is, at least in part, a consequence of the strong 2015-2016 El Nino, which began a few months ago. In other words, in the push and shove match between global warming and freshwater cooling on the Southern Ocean, global warming gets a boost from El Nino, but that boost is temporary. …


….Predictions of ice sheet mass loss and sea level rise. In our paper we discuss potential ice melt doubling times of 10, 20 and 40 years, which respectively would lead to multi-meter sea level rise in about 50, 100, and 200 years. For the sake of analyzing the effect of freshwater on ocean circulation and planetary energy balance, we made climate simulations for doubling times of 5, 10 and 20 years, omitting 40-year doubling because of its larger computing requirement. These cases were sufficient for conclusions about the effect of freshwater on the planetary energy balance and shutdown of overturning ocean circulations (AMOC and SMOC). Here we give our opinion about the likely speed at which ice sheets will respond to the climate forcing for “business-as-usual” growth of fossil fuel emissions. The resulting rate of increasing climate forcing is far outside the rate Earth has ever experienced. We suspect that glaciologists anticipating very slow response of ice sheets base their opinion in part on the rates of ice sheet change that occurred in response to natural climate forcings, which changed much more slowly than the human-made forcing. The rate of change of greenhouse gases determines Earth’s energy imbalance, and the energy imbalance is the “drive” or “forcing” of ice sheet change. …Given all the evidence, a claim that a scenario with 600-900 ppm CO2 forcing within a century would not yield multi-meter sea level rise this century is an extraordinary claim that would require extraordinary proof. Today’s ice sheet models are not capable of providing that proof.Even though a certain “scientific reticence” seems to infect the sea level rise issue, we do not agree that it is already too late to avert climate disasters including: (1) sea level rise inundating coastal cities, (2) shutdown of the Atlantic Meridional Overturning Circulation. Moreover, we will conclude that the actions required to avoid sea level disaster should be sufficient to also avert shutdown of the AMOC and begin to reverse other climate impacts that are beginning to appear and would otherwise be expected to grow under business-as-usual fossil fuel emissions….Let’s discuss actions required to avert climate disasters in the context of responding to a request that we specify needed observations. Critical climate metrics include:


(1) Global surface temperature. Our paper makes clear that the United Nations choice of 2°C as a “guardrail” is not justified by the science, indeed global mean temperature is a flawed metric for that purpose. However, surface temperature is a good diagnostic of the climate system, and, as discussed above, Southern Ocean and North Atlantic temperature patterns will provide an indication of the effect of ice melt on the Southern Ocean and North Atlantic overturning.


(2) Earth’s energy imbalance. The planet’s energy imbalance provides a simple measure of where climate is headed. We must eliminate this imbalance to stabilize climate, and perhaps we will need to achieve a slightly negative imbalance for the purpose of cooling the ocean and avoiding demise of ice shelves and the ice sheets….


(3) Atmospheric CO2. Atmospheric CO2 amount is a critical measure of the state of the planet, which governments apparently prefer to ignore, perhaps because they do not like its implications…. The need to restore Earth’s energy balance informs us about the required limit on greenhouse gases (GHGs), specifically that the CO2 stabilization level cannot be as high as 450 ppm or even 400 ppm, the present amount. Instead it is no more than 350 ppm and possibly lower12, which has immediate implications for policy.


(4) Sea level à ice sheet mass change. Most large cities are located on coast lines. Multi-meter sea level rise has the potential to wreak global economic havoc, create hundreds of millions of refugees, and thus perhaps make the world practically ungovernable….However, large ice sheets are the source of potentially disastrous sea level rise and it is important to measure their rates of change accurately on a regional basis. Thus a critical measurement is continuation of precise gravity measurements from satellites.


(5) Aerosols. Measurements of the largest climate forcings affecting Earth’s energy imbalance are needed for policy prescription. Greenhouse gases are monitored, but the other large human-made forcing, aerosols, including effects on clouds, are not monitored….Analogous to gravity measurements, precise aerosol measurements would be done best from a small satellite, thus making continuous or near -continuous monitoring feasible.


Now let us return to the question: is it already too late? The conclusion that dangerous climate change is reached at global warming less than 2°C, and that it will be necessary to reduce CO2 back below 350 ppm, makes clear how difficult the task will be. The bright side is the fact that the climate forcing limitation required to avoid sea level disaster is so stiff that it should also avert other climate impacts such as AMOC shutdown. Furthermore, we would roll back undesirable climate impacts that are already beginning to appear. There is a misconception that slow feedbacks associated with climate forcings already in place will have unavoidable consequences. Most slow feedbacks will never occur, if we succeed in restoring Earth’s energy balance. Restoration can be aided by reducing non-CO2 forcings. However, the dominance of CO2 in present climate forcing growth, and the long life of fossil fuel carbon in the climate system, demand first attention on phase-out of fossil fuel emissions…..