More than half a century after scientist Rachel Carson warned of the dangers of overusing the pesticide DDT, conservative groups continue to vilify her and blame her for a resurgence of malaria. But DDT is still used in many countries where malaria now rages.
Weaning the U.S. economy off fossil fuels will involve the wide deployment of utility-scale solar power. But for that to happen, the environmental community must resolve its conflict between clean energy advocates and those who regard solar farms as blights on the landscape.
Many hydroelectric dams produce modest amounts of power yet do enormous damage to rivers and fish populations. Why not take down these aging structures, build solar farms in the drained reservoirs, and restore the natural ecology of the rivers?
The record-breaking drought in California is not chiefly the result of low precipitation. Three factors – rising temperatures, groundwater depletion, and a shrinking Colorado River – mean the most populous U.S. state will face decades of water shortages and must adapt.
It’s not just the potential for a catastrophic spill that makes President Obama’s proposal to open Atlantic Ocean waters to oil exploration such a bad idea. What’s worse is the cumulative impact on coastal ecosystems that an active oil industry would bring.
After years of frustration and failure, a more flexible approach to reaching an international strategy on climate action is emerging – and it could finally lead to a meaningful agreement at climate talks in Paris later this year.
The U.S. Congress is preparing to vote on expediting the Keystone XL pipeline. But plummeting oil prices and opposition to other proposed pipelines for tar sands oil are upending the rationale for this controversial project.
After decades of sobering news, a prominent conservationist says he is finally finding reason to be optimistic about the future of tropical forests. Consumer pressure on international corporations and new monitoring technology, he says, are helping turn the tide in efforts to save forests from Brazil to Indonesia.
A grim new census of the world’s dwindling wildlife populations should force us to confront a troubling question: Are humans capable of acting in ways that help other species at a cost to themselves?
The international community should stop chasing the chimera of a binding treaty to limit CO2 emissions. Instead, it should pursue an approach that encourages countries to engage in a “race to the top” in low-carbon energy solutions.
A new strategy of granting animals “personhood” under the law is being advanced by some in academia and the animal rights movement. But this approach fails to address the fundamental truth that all species have an equal right to their own existence.
One year after Hurricane Sandy devastated parts of the U.S. East Coast, the government is spending billions to replenish beaches that will only be swallowed again by rising seas and future storms. It’s time to develop coastal policies that take into account new climate realities.
Every U.S. president since Ronald Reagan has backed programs to develop alternative transportation fuels. But there are better ways to foster energy independence and reduce greenhouse gas emissions than using subsidies and mandates to promote politically favored fuels.
The U.S. Fish and Wildlife Service has stirred controversy with its proposal to remove endangered species protection for wolves, noting the animals’ strong comeback in the northern Rockies and the Midwest. It’s the latest in the long, contentious saga of wolf recovery in the U.S.
A marine biologist traveled to southwestern Alaska in search of ocean trash that had washed up along a magnificent coast rich in fish, birds, and other wildlife. He and his colleagues found plenty of trash – as much as a ton of garbage per mile on some beaches.
New UN projections forecast that world population will hit nearly 11 billion people by 2100, an unsettling prospect that reflects a collective failure to provide women around the world with safe, effective ways to avoid pregnancies they don't intend or want.
Scientists are predicting that warming conditions will bring more frequent and more intense extreme weather events. Their warnings hit home in densely populated Bangladesh, which historically has been hit by devastating sea surges and cyclones.
An international agreement to study how to redress developing nations for damages from climate change illustrates how ineffective climate diplomacy has been over the last two decades. But this move may pave the way for future court suits against polluting countries and companies.
As part of the sorely-needed aid package to help victims of Hurricane Sandy, Congress is also considering spending billions on ill-advised and environmentally damaging beach and coastal rebuilding projects that ignore the looming threats of rising seas and intensifying storms.
As the United States experiences a glut of natural gas, a host of facilities are being proposed that would convert gas to a liquid and export it. But before embracing a gas export boom, the nation should carefully weigh the implications for both the economy and the environment.
Climate change received scant attention in the election campaign. But with public concern about global warming growing in the wake of Hurricane Sandy, President Obama has an unprecedented opportunity to take bold action on climate and clean energy.
Given the failure of international climate negotiations, a tax on carbon consumption is the most effective way of lowering CO2 emissions. If nations are serious about addressing climate change, then they must pay for the carbon pollution caused by what they consume.
On issues ranging from genetically modified crops to nuclear power, environmentalists are increasingly refusing to listen to scientific arguments that challenge standard green positions. This approach risks weakening the environmental movement and empowering climate contrarians.
This summer has seen record heat waves and wildfires in the U.S, the worst flooding in Beijing’s modern history, and droughts that devastated the U.S. corn crop and led India to set up “refugee camps” for livestock. These extreme events were not freak occurrences — this is how the earth works now.
The boom in natural gas production has undeniable benefits for the United States. But two policy analysts argue that embracing a monolithic energy future dominated by gas will mean the loss of a golden opportunity: Leveraging cheap, abundant gas to create a sustainable future based on renewable power.
When Silent Spring was published in 1962, author Rachel Carson was subjected to vicious personal assaults that had nothing do with the science or the merits of pesticide use. Those attacks find a troubling parallel today in the campaigns against climate scientists who point to evidence of a rapidly warming world.
The North Carolina Senate has approved legislation that would prohibit the state from considering projected sea level increases in its coastal management strategy. But a scientist involved in the debate argues that ignoring these projections will wind up costing North Carolina — and the rest of the U.S. — far more.
The Clean Water Act of 1972, one of the boldest environmental laws ever enacted, turns 40 this year, with an impressive record of cleaning up America's waterways. But from New York Harbor to Alaska’s Bristol Bay, key challenges remain.
Climate scientist Michael Mann, who has faced years of attacks from climate-change skeptics, explains why he believes bad-faith assaults on science have no place in a functioning democracy and why the truth about global warming will inevitably gain wide acceptance.
Large-scale industrial agriculture depends on engineering the land to ensure the absence of natural diversity. But as the recent emergence of herbicide-tolerant weeds on U.S. farms has shown, nature ultimately finds a way to subvert uniformity and assert itself.
A physicist argues that if we allow our overblown and often irrational fears of nuclear energy to block the building of a significant number of new nuclear plants, we will be choosing a far more perilous option: the intensified burning of planet-warming fossil fuels.
Innovative energy technologies are certainly essential if the world is to curb carbon emissions. But in response to a recent e360 article by the co-founders of the Breakthrough Institute, an economist argues we must also cap emissions or put a price on carbon in order to avoid the worst impacts of climate change.
Putting a price and a binding cap on carbon is not the panacea that many thought it to be. The real road to cutting U.S. emissions, two iconoclastic environmentalists argue, is for the government to help fund the development of cleaner alternatives that are better and cheaper than natural gas.
Twenty years ago, an historic environmental summit in Rio de Janeiro produced groundbreaking treaties and high hopes that pressing issues would be addressed. But as organizers prepare for the Rio+20 conference in June, there is little on the agenda to suggest any substantive action will be taken.
From Brazil to Borneo, new roads are being built into tropical forests at a dizzying pace, putting previously intact wilderness at risk. If we hope to preserve rainforests, a leading researcher says, new strategies must be adopted to limit the number of roads and reduce their impacts.
More than a billion people worldwide lack access to electricity. The best way to bring it to them — while reducing greenhouse gas emissions — is to launch a global initiative to provide solar panels and other forms of distributed renewable power to poor villages and neighborhoods.
The Australian government will begin imposing a tax on carbon emissions in mid-2012. But large giveaways to industry mean Australia’s scheme doesn’t go nearly far enough in reducing the nation’s CO2 emissions or providing economic stimulus.
Some U.S. politicians have been attacking environmental regulations, arguing that they hurt the economy and that the costs outweigh the benefits. But four decades of data refute that claim and show we need not choose between a clean environment and economic growth.
The global challenge of climate change poses a perfect moral storm — by failing to take action to rein in carbon emissions, the current generation is spreading the costs of its behavior far into the future. Why should people in the future pay to clean up our mess?
For environmentalists protesting the Keystone XL pipeline, the battle is about more than just transporting tar sands oil from Alberta. It’s about whether the United States — and the rest of the world — will finally come to its senses about global warming.
There are striking similarities between the current economic and ecological crises — both involve indulgent over-consumption and a failure to consider the impacts on future generations. But it’s not too late to look to new economic and environmental models and to dramatically change course.
With global population expected to surpass 7 billion people this year, the staggering impact on an overtaxed planet is becoming more and more evident. A two-pronged response is imperative: empower women to make their own decisions on childbearing and rein in our excessive consumption of resources.
Building bike paths alone will not get people out of their cars in the U.S. and onto bicycles. To create a thriving bike culture in America’s cities, people must begin to view bicycling as Europeans do — not just as a way of exercising, but as a serious form of urban mass transportation.
The idea of economic growth as an unquestioned force for good is ingrained in the American psyche. But a longtime environmental leader argues it’s time for the U.S. to reinvent its economy into one that focuses on sustaining communities, family life, and the natural world.
Despite soaring rhetoric and some promising proposals, President Obama is repeating the same mistakes that have doomed U.S. energy policy to failure for 40 years. Until Obama and Congress finally put a true price on the fossil fuels America consumes, the U.S. will continue its addiction to foreign oil and domestic coal.
On the anniversary of the Deepwater Horizon explosion, the worst fears about the long-term damage from the oil spill have not been realized. But the big challenge is more fundamental: repairing the harm from the dams, levees, and canals that are devastating the Mississippi Delta and the Louisiana coast.
Electric cars are finally coming to market in the U.S., but what is the future potential for this much-touted technology? A good way to find out would be to launch demonstration projects in selected U.S. cities to determine if, given incentives and the proper infrastructure, the public will truly embrace plug-in vehicles.
In recent months, several conservative governors have rejected federal funds to begin constructing high-speed rail lines in their states. But a high-speed rail advocate argues that such ideologically driven actions are folly, as other U.S. states and countries around the world are moving swiftly to embrace a technology that is essential for competitive 21st-century economies.
As agriculture and energy production have made strides toward becoming more sustainable, the world’s fisheries have lagged behind. But restoring our beleaguered oceans to health will require an emphasis on diversification and conservation — and a more sensible mix of fishing practices.
A decade ago, Nobel Prize-winning scientist Paul Crutzen first suggested we were living in the “Anthropocene,” a new geological epoch in which humans had altered the planet. Now, in an article for Yale Environment 360, Crutzen and a coauthor explain why adopting this term could help transform the perception of our role as stewards of the Earth.
The Cancun conference is being credited with keeping international climate talks alive. But the real potential for bringing emissions under control may lie in a Plan B, with nations acting on their own in moving toward a low-carbon economy.
With an aggressive campaign focused on advertising, lobbying, and political contributions, America’s coal industry has succeeded in beating back a challenge from environmentalists and clean-energy advocates. The dirty truth is that Big Coal is more powerful today than ever.
The sludge spill in Hungary dominated world news for days, as horrific images of red-mud rivers appeared nonstop on the Internet, newspaper front pages, and TV screens. Yet other environmental threats — less visible, but potentially more devastating — often go largely unnoticed.
Climate policies that require public sacrifice and limiting economic growth are doomed to failure. To succeed, policies to reduce emissions must promise real benefits and must help make clean energy cheaper.
How significant would it be if America’s 29 million small businesses increased their energy efficiency and reduced their emissions? Judging from the example of one California entrepreneur, the impact could be far greater than you might expect.
When officials gather for an international summit on biodiversity next month, they might look to remind the world why species matter to humans: for producing oxygen, finding new drugs, making agricultural crops more productive, and something far less tangible — a sense of wonder.
An activist caravan to bring one of Jimmy Carter’s solar panels back to the White House symbolizes the time that the U.S. has lost in developing new energy technologies – and the urgent need for taking action on climate.
LEED certification has emerged as the green standard of approval for new buildings in the United States. But the criteria used for determining the ratings largely ignore factors relating to human health, particularly the use of potentially toxic building materials.
Many energy experts contend natural gas is the ideal fuel as the world makes the transition to renewable energy. But since much of that gas will come from underground shale, potentially at high environmental cost, it would be far better to skip the natural gas phase and move straight to massive deployment of solar and wind power.
For years, free-market fundamentalists opposed to government regulation have sought to create doubt in the public’s mind about the dangers of smoking, acid rain, and ozone depletion. Now they have turned those same tactics on the issue of global warming and on climate scientists, with significant success.
As global warming intensifies, demands for human manipulation of the climate system are likely to grow. But carrying out geoengineering plans could prove daunting, as conflicts erupt over the unintended regional consequences of climate intervention and over who is entitled to deploy climate-altering technologies.
In response to the widening disaster in the Gulf of Mexico, government officials have approved a plan to intercept the oil by building a 45-mile sand berm. But scientists fear the project is a costly boondoggle that will inflict further environmental damage and do little to keep oil off the coast.
Flying dwarfs any other individual activity in terms of carbon emissions, yet more and more people are traveling by air. With no quick technological fix on the horizon, what alternatives — from high-speed trains to advanced videoconferencing — can cut back the amount we fly?
The chairman of the Intergovernmental Panel on Climate Change acknowledges it has been a rough few months for his organization. But, he argues, no amount of obfuscation and attacks by conspiracy theorists will alter the basic facts — global warming is real and intensifying.
This April marks the 40th anniversary of Earth Day, an event that has attracted millions to environmental causes. But winning passage of meaningful legislation on climate change requires more than slogans and green talk — it demands intense, determined political action.
In Africa and elsewhere, burgeoning population growth threatens to overwhelm already over-stretched food supply systems. But the next agricultural revolution needs to get local — and must start to see rising populations as potentially part of the solution.
Environmentalists have long sought to use the threat of catastrophic global warming to persuade the public to embrace a low-carbon economy. But recent events, including the tainting of some climate research, have shown the risks of trying to link energy policy to climate science.
Despite strong evidence that growing food crops to produce ethanol is harmful to the environment and the world’s poor, the Obama administration is backing subsidies and programs that will ensure that half of the U.S.’s corn crop will soon go to biofuel production. It’s time to recognize that biofuels are anything but green.
The obscenely profitable market for bluefin tuna in Japan has led to years of overfishing and left the world’s bluefin population badly depleted. A ban on the bluefin trade, if adopted at international talks this month, would go a long way toward giving this magnificent fish a chance to recover.
The U.S. Chamber of Commerce has been fighting climate-change legislation and is now opposing federal efforts to regulate CO2 emissions. Its actions stand in stark contrast to an earlier business group, which more than a century ago fought to create New York’s vast Adirondack Park.
As burgeoning human populations place greater pressure on wild areas, a strategy is emerging for preserving threatened lands and wildlife. Known as ‘rewilding,’ it involves expanding core wilderness areas, connecting them via corridors that allow humans and animals to co-exist, and protecting and reintroducing top predators.
The traditional parks model of closing off areas and keeping people out simply may not work in Africa, where human demands on the land are great. Instead, what’s needed is an approach that finds ways to enable people and animals to co-exist.
As governments, businesses, and homeowners plan for the future, they should assume that the world’s oceans will rise by at least two meters — roughly seven feet — this century. But far too few agencies or individuals are preparing for the inevitable increase in sea level that will take place as polar ice sheets melt.
Much was left undone in Copenhagen, and the many loopholes in the climate accord could lead to rising emissions. But the conference averted disaster by keeping the UN climate negotiations alive, and some expressed hope that the growth of renewable energy technology may ultimately save the day.
The Copenhagen summit turned out to be little more than a charade, as the major nations refused to make firm commitments or even engage in an honest discussion of the consequences of failing to act.
As the world weighs how to deal with warming, the idea of human manipulation of climate systems is gaining attention. Yet beyond the environmental and technical questions looms a more practical issue: How could governments really commit to supervising geoengineering schemes for centuries?
Governments from the developed world will never come up with enough money to help poorer nations adapt to global warming and implement renewable energy technologies. The solution may lie in using a modest allocation of government funds to spur private sector investment in green energy projects in Africa, Asia, and Latin America.
As the UN conference enters its second and decisive week, the calls for strong global action to deal with climate change do not appear to be penetrating inside Copenhagen’s Bella Center.
The way that climate scientists have handled the fallout from the leaking of hacked e-mails is a case study in how not to respond to a crisis. But it also points to the need for climate researchers to operate with greater transparency and to provide more open access to data.
Twelve years ago in Kyoto, the world was poised to act on a climate treaty but looked for a clear signal from the United States. Now, with the Copenhagen talks set to begin, the outcome once again hinges on what the U.S. is prepared to do.
Even as the climate science becomes more definitive, polls show that public concern in the United States about global warming has been declining. What will it take to rally Americans behind the need to take strong action on cutting carbon emissions?
Long a ubiquitous part of modern life, plastics are now in everything from diapers to water bottles to cell phones. But given the proven health threats of some plastics — as well as the enormous environmental costs — the time has come for the U.S. to pass a comprehensive plastics control law.
As the world warms, how different societies fare in dealing with rising seas and changing weather patterns will have as much to do with political, social, and economic factors as with a changing climate.
Green rankings in the U.S. don’t tell the full story about the places where the human footprint is lightest. If you really want the best environmental model, you need to look at the nation’s biggest — and greenest — metropolis: New York City.
Amid a growing call for reducing atmospheric concentrations of CO2 to 350 parts per million, a group of economists maintains that striving to meet that target is a smart investment — and the best insurance policy humanity could buy.
As the international community focuses on climate change as the great challenge of our era, it is ignoring another looming problem — the global crisis in land use. With agricultural practices already causing massive ecological impact, the world must now find new ways to feed its burgeoning population and launch a "Greener" Revolution.
It has been more than 30 years since a groundbreaking book predicted that if growth continued unchecked, the Earth’s ecological systems would be overwhelmed within a century. The latest study from an international team of scientists should serve as an eleventh-hour warning that cannot be ignored.
The average American produces three times the amount of CO2 emissions as a person in France. A U.S. journalist now living in Europe explains how she learned to love her clothesline and sweating in summer.
Introduced more than a decade ago, genetically modified crops are now planted on millions of acres throughout the world. But the fundamental questions about them remain — both about their safety and their long-term impact on global food security and the environment.
The U.S. can build all the wind turbines and solar arrays it wants, but until it does something about improving its outmoded electricity grid, renewable energy will never reach its potential. What we need is a new electricity transmission system, with the costs shared by all.
If a cap-and-trade bill passes Congress this year, it may include weak emissions targets and will likely need to be strengthened in the years to come. One way to guide future policy: create a Global Climate Change Index that could be used to track global warming’s impacts.
In the Yaak Valley of Montana, environmentalists have been talking to loggers, snowmobilers and other longtime opponents of wilderness protection about the future of public lands. Their accord is part of a cooperative effort that could lead to the first wilderness-area designation in the state in a quarter century.
Setting unattainable emissions targets is not a policy — it’s an act of wishful thinking, argues one political scientist. Instead, governments and society should focus money and attention on workable solutions for improving energy efficiency and de-carbonizing our economies.
As the International Whaling Commission debates whether to ban all whaling or to expand the limited hunts now underway, recent research has convinced some scientists that the world’s largest mammal should never be hunted again.
Tighter restrictions on mountaintop removal mining are simply not enough. Instead, a leading climate scientist argues, the Obama administration must prohibit this destructive practice, which is devastating vast stretches of Appalachia.
The United States powered its rise to affluence with fossil fuels, and China resents being told it should not be free to do the same. So as negotiators prepare for crucial climate talks this December, the prospects for reaching agreement remain far from certain.
A leading environmentalist explains why drastically reducing carbon dioxide emissions now will be easier, cheaper, and more ethical than dealing with runaway climate destabilization later.
Two prominent — and iconoclastic — environmentalists argue that current efforts to tax or cap carbon emissions are doomed to failure and that the answer lies not in making dirty energy expensive but in making clean energy cheap.
The magnificent creature at the heart of the Greater Yellowstone Ecosystem now confronts two grave perils: the loss of its key food source because of rising temperatures, and increased killing by humans. A renowned grizzly expert argues that it’s time to once again protect Yellowstone’s grizzlies under the Endangered Species Act.
For spurring the transformation to a low-carbon economy, the federal and state governments, universities, and the private sector must join together to create a network of energy research institutes that could speed development of everything from advanced batteries to biofuels.
It's overconsumption, not population growth, that is the fundamental problem: By almost any measure, a small portion of the world's people — those in the affluent, developed world — use up most of the Earth's resources and produce most of its greenhouse gas emissions.
On March 2, environmentalist Bill McKibben joined demonstrators who marched on a coal-fired power plant in Washington D.C. In this article for Yale Environment 360, he explains why he was ready to go to jail to protest the continued burning of coal.
Charles Darwin brought an insatiable inquisitiveness to his view of the natural world. On the bicentennial of his birth, author Verlyn Klinkenborg reflects on what Darwin’s most fundamental observations mean to us.
Secretary of State Hillary Clinton’s trip to China could be the first step in forging a partnership between the world’s largest emitters of greenhouse gases. A leading China expert sets forth a blueprint for how the U.S. and China can slow global warming – and strengthen their crucial relationship.
If crucial climate negotiations later this year in Copenhagen are to have any chance of success, the U.S. must take the lead. To do that, President Obama needs to act boldly in the coming months.
Key developing countries have long been exempt from efforts to reduce greenhouse gas emissions. Now, as global climate talks move forward, that policy must change.
In response to industry pressure, the U.S. Food and Drug Administration has failed to set adequate restrictions on mercury levels in fish. Now the Obama administration must move forcefully to tighten those standards and warn the public which fish are less safe to eat.
Many environmentalists assume that putting a price on carbon and creating a renewable energy economy will require major public sacrifice. But the Sierra Club’s Carl Pope argues that a well-designed package of market reforms — not austerity — will lead to a prosperous, low-carbon future.
Europe’s backpedaling last month on toughening its carbon trading system may have signaled the end of its leadership on climate change. Now, with a new administration and Congress, America appears ready to commit itself to tackling global warming.
In evaluating an economic recovery package, the new U.S. administration and Congress must weigh any proposed spending – on highways or mass transit or wind-power transmission routes – on the basis of clear criteria that would assess just how green the projects will be.
The international commission charged with protecting the giant bluefin tuna is once again failing to do its job. Its recent decision to ignore scientists’ recommendations for reducing catch limits may spell doom for this magnificent – and endangered – fish.
In the last eight years, vast areas of offshore Alaska have been opened to oil drilling. Now, a conservationist argues, the Obama administration must reverse the Bush-era policies if the state is to avoid irreparable harm to Arctic wildlife and to some of the most biologically productive waters on earth.
As he assumes the presidency, Barack Obama must make climate-change legislation and investment in green energy top priorities. And he must be ready to take bold — and politically unpopular — action to address global warming.
The next U.S. president should not wait for Congress to act on climate-change legislation. Instead, he should make use of the Clean Air Act to begin controlling greenhouse gas emissions and to implement a national cap-and-trade program.
The U.S. environmental movement is failing – by any measure, the state of the earth has never been more dire. What’s needed, a leading environmentalist writes, is a new, inclusive green politics that challenges basic assumptions about consumerism and unlimited growth.
Oil isn't America's only fuel addiction. Inefficient and environmentally damaging, the corn-ethanol boondoggle will nonetheless be hard to stop.
Congress has repeatedly failed to extend the tax credits for renewable energy, which expire at the end of this year. The gridlock is discouraging investment in renewables and jeopardizing major solar and wind projects throughout the country.
The crackdown on dissent surrounding the Beijing Olympics has been a reminder of China’s lingering authoritarianism. Yet for all our differences, the U.S. and China — the world’s two largest emitters of carbon dioxide — have no choice but to work together to tackle climate change.
Paul Ehrlich still believes that overpopulation imperils the Earth’s future. But the good news is we are approaching a demographic turning point: Birth rates have been falling dramatically, and population is expected to peak later this century — after that, for the first time in modern history, the world's population should actually start to decline.
Four decades after his controversial book, The Population Bomb, scientist Paul Ehrlich still believes that overpopulation — now along with overconsumption — is the central environmental crisis facing the world. And, he insists, technological fixes will not save the day.
President Bush is urging Congress to open the U.S. coasts and the Arctic National Wildlife Refuge to oil and gas drilling. But America must ultimately wean itself off fossil fuels. The question is whether it makes the transition now — or waits until every last one of its unspoiled places has been drilled.
A cap-and-trade system is not the answer, according to a leading alternative-energy advocate. To really tackle climate change, the United States must revolutionize its entire energy strategy.
New evidence suggests that we have already passed a dangerous threshold for the amount of carbon dioxide in the atmosphere – and that the time for taking strong action is slipping away.
The coal industry and its allies are spending more than $60 million to promote the notion that coal is clean. But so far, “clean coal” is little more than an advertising slogan.
With the Bush Administration and Congress failing to act, many states are devising sweeping climate and energy policies that could be a blueprint for a future national climate policy.
When it comes to setting climate change policy, science can only tell us so much. Ultimately, a lead report author for the Intergovernmental Panel on Climate Change writes, it comes down to making judgments about what is fair, equitable, and just.