Epidemiologist Anthony McMichael of Australian National University surveyed how human societies fared during previous episodes of extreme weather brought on by climate shifts. The big threat is changes to food production, or as McMichael puts it “the drought-famine-starvation nexus.” And we’ve never weathered a climate change so big, so rapid and so widespread as the one we are now busily creating by burning fossil fuels, notes McMichael.

Long-running climate changes have often brought about the downfall of cultures, including foiling the earliest human attempts at settled farming nearly 13,000 years ago. Around that time, a major millennia-long climate cooling event known as the “Younger Dryas” coincides with the end of most settlements along the Nile Delta and in modern-day Syria. Skeletons from the era evince “an unusually high proportion of violent deaths, many accompanied by remnants of weapons,” McMichael noted. More recently, three back-to-back decades-long droughts afflicted Mayan society in Central America between roughly 760 and 920 CE, and marked the end of that culture’s regional dominance.

Shorter term climate changes have proven equally devastating. Decade-long droughts in 17th century China led to starvation, internal migration and, ultimately, the collapse of the Ming Dynasty. A seven year span of torrential rains, attendant floods and cold in the early 1300s helped cause a famine that may have killed as much as 10 percent of the people in northern Europe a generation that would then face the Black Death a few decades later.

Even a single bad summer can be enough like the hot summer of 1793 in Philadelphia that, paired with an influx of refugees from modern day Haiti, saw an outbreak of yellow fever that killed tens of thousands.

Of course, none of these societies had the benefits of modern technology or modern energy, whether medicine or air conditioning. But even that may not be enough to offset the roughly 2 to 4 degrees Celsius of warming in average global temperatures the world is on pace to achieve via emissions of greenhouse gases. “Such a change will surely pose serious risks to human health and survival,” McMichael wrote, “impinging unevenly, but sparing no population.”

What happened to “climate change” and “global warming”?

The Earth is still getting hotter, but those terms have nearly disappeared from political vocabulary. Instead, they have been replaced by less charged and more consumer-friendly expressions for the warming planet.

President Obama’s State of the Union address Tuesday was a prime example of this shift. The president said “climate change” just once — up from zero mentions in the 2011 address. When he did utter the phrase, it was merely to acknowledge the polarized atmosphere in Washington, saying, “The differences in this chamber may be too deep right now to pass a comprehensive plan to fight climate change.” By contrast, Obama used the terms “energy” and “clean energy” nearly two dozen times.

That tally reflects a broader change in how the president talks about the planet. A recent Brown University study looked specifically at the Obama administration’s language and found that mentions of “climate change” have been replaced by calls for “clean energy” and “energy independence.” Graciela Kincaid, a co-author of the study, wrote: “The phrases ‘climate change’ and ‘global warming’ have become all but taboo on Capitol Hill. These terms are stunningly absent from the political arena.”

In 2009, the Obama administration purposefully began to refer to greenhouse gas emissions as “carbon pollution” and “heat-trapping emissions.” This change has been noted in statements from top officials such as White House science adviser John Holdren, Energy Secretary Steven Chu, National Oceanic and Atmospheric Administration head Jane Lubchenco and Environmental Protection Agency Administrator Lisa Jackson. Lubchenco told a reporter that the choice of those terms “is intended to make what’s happening more understandable and more accessible to non-technical audiences.”

These choices are also reflected in news coverage around the world. My colleague Maria Mansfield and I monitor 50 major newspapers in 20countries, and we documented that explicit mentions of “climate change” and “global warming” dropped by more than a third from 2010 to 2011.

There is power in how language is deployed, and people setting policy agendas know this well. In 2002, Republican political strategist Frank Luntz issued a widely cited memo that the Bush administration should shift its rhetoric on the climate. “It’s time for us to start talking about ‘climate change’ instead of global warming. . . . ‘Climate change’ is less frightening than ‘global warming,’ ” the memo said.

Luntz was not alone in wanting to change the terminology. The nonprofit group EcoAmerica issued a report in 2009 arguing that the terms “global warming” and “climate change” both needed rebranding. In their place, the group recommended the phrase “our deteriorating atmosphere.”

But what do we lose when global warming and climate change get repackaged as clean energy? We wind up missing a thorough understanding of the breadth of the problem and the range of possible solutions.

To start, talking only about clean energy omits critical biological and physical factors that contribute to the warming climate. “Clean energy” doesn’t call to mind the ways we use the land and how the environment is changing. Where in the term is the notion of the climate pollution that results from clear-cutting Amazon rain forests? What about methane release in the Arctic, where global warming is exposing new regions of soil in the permafrost?

“Clean energy” also neatly bypasses any idea that we might need to curb our consumption. If the energy is clean, after all, why worry about how much we’re using — or how unequal the access to energy sources might be?

And terms such as “carbon pollution” ignore that climate change isn’t just a carbon issue. Some greenhouse gases, such as nitrous oxide, do not contain carbon, and not all carbon-containing emissions, such as carbon monoxide, trap heat.

When the president moves away from talking about climate change and talks more generally about energy, as he did in the State of the Union, calling for “an all-out, all-of-the-above strategy that develops every available source of American energy,” the impact is more than just political.

Calling climate change by another name creates limits of its own. The way we talk about the problem affects how we deal with it. And though some new wording may deflect political heat, it can’t alter the fact that, “climate change” or not, the climate is changing.

Maxwell T. Boykoff is an assistant professor in the Center for Science and Technology Policy Research at the University of Colorado at Boulder and the author of “Who Speaks for the Climate? Making Sense of Media Reporting on Climate Change.”

The study, by Britain’s Meteorological Office and the university of Reading, found that the Sun’s output would decrease up until 2100 but this would only lead to a fall in global temperatures of 0.08 degrees Celsius.

Scientists have warned that more extreme weather is likely across the globe this century as the Earth’s climate warms.

The world is expected to heat up by over 2 degrees Celsius this century due to increased greenhouse gas emissions.

Current global pledges to cut carbon dioxide and other greenhouse gas emissions are not seen as sufficient to stop the planet heating up beyond 2 degrees, a threshold scientists say risks an unstable climate in which weather extremes are common.

“This research shows that the most likely change in the sun’s output will not have a big impact on global temperatures or do much to slow the warming we expect from greenhouse gases,” said Gareth Jones, climate change detection scientist at the Met Office.

“It’s important to note this study is based on a single climate model, rather than multiple models which would capture more of the uncertainties in the climate system,” he added.

During the 20th century, solar activity increased to a maximum level and recent studies have suggested this level of activity has reached, or is nearing, an end.

The scientists used this maximum level as a starting point to project possible changes in the sun’s activity over this century.

The study also showed that if the sun’s output went below a threshold reached between 1645 and 1715 – called the Maunder Minimum when solar activity was at its lowest observed level – global temperature would fall by 0.13 degrees Celsius.

“The most likely scenario is that we’ll see an overall reduction of the sun’s activity compared to the 20th Century, such that solar outputs drop to the values of the Dalton Minimum (around 1820),” said Mike Lockwood, solar studies expert at the university of Reading.

“The probability of activity dropping as low as the Maunder Minimum – or indeed returning to the high activity of the 20th Century – is about 8 percent.”

I work for a nonpartisan, tax-exempt organization that can’t endorse candidates. We do, however, educate the public and promote government policies based on science. So I can’t get into the Republican or Democratic presidential candidates’ positions on climate, which you can easily find with a quick Internet search. But I can tell you how battered their respective states’ economies will be if we don’t dramatically reduce carbon emissions, and do it soon.

The snapshot projections below are what scientists expect the climate in each state to look like over the next three decades and beyond under a business-as-usual scenario where we continue to burn fossil fuels and destroy tropical forests at today’s rates. It’s not a pretty picture. In general, Americans should expect more smog, more heat, more droughts, and more flooding.

Georgia: First, let’s look at the home of former House Speaker Newt Gingrich. Georgia’s largest industry is agriculture, which contributes more than $68 billion annually to the state economy. It’s the nation’s number one producer of broiler chickens, peanuts, pecans and watermelons, and among the top producers of blueberries, cabbage, cantaloupes, cotton, eggs, onions, peaches, tomatoes and tobacco. Unchecked climate change likely would saddle those farmers with more droughts.

In 2007, a major drought across most of the Southeast caused $1.3 billion in economic damage in Georgia, including losses of $63.1 million in corn, $160.1 million in cotton, $83.8 million in hay, and $92.5 million in peanuts. A 2008 report by the National Conference of State Legislatures (NCSL) and the Center for Integrative Environmental Research at the University of Maryland calculated that an additional 5 percent in crop losses due to climate change would mean nearly $110 million in direct and indirect economic losses in Georgia annually.

Rising sea levels and more intense hurricanes, meanwhile, would threaten Georgia’s coastline. According to the NCSL report, the cumulative cost to replenish sand to protect the state’s coastline from a 20-inch rise in sea level could reach $154 million to $1.3 billion by 2100. Georgia generally does not suffer as much damage from hurricanes as its neighboring states Florida and South Carolina, but in 2004, Hurricane Ivan caused nearly $70 million in property damage in the Peach State.

Illinois: You might remember that Barack Obama’s Chicago suffered through a horrific heat wave in July 1995 that led to more than 700 heat-related deaths over a five-day stretch. By 2050, under the business-as-usual scenario, Chicago would experience a heat wave as hot as that one every summer, according to “Confronting Climate Change in the U.S. Midwest,” a 2009 report by the Union of Concerned Scientists (UCS). Peoria, Rockford, Springfield and other Illinois cities would face similar conditions. Such searing heat, combined with higher smog and soot levels, would aggravate asthma and other respiratory problems and cause more premature deaths across the state.

In July 1995, a deadly hot air mass settled over Chicago, killing more than 700 residents. By mid-century, Chicago likely will suffer similar heat waves every summer unless we dramatically reduce global warming emissions. (Photo: © Gary Braasch 2007)

Scientists project that Illinois likely would experience an increase of at least 20 percent in heavy precipitation over the next 30 years, mainly in the winter, spring and fall, which could mean more flooding. That, coupled with more frequent short-term summer droughts, heat stress, and wider insect ranges, would spell trouble for the state’s $11 billion-a-year agricultural sector. Corn yields, for example, could decline as much as 50 percent by the middle of the century. Meanwhile, hog and pig producers already are losing $20.5 million a year due to heat stress, and nearly permanent summer heat stress would threaten dairy cows, hogs, pigs and other livestock toward the end of the century.

Massachusetts: Mitt Romney was governor of a state that today is experiencing earlier springs, hotter summers, and milder winters than it did in 1970–all consistent with climate change. Under the business-as-usual scenario, it would get worse. According to UCS’s 2007 report, “Confronting Climate Change in the U.S. Northeast,” over the next 30 years, the state’s largest cities, including Boston, Springfield and Worcester, likely would experience nearly 20 summer days with temperatures higher than 90º F. That could worsen the state’s smog problem and accelerate pollen production, which could lengthen the allergy season.

Massachusetts is home to one of the country’s biggest commercial fishing industries. Based on current emissions trends, scientists project that ocean temperatures will be too warm by the end of this century to support the historically important Atlantic cod. Lobsters in coastal waters south of Cape Cod, meanwhile, would be cooked by mid-century. The state also produces a quarter of the nation’s cranberries. Heat stress would significantly depress yields for them and other fruit and vegetable crops, which currently generate about $94 million annually, by mid-century.

Rising sea level not only would increase the frequency and severity of storm surges and coastal flooding, it is expected to overwhelm some low-lying coastal areas and dramatically accelerate erosion. Sea-level rise also would threaten salt marshes and estuaries, which provide nursery habitat for commercial fish and feeding grounds for migrating birds.

Finally, by mid-century, warmer winters would drive many ski resorts out of business, and by late-century, the trees that provide the state’s spectacular fall foliage displays–maple, beech and birch–would disappear.

Pennsylvania: Rick Santorum, a former senator and representative, hails from Pennsylvania. The top agricultural industry in the Keystone State is dairy farming, and major cash crops include corn, vegetables, mushrooms and fruit, especially grapes and apples. Over the coming decades, Pennsylvanians likely would have to deal with longer, more intense summer heat waves; reduced winter snowpack; and declining farm yields, according to a 2008 UCS study, “Climate Change Impacts and Solutions for Pennsylvania.”

Most state residents would have to suffer through twice as many summer days over 90º F than they did before 1990. That would degrade air quality, exacerbating allergies, asthma and other respiratory illnesses; stress dairy cows, limiting milk production; and reduce yields of Concord grapes, sweet corn and apples. Prized hardwood trees, including black cherry, sugar maple and American beech, would decline precipitously.

Winters, on the other hand, would be milder. The areas in the state that typically experienced 30 days or more of snow before 1990 likely would only see only about two weeks of the white stuff. That would mean significantly fewer ski resorts and very little, if any, snowmobiling.

Texas: Texas Gov. Rick Perry dropped out of the race a few days after the first South Carolina debate, but Ron Paul, the U.S. representative from the state’s 14th district–just south of Houston on the Gulf coast–is still in contention. Given the state’s size, not all counties would be affected in quite the same way over the next few decades, but significant areas already are experiencing extreme heat, drought and wildfires.

Last summer, for example, some counties endured more than a month of consecutive 100º F-plus days, and much of the state is still suffering from a devastating year-long drought that is expected to stretch through at least next summer. The state also is beset by a range of extreme weather, including tornadoes, hail, thunderstorms, damaging winds and hurricanes, but not all are associated with climate change. That said, unchecked climate change is bound to make the withering heat, extended drought and deadly wildfires in the Lone Star State routine.

Texas is suffering from a year-long drought that completely dried up O.C. Fisher Lake in San Angelo. Droughts like this current one, which is expected to last through next summer, likely will become routine in the Lone Star State. (Photo: AP)

That isn’t good news for the state’s $20 billion agricultural sector. Texas boasts the most farms in number and acreage in the country. It produces the most cattle and is a leading state for sheep and goat production. It also is the top state for cotton, its leading crop and second-most-valuable farm product, and is a major producer of cantaloupes, cereal grains, grapefruits and watermelons.

The current drought has hit them all, triggering $5.3 billion in losses last year, according to the Texas AgriLife Extension Service at Texas A&M University. Including the drought’s ripple effect on fertilizer dealers, processing plants, grocery stores and other related businesses, the estimated loss balloons to $8.7 billion.

It’s climate change, stupid: Not to let the Republican presidential hopefuls off the hook, but one reason they have largely ignored global warming is because journalists haven’t pressed them on it, especially during the televised debates. I can’t say that I have watched all 23 of the debates that have occurred so far. But I have seen a number of them, and I have read the coverage. As far as I can tell, other than a brief mention about climate science during a debate in early September, moderators have abdicated their responsibility to address one of the most critical issues of our time.

Of course, for most Americans today, the biggest issue is the economy. It reminds me of the 1992 campaign, when then-Arkansas Gov. Bill Clinton challenged President George H.W. Bush. To keep the Clinton campaign focused, lead strategist James Carville hung a sign in Clinton’s Little Rock headquarters that said, in part: “The economy, stupid.” Although the sign was only meant for internal consumption, “It’s the economy, stupid” became the de facto slogan of the Clinton campaign.

The difference today is we know a lot more about the threat of global warming than we did two decades ago. We know that, next to a nuclear war, it poses the most significant long-term threat to not only our economy, but to the future of the planet. So it would be fitting to update that 20-year old sign to read “Climate change, stupid” and hang it on the stage during not only the presidential candidate debates, but during the debates for all candidates running for office this year.

Elliott Negin is the director of news and commentary at the Union of Concerned Scientists in Washington, D.C.

“I thought the media had just picked that up and blown it out of proportion,” he said.

Hogan remembers the day the “lightbulb went off,” about four years ago. He’d always been into cars and would get defensive if someone tried to pin climate change on vehicle emissions. But when Mr. Visco pointed out that the methane spewing from livestock was actually a more potent greenhouse gas than carbon dioxide, Hogan opened up and began to reconsider, and then accept, the scientific consensus on anthropogenic climate change.

“Keith was like George Bush in disguise,” recalled Chris Visco, who is now retired. “It’s funny how things progressed with him.”

Imparting the science of climate change is not always so easy. Many of Hogan’s conservative classmates at Sachem High School in Long Island, N.Y. avoided taking Mr. Visco’s class, aware that they’d hear views that conflicted with their own. And around the country — from Washington State to Oklahoma — pressure and pushback from skeptical students, teachers and administrators pose challenges.

In 2008, Louisiana voted to allow public school teachers to teach both creationism and the views of climate change skeptics. Last May, a school board in Las Alamitos, Calif., voted unanimously to require environmental science teachers cover “multiple perspectives” on climate change. That decision was later rescinded.

“For every [conflict] you hear about there are probably 10 you don’t, and probably 100 teachers that will just not teach it because that is the easiest way out,” said Mike Town, an environmental science teacher at Redmond High School in Washington and a participant in a National Academy of Sciences workshop on climate change education.

The National Center for Science Education, long-touted for its efforts to help teachers address evolution in the classroom, has recognized the predicament and announced this week that it would add climate change to its repertoire, offering teachers a range of tools and legal support.

“It’s a bit daunting to tell you the truth,” said Eugenie Scott, executive director of the NCSE. “It’s not like we were bored. There’s still plenty to do in the evolution realm.”

THE FACTS: NOT ENOUGH

About a quarter of teachers recently polled by the National Science Teachers Association (NSTA) reported facing skepticism about climate change and climate change education from their administrators; more than half faced the same from parents. Further, 82 percent noted that they had dealt with skepticism from their students.

This pressure can have consequences, warns other data. Despite the estimated 89 percent of teachers who believe climate change is happening, a survey by the National Earth Sciences Teachers Association also found that 36 percent had been influenced to teach “both sides” of the debate.

A case in point: After Al Gore’s “An Inconvenient Truth” was shown in a Portola Valley, Calif., middle school class, a parent requested that the teacher hold a debate between a climate change-denier and a climate scientist to provide “balance.” John Davenport, the union representative who spoke for the teacher in the controversy, consulted with the NCSE.

“They made it clear that this was virgin ground for them,” Davenport said, adding that the center told the district that the policy issue belonged in a social studies class, not a science class.

Overall, 63 percent of the U.S. general public agrees that global warming is happening and 35 percent attribute it to natural changes, according to a new Yale report which found similar rates for teenagers’ knowledge of the subject.

Most politicians, meanwhile, lack a science background. “We need an informed citizenry to help the politicians make the best decisions,” said Scott. “In the case of climate change, the reality is there and the consequences for society are profound.”

Anthony Leiserowitz, director of the Yale Project on Climate Change Communication and lead researcher of the report, added that an understanding of climate change is “necessary but not sufficient” for making such decisions. Facts also need to be interpreted through the lenses of values.

He calls climate change the “policy problem from hell,” partly because of the long lag time between actions and results on the issue.

Religious and political beliefs also come into play.

Last Friday, in a conversation with Arianna Huffington, public television icon Bill Moyers highlighted other recent findings: “Even if you, a modern American, are presented with a fact you know to be false, you nonetheless reject it if it offends or undermines your belief system,” he said.

In his new book, “Fool Me Twice: Fighting the Assault on Science in America,” Shawn Lawrence Otto suggests that the same conflict between science and beliefs has played out through much of history. He quotes a letter that Albert Einstein wrote to a friend. “This world is a strange madhouse,” Einstein said. “Currently every coachman and every waiter is debating whether relativity theory is correct. Belief in this matter depends on political party affiliation.”

Town suggests little has changed today. “If you come from a Republican household and your parents are watching Fox News and trying to pick a candidate, and your science teacher is telling you that climate change is one of the most important things that could impact your life,” added Town, “then it’s easy to have to find a way to discredit” the latter.

THE NEXT EVOLUTION

Visco first taught climate change in 1977, at a Catholic high school. Since then, he said he’s noticed public perception of the topic go from “nothing to awareness to negativity.”

That last turning point, Visco said, came around the release of “An Inconvenient Truth.” He said the film brought climate change into the public’s consciousness, but it also sparked a build-up of denialist propaganda, which then flooded teachers’ mailboxes and students’ minds.

“In many ways, climate change is where evolution education was about 20 yeas ago,” said Scott, noting NCSE’s constant struggle with anti-evolution propaganda.

There are many parallels between the two battles, as well as some important differences.

“In the case of evolution, the objection to teaching it is based in religious ideology,” said Scott. “In climate change, the objection is based in political and economic ideology.”

While both cases are unscientific, only the former has the backing of the First Amendment: “Climate change is going to be a much harder battle to fight,” Scott said.

Another key difference is that evolution fits into a core high school course: biology. Climate change, on the other hand, may only come up in an elective course or during middle school — before most kids have the background to comprehend the complex concepts.

A revision to the science education standards is currently underway, in which climate change will be “explicitly noted,” said Francis Eberle, executive director of the NSTA.

Mark McCaffrey, the new programs and policy director for climate change at the NCSE, also emphasized that it was important for the subject to be taught in a “relevant” and “practical” manner.

During his time with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado at Boulder, McCaffrey helped spearhead the Climate Literacy and Energy Awareness Network, which offers resources for teachers to connect the dots between climate and energy consumption.

For Visco’s class, that meant teaching his students that small changes could have a large impact on the planet. “I had lots of students who would come in and say, ‘My parents hate you. I’m driving them nuts, making them recycle and turn heat down and change lightbulbs,’” he recalled.

In many cases, by teaching his students he was also teaching their parents, something that Yale’s Leiserowitz has also found. “Do parents influence kids, or do kids influence parents? Evidence suggests that it works both ways.”

“I definitely saw changes in my students, and I definitely saw parents that softened,” said Visco.

U.S. Interior Department Deputy Secretary David Hayes said rising sea levels, warming temperatures and other climate issues are having an effect on everything from wildlife to natural resources.

“The impacts of climate change are already here and those who manage our landscapes are already dealing with them,” he said in a statement.

The strategy, available for public comment through March, outlines guidelines for local, state and federal agencies to tackle climate issues tied to everything from migration patterns to rising sea levels and invasive species.

Climate talks under the auspices of the United Nations have resulted in few dramatic reforms aimed at reducing climate change.

Environmental scientists added in a report to Congress that they observed “measurable improvements” in the levels of acid rain. Because of programs enacted in the 1990s, scientists said there were “dramatic” reductions in levels of sulfur dioxide and nitrogen oxides from power plants.

“The emissions that form acid rain have declined and some U.S. areas are beginning to recover,” said Doug Burns, lead author of the study and U.S. Geological Survey hydrologist. “However, some sensitive ecosystems are still receiving levels of acid rain that exceed what is needed for full and widespread recovery.”

In the northern mountains of Arizona, elk spend their winters in lower elevations where there’s much less snow and the cold is less pronounced. But the decrease in high-elevation snowfall in the mountains over the last 25 years has allowed elk to forage in these areas throughout winter. Researchers found that the elks’ year-round high-elevation browsing has decimated the density of seasonal woodsy plants, which, in turn, has impacted the populations of songbirds (animals you might expect would actually benefit from less snow).

By preventing elk from entering several study sites for six years, the researchers were able to reverse the multi-decadal decline in plant and bird populations in these locations.

“Ecologic communities are pretty complex. There are all these tight interactions going on,” said study co-author Tom Martin, a wildlife researcher with the U.S. Geological Survey. “Perturbation from climate can affect those communities in many indirect ways and cause all of these ramifying effects.” [Odd Effects of Climate Change]

Dramatic declines

The densities of seasonal woodsy plants, including aspen and maple trees, in the northern Arizona mountains have steadily declined over the last two decades. Martin and his colleague John Maron, a biologist at the University of Montana, hypothesized that this decline is primarily the result of one of two things: decreased soil water or increased exposure to hungry elk.

To find out, the researchers set up 25-acre enclosures around three drainages, or vegetation-rich valleys created by snowmelt. By keeping the elk out, the enclosures essentially mimicked the effects of large snowfall.

The researchers found that plant populations in the enclosures rebounded to levels last seen in 1996 — suppressing winter-browsing elk for six years effectively reversed 15 years of plant-density decline. Plant populations in nearby open drainages, however, did not improve over the six years.

Similarly, the populations of five key songbird species rebounded in enclosed drainages. “With more vegetation, there are more nesting areas, and it becomes harder for predators to find the nests,” Martin told Livescience.

Since the populations of elk have also strongly declined over the last 11 years, the results show that the elks’ new tendency to stick around over winter is ravaging the plant and bird communities. “It doesn’t take very many animals to have a pretty large impact if they’re there year-round,” Martin explained.

Conservation implications

Eric Post, a biologist at Pennsylvania State University who was not involved with the research, said that the study demonstrates how observational and experimental research can compliment each other. “Both are necessary to study climate change ecology,” Post told LiveScience.

While impressed with the study, Post thinks that the researchers “didn’t nail down the driving factor in the relationship between plant growth and bird abundance.” It seems convincing that the architecture of the vegetation would provide the birds with more nesting opportunities, he said, but that theory doesn’t take into account the effect of invertebrate (animals without a backbone) abundance. The winter elk may also be affecting the populations of local insects, which the birds eat.

Still, Post believes that the study has important implications for conservation. “If you are interested in the conservation of birds, you need to look at more than just the birds and the vegetation they are dependent on,” Post said. “You need to look at the broader system of browsing animals.”

Martin agrees, adding that by “recognizing that these things happen, we can target priority habitats for conservation.”

The study was published online Jan. 10 in the journal Nature Climate Change.

Although the organization’s title refers to science education generally, evolution has been the primary area of science that has been under attack for reasons that have nothing to do with the latest research. But over the last several years, that’s changed as more and more bills have been introduced that target both evolution and climate change. With times changing, the NCSE is changing with them. Today, it’s announcing that its support of students and educators will be broadened to include climate change. We talked with the NCSE’s executive director, Eugenie Scott, about the decision.

Scott said that the NCSE’s work with teachers on evolution made them aware that teaching climate science was becoming controversial. “It’s been a growing realization of ours that, just as teachers get hammered for teaching evolution, they also are getting hammered for teaching global warming and other climate change topics,” she told Ars. “They’ll start talking about global warming and a student’s hand will shoot up, ‘teacher, my dad says global warming is a hoax.’ We’ve had accounts where students would get up and walk out of the room.”

The NCSE also heard about school boards that enacted policies that would dictate how things would be handled in the classrooms, and noticed the legislation we mentioned above. Scott said that all these events left the NCSE staff thinking “we really should look into this.”

What they found were some clear parallels between evolution and climate science. Just as the controversy over evolution takes place within the public and not among scientists, Scott said, “There’s not a debate going on within the science community about whether the climate is getting warm and whether people have a great deal to do with this.” There were also parallels in terms of motivation. “The basis for antievolution is ideological,” Scott said, pointing to its religious nature. “There’s also an idealogical basis for anti-global warming, it just happens to be a political and economic ideology.”

The details of the arguments differ—”creationists don’t talk a lot about sun spots,” Scott joked—but the NCSE considers the structure of the arguments to be very similar. Ultimately, “Both [groups] are making a pedagogical argument, that it is somehow good pedagogy, good critical thinking, for students to learn both. That it is somehow a good pedagogy for students to learn good science and bad science.”

Because of these similarities, the NCSE has decided that their past experience can be helpful. “The anti-climate change controversy is about where the antievolution controversy was 20 years ago,” Scott told Ars. “We’ve learned a lot—we including the scientific community—dealing with the evolution controversy and, with luck, maybe we can get ahead of this.” One of the things they’ve learned is that the “deficit model”—the idea that people don’t like the science because they don’t understand it—doesn’t really apply. “You’re not going to be effective if you are talking about only throwing more science at people who hold different views from you—you have to deal with the ideological component as well,” Scott said. “Our experience with that will hopefully be useful.”

As with evolution, most of the focus will be on tracking efforts by state legislators to dictate how science education is handled (Scott says there are already five bills that target evolution active in various states). The NCSE will also continue to advise and support teachers and families that find science education under attack in their communities. Right now, many schools don’t teach climate science at all; if they do, it’s likely to be in middle school earth sciences or high school ecology classes. But that may change, as Scott said national science standards that are in the works are poised to include climate science, and nearly half the states have promised to adopt them.

But there will be some distinct challenges. “We’ve always argued ‘do what’s best for the kids, teach good science.’ The nice thing about evolution is that we can also say ‘and by the way, if you try to teach creationism/intelligent design, you will be sued and you will lose, because all the case law is against you,’” Scott said. “There’s nothing comparable with climate change. There’s no constitutional protection against bad science. What we have to do is persuade people, help them understand what is good science, and why their kids should learn good science.”

To help get the organization ready for the challenge of persuading people, the NCSE has hired Mark McCaffrey, a scientist that has focused on climate literacy. They’ve also placed the Pacific Institute’s Peter Gleick on their board.

For now, Scott doesn’t see any other areas that the NCSE would need to handle. She called politically controversial scientific topics the group’s “ecological niche,” since the group’s goal is to try to keep the politics out of science education: “Our big concern is that science education not be politicized. We see it happening with climate change science. We’d like to do what we can the help teachers from keeping it from getting worse.”

They say the key is to reduce emissions of two powerful and fast-acting causes of global warming — methane and soot.

Carbon dioxide is the chief greenhouse gas and the one world leaders have spent the most time talking about controlling. Scientists say carbon dioxide from fossil fuels like coal and oil is a bigger overall cause of global warming, but reducing methane and soot offers quicker fixes.

Soot also is a big health problem, so dramatically cutting it with existing technology would save between 700,000 and 4.7 million lives each year, according to the team’s research published online Thursday in the journal Science. Since soot causes rainfall patterns to shift, reducing it would cut down on droughts in southern Europe and parts of Africa and ease monsoon problems in Asia, the study says.

Two dozen scientists from around the world ran computer models of 400 different existing pollution control measures and came up with 14 methods that attack methane and soot. The idea has been around for more than a decade and the same authors worked on a United Nations report last year, but this new study is far more comprehensive.

All 14 methods — capturing methane from landfills and coal mines, cleaning up cook stoves and diesel engines, and changing agriculture techniques for rice paddies and manure collection — are being used efficiently in many places, but aren’t universally adopted, said the study’s lead author, Drew Shindell of NASA.

If adopted more widely, the scientists calculate that would reduce projected global warming by 0.9 degrees Fahrenheit (0.5 degrees Celsius) by the year 2050. Without the measures, global average temperature is projected to rise nearly 2.2 degrees Fahrenheit (1.2 degrees Celsius) in the next four decades. But controlling methane and soot, the increase is projected to be only 1.3 degrees (0.7 degrees Celsius). It also would increase annual yield of key crops worldwide by almost 150 million tons (135 million metric tons).

Methane comes from landfills, farms, drilling for natural gas, and coal mining. Soot, called black carbon by scientists, is a byproduct of burning and is a big problem with cook stoves using wood, dung and coal in developing countries and in some diesel fuels worldwide.

Reducing methane and black carbon isn’t the very best way to attack climate change, air pollution, or hunger, but reducing those chemicals are among the better ways and work simultaneously on all three problems, Shindell said.

And shifting the pollution focus doesn’t mean ignoring carbon dioxide. Shindell said: “The science says you really have to start on carbon dioxide even now to get the benefit in the distant future.”

It all comes down to basic chemistry. There’s far more carbon dioxide pollution than methane and soot pollution, but the last two are way more potent. Carbon dioxide also lasts in the atmosphere longer.

A 2007 Stanford University study calculated that carbon dioxide was the No. 1 cause of man-made global warming, accounting for 48 percent of the problem. Soot was second with 16 percent of the warming and methane was right behind at 14 percent.

But over a 20-year period, a molecule of methane or soot causes substantially more warming then a carbon dioxide molecule.

The new research won wide praise from outside scientists, including a conservative researcher who held a top post in the George W. Bush administration.

“So rather than focusing only on carbon dioxide emissions, where we have to make a tradeoff with energy prices, this strategy focuses on ‘win-win-win’ pathways that have benefits to human health, agriculture and stabilizing the Earth’s climate,” said University of Minnesota ecology professor Jonathan Foley, who wasn’t part of the study. “That’s brilliant.”

John D. Graham, who oversaw regulations at the Office of Management and Budget in the Bush administration and is now dean of public and environmental affairs at Indiana University, said: “This is an important study that deserves serious consideration by policy makers as well as scientists.”

The study even does a cost-benefit analysis to see if these pollution control methods are too expensive to be anything but fantasy. They actually pay off with benefits that are as much as ten times the value of the costs, Shindell said. The paper calculates that as of 2030, the pollution reduction methods would bring about $6.5 trillion in annual benefits from fewer people dying from air pollution, less global warming and increased crop production.

In the United States, Shindell calculates the measures would prevent about 14,000 air pollution deaths in people older than 30 by the year 2030. About 0.8 degrees Fahrenheit of projected warming in the U.S. would be prevented by 2050.

But health benefits would be far bigger in China and India where soot is more of a problem.

The study comes a day after the U.S. Environmental Protection Agency released the most detailed data yet on American greenhouse gas emissions. Of the emissions reported to the government, nearly three-quarters came from power plants. But with methane, it’s different. Nineteen of the top 20 methane emitters were landfills.

Stanford University climate scientist Chris Field, who is a leader in the Intergovernmental Panel on Climate Change but wasn’t part of this study, praised the study but said he worried that officials would delay cutting back on the more prevalent carbon dioxide. Focusing solely on methane and soot and ignoring carbon dioxide “tends to exacerbate climate change,” he said.

Another outside climate expert Andrew Weaver of the University of Victoria in Canada said the study is good news amid a sea of gloomy reports about climate change.

“This is a no-brainer,” he said. “We have solutions at hand.”

Researchers used data on the Earth’s orbit and other things to find the historical warm interglacial period that looks most like the current one.

In the journal Nature Geoscience, they write that the next Ice Age would begin within 1,500 years – but emissions have been so high that it will not.

“At current levels of CO2, even if emissions stopped now we’d probably have a long interglacial duration determined by whatever long-term processes could kick in and bring [atmospheric] CO2 down,” said Luke Skinner from Cambridge University.

Dr Skinner’s group – which also included scientists from University College London, the University of Florida and Norway’s Bergen University – calculates that the atmospheric concentration of CO2 would have to fall below about 240 parts per million (ppm) before the glaciation could begin.

The current level is around 390ppm.

Other research groups have shown that even if emissions were shut off instantly, concentrations would remain elevated for at least 1,000 years, with enough heat stored in the oceans potentially to cause significant melting of polar ice and sea level rise.
Orbital wobbles

The root causes of the transitions from Ice Age to interglacial and back again are the subtle variations in the Earth’s orbit known as the Milankovitch cycles, after the Serbian scientist Milutin Milankovic who described the effect nearly 100 years ago.

The variations include the eccentricity of the Earth’s orbit around the Sun, the degree to which its axis is inclined, and the slow rotation of its axis.

These all take place on timescales of tens of thousands of years.

The precise way in which they change the climate of the Earth from warm interglacial to cold Ice Age and back every 100,000 years or so is not known.

On their own, they are not enough to cause the global temperature difference of about 10C between Ice Age and interglacial. The initial small changes are amplified by various factors including the release of carbon dioxide into the atmosphere as warming begins, and absorption of the gas by the oceans as the ice re-forms.

It is also clear that each transition is different from previous ones, because the precise combination of orbital factors does not repeat exactly – though very similar conditions come around every 400,000 years.

The differences from one cycle to the next are thought to be the reason why interglacial periods are not all the same length.

Using analysis of orbital data as well as samples from rock cores drilled in the ocean floor, Dr Skinner’s team identified an episode called Marine Isotope Stage 19c (or MIS19c), dating from about 780,000 years ago, as the one most closely resembling the present.

The transition to the Ice Age was signalled, they believe, by a period when cooling and warming seesawed between the northern and southern hemispheres, triggered by disruptions to the global circulation of ocean currents.

If the analogy to MIS19c holds up, this transition ought to begin within 1,500 years, the researchers say, if CO2 concentrations were at “natural” levels.

As things stand, they believe, it will not.
Loving CO2

The broad conclusions of the team were endorsed by Lawrence Mysak, emeritus professor of atmospheric and oceanic sciences at McGill University in Montreal, Canada, who has also investigated the transitions between Ice Ages and warm interglacials.

“The key thing is they’re looking about 800,000 years back, and that’s twice the 400,000-year cycle, so they’re looking at the right period in terms of what could happen in the absence of anthropogenic forcing,” he told BBC News.

He suggested that the value of 240ppm CO2 needed to trigger the next glaciation might however be too low – other studies suggested the value could be 20 or even 30ppm higher.

“But in any case, the problem is how do we get down to 240, 250, or whatever it is? Absorption by the oceans takes thousands or tens of thousands of years – so I don’t think it’s realistic to think that we’ll see the next glaciation on the [natural] timescale,” Prof Mysak explained.

Groups opposed to limiting greenhouse gas emissions are already citing the study as a reason for embracing humankind’s CO2 emissions.

The UK lobby group the Global Warming Policy Foundation, for example, has flagged up a 1999 essay by astronomers Sir Fred Hoyle and Chandra Wickramasinghe, who argued that: “The renewal of ice-age conditions would render a large fraction of the world’s major food-growing areas inoperable, and so would inevitably lead to the extinction of most of the present human population.

“We must look to a sustained greenhouse effect to maintain the present advantageous world climate. This implies the ability to inject effective greenhouse gases into the atmosphere, the opposite of what environmentalists are erroneously advocating.”

Luke Skinner said his group had anticipated this kind of reception.

“It’s an interesting philosophical discussion – ‘would we better off in a warm [interglacial-type] world rather than a glaciation?’ and probably we would,” he said.

“But it’s missing the point, because where we’re going is not maintaining our currently warm climate but heating it much further, and adding CO2 to a warm climate is very different from adding it to a cold climate.

“The rate of change with CO2 is basically unprecedented, and there are huge consequences if we can’t cope with that.”