Conspiracy of silence: The irresponsible politics of climate change

In a summer dominated by heat waves and a devastating nationwide drought, it would seem that climate change would be a major issue in the US presidential campaign. However, quite the opposite is happening. Neither President Barack Obama nor the presumptive Republican nominee, Mitt Romney, has focused any attention on this critical issue. In a recent speech on the Senate floor, Senator John Kerry characterized the political discourse in the United States as a "conspiracy of silence … a story of disgraceful denial, back-pedaling, and delay that has brought us perilously close to a climate change catastrophe." This silence means that we can expect further delays in addressing climate change, delays that we cannot afford.

Presidential politics. Both presidential campaigns have ignored climate change on their web sites. The Romney site advocates vigorous energy development of coal, gas, oil, and nuclear power. Obama's site focuses on an "all of the above" energy strategy, which advocates the development of all energy sources, including "clean" coal and alternative energy. The statements by the candidates echo this approach.

Romney, at one time, believed in climate change. In his 2010 book No Apology: The Case for American Greatness, Romney wrote: "I believe that climate change is occurring -- the reduction in the size of global ice caps is hard to ignore. I also believe that human activity is a contributing factor. I am uncertain how much of the warming, however, is attributable to factors out of our control." Even this lukewarm statement blurred as the presidential primary contest heated up and opposition to climate change became a litmus test for Republican presidential candidates. At a January 2012 campaign event in Pittsburgh, Romney was uncertain regarding the cause of global climate change: "My view is that we don't know what's causing climate change on this planet. And the idea of spending trillions and trillions of dollars to try to reduce CO2 emissions is not the right course for us."

President Obama has seemingly forgotten about climate change. As recently as Earth Day 2011, Obama was forthright about the need to address climate change: "Today, our world faces the major global environmental challenge of a changing climate. Our entire planet must address this problem because no nation, however larger or small, wealthy or poor, can escape the impact of climate change." Now Obama cannot even say the words "climate change." In his 2012 Earth Day address, he coupled auto efficiency standards with "reducing greenhouse gas emissions," but Obama made no mention of climate change or why emissions should be reduced. In a major address on energy one month later, Obama omitted any reference to climate change, greenhouse gases, or even air pollution. More

 

Chronic 2000-04 Drought, Worst in 800 Years, May Be the 'New Normal'

ScienceDaily (July 29, 2012) — The chronic drought that hit western North America from 2000 to 2004 left dying forests and depleted river basins in its wake and was the strongest in 800 years, scientists have concluded, but they say those conditions will become the “new normal” for most of the coming century.

Such climatic extremes have increased as a result of global warming, a group of 10 researchers reported July 29 in Nature Geoscience. And as bad as conditions were during the 2000-04 drought, they may eventually be seen as the good old days.

Climate models and precipitation projections indicate this period will actually be closer to the “wet end” of a drier hydroclimate during the last half of the 21st century, scientists said.

Aside from its impact on forests, crops, rivers and water tables, the drought also cut carbon sequestration by an average of 51 percent in a massive region of the western United States, Canada and Mexico, although some areas were hit much harder than others. As vegetation withered, this released more carbon dioxide into the atmosphere, with the effect of amplifying global warming.

“Climatic extremes such as this will cause more large-scale droughts and forest mortality, and the ability of vegetation to sequester carbon is going to decline,” said Beverly Law, a co-author of the study, professor of global change biology and terrestrial systems science at Oregon State University, and former science director of AmeriFlux, an ecosystem observation network.

“During this drought, carbon sequestration from this region was reduced by half,” Law said. “That’s a huge drop. And if global carbon emissions don’t come down, the future will be even worse.”

This research was supported by the National Science Foundation, NASA, U.S. Department of Energy, and other agencies. The lead author was Christopher Schwalm at Northern Arizona University. Other collaborators were from the University of Colorado, University of California at Berkeley, University of British Columbia, San Diego State University, and other institutions. More

 

Climate change study forces sceptical scientists to change minds

Earth's land shown to have warmed by 1.5C over past 250 years, with humans being almost entirely responsible.

The Earth's land has warmed by 1.5C over the past 250 years and "humans are almost entirely the cause", according to a scientific study set up to address climate change sceptics' concerns about whether human-induced global warming is occurring.

Prof Richard Muller, a physicist and climate change sceptic who founded the Berkeley Earth Surface Temperature (Best) project, said he was surprised by the findings. "We were not expecting this, but as scientists, it is our duty to let the evidence change our minds." He added that he now considers himself a "converted sceptic" and his views had undergone a "total turnaround" in a short space of time.

"Our results show that the average temperature of the Earth's land has risen by 2.5F over the past 250 years, including an increase of 1.5 degrees over the most recent 50 years. Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases," Muller wrote in an opinion piece for the New York Times.

The team of scientists based at the University of California, Berkeley, gathered and merged a collection of 14.4m land temperature observations from 44,455 sites across the world dating back to 1753. Previous data sets created by Nasa, the US National Oceanic and Atmospheric Administration, and the Met Office and the University of East Anglia's climate research unit only went back to the mid-1800s and used a fifth as many weather station records.

The funding for the project included $150,000 from the Charles G Koch Charitable Foundation, set up by the billionaire US coal magnate and key backer of the climate-sceptic Heartland Institute thinktank. The research also received $100,000 from the Fund for Innovative Climate and Energy Research, which was created by Bill Gates. More

 

Vacuuming the Atmosphere

"If all of the proven reserves of coal, oil and gas were to be burned by 2100 (2795 Gt), and at the same time the air extraction experiment of Global Thermostat were to be scaled up as Eisenberger and Chicilnisky project (withdrawing 2400 Gt), then Earth’s atmospheric parking lot would still have space for 170 more Gt before it hits the Kyoto limit of 2 degrees of warming."

My beef with the whole “solutions” thing comes from my travels around the country, talking on college campuses and such; there is this whole clamor for “solutions.” The idea is, if you’re not optimistic enough, you should shut up. But there are subtexts to all these things. And the subtext to that particular meme is, “Give us the solutions that will allow us to keep running our stuff the same way we’re running it now, except by other means.” They don’t really want to hear about other arrangements. They want to keep on running all the cars, only differently. You know, like hybrid electric cars, or electric cars, or cars that run on algae secretions. But they don’t get that we’re done with that way of life. The mandates of reality are telling us something very different. They are telling us we have to inhabit the landscape and move around in it very differently in the future.

— James Howard Kunstler, in Rolling Stone, July 12, 2012

Scientists grasping at geoengineering straws to maintain a quasihuman technotopia into the post-Anthropocene have proposed a lot of bad ideas but occasionally something pops up that could conceivably work. Those in the latter category need to be put to the proof. We will have a closer look at one of those, but first a quick bit of background.

In 1989, when we were proofreading publishers’ galleys and drawing illustrations to go with our planned January 1990 release of Climate in Crisis: The Greenhouse Effect and What You Can Do, two new books came across our desk that seemed to confirm the importance of what we were writing. The two were Bill McKibben’s End of Nature and Steven Schneider’s Global Warming. The first we dismissed out of hand because it seemed overly prosaic and we did not agree with the premise — nature was not going away, although we humans well might.

The second gave us greater concern because, like Climate in Crisis, it put the science out there for the average person to read in terms that were easy to comprehend, and it told a story by scientific discoveries, in a sequence not unlike our own, from ice cores to better light bulbs. More

 

GDP Cannot Capture the Economics of Climate Change

The newest GDP release shows an increase of 1.5 percent in the second quarter of 2012, down from a 1.9 percent growth in the first quarter and three percent growth in 2011. But, as Dēmos continually asks in our Beyond GDPwork: What exactly is GDP measuring?

GDP doesn't measure things that are good for our economy and society, like home production and volunteer work, and doesn't count things that are bad, like inequality and pollution. More pressingly, GDP cannot reflect the importance of ecosystem services and without valuing them, preserving them becomes only a cost and not a benefit. As we see more and more impacts from climate change, ecosystems play a vital role in adaptation and mitigation practices, not just as carbon sinks, but also by reducing erosion, providing shade and providing fresh air and water. Yet, their importance does not show up in GDP calculations.

The main difficulty with valuing ecosystems has always been pricing- how do you put a price on forests that act as carbon sinks? There are efforts to start to capture these values, including the System for Environment and Economic Accounts, which provides methods for countries to account for natural resources like minerals, timber and fisheries. There is also the Inclusive Wealth Index, which includes natural capital, in addition to manufactured and human capital, as part of a nation's overall capital assets. Currently, at least 24 countries use some form of natural capital accounting.

While not widely used yet, capturing the value that ecosystems currently provide seems tangible. The more challenging accounting question is how do we capture future costs? The recent heat waves are causing damage not just to natural environments, but also to our built environments. Airplanes are getting stuck in asphalt that has softened from heat, subway trains are derailing after tracks become warped, and highways are shrinking, leading to cracking, because the soil under them is getting too dry. So, how do we capture the role that healthy ecosystems play in preventing these future impacts and costs? More

 

Antarctic: Grand Canyon-sized rift 'speeding ice melt'

A rift in the Antarctic rock as deep as the Grand Canyon is increasing ice melt from the continent, researchers say.

A UK team found the Ferrigno rift using ice-penetrating radar, and showed it to be about 1.5km (1 mile) deep.

Antarctica is home to a geological rift system where new crust is being formed, meaning the eastern and western halves of the continent are slowly separating.

The team writes in Nature journal that the canyon is bringing more warm sea water to the ice sheet, hastening melt.

The Ferrigno rift lies close to the Pine Island Glacier where Nasa scientists found a giant crack last year; but the newly discovered feature is not thought to be influencing the "Pig", as it is known.

The rift lies beneath the Ferrigno Ice Stream on a stretch of coast so remote that it has only been visited once previously.

The British Antarctic Survey (BAS) project revisited the area two years ago in the person of Aberdeen University glaciologist Robert Bingham.

The plan was to make ground observations that could link to the satellite data showing unexpectedly pronounced ice loss from the area.

The team towed ice-penetrating radar kit behind a snowmobile, traversing a total of about 2,500km (1,500 miles).

"What we found is that lying beneath the ice there is a large valley, parts of which are approximately a mile deeper than the surrounding landscape," said Dr Bingham. More

 

Satellites See Unprecedented Greenland Ice Sheet Surface Melt

July 24, 2012: For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

"The Greenland ice sheet is a vast area with a varied history of change. This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Tom Wagner, NASA's cryosphere program manager in Washington. "Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system." More

 

The world is closer to a food crisis than most people realise

Unless we move quickly to adopt new population, energy, and water policies, the goal of eradicating hunger will remain just that.

Food riots in Algeria in 2008. Photograph: Fayez Nureldine/AFP/Getty Images

In the early spring this year, US farmers were on their way to planting some 96m acres in corn, the most in 75 years. A warm early spring got the crop off to a great start. Analysts were predicting the largest corn harvest on record.

The United States is the leading producer and exporter of corn, the world's feedgrain. At home, corn accounts for four-fifths of the US grain harvest. Internationally, the US corn crop exceeds China's rice and wheat harvests combined. Among the big three grains – corn, wheat, and rice – corn is now the leader, with production well above that of wheat and nearly double that of rice.

The corn plant is as sensitive as it is productive. Thirsty and fast-growing, it is vulnerable to both extreme heat and drought. At elevated temperatures, the corn plant, which is normally so productive, goes into thermal shock.

Time is running out. The world may be much closer to an unmanageable food shortage – replete with soaring food prices, spreading food unrest, and ultimately political instability– than most people realise.

As spring turned into summer, the thermometer began to rise across the corn belt. In St Louis, Missouri, in the southern corn belt, the temperature in late June and early July climbed to 100F or higher 10 days in a row. For the past several weeks, the corn belt has been blanketed with dehydrating heat.

Weekly drought maps published by the University of Nebraska show the drought-stricken area spreading across more and more of the country until, by mid-July, it engulfed virtually the entire corn belt. Soil moisture readings in the corn belt are now among the lowest ever recorded.

While temperature, rainfall, and drought serve as indirect indicators of crop growing conditions, each week the US Department of Agriculture releases a report on the actual state of the corn crop. This year the early reports were promising. On 21 May, 77% of the US corn crop was rated as good to excellent. The following week the share of the crop in this category dropped to 72%. Over the next eight weeks, it dropped to 26%, one of the lowest ratings on record. The other 74% is rated very poor to fair. And the crop is still deteriorating.

Over a span of weeks, we have seen how the more extreme weather events that come with climate change can affect food security. Since the beginning of June, corn prices have increased by nearly one half, reaching an all-time high on 19 July. More

 

Politics: Global Warming's Terrifying New Math

If the pictures of those towering wildfires in Colorado haven't convinced you, or the size of your AC bill this summer, here are some hard numbers about climate change: June broke or tied 3,215 high-temperature records across the United States. That followed the warmest May on record for the Northern Hemisphere – the 327th consecutive month in which the temperature of the entire globe exceeded the 20th-century average, the odds of which occurring by simple chance were 3.7 x 10-99, a number considerably larger than the number of stars in the universe.

Meteorologists reported that this spring was the warmest ever recorded for our nation – in fact, it crushed the old record by so much that it represented the "largest temperature departure from average of any season on record." The same week, Saudi authorities reported that it had rained in Mecca despite a temperature of 109 degrees, the hottest downpour in the planet's history.

Not that our leaders seemed to notice. Last month the world's nations, meeting in Rio for the 20th-anniversary reprise of a massive 1992 environmental summit, accomplished nothing. Unlike George H.W. Bush, who flew in for the first conclave, Barack Obama didn't even attend. It was "a ghost of the glad, confident meeting 20 years ago," the British journalist George Monbiot wrote; no one paid it much attention, footsteps echoing through the halls "once thronged by multitudes." Since I wrote one of the first books for a general audience about global warming way back in 1989, and since I've spent the intervening decades working ineffectively to slow that warming, I can say with some confidence that we're losing the fight, badly and quickly – losing it because, most of all, we remain in denial about the peril that human civilization is in.

When we think about global warming at all, the arguments tend to be ideological, theological and economic. But to grasp the seriousness of our predicament, you just need to do a little math. For the past year, an easy and powerful bit of arithmetical analysis first published by financial analysts in the U.K. has been making the rounds of environmental conferences and journals, but it hasn't yet broken through to the larger public. This analysis upends most of the conventional political thinking about climate change. And it allows us to understand our precarious – our almost-but-not-quite-finally hopeless – position with three simple numbers. More

 

Global CO2 Emissions Continued to Increase in 2011, With Per Capita Emissions in China Reaching European Levels

ScienceDaily (July 19, 2012) — Global emissions of carbon dioxide (CO₂) -- the main cause of global warming -- increased by 3% last year, reaching an all-time high of 34 billion tonnes in 2011. In China, the world's most populous country, average emissions of CO₂ increased by 9% to 7.2 tonnes per capita. China is now within the range of 6 to 19 tonnes per capita emissions of the major industrialised countries. In the European Union, CO₂ emissions dropped by 3% to 7.5 tonnes per capita. The United States remains one of the largest emitters of CO₂, with 17.3 tones per capita, despite a decline due to the recession in 2008-2009, high oil prices and an increased share of natural gas.

These are the main findings of the annual report 'Trends in global CO₂ emissions', released July 19 by the European Commission's Joint Research Centre (JRC) and the Netherlands Environmental Assessment Agency (PBL).

Based on recent results from the Emissions Database for Global Atmospheric Research (EDGAR) and latest statistics on energy use and relevant activities such as gas flaring and cement production, the report shows that global CO₂ emissions continued to grow in 2011, despite reductions in OECD countries. Weak economic conditions, a mild winter, and energy savings stimulated by high oil prices led to a decrease of 3% in CO₂ emissions in the European Union and of 2% in both the United States and Japan. Emissions from OECD countries now account for only one third of global CO₂ emissions -- the same share as that of China and India combined, where emissions increased by 9% and 6% respectively in 2011. Economic growth in China led to significant increases in fossil fuel consumption driven by construction and infrastructure expansion. The growth in cement and steel production caused China's domestic coal consumption to increase by 9.7%. More

 

Iceberg breaks off from Greenland's Petermann Glacier

The Petermann Glacier in northern Greenland has calved an iceberg twice the size of Manhattan, scientists say.

Images from a Nasa satellite show the island breaking off a tongue of ice that extends at the end of the glacier.

In 2010 an ice island measuring 250 square km (100 square miles) broke off the same glacier.

Glaciers do calve icebergs naturally, but the extent of the changes to the Petermann Glacier in recent years has taken many experts by surprise.

“It is not a collapse but it is certainly a significant event,” Eric Rignot from Nasa said in a statement.

Some other observers have gone further. “It’s dramatic. It’s disturbing,” University of Delaware’s Andreas Muenchow told the Associated Press.

“We have data for 150 years and we see changes that we have not seen before,” Mr Muenchow added.

However, the calving is not expected have an impact on sea levels as the ice was already floating.

Icebergs from the Petermann Glacier sometimes reach the coast off Newfoundland in Canada, posing a danger to shipping and navigation, according to the Canadian Ice Service. More

 

Dr.James Hansen on Climate Change - TED

www.ted.com Top climate scientist James Hansen tells the story of his involvement in the science of and debate over global climate change. In doing so he outlines the overwhelming evidence that change is happening and why that makes him deeply worried about the future.TEDTalks is a daily video podcast of the best talks and performances from the TED Conference, where the world's leading thinkers and doers give the talk of their lives in 18 minutes. Featured speakers have included Al Gore on climate change, Philippe Starck on design, Jill Bolte Taylor on observing her own stroke, Nicholas Negroponte on One Laptop per Child, Jane Goodall on chimpanzees, Bill Gates on malaria and mosquitoes, Pattie Maes on the "Sixth Sense" wearable tech, and "Lost" producer JJ Abrams on the allure of mystery. TED stands for Technology, Entertainment, Design, and TEDTalks cover these topics as well as science, business, development and the arts. Closed captions and translated subtitles in a variety of languages are now available on TED.com, at http If you have questions or comments about this or other TED videos, please go to support.ted.com

Southern Russia hit by devastating flooding

In the worst natural disaster in a decade, severe floods have hit southern Russia, killing at least 150 people and forcing thousands from their homes. The rising waters came when a torrential downpour brought a month's worth of rain to the Krasnodar region in just a few hours. Black Sea ports have been closed by the flash flood and landslides. Al Jazeera's Andrew Simmons reports.

Is this climate change? Have we passed a tipping point? Should we be waking up to the idea that we have a global crisis on our hands? Editor

Japanese ordered to evacuate flood-hit Island

Heavy rain and floods kill at least 20 in southwestern Japan as tens of thousands ordered to evacuate their homes on the island of Kyushu. Al Jazeera's Bhanu Bhatnagar reports.

Is this climate change? Have we passed a tipping point? Should we be waking up to the idea that we have a global crisis on our hands? Editor

Global warming in our backyard

It's not just about the polar bears anymore. There was a time when the conversation about global warming was dominated by news about the Arctic, where its effects are the most easily visible to the lay public. The narrative involved shrinking glaciers and the ferocious white bears that live part of their lives on drifting ice floes that now are melting.

But polar bears are far away and ice is just, well, ice. So it would be a good idea for the public — and especially Southern Californians — to pay rapt attention to several reports published within the last couple of weeks that bring the reality of climate change from the polar ice caps to our backyard.

A climate change study at UCLA predicted big increases in the number of very hot days in the inland areas of Los Angeles County. Starting in about three decades, the report said, the number of days with temperatures above 95 is likely to quadruple in the San Fernando Valley, for example. The result will be more allergies among residents, bigger populations of some insect pests and worsening wildfires.

But don't get smug if you live along the coast. The UCLA study was followed a few days later by a National Research Council report predicting that rises in the sea level will be more dramatic along the California coast than the global average, with a rise of up to a foot in 20 years and possibly more than 5 feet by the end of the century. That's even worse than the scenario described the same week in a U.S. Geological Survey report that found sea levels already arerising more quickly along the East Coast from Massachusetts to North Carolina than they are globally. This sets the stage for catastrophic flooding, destruction of valuable buildings, costly damage to ports and even some airports, inundation of low-lying towns unless adequate sea walls are built, and erosion of coastal cliffs and beaches. More


 

Storm-hit US states declare emergencies: Climate Change Anyone?

States of emergency have now been declared in four states and the US capital after violent storms cut a swathe through the east of the country.

Thirteen deaths have been linked to the sudden storms, which, packing hurricane-strength winds, uprooted trees and downed power lines.

Amid an intense heatwave, three million people were left without power.

Power companies are warning that some may not have electricity restored for up to a week.

Officials have warned that the heatwave - compounded by the loss of air conditioning due to power outages - could threaten the very young, old and sick.

In Bradley county, eastern Tennessee, the high temperature has been blamed for the deaths of two brothers, age three and five, who were playing outside in 105F (40.6C) heat, Reuters news agency reports.

‘Dangerous’

Maryland, West Virginia, Virginia, Ohio and the District of Columbia have all now declared states of emergency.

Virginia Gov Bob McDonnell said the state - where six people died from the storms - had had its largest non-hurricane power outage in history.

“This is a very dangerous situation,” he said, according to Associated Press. More

 

What Would A Real Transition To A Sustainable Society Look Like?

Climate scientists are clear that modern human societies are changing the atmosphere of the planet, mainly by clearing forests, grasslands, wetlands, and other natural ecosystems for the purposes of development and logging and by burning fossil fuels such as coal, oil, and natural gas. These activities are releasing greenhouse gases and destroying natural greenhouse gas reservoirs. The result of all this activity is that the Earth is growing steadily warmer, year after year, and this is causing problems all over the world.

That additional heat is powering up weather systems and altering global flows of energy. Storms are more powerful and frequent than in the past. Drought, wildfires, tornadoes, floods, and other weather patterns are becoming increasingly unpredictable and dangerous. “Freak” events like the disastrous heat wave in Russia in 2011 are becoming more common. Annual deaths ascribed to climate change were estimated in a 2002 study to be 150,000 per year at that time, using what the authors called an “extremely conservative” methodology.

we need 100% cuts by 2050 to avert 2°C warming.

Every year representatives from governments around the world gather to discuss the problem of global warming as part of the United Nations Framework Convention on Climate Change, a 1994 treaty which has been signed by 194 nations. In 2012, the 17th annual meeting was held in Durban, South Africa. The stated goal of these meetings has been to limit global warming to 2° Celsius – about 3.5° Fahrenheit over average pre-industrial temperature. This is the maximum level of warming that has been labeled as safe by the Intergovernmental Panel on Climate Change (IPCC) – the United Nations scientific advising body on the matter.

Warming beyond this level is not safe because it threatens to accelerate due to “tipping points” in the global climate. These tipping points refer to a specific time at which a natural system, after being stressed by global warming, “flips” into a different state and begins to release greenhouse gases in a self-sustaining reaction instead of being a carbon dioxide ‘sink’. James Hansen and other climate scientists have issued dire warnings about this possibility. In fact, Hansen and other scientists have recently revised their assertions that limiting warming to 2°C will prevent climate tipping points. They, and many other climate scientists, believe now that warming must be limited to 1°C to avoid these catastrophic feedbacks, which are already beginning to take effect.

“With the current global warming of ~0.8°C evidence of slow feedbacks is beginning to appear,” Hansen wrote in 2011.

These “slow feedbacks” include processes like ice sheet melt and the release of methane from thawing Arctic permafrost and warming shallow oceans, and threaten to rapidly increase the effects of global warming if climate tipping points are exceeded. Their effects are rarely included in climate models and policy, and are a major reason why some scientists are concerned that estimates and forecasts have been underestimating the speed and severity of climate change.

“There’s evidence that climate sensitivity [to greenhouse gases] may be quite a bit higher than what the models are suggesting,” said Ken Caldeira, senior scientist at the Carnegie Institute for Science at Stanford University.

That is why many scientists and policy analysts are calling for greater emissions cuts than what has been proposed in international negotiations. So what is necessary to avoid runaway global warming? More