Climate and Development Affecting CA’s Butterflies

Atlantis Fritillary butterfly at Sierraville, CA     Photo: Jennifer Wolf

Atlantis Fritillary butterfly at Sierraville, CA Photo: Jennifer Wolf

California’s butterfly populations are suffering from the combination of a warming climate and increased land development, according to a new analysis from scientists at UC Davis.

The study, scheduled to be published online this week in the journal Proceedings of the National Academy of Sciences, draws from butterfly expert Arthur Shapiro’s database of more than three decades of observations of 159 species from 10 sites in the Sierra Nevada at varying elevations, from sea level to tree line.

The data shows that over the last three decades butterfly species diversity declined at half of the sites, with the most severe reductions occurring at the lowest elevations, where habitat destruction is greatest.  The sites in the middle range showed evidence of habitats shifting upslope, as lower elevation butterflies began appearing at higher elevations.  The only site studied where butterfly biodiversity and abundance has increased is at the highest elevation site, at 2,400-2,775 meters.

“These patterns are quite consistent with other studies on a variety of organisms,” said Shapiro.  “The trend is for organisms to seek the climate to which they are adapted. So if it’s getting warmer, that means you go north, or you go up.”

While the population shifts appear consistent with warming temperatures (Both average maximum temperatures and average daily minimum temperatures increased across the majority of the sites), the study finds that warming alone is not enough to account for the loss of biodiversity at low and middle elevations.  Researchers analyzed county land use data at the sites, and found that it correlates with the butterfly population data.  The authors propose that habitat destruction due to urban and suburban development is most likely the leading cause of butterfly population deterioration at the lower elevation sites.

Citing pressures from human development as the main cause for species loss, the United Nations declared 2010 to be the International Year of Biodiversity.  At the Johannesburg summit of 2002,  governments agreed to achieve “significant reduction” in the rate of biological diversity loss by 2010, but according to the BBC, conservation organizations are acknowledging that this target is not going to be met, and that, in fact, the problem may be worsening.

Western Lakes Warming Up Rapidly

Craig Miller

Lake Tahoe from above Emerald Bay. Photo: Craig Miller

Some lakes in Northern California and Nevada are warming twice as fast as the surrounding air temperature, raising concerns that climate change may be affecting aquatic ecosystems more rapidly than terrestrial ones, according to a recently published study.

Researchers from the Tahoe Environmental Research Center, UC Davis and NASA’s Jet Propulsion Laboratory in Pasadena, studied Lake Tahoe, Lake Almanor, Clear Lake, and Mono Lake in California, and Nevada’s Pyramid and Walker Lakes, by analyzing 18 years of temperature data from satellite sensors.

Long-established instrument buoys provided a flow of temperature data for Tahoe, dating back to 1968, which allowed the team to calibrate satellite readings, raising confidence in data gathered from the other lakes. Previous studies have documented the warming of Lake Tahoe but John Reuter, associate director of the Tahoe Environmental Research Center (TERC), says the new study takes that information one step further.

“This study really shows that this phenomenon is happening on a much larger scale than just Lake Tahoe,” said Reuter.

All of the lakes studied showed a strong warming trend among summer nighttime temperatures between 1992 and 2008.  The two lakes that warmed the most during that time, Almanor and Mono, warmed 4.3 degrees (F).  During that time Lake Tahoe’s surface waters warmed 3.7 degrees, averaging .23 degrees annually.  In contrast, Tahoe City’s air temperature increased just .1 degree each year.

TERC director Geoffrey Schladow, who co-authored the study, said there is no doubt in his mind that rising lake temperatures are related to climate change, and he expects that it’s happening across the world, not just in Northern California and Nevada.

“The significance of this study is that across the western United States these very different lakes are displaying signs of warming.  It’s not just a Tahoe issue, it’s a regional issue.  And in all likelihood, it’s a global issue,”said Schladow.

Over the next six months, researchers will be using the remote sensors to extend the study to 50 lakes across the world to evaluate whether or not large lakes everywhere are warming at similar rates.

Warmer temperatures can affect water circulation, which influences the amount of oxygen and nutrients available throughout the lake.  A 2008 study from TERC predicts that warming due to climate change could dramatically affect the amount of mixing in Lake Tahoe, which would deplete the bottom water of oxygen and drastically disrupt the food web.

“Temperature is one of the conditions that dictates who lives in the lakes,” said Schladow. “Warmer temperatures may make the lakes more hospitable to invasive species and put native species under stress.  I’m not saying this is happening yet, but it could.”

In his article about the study, Matt Weiser of the Sacramento Bee has some examples of how warmer temperatures can affect lake ecosystems. And KQED news editor Dan Brekke has assembled an interactive map (below), showing the locations and some temperature data for lakes in the study.

View California’s Warming Lakes in a larger map

The Heated Debate Over Temperatures

87583224As the war over warming perception spills into a new decade, the last month of 2009 provided fresh ammo for the prevailing view. According to a preliminary report from the World Meteorological Organization (WMO), the “noughties” may have been the warmest decade on record.

And despite the rare sprinkling of snow we woke up to one December morning in the Bay Area, the report also says that 2009 will likely go down as one of the hottest years in modern history. Based on climate data from January to October, the WMO says that 2009 will likely be the fifth warmest since scientists began keeping records in 1850.

If that last claim seems improbable, you’re likely in Canada or the United States: The data shows that every continent but North America saw above-average temperatures in 2009, and that parts of Asia and Africa experienced their warmest year yet.

Dean Moosavi, a professor at the University of Massachusetts, Dartmouth, chalked the apparent discrepancy up to the Pacific ocean phase known as La Nina, and said it’s important to note the difference between weather and climate. “Snow in Houston this week, for example, is not proof of the absence of global warming any more than a large drought in the summer is proof that global warming is occurring,” Moosavi wrote in an email to Climate Watch. “You have to look over much longer periods of time…decades at the least before you can see a climatic trend of significance.”

This is perhaps a good place to acknowledge the oft-heard claim that the planet has actually been cooling down for more than a decade. In an article published in NOAA’s online magazine ClimateWatch (not affiliated with KQED Climate Watch), David Easterling of NOAA’s Climatic Data Center explains the statistical quirk that produces that mirage.

But Moosavi says he’s not quite ready to make a pronouncement. “I am not yet convinced that the 2000’s were warmer than the 90’s at this point,” Mossavi wrote. “Given the political and economic stakes of a statement of this type…I would be very cautious before declaring the 2000’s the warmest decade.”

Stanford’s Mark Jacobson, on the other hand, was less equivocal: “As 8 of the 10 warmest years in the history of surface measurements are in the 2000’s, it is clear that the 2000s was the warmest decade on record,” he wrote in an email.

The WMO findings come on the heels of a pair of reports that indicate that despite the global recession, average temperatures are on track to rise between 4 and 6 degrees Celsius by the end of the century.

For some perspective, the California Climate Change Center’s 2006 report on the risks of global warming predicts that a 6 C increase would have a devastating effect on the state. The report projects that a 10.5 F increase (just a little under 6 C) would result in up to 100 extra days of “extreme heat” in Los Angles and Sacramento, a 90% reduction in the Sierra snowpack and a 2-to-3-foot increase in sea levels.

The half-dozen climate scientists contacted for this post agreed that the 6 C prediction was within the realm of possibility, and most had the same answer when asked how the world should combat this risk. Stanford professor Ken Caldeira chose to respond in capital letters: “WE HAVE TO ACT NOW.”

“The question isn’t so much whether we need to take action this year or next, but rather how much more expensive and difficult are the solution and the impacts, if we delay,” Chris Field, director of the Carnegie Institution’s Department of Global Ecology, said. “Delaying action on climate is sort of like delaying action on paying your credit card bill. You may get by for a few months, but the problems get worse through time and more expensive to address.”

Polar Bears and Sea Ice: Sorting it Out

87514496A recent post I wrote to highlight a radio discussion of the current plight of polar bears, drew a challenge from Russell Steele, one of our regular readers. Steele questioned some of the scientific conclusions underlying dire predictions for the bears.

To help sort some of this out, I asked for responses from two highly regarded scientists in the field. Here’s a response to the specific reader challenge from Mark Serreze, Director of the National Snow & Ice Data Center, in Boulder, CO:

It is unclear what Mr. Steele is trying to get at with reference to the seasonal cycles in sea ice extent from the AMSR-E data. The AMSR-E data, while valuable, only go back to 2002. Through combining SSM/I and SMMR satellite data with other information sources for earlier years, we have a decent record of Arctic sea ice extent going back to the early 1950s. The relevant issue is the long-term decline in end-of-summer (September) ice extent evident in this record, with the extreme September minima of recent years (represented in the short AMSR-E record) serving as exclamation points. The observed rate of September ice loss exceeds expectations from nearly all climate models.

I also turned to Waleed Abdalati. Now director of the Earth Sciences Observation Center at the University of Colorado, Abdalati is a veteran of the Cryospheric Sciences and Terrestrial Hydrology programs at NASA, and one of the most articulate people I’ve heard speak on the subject of polar ice. He offers the following:

I am not an expert on polar bears, but I do think it is safe to say that
 their primary habitat, the Arctic sea ice, is severely threatened.  I, and 
most of my colleagues believe we are well on our way to an ice-free Arctic
 in summer any time between this decade and the next 40 years.

 is because of two things:  1) it will be decades before the ocean has 
finished its response to present-day greenhouse forcing, so the impacts of 
what we’ve done already have not been fully realized; and 2) the loss of
 sea ice is self-compounding: when it starts to shrink, exposing a 
darker more (heat) absorbing ocean underneath, the likelihood of its continued
 shrinking is greater (ice melts, exposes darker ocean, absorbs more heat, 
melts more ice, exposes darker ocean, and so-on).

Of course the flipside
 of this is that as ice starts to grow, it is more inclined to grow, but
 against the backdrop of the increased warming, the former is far more likely 
than the latter. Finally, as thick multi-year ice disappears, it is
 replaced with thinner and younger ice that is more vulnerable to surface 
melt from the atmosphere, bottom melting from sea water, and being carried
 away to lower, warmer latitudes by ocean current and wind.

So back to the polar bears: If their habitat disappears and they are unable 
to hunt seals, their main source of food, they seem to stand little or no
 chance of survival. I am not a wildlife biologist but its hard for me to 
believe they as a population can sustain themselves on land and with only a
 seasonally-present ice cover. In some cases, the fact that they face more
 challenges on sea ice than in the past, has driven them to forage inland,
 creating the illusion in some people’s minds that their populations are 
increasing, because there are more sightings on land. Who knows? Maybe 
they’ll evolve to hibernate in late summer, when there is no ice, and hunt
 the rest of the year.

There is an added effect that doesn’t get much attention.  There was a 
fascinating study by a Canadian Biologist (Ian Stirling) and a sea ice
 expert (Claire Parkinson) [Stirling, I., and C.L. Parkinson. 2006. Possible 
Effects of Climate Warming on Selected Populations of Polar Bears (Ursus
maritimus) in the Canadian Arctic. Arctic 59(3): 261-275.], which suggested 
that the bears are also losing weight, and approaching the weights at which 
they have historically not been able to bear cubs.  So not only is the
population threatened by starvation, the ability to replenish the population
 seems diminished.

I don’t believe we can say anything with absolute certainty,
 so I, myself would not make the statement that the polar bears are doomed–but I will say that the outlook for them, in my view, looks very, very bad.

Thousand-Year-Old Trees Get a Growth Spurt

Bristlecone pine. Photo: US Forest Service

Bristlecone pine in the Inyo National Forest. Photo: US Forest Service

There’s a lot of history packed into a tree with more than 4,000 annual growth rings. Scientists who count them (dendrochronologists) have been able to learn a lot about the drought history of California and the West.

The Great Basin bristlecone pines that grow along the spine of the Sierra are the oldest living things on Earth–older, even, than the giant sequoias. Studying the uppermost trees, around 12,000 ft., researchers stumbled on a strange trend. The trees, legendary for their slow rate of growth, have been growing faster over the last 50 years or so, than at any time in the last three millennia.

If you missed it this week, Malcolm Hughes, one of the study’s lead researchers and a professor of dendrochronology at the University of Arizona’s Laboratory for Tree-Ring Research, spoke to NPR’s All Things Considered about the possible cause.

There’s more on the study in a recent post on the RealClimate blog.

You can see these astonishing trees for yourself in the Ancient Bristlecone Pine Forest of Inyo National Forest–but you might want to wait until spring. The visitor center is not staffed between November and May and winter access is iffy at 10,000 feet. Worse yet, the original vistor center burned down in the fall of last year. The Forest Service is using a temporary (trailer) facility until a permanent one is rebuilt. According to the Forest Service website:

“…the visitor center is being designed to be a model of energy efficiency, utilizing the latest in “green” building practices.   According to Bristlecone Pine Forest Manager John Louth, some of the improvements that visitors will see will be a state-of-the art solar power system, updated exhibits addressing the impacts of global warming on the ancient trees, a small research library, a slightly larger theatre room and a fire/intrusion detection & suppression system.”

Warmer Temperatures Threatening CA Fruit Crops?

Almond trees in winter, Photo by Sahsa Khokha

Almond trees in winter, Photo by Sasha Khokha

 Increasingly warmer temperatures  in the Central Valley could pose a serious threat to California’s  fruit and nut crops in the not-too-distant future, according to a new study out of UC Davis.   The study finds that winter chill, which is an important factor in the productivity of tree crops, is likely to decrease by more than 50% by 2100, making the region less hospitable for crops like walnuts, peaches, plums, and cherries, unless changes in growing techniques are adopted.

Tree crops go dormant in the winter when temperatures drop to a certain level for a certain period of time.  Each crop then needs a certain number of  ‘chilling hours’ – between 32 and 45 degrees Fahrenheit – in order to break dormancy and resume growth.  

If crops don’t recieve their specific chilling requirement during the winter,  problems arise.  Flowering time is disturbed, which could be devastating for crops such as walnuts and pistachios that depend on simultaneous male and female flowering for pollination.   And if crops don’t recieve enough winter chill to go dormant in the first place, they will continue producing buds and sprouting branches, but they may not yield fruit, having dire consquences for California’s $7.8 billion fruit and nut industry, explained study author Minghua Zhang.

“We hope that people will take this study as a wake up call,” said Zhang. “Crops are going to be seriously impacted.”

Zhang and her fellow reaserchers found that in certain parts of the Central Valley, winter chill declined by nearly 30% between 1950 and 2000.  They expect that the decline will be 60% by 2050 and 80% by the end of the century. 

“There is a problem coming up that we need to prepare for,” said Eike Luedeling, another of the study’s authors. “So far low chilling requirement haven’t even been a breeding goal, but we are going to need a long-term strategy to cope with this.”

The researchers found that by 2000, winter chill had declined to the point that only 4% of the Central Valley was suitable for growing apples, cherries, and pears, down from 50% earlier in the 20th century.  They predict that by the end of the century, the region might no longer be suitable for growing these crops as well as walnuts, pistachios, peaches, plums, and apricots.   Crops like almonds and pomegranates will most likely be affected the least, as they have low winter chill requirements.

NOAA Confirms El Nino

Image from NASA

Warm water patterns in the Pacific during normal (upper) and El Nino (lower) years. The lower image is from 1995-96. Image from NASA

Scientists with the National Oceanic and Atmospheric Administration today confirmed what many had pretty much surmised: El Nino is back.

Officially the El Nino Southern Oscillation (ENSO), the cyclical pattern of ocean conditions has broad implications for weather and the Pacific food chain.

According to the NOAA news release:

“NOAA expects this El Niño to continue developing during the next several months, with further strengthening possible. The event is expected to last through winter 2009-10.”

NOAA’s Climate Prediction Center suggested about a month ago that conditions were right for the return of El Nino.

More recently, the high incidence of underweight sea lion pups turning up along the California coast was taken by some as a harbinger of ENSO. During El Nino cycles, normal upwelling of deep, cold water slows down, essentially shutting down the “food elevator” for many species.

Of course, there can be an upside. According to NOAA:

“El Niño’s impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.”

Links to climate change are less clear. Some scientists have suggested that warming air and sea temperatures might bring about more and longer El Nino events.

Parsing the White House Climate Report

At least one researcher cited in the 196-page climate impacts report issued this week by the Obama administration is not impressed with the final product. Roger Pielke of the University of Colorado’s Center for Science & Technology Research has written a blog post critical of the report and in particular, the way in which his work was interpreted. If you’d rather not plow through the entire post, John Tierney has an overview of Pielke’s critique on his blog for the New York Times.

California heat wave, from the Aqua satellite. Image: NASA

2004 California heat wave, from the Aqua satellite. Image: NASA

The report was arguably the first to break down both observed and projected effects of climate change into coherent regional summaries. For the purposes of the report, California was considered part of the Southwest region, which included states as far east as Colorado and New Mexico.

Not surprisingly, many of the points raised in the Southwest section (beginning on p. 129) have to do with water supply. Most have been reported or discussed in our Climate Watch coverage, either here or in our radio reports. Selected “highlights” include:

– Past climate records based on changes in Colorado River flows indicate that drought is a frequent feature of the Southwest, with some of the longest documented “megadroughts” on Earth.

– The prospect of future droughts becoming more severe as a result of global warming is a significant concern, especially because the Southwest continues to lead the nation in population growth.

– Human-induced climate change appears to be well underway in the Southwest. Recent warming is among the most rapid in the nation, significantly more than the global average in some areas.

– Projections suggest continued strong warming, with much larger increases under higher emissions scenarios compared to lower emissions scenarios. Projected summertime temperature increases are greater than the annual average increases in some parts of the region, and are likely to be exacerbated locally by expanding urban
heat island effects.

– Water supplies in some areas of the Southwest are already becoming limited, and this trend toward scarcity is likely to be a harbinger of future water shortages. Groundwater pumping is lowering water tables, while rising temperatures reduce river flows in vital rivers including the Colorado.

– Projected temperature increases, combined with river-flow reductions, will increase the risk of water conflicts between sectors, states, and even nations.

– Increasing temperature, drought, wildfire, and invasive species will accelerate transformation of the landscape.

– Under higher emissions scenarios, high-elevation forests in California, for example, are projected to decline by 60 to 90 percent before the end of the century.

– In California, two-thirds of the more than 5,500 native plant species are projected to experience range reductions up to 80 percent before the end of this century under projected warming.

– Projected changes in the timing and amount of river flow, particularly in winter and spring, is estimated to more than double the risk of Delta flooding events by mid-century, and result in an eight-fold increase before the end of the century.

– A steady reduction in winter chilling could have serious economic impacts on fruit and nut production in the region. California’s losses due to future climate change are estimated between zero and 40 percent for wine and table grapes, almonds, oranges, walnuts, and avocados, varying significantly by location.

By the way, Pielke’s critique does not directly address anything in this list, though his work does involve weather-related disasters, which would include floods. Asked by a commentator on his blog if he thinks the entire report should be dismissed based on the flawed interpretation of his research, Pielke replied: “I wouldn’t think so and would certainly hope not. At the same time the section which covers my research does not give me a lot of confidence in the process that led to the report.”

The Return of El Nino?

The federal Climate Prediction Center, operated by NOAA, reported this week that current conditions in the Pacific would seem to foreshadow a return to El Nino conditions, possibly within the next few weeks.

2006 El Nino conditions, as observed by the Jason satellite. Photo: NASA

2006 El Nino conditions, as observed by the Jason satellite. Photo: NASA

The ocean conditions formally known as ENSO, or the El Nino/Southern Oscillation, arise when normal upwelling of deep, cold water abates, causing warmer surface temperatures (SST).

El Nino and its opposite, La Nina, have far-reaching implications on weather patterns. Here on the West Coast, it usually means wetter winters in southern California and drier ones in the Pacific Northwest.  Because northern and central California lie in between, things there can go either way.

El Nino can also have a significant impact on fisheries, as much of the food chain is interrupted when upwelling slows.

Here’s a good overview of El Nino “mechanics” from UC Berkeley.

Pika One Step Closer to ESA Listing


American pika. Photo by Chris Ray.

American pika. Photo by Chris Ray.

UPDATE: Federal fish & wildlife authorities have decided to proceed with a full review of the American pika, for potential listing under the Endangered Species Act. The US Fish & Wildlife Service will formally publish its decision this week, including this summary:

“We, the U.S. Fish and Wildlife Service, announce a 90-day finding on a petition to list the American pika (Ochotona princeps) as threatened or endangered under the Endangered Species Act of 1973, as amended. We find that the petition presents substantial scientific or commercial information indicating that listing of the American pika may be warranted. Therefore, with the publication of this notice, we are initiating a status review of the species, and we will issue a 12-month finding to determine if the petitioned action is warranted. To ensure that the status review is comprehensive, we are soliciting scientific and commercial data regarding this species. We will make a determination on critical habitat for this species if, and when, we initiate a listing action.”

The Center for Biological Diversity (CBD) first petitioned for listing in 2007, and then followed with a lawsuit a year later, when federal authorities shelved the request.

The significance of this week’s decision, according to a CBD news release, is that “the pika will become the first mammal considered for protection under the Act due to global warming in the continental United States outside of Alaska.”

Last month a San Francisco court ruled that state wildlife officials wrongly denied the CBD’s petition for listing under California’s ESA. So it looks like the little critter will get a fresh review at both the state and federal levels.