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Archive by date: December 2008

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Contrail climate effects questioned

contrailfigure.jpgIt was an irresistible factoid, widely covered and still found all over the web: in the three days after the September 11 terrorist attacks, when all commercial air traffic was banned from American skies, the average daily temperature range over the continental US got a sudden, substantial stretch (see chart).

The disappearance of jet condensation trails, or contrails, had unmasked their remarkable effects, researchers suggested (Nature News, subscription). Lack of contrails seemed to widen the gap between the lowest overnight temperatures and the daytime highs.

But this may be a mere coincidence, not evidence of aviation impacts, according to a series of studies since then. These doubts have gotten little if any press, though climatologists seem to be listening - the latest paper made Geophysical Research Letters’ top five downloads last week. The study (subscription) gets a story today in Nature News.

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Roundup of roundups, 2008

While we wait for Stoat’s response to our 2008 climate science year-in-review, here are some of the annual roundups popping up elsewhere.

First, the science: the most thorough state-of-the-Earth report is on Earthbeat Radio, where Andrew Revkin and Joe Romm sum up trends in temperatures (more on RealClimate), receding sea ice (one of Nature's top science stories this year), and other climate impacts.

“Change” was the word of the year, says Chris Tobias at Celsias, and we’re not just talking climate. It was the inescapable mantra behind Barack Obama’s victory in the US election - 2008’s number-one ‘green story’, according to both Time and Grist. (Link-clickers will note that Time’s list is almost absolutely America-centric. For the UK equivalent, check the Telegraph, which posits that “The whole year has been building up to the Climate Change Bill”.)

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Climate science in 2008

In the latest issue of Nature Reports Climate Change, we have a round-up by Amanda Leigh Mascarelli of some of the major breakthroughs in climate science in 2008. This is a just a pick of the top five; there are of course others we could have mentioned. Also listed are those issues where large gaps remain in our knowledge, such as how fast Greenland is melting, or on which agreement has yet to be reached, such as where to stabilize atmospheric greenhouse gas concentrations.

All illustrated with a cartoon by Marc Roberts:

NF-ALM image 2.jpg


Please share others with us in the comments.

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AGU 2008: Asteroid impacts and climate change: which is the greater threat?

What do Boston, London, New York, Frankfurt, San Francisco, and Paris have in common? They have all been destroyed by asteroid impacts—in the movies. The death toll was enormous in every case. Understandably, people are worried that such a catastrophe might actually occur within their lifetime.

Actually, says climate scientist Mark B. Boslough, “if you’re going to stay up late at night worrying about something, worry about climate.” Boslough, a researcher at the Sandia National Laboratories in Albuquerque, New Mexico, US, says, “you are much more likely to die from climate change than from an asteroid impact by a factor of something like a thousand.” He presented his findings at the Fall Meeting of the American Geophysical Union in San Francisco, California.

Boslough cannot put a precise number on that ratio, because climate science is still replete with gaps in the relevant data. He is much more confident about the asteroid threat, though. He says that there is no evidence that anyone has died from an asteroid or meteorite impact—ever. He does not make a distinction between asteroids and meteors, saying the latter are basically fragments of the former and there is no size boundary to distinguish one from the other.

Looking at worst case scenarios for asteroid impacts and climate change over the next 100 years, Boslough estimates that the largest asteroid to impact Earth would be around 50 metres in diameter. It would explode in the atmosphere and not make an impact crater, he says, and it would kill no one. Asteroids larger than 50 metres across and likely to cross Earth’s orbit are rare, and the larger they are, the rarer they are. They are also well tracked. Smaller ones are more numerous, but even less likely to cause death and destruction on Earth.

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Obama’s key science appointments

US President-elect Barack Obama has selected two key advocates for action on climate change to serve in his administration.

The appointments of physicist John Holdren of Harvard University as White House science advisor and marine biologist Jane Lubchenco of Oregon State University as the first female head of the National Oceanic and Atmospheric Administration are expected to be announced tomorrow, according to Juliet Eilperin and Joel Achenbach of the Washington Post.

Following from the appointment last week of Steven Chu of the Lawrence Berkeley National Laboratory as Energy Secretary, the selections bring high hopes for strong national action on curbing greenhouse gas emissions.

Over on Dot Earth, Andy Revkin has the lowdown on the appointees, both of whom have received MacArthur Foundation “genius” grants.

Lubchenco has been a leading voice on marine conservation issues in recent decades. Holdren has been consistent in calling for tough action on climate change but has had a bugbear with the term itself, which he believes is a misnomer. Instead he would rather ‘global climate disruption’; I wonder if we’ll hear more of that in the future?

Olive Heffernan

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AGU 2008: And the winner is ... Wind!

Cross-posted from In the Field

This according to Stanford University researcher Mark Jacobson, who has compared various energy technologies in terms of not only greenhouse gas emissions but also conventional pollutants, land use, water resources and more. Speaking after a news conference here, Jacobson said he is trying to provide a more holistic analysis of the various energy options. "There's a lot of misinformation out there," he said.

A few of the key results follow:

Life cycle emissions -- Wind and solar thermal come out on top; tidal, wave and hydro all beat out solar photovoltaics, geothermal and nuclear, thanks to energy spent on equipment and installation; coal was the big loser, even with carbon sequestration (CCS), thanks to energy spent on mining and transport.

Mortalities due to air pollution from US vehicles -- For gasoline, projected deaths drop from 20,000 to 15,000 annually in 2020 due to improved technology and air quality standards. That figure would remain steady or perhaps even rise if ethanol (corn or otherwise) made up 85 percent of the transport fuels. Assuming electric transport takes off, wind reduces mortalities to almost zero, although the full suite of renewables fared almost as well. Coal with CCS would cut mortalities by upward of two-thirds. Nuclear falls between coal and renewables (assuming non-proliferation regimes hold and there aren't any explosions).

Footprint required to power US vehicle fleet -- Accounting for the base of the turbine alone (not roads), wind could power the entire vehicle fleet using less than 3 square kilometers of land. Corn ethanol and concentrated solar power are the big losers, with each requiring a chunk of land that is larger (and perhaps significantly larger) than the state of California.

Water usage -- Wind, solar photovoltaic, geothermal, tidal and wave all come in around zero; coal, nuclear and concentrated solar do well; hydropower gets a poor rating, thanks to evaporation rates from reservoirs (Jacobson divvies up the losses among energy and other uses). But the clear loser is ethanol, whether the source is corn or something else.

Jeff Tollefson

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AGU 2008: Uncertainty and overshooting 2°C

As speculation grows that agreeing a global deal on climate change may extend well beyond the 2009 deadline, the risk of overshooting the EU’s target to limit the increase in global temperature to 2°C over pre-industrial levels looks increasingly likely.

The target is based on scientific evidence that below a 2°C increase, some of the worst impacts of climate change would be avoided. In its fourth assessment report, the IPCC calculated that limiting warming to that extent would mean stabilizing atmospheric concentrations at roughly 450 ppm CO2-equivalents.

But it’s clear at this year’s AGU that much uncertainty, and disagreement, remains on whether 2°C is an appropriate target and on the atmospheric greenhouse gas concentrations that equate to a given amount of warming.

Speaking here yesterday, James Hansen, director of the NASA Goddard Institute of Space Studies, called for atmospheric greenhouse gas concentrations to be restricted to 350ppm. Hansen also recently advised the UK government’s Environmental Audit Committee that the 2°C target should be revised to a 1°C increase above pre-industrial levels. Meanwhile, many of the scientists presenting work here are wrangling with whether stabilizing at 450ppm – or higher – is economically and technologically feasible.

The debate on where to stabilize is largely due to what Stanford’s Stephen Schneider dubs ‘double-barrelled uncertainty’ a term that encompasses the unknown factor in how far we can reduce emissions and in how the climate system will respond to any reductions we make.

The latter uncertainty – that inherent in the system – is measured in terms of climate sensitivity i.e. how much warming would occur if atmospheric GHG concentrations were doubled. This is currently estimated at 2-4.5°C, but Schneider said here on Tuesday that it’s more important for society to know the uncertainty around this range i.e. the chance that we will see a much larger degree of warming than anticipated for various atmospheric concentrations.

Given the fact that a massive reduction in emissions in the coming decades it is very unlikely, he says, and the fact that we could overshoot our target anyway, we need to take a serious look at the consequences. Schneider suggests that the IPCC should take it on board to evaluate climate scenarios for overshooting to 600 ppm and then subsequently reducing atmospheric concentrations to say 500ppm or 450ppm.

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AGU 2008: Peak fuel reserves

Whether peak oil is good news for the climate ultimately depends on what replaces oil as our staple fuel source. It will be unsurprising to most that replacing dwindling oil reserves with coal would do little to solve the climate problem, but how much coal remains is also highly uncertain, according to Prof. David Rutledge of Caltech, who spoke to the press at the AGU this morning.

Andy Dessler of Texas A&M touched on this in a guest commentary posted here last month. In short, Dessler called for a global IPCC-like assessment of our fossil fuel reserves, pointing to a new analysis by Rutledge that shows the world’s available coal reserves are far lower than traditional estimates would suggest. If Rutledge’s estimates are correct, combustion of all remaining conventional oil, gas, and coal reserves would produce an atmospheric concentration of carbon dioxide of approximately 470 ppmv in 2100, near the stabilization target that many climatologists argue we must achieve to avoid the worst impacts of climate change.

While Rutledge’s estimates suggest that the worst-case scenarios of the IPCC may be unachievable, Ken Caldeira of Washington’s Carnegie Institute had a more sobering message. Caldeira and colleagues used a climate and carbon cycle model to look at how running out of oil could affect future climate scenarios. Their analysis showed that if we replaced oil with liquefied coal fuel promptly, we would reach 2°C above pre-industrial temperatures in 2042 instead of 2045. Replacing oil with renewables, however, would delay reaching 2°C above pre-industrial temperatures by 11 years. This is simply because per coal emits more carbon dioxide per unit of energy than oil; add to that the energy costs associated with conversion of coal to liquid fuels, a likely option if we run out of oil.

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A done deal, finally

After eleven months of legislative work, the European Parliament gave its backing today to the European Union’s (EU) climate change package which aims to ensure that the EU will achieve its self-set climate targets by 2020: a 20% reduction in greenhouse gas emissions relative to 1990 levels, a 20% improvement in energy efficiency, and a 20% share for renewables in the EU energy mix.

EU heads of states, who had hammered out the agreement last week, called the legislation "historic". But critics say the reduction targets are less ambitious than they appear, basically a bluff. What bothers environmentalist most are the many far-reaching concessions to power plants and other emission-intensive industries participating in the EU’s mandatory emissions trading system.

More about this is in my story over on Nature News.

Quirin Schiermeier

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2008 cooling, but the heat is on

The year 2008 was likely the coolest year of the current decade, but it was still the tenth warmest year on record since instrumental climate records began in 1850.

The average global sea-surface and land-surface air temperature from December 2007 to November 2008 was 14.3 °C, the World Meteorological Organization (WMO) has announced. This is slightly lower than for all previous years of the ‘naughties’, but still some 0.3 °C above the 1961-1990 annual average. The warmest year on record is 1998, with an average global temperature just above 14.5 °C.


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Left: Global map of surface temperature anomalies in degrees Celsius for the 2008 meteorological year. Right: Annual-mean global-mean anomalies, except 2008, which is the 11-month (Jan-Nov) mean anomaly. Credit: NASA Goddard Institute for Space Studies.

When calculating global average temperatures, climatologists prefer the meteorological year, from December through November, as it is easier to split it into actual seasons than is the calendar year.

The WMO temperature analysis is based on land-based weather stations in 188 countries, complemented by measurements from ships, buoys and satellites. NASA’s Goddard Institute for Space Studies and the UK Met Office, which both contributed their own datasets to the WMO analysis, independently arrive at very similar values.


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AGU 2008: On the home front

I hadn’t anticipated quite so much rain during the AGU’s Fall conference in San Francisco, but apparently this exact week is, on average, the city’s wettest of the year. Or so I heard at today’s session on how the region is likely to be impacted by climate change.

California has been long recognized as a leader on climate policy, both on the home front and even internationally. It passed its first climate bill twenty years ago and just last week, the state adopted the nation's most sweeping climate action plan to date, pledging to cut its greenhouse gas emissions by 15% by 2020.

A close look at how the region is expected to fare under various warming scenarios makes its leadership in this arena look a lot like common sense. While temperatures in California are expected to increase in line with global averages, more worrying for the state is the projected water shortages, according to Dan Cayan of the Scripps Institution of Oceanography in La Jolla, San Diego, who spoke at AGU today. California faces the possibility of a 10% decrease in precipitation over the course of the century and could concurrently lose half of its late spring snowmelt. That's bad news for a region that is already heavily reliant on external water sources.

Sea-level rise will also be part of the equation, especially for the numerous coastal properties with little protection, said Peter Gleick, president of the Oakland, California –based Pacific Institute. Should those in the interior think they’re better off, though, climate models show that inland regions will warm more rapidly than the coast and will likely be more populated in the future owing to lack of available living space on the coast.

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AGU 2008: Screening of ‘Crude’

This evening at AGU there was a special screening of Crude, a film about our love affair with petroleum– oil that is, black gold, Texas tea.

The documentary won Richard Smith of the Australian Broadcasting Corporation this year’s AGU Walter Sullivan Award for Excellence in Science Journalism, a prestigious prize for outstanding reporting that makes geophysical science accessible and interesting to the general public. In Crude, Smith explores the geological formation of oil, its discovery and ascendancy in society and the potentially catastrophic consequences of our absolute dependence on it. Ironically, the very conditions under which oil was originally formed – a greenhouse world with elevated CO2 levels – are exactly those that its consumption could return us to.

Smith does an excellent job of conveying how oil, formed from the compressed remains of tiny plants and animals, could cause the demise of the most sophisticated species to have ever lived. And although we may be running out of the stuff, its pervasiveness in society means that weaning ourselves off oil will be no mean feat. There are no clear estimates of exactly how much oil is left in the ground, but the overwhelming message in Crude is that there are easily enough fossil fuel reserves to radically alter our climate should we use them all.

Overall, well worth a watch…

Olive Heffernan

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AGU 2008: conference kicks off

Over the past 24 hours, some 15,000 earth scientists descended on San Francisco for the annual Fall conference of the American Geophysical Union. Delegates were a dead give away at the airport and on the BART yesterday with their large poster tubes in tow. It’s my first AGU and it could be the jet lag, but I’m feeling slightly overwhelmed by the sheer size and number of parallel sessions; at any given time I could be at one of at least four climate-related talks and invariably find myself wondering why the session next door is receiving louder applause.

A number of talks today focused on the need for climate science to become less curiosity driven and more specific to the needs of stakeholders such as local authorities and natural resource managers.

This is a topic that’s been getting a lot of attention recently. Earlier this year, for example, scientists called for a billion dollar investment in climate computing facilities to enable regional scale climate predictions on decadal time scales. At a press conference this morning, scientists including Jonathan Overpeck from the University of Arizona and Jack Fellows of UCAR highlighted the importance of partnerships between universities and decision makers in enabling states and regions to plan for climate change.

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Forecasting the future of hurricanes

The world's most advanced simulation of extreme weather on a warming Earth completed its first run last Friday - though the data won't be fully digested into human-readable format until spring. Yesterday I talked to meteorologist Greg Holland, co-leader of the study, at the Willis insurance company's London office - whose cycle racks, I can report, are tucked away discreetly across the street from its intimidatingly curved and purple-lit lobby.

Willis's research arm funded the work, along with the offshore oil industry, the US Department of Energy and the US National Center for Atmospheric Research (NCAR), where Holland is based. They all want to know how climate change will alter hurricane patterns in the Atlantic. At the request of several US state governors, the project is also looking at rainfall over the Rockies and winds in the Great Plains. Says Holland:

I'm not going to forecast a squall line through New York in 2050. But what we want to do is be able to say: "What are the statistics of squall lines going through New York in 2050?" or "What are the statistics of hurricanes coming into Miami in 2050?"

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The latest on the Southern Ocean sink

At a conference this week, marine scientist Andrew Lenton of the Université Pierre et Marie Curie presented a new model that sketches out a beautiful causal chain: from the ozone hole over Antarctica, to rising southern winds, to stronger Southern Ocean currents, to more deep-sea stored carbon arriving at the sea surface.

The simulation, which Lenton reported at a meeting of the CARBOOCEAN research consortium in Dourdan, France, is the first coupled carbon-climate model to account for what biogeochemists have recently seen in the Antarctic waters. As I noted last month, observations (Science, subscription required) suggest the Southern Ocean's considerable carbon dioxide sink isn't soaking up as much of the gas as climate modellers expected, perhaps because there's already too much dissolved in surface waters. That means more climate-warming carbon accumulates in the atmosphere.

By bringing in stratospheric ozone damage, which earlier studies had excluded, the model of Lenton and his colleagues manages to reproduce the recent disappointing sink - a step toward resetting future projections.

I reported this story for Nature News this week, and it posed two problems. One, I didn't get to go to France - I heard it all here at my desk. Two, an issue flagged up in my earlier post also dogs Lenton's research. One of the links in the chain - between speedy winds and more powerful Southern Ocean circulation - isn't supported by oceanographic data (Nature Geoscience, subscription required).

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American Geophysical Union 2008

I'll be heading to the 2008 AGU Fall meeting this weekend.

Join me here next week for daily climate coverage from the largest annual earth science event, taking place this year in San Francisco from December 15-19.

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Progress predictably slow in Poznan

The latest UN negotiations on a global climate deal taking place in Poznan, Poland are failing to make fast enough progress to secure a treaty by next December in Copenhagen, according to various media reports.

Reuters reported yesterday that even the eternally buoyant UN climate chief Yvo de Boer believes that it will only be possible to nail "the key political issues" by this deadline. But he still maintains that an overarching treaty must be signed with specific greenhouse gas reduction targets for developed nations, writes Jeff Tollefson on In the Field.

Over on the Guardian’s ‘Comment is Free’ Jonathan Porritt, chairman of the UK Sustainable Development Commission, says it’s time to press the panic button. He points out that the UN negotiations are acting as though the 2007 IPCC report still reflects the latest science, when in fact we’ve had three years of peer-reviewed research since – and a lot of it from the frontline of the eco-systems most directly affected by climate change.

His advice for Senator John Kerry, who is reportedly acting as incoming US President Barack Obama’s ‘eyes and ears’ in Poznan:

Suggest on behalf of the US Senate that the IPCC should be reconvened as early as possible in 2009 to undertake an emergency review of all the science that has emerged since 2005. It should be asked to report to the UN by the end of June, giving just enough time to inform the debate about appropriate policy responses before the Copenhagen conference in November.

In the meantime, Obama has met with Al Gore to discuss the state of the climate and has promised to treat climate change as a matter of urgency and national security.

Olive Heffernan

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Frozen tundra bursting with gas

Tundra 2 ISTOCKPHOTO _ RYERSON CLARK.jpgThe Arctic tundra is letting loose a large and unexpected burst of methane in the autumn, finds a new study out in Nature today. Unlike the oceanic methane bubbles that made headlines a few months ago, this isn’t suggested to be an effect of climate change – it’s the formerly overlooked (or rather, never-looked-for) tail of a natural seasonal cycle. But it’s important for understanding natural methane-emitting processes that may be affected by future warming. I’ve got the full story over on Nature News.

The newly discovered surge of greenhouse gas is brought to you by International Polar Year. Thanks to that research push, a team led by biogeochemist Torben Christensen of Lund University, Sweden, got a two-month extension on the usual field season at a monitoring station in northeast Greenland. Scientists have been measuring methane emissions from far-northern tundra during the growing season for decades, but it had been assumed that once methane levels taper off in late summer, they stay at next to nil over the freezing fall and winter.

Far from it. Emissions actually spike as the ground starts to frost over, the researchers found, and cumulative emissions during the freeze-in are about equal to those in summer. If all wet meadow tundras release a similar methane burst, they calculate, about 4 million tonnes may be emitted each winter. That’s not enough to affect estimates of the total annual methane emissions from tundra (30 to 100 million tonnes), but it’s just right to account for an observed autumn surge in atmospheric methane over the frozen north that had previously gone unexplained.

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Pole positions

The latest round of UN climate talks kicked off in Poznan, Poland yesterday. Jeff Tollefson has a nice round-up over on The Great Beyond of how the first day of the conference went down - unsurprisingly, with world leaders calling for immediate action. [Update: All Poznan-related posts from Jeff T, who will be at the talks next week, can be found here].

As I mentioned here last week, it’s generally accepted that the current negotiations will not address the really crucial issues of a post-Kyoto climate deal, namely how far to reduce emissions and how to do so equitably. So much as for fighting the urge to postpone everything until Copenhagen.

But what can be expected to emerge from Poznan is greater clarity on how various players will position themselves for next year's endgame, a point that I elaborate on in my latest editorial on Nature Reports Climate Change.

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There’s life in the cold sink yet

In what could be good news for the Earth’s ability to mitigate warming, scientists have reported that deep convection has resumed in the North Atlantic after more than a decade of little activity.

Also known as overturning, deep convection transports cold water to depths of more than 1000m, bringing carbon dioxide with it and keeping the greenhouse gas out the atmosphere for centuries. It's also partly reponsible for maintaining the global climate system, as we know it - at high latitudes, deep convection forms a mass of cold water that drives the Atlantic oceanic conveyor belt and carries warm water northwards.

In the past decade, however, the process of deep convection has been sluggish, causing some to speculate that warming of surface waters due to climate change is already taking its toll on ocean circulation.

Its recent return has now been independently reported by two groups of scientists; the first team, led by Kjetil Våge of the Woods Hole Oceanographic Institution in Massachusetts, publish their data in the latest issue of Nature Geoscience. Igor Yashayaev and John Loder of the Bedford Institute of Oceanography in Nova Scotia, Canada, have a forthcoming paper in Geophysical Research Letters.

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James Jones's poor energy policy

Cross-posted from Heliophage

I’ve just been reading some advice for Obama (pdf) from the Institute for 21st century energy, an organism of the US Chamber of Commerce. It's pretty standard (and depressing) stuff of the “must be win-win, mustn’t hurt business, do nothing until there’s an international agreement” sort, sometimes spot on in its prescriptions but overall tainted by a failure to really engage with the climate issues. So far so standard, but it takes new salience from the fact that the person whose signature is at the top is General James L. Jones. Jones, it was announced yesterday and widely leaked before that, will be the new National Security Adviser. The shocker here – and it really is quite shocking – is that the executive summary of this document makes no mention of climate as a factor in energy policy and planning at all.

In the body there is climate stuff, but it's mostly not good; Brad Johnson at the Wonk Room gets into the details

The institute deserves credit for having its first strategic priority be energy efficiency, but its other priorities and specific policy suggestions are wrongheaded and reflect the U.S. Chamber of Commerce’s typical anti-regulatory, pro-pollution industry agenda. Jones’ Transition Plan calls for billions of dollars in subsidies for the nuclear and coal industry, a dramatic expansion in domestic oil and natural gas drilling into protected areas, and massive new energy industry tax breaks and loopholes.

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