Kimberly Ayers

Green roofs like this one at Vista Hermosa City Park are part of the solution for Los Angeles

Listen to the radio version of this story on The California Report.

The City and County of Los Angeles now have customized climate predictions, thanks to a new UCLA study that took global climate science and made it local. A UCLA supercomputer ran for eight months to downscale 22 different global climate models, distilling them into a surgically precise look at L.A. County and beyond. It’s a new kind of Hollywood close-up and it’s a sobering one: temperatures will rise in areas of Los Angeles County by an average of 4 to 5 degrees by mid-century.

Commissioned by the city of Los Angeles, funded by a U.S. Department of Energy grant and conducted by UCLA’s Department of Atmospheric and Oceanic Science, the study focused on forecasting for the metro area between 2041 and 2060. But instead of relying on the global climate model grids that use data from 100 kilometer-square cells of the earth’s surface, the UCLA team’s “quintillion-plus” calculations — yes, that’s with 18 zeros — zoom in to a resolution of 2 square kilometers, just over a square mile.  So instead of data and forecasting for the whole county, you can talk specifically about climate change for Corona, for example.

Mitigating those risks is a whole lot easier to sell when the science has your town’s name on it. County supervisor Zev Yaroslavsky told me. “That’s what this study has done. It’s given us the science. It’s not anecdotal. It’s not instinct. It’s based on science and it’s very specific.”

And there’s a brand new website, c-change.LA, that includes a slew of suggestions for Angelenos looking to mitigate and adapt to climate change in their own neighborhoods. This new study also gives further momentum to the city’s existing program, Adapt LA, which was started five years ago to green up the city’s energy and landscapes and clean up its air, efforts the city’s mayor Antonio Villaraigosa wants to keep moving.

“This stuff isn’t a luxury. We gotta do it. We can target it smart, we can do it in a way that’s phased in, but we’re definitely going to have to move.”

Josh Simerman, Flickr

Hot Creek, near Mammoth Lakes, was one of 20 streams in the Western U.S. examined in a study by Oregon State researchers who found no clear relationship between increasing air temperatures and stream temperatures.

Rising sea levels, melting glaciers, intensifying storm events – evidence is mounting that the effects of a warming planet will be far-reaching and potentially catastrophic. But one natural system may be more resilient than others when it comes to global warming: mountain streams.

Researchers from Oregon State University report in the journal Geophysical Research Letters that small streams in the western United States have not heated up in response to the region’s warming air temperatures.

Water temperature is a critical variable for aquatic ecosystems. Some fish, for example, time egg-laying to minute changes in water temperatures; in other species, stream temperatures are a key factor in determining the sex of juvenile fish.

The Oregon State team’s findings are based on an analysis of temperature data from 20 streams in seven western states, including California’s Hot Creek, a waterway fed by geothermal springs in Inyo National Forest, near Mammoth Lakes. (More than 600 streams were originally considered but that set was winnowed down, taking into account only streams with few human impacts and  records spanning more than 12 years.)

“It is a small set and we are trying not to extrapolate too much from this data. But some streams in our study seem to be getting warmer,” lead author Ivan Arismendi told me. “Others are getting cooler and some have not changed much at all. But our data suggests that warming air temperatures are not having a corresponding effect on streams.”

The question, of course, is why. Arismendi explains that a number of factors in addition to ambient air temperature influence — and may buffer — stream temperatures, including wind and humidity, timing of snow melt, interaction with groundwater, and variations in solar radiation.

Other studies, such as a 2010 report published in the journal Frontiers in Ecology and the Environment, have suggested that streams and rivers in the U.S. are warming up along with the climate. But Arismendi points out that many of the waterways in those studies had lots of human influences such as stormwater runoff, impoundments and diversions. All can drastically influence water temperature, he adds, which makes it impossible to determine if it is the air or some other host of factors causing the rising water temperatures.

Arismendi says the research will continue, focusing on current computer models used to predict how streams will respond to a warming climate.  “Most of the predictions in the models are based on a correlation [between air and stream temperature],” says Arismendi. “So we are trying to test how good those models are for specific sites.”

Gretchen Weber

Navajo Generating Station, near Page, AZ

By Susanne Rust

Just as the federal government released its annual index of greenhouse gases, showing a steady increase over the past 21 years, the International Energy Agency warned that we are on the path to 11-degree warming if we don’t curb emissions now.

“Delaying action is a false economy: For every $1 of investment in cleaner technology that is avoided in the power sector before 2020, an additional $4.30 would be needed to be spent after 2020 to compensate for the increased emissions,” the authors of the energy agency report wrote in their 2011 World Energy Outlook.

Last week, the National Oceanic and Atmospheric Administration released its annual accounting of greenhouse gases in the atmosphere. The index showed a 29 percent increase over levels recorded in 1990, the agency’s baseline year, as established by the Kyoto protocol.

“The increasing amounts of long-lived greenhouse gases in our atmosphere indicate that climate change is an issue society will be dealing with for a long time,” said Jim Butler, director of the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo.

Butler says you have to think of this number not as a predictor, but more like a dial on an electric blanket. You know that if you turn the dial up, the blanket will get warmer. You may not feel the warmth immediately, but it will get warmer – just how warm, you don’t know.

One of the more striking findings in the agency’s report includes the increase in methane found in the atmosphere. The level of that gas has increased in the last four years, after holding steady for more than a decade. Methane is 25 times more potent than carbon dioxide as a greenhouse gas.

Butler said that increase is likely attributable to the thawing of permafrost and an increase of methane escaping from tropical areas.

“Climate warming has the potential to affect most aspects of society, including water supplies, agriculture, ecosystems and economies,” said Butler, who added that his agency will continue to monitor these gases “into the future to further understand the impacts on our planet.”

His warning was echoed by the International Energy Agency, which said “rising fossil energy use will lead to irreversible and potentially catastrophic climate change.”

Joe Romm, former assistant secretary in the U.S. Department of Energy and now editor of the blog Climate Progress, said the International Energy Agency “is one of the few organizations in the world with a sophisticated enough global energy model to do credible … projections of the cost of different emissions pathways and the costs of delaying efforts to achieve them.”

He said the key point of the report is that in the 2020s, “the world is going to be considerably more desperate than we are now. The evidence of human-caused climate change will be difficult for all but the most extreme deniers to ignore.”

He added that superstorms, like the one in Alaska last week, “will increasingly just be the normal weather – and we’ll start to see what really extreme weather is like.”

This post also appears at California Watch, a content partner of Climate Watch.

Berkeley Earth

Berkeley Earth

The head of the Berkeley Earth Surface Temperature (BEST) study, Richard Muller, a Berkeley physicist previously known for his skeptical views on anthropogenic warming, appeared on Capitol Hill Monday, for the first time since the release of the study’s results.

As we’ve reported, the study found that the Earth is warming. Surface temperatures have increased about one degree Celsius since the mid 1950s, according to the study, which relied on a database of 1.6 billion records.

According to a report from AFP, Muller told lawmakers that he no longer doubts that global warming is real and caused by humans.  However, the extent of human influence remains uncertain, he reportedly said.

This animation shows the Muller’s team’s analysis of the Earth’s surface temperature changes since 1800:

Climate scientist Phil Duffy and meteorologist Jan Null joined Michael Krasny on KQED’s Forum to discuss California’s cooler-than-usual summer and what it might reveal about climate change in the region. The upshot? We don’t really know.

“I think we’re seeing plain old climate variability,” said Duffy, who is a visiting scholar at Stanford and the Carnegie Institution for Science and chief scientist for Climate Central, a Climate Watch content partner.

Null agreed with Duffy, saying that in any given year, “stuff happens,” which can’t necessarily be attributed to a larger trend.

“It’s hard to take an individual year and say ‘This is the result of climate change’,” said Null. “It could be just the roll of the dice. If we see a lot of stuff happening over the next decades, then we’re talking about climate change.”

Null said this summer’s cool weather is due to a persistent trough of low pressure along the west coast.

“Anytime you have that for an extended period of time, you get what people call ‘unusual’ or ‘freakish’ weather,” he said.

Duffy said there is a theory that ties colder weather on the California coast to human-caused climate change, which he thinks has merit. That theory argues that as inland areas (which are already much hotter than the coast) heat up due to climate change, they’ll warm faster than the coastal areas. This could make the existing sea breeze stronger, pulling the cool marine air further inland. Duffy says that there is some research that suggests this is already happening.

However, he said, that’s not what we’re seeing this summer here in the Bay Area. This summer, cooler than average temperatures are present as much as a 1,000 miles inland, he said, which doesn’t fit this theory.

Regardless, said Duffy, what’s happening here in the Bay Area this year is not representative of the rest of the country or the world, which are experiencing record heat in many places. And even if we can’t attribute the weather in one particular year to climate change, he said, that doesn’t mean scientists are uncertain about climate change in general.

“There is a lot we do know,” he said. “We know increased greenhouse gases cause warming overall, changes in precipitation, and an increased frequency in certain types of extreme weather events…It’s frustrating that we can’t explain every weather variation, but the point is that when humans emit greenhouse gases, it does push things in a certain direction.”

You can listen to the entire episode on the Forum website.

Joshua trees in Eureka Valley, CA (Photo: Ken Cole, USGS)

Joshua trees, the spiky desert-dwellers that are so iconic to Southern California’s dry country that they got a national park named after them, will likely disappear from 90% of their current range by the end of the century, according to a new study by scientists at the US Geological Survey.

Ecologist Ken Cole, the study’s lead author, said that means no more Joshua Trees in Joshua Tree National Park, which is currently in the southernmost part of the species’ range. It also means elimination of the trees across wide swathes of other parts of Southern California as well as Nevada and Arizona.

Cole and his team used climate models, field work, and the fossil record to project the future distribution of Joshua trees. They compared the projected increase in temperatures for the Southwest (four degrees Celsius, according to a “middle of the road” IPCC scenario) to a similar rapid increase in temperatures nearly 12,000 years ago, at the end of the ice age.

Using fossil sloth dung and packrat midden, the scientists reconstructed how Joshua trees responded to that warming. (Sloths, which are now extinct in the region, and packrats, ate the Joshua tree fruit, spreading the seeds and leaving them behind for the scientists to track.)

“Sometimes the climate changes rapidly, like it did 11,700 years ago,” said Cole. “At that time the Joshua trees squashed into a narrow band at the northern edge of their range. That’ll happen again. The southerly ones will not be able to persist.”

This loss of southern territory is particularly significant for a species like the Joshua Tree, which has a “pretty pitiful” expansion rate, according to Cole. That’s because, unlike the Ponderosa pine, which can expand its range 500 meters a year thanks to birds and other factors, the range of Joshua trees can stretch just about six feet per year.

“They don’t release their seeds until some animal chomps on them,” said Cole, referring to the fruit of the Joshua tree. “They’re spread by squirrels and pack rats that might run 100 feet and stash some seeds in the ground. Some of them might grow, but it could take 20, 30, or 40 years. Going 100 feet every 20 years is not moving as quickly as it needs to to keep up with climate change.”

Researchers mapped where in the Southwest Joshua trees are currently located, where they are likely to disappear, and where they will likely persist (small pockets in Nevada and in southeastern California).  They also mapped where future climate will likely be suitable for the trees, should anyone want to undertake a program of managed relocation.  But even that, said Cole, has its risks.

“We don’t know how well they would grow then,” he said. “Joshua trees are very picky.”

Not only that, but relocating the trees would be expensive, and he said, “You’d have to assume that the climate wouldn’t change again. That’s a really bad assumption.”

Cole says his field observations support the study’s projections.  Temperatures in the region have been warming since 1975, he said, and there’s no record of Joshua trees reproducing in the southern stands in the last 30 years.

“You don’t see any seedlings or saplings in the southern stands,” said Cole.

That’s a big contrast to the northerly stands in the Inyo Mountains above Eureka Valley, where, he said, Joshua trees are thriving.

“The ones in the north are really vigorous,” he said. “They’re going like mad.”

The full study is located on the Ecology Society of America’s website, but a subscription is required to access it.

Read more on climate change impacts facing the national parks.

A new study says melting ice sheets will likely be “the dominant contributor to sea level rise in the 21st century.”

A tidewater glacier in Greenland, pictured in 2008. (Photo: Michael Lemonick)

About 110,000 years ago, global sea level began to drop as the planet cooled, and evaporating seawater was transformed into massive ice sheets that covered large parts of the Northern Hemisphere. About 10,000 years ago, the Earth warmed up again. The ice retreated dramatically, and sea level rose. Since then, the planet’s ice, and the level of the ocean have been more or less stable.

Not any more, though. Thanks largely to human-generated greenhouse gases, the ice that remains in mountain glaciers and ice caps — and more significantly, in the massive ice sheets that smother Antarctica and Greenland under frigid blankets up to two miles thick in places — is moving to the sea once again. Just how high and how fast global sea level will rise as a result is still uncertain, though. One big reason: scientists haven’t been able to get a firm handle on how ice melting has already changed as a consequence of the warming that’s already taken place.

A new paper in the journal Geophysical Research Letters is sure to help, though. Using two different measurement techniques, a team of geophysicists from the U.S. and Netherlands has shown that the ice in Antarctica and Greenland is not only vanishing into the sea: the rate of disappearance has been accelerating over an 18-year period, with about 36.3 billion metric tons more ice lost each year compared to the year before.

By 2006, a year in which a total of about 475 billion metric tons of ice were lost, the acceleration in ice mass loss from the ice sheets had already surpassed acceleration in ice mass loss from mountain glaciers and ice caps — and that lead is likely to grow over the coming century, the study indicates, to the point where ice sheets will be “the dominant contributor to sea level rise in the 21^st century.”

What makes this study so important, says co-author Isabella Velicogna, of the University of California, Irvine and NASA’s Jet Propulsion Laboratory in Pasadena, is that the ice loss was measured in two entirely independent ways. The first involved the Gravity Recovery and Climate Experiment, or GRACE. It’s a pair of satellites that measure the local gravity at every spot on Earth. In both Greenland and Antarctica, the ice generates some of that gravity — and as the ice melts in response to warming air and ocean temperatures, the gravity diminishes. “GRACE basically weighs the ice every 30 days,” says Velicogna, “and sees how much it’s changing.”

How Do We Know: Greenland’s Melting Ice Sheet from Climate Central on Vimeo.

How Do We Know: Greenland’s Melting Ice Sheet from Climate Central on Vimeo.

The second technique looks at the ice sheets in the same way you’d look at your bank account. The deposits, in the form of snowfall, are calculated using a combination of observations and models that estimate annual precipitation. The withdrawals — physical shrinkage of the ice as it melts and as tidewater glaciers dump icebergs into the ocean — are measured with satellite-mounted radars. If you withdraw money faster than you deposit it, your bank balance shrinks. Similarly, if the shrinkage of the ice outpaces the growth from precipitation, the so-called “mass-balance” shrinks.

“There’s very solid agreement between the two [measurements],” says lead author Eric Rignot, also of UC-Irvine and NASA. And while the GRACE satellites have only been orbiting since 2000, that agreement gives the scientists confidence that the mass-balance estimates, which go back some 18 years, are reliable throughout that whole period.

What that means for sea-level rise over the coming century, however, is still unclear. However, in light of this study and other recent findings, the projections in the 2007 U.N. Intergovernmental Panel on Climate Change (IPCC) report of up to a half-meter of sea-level rise by 2100 may be too low. “If you take our 18 years of good records,” says Rignot, “and extend them forward, you’re going to get to a meter easily. Beyond that, it’s difficult to say.”

“It all depends,” says Rignot, “on whether the ice loss continues at this rate, or slows, or accelerates.”

Nevertheless, says Velicogna, “I personally don’t think it’s going to slow down. I believe we should be a little more concerned than we are now. It’s going to take many years to prepare for this degree of sea-level rise. It’s happening — so what are we going to do about it?”

Use the “Envisioning Ice Loss” tool to find out how recent Greenland ice loss would look if it occurred in your home state.

Parts of the northern hemisphere may have had an extremely cold December, but nevertheless, last year tied for the second-warmest in 130 years of global instrumental temperature records, according to the latest surface temperature analysis of the NASA Goddard Institute for Space Studies (GISS).  The analysis finds that global temperatures were so similar in 1998, 2002, 2003, 2006, 2007, and 2009, that they are all tied for second place. In the Southern Hemisphere, 2009 set the record as the warmest year, according to this report.

James Hansen, head of NASA’s GISS, and his team have released their end-of-year summary for 2009, initially posted on the Real Climate blog.  It’s pretty dense, but here are some additional highlights:

- The scientists offer an explanation for an apparent data discrepancy over whether 1998 or 2005 was the warmest year.  In short, it comes down to the difference in the way GISS and HadCRUT (Hadley Centre/University of East Anglia Climatic Research Unit) assign or do not assign temperature data for areas without observing stations.  (HadCRUT leaves them out of the analysis, while GISS assigns values based on various factors outlined in the summary.)  GISS maintains that 2005 was the warmest year.

- According to the report:

“There were strong negative temperature anomalies at middle latitudes in the Northern Hemisphere, as great as ‐8°C in Siberia, averaged over the month. But the temperature anomaly in the Arctic was as great as +7°C.”

In other words, 2009′s cold December in certain areas of the planet, as well as an unusually cold 2009 summer in the United States and Canada, do not reflect overall global temperatures nor signal a cooling trend:

“It is obvious that in December 2009 there was an unusual exchange of polar and mid‐latitude air in the Northern Hemisphere. Arctic air rushed into both North America and Eurasia, and, of course, it was replaced in the polar region by air from middle latitudes. The degree to which Arctic air penetrates into middle latitudes is related to the Arctic Oscillation (AO) index, which is defined by surface atmospheric pressure patterns…”

According to GISS data, December 2009 was the most extreme negative Arctic Oscillation since the 1970s.

- The report underscores that monthly temperature anomalies tend to be greater than seasonal anomalies and that the the mean temperature of a particular month might not be the best way to identify global warming. Instead, one needs to look at measurements over the long-term, which, according to GISS data, indicate general warming over at least the last 50 years, just about everywhere on the planet.

The summary concludes with a sort of admonishment:

“The bottom line is this: there is no global cooling trend. For the time being, until humanity brings its greenhouse gas emissions under control, we can expect each decade to be warmer than the preceding one. Weather fluctuations certainly exceed local temperature changes over the past half century. But the perceptive person should be able to see that climate is warming on decadal time scales.”

When signs on Burger King outlets started opining that “Global warming is baloney,” a Memphis reporter decided to check it out. His exchanges with the local burgermeister and the parent company make for pretty amusing reading.

Interesting that while polls taken within the last year have indicated flagging faith in the prevailing view of climate scientists that the world is warming, a spring poll by the Pew Research Center showed 59% of Americans supporting some kind of cap on carbon emissions. Though still sharply divided along party lines, that could indicate that some kind of reluctant consensus is forming around the issue.

BERKELEY, CA – In the hotly debated arena of global climate change, using short-term trends that show little temperature change or even slight cooling to refute global warming is misleading, write two climate experts in a paper recently published by the American Geophysical Union–especially as the long-term pattern clearly shows human activities are causing the earth’s climate to heat up.

In their paper “Is the climate warming or cooling?” David R. Easterling of the National Oceanographic and Atmospheric Administration’s National Climatic Data Center and Michael Wehner of the Computational Research Division at the Department of Energy’s (DOE) Lawrence Berkeley National Laboratory note that a number of publications, websites and blogs often cite decade-long climate trends, such as that from 1998-2008, in which the earth’s average temperature actually dropped slightly, as evidence that the global climate is actually cooling.

However, Easterling and Wehner write, the reality of the climate system is that, due to natural climate variability, it is entirely possible, even likely, to have a period as long as a decade or two of “cooling” superimposed on the longer-term warming trend. The problem with citing such short-term cooling trends is that it can mislead decision-makers into thinking that climate change does not warrant immediate action. The
article was published April 25 in Geophysical Research Letters.

“We wrote this paper, which was carefully reviewed by other researchers and is scientifically defensible, to clearly show that even though our climate is getting warmer, we can’t expect it to do so in a monotonic way–or that each year will be warmer than the preceding year,” said Wehner. “Even with the climate changes caused by human activity, we will continue to see natural variability including periods of cooler temperatures despite the fact that globally averaged temperatures show
long-term global warming.”

“It is easy to ‘cherry pick’ a period to reinforce a point of view, but this notion begs the question, what would happen to the current concerns about climate change if we do have a sustained period where the climate appears to be cooling even when, in the end, the longer term trend is warming?” write Easterling and Wehner.

The research was funded by the DOE Office of Science’s Office of Biological and Environmental Research through its Climate Change Prediction Program.

Citing an accepted climate modeling scenario in which no efforts are made to reduce the amount of greenhouse gases released into the atmosphere, the earth’s climate is expected to warm by 4 degrees Celsius (7.2 degrees Fahrenheit) by the end of the 21st century. The authors point out that this is consistent with other simulations contained in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC 2007), which was recognized with the 2007 Nobel Peace Prize.

“Climate scientists pay little attention to these short-term fluctuations as the short term ‘cooling trends’…are statistically insignificant and fitting trends to such short periods is not very meaningful in the context of long-term climate change,” the authors write. “On the other hand, segments of the general public do pay attention to these fluctuations and some critics cite the most recent period as evidence against anthropogenic-forced (human-induced) climate change.”

The authors used both observed climate data from 1901-2008 and a series of climate model simulations performed on supercomputers to study the occurrence of decade-long trends in globally averaged surface air temperature. They found that it is possible, and indeed likely, to see periods as long as a decade in the recent past which do not show a warming trend. The authors even found that running computer simulations for the 21st century with significant increases in greenhouse gas emissions showed some decades with lower or static average temperatures. One such example can be found by looking at data from 1998 to 2008, which shows no real trend, even though global temperatures remain well above the long-term average.

According to the authors, the unusually strong 1997-98 El Niño contributed to unusual warmth in the global temperature for 1998, so that without similar dramatic changes, the following decade does not appear to be warming. A similar interpretation can be made by looking at the short-term data from 1977-85 or 1981-89, “even though these periods are embedded in the 1975-2008 period showing a substantial overall
warming,” Easterling and Wehner write. In the first example, dropping data from 1998 and looking at 1999-2008, the researchers found a strong warming trend.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

Editors’ Note: Of course, this cuts both ways. Though it may be tempting to do so, it’s no more legitimate to point to the latest heat wave or a single fire season as proof of global warming. This is a conundrum that makes it difficult to find consensus on pubic policy. There are additional links posted with the full news release at the LBNL site.