The F.A.Q’s of Climate Change from

So, what is global warming and what’s the problem anyway?

The science is clear: global warming is happening faster than ever and humans are responsible. Global warming is caused by releasing what are called greenhouse gases into the atmosphere. The most common greenhouse gas is carbon dioxide. Many of the activities we do every day like turn the lights on, cook food, or heat or cool our homes rely on the combustion of fossil fuels like coal and oil, which emit carbon dioxide and other heat-trapping gases when burned. This is a major problem because global warming destabilizes the delicate balance that makes life on this planet possible. Just a few degrees in temperature can completely change the world as we know it, and threaten the lives of millions of people around the world. But don’t give up hope! You can help stop global warming by taking action here at

And what does this 350 number even mean?

350 is the number that leading scientists say is the safe upper limit for carbon dioxide—measured in “Parts Per Million” in our atmosphere. 350 PPM—it’s the number humanity needs to get back to as soon as possible to avoid runaway climate change.

If we’re already past 350, are we all doomed?

No. We’re like the patient that goes to the doctor and learns he’s overweight, or his cholesterol is too high. He doesn’t die immediately—but until he changes his lifestyle and gets back down to the safe zone, he’s at more risk for heart attack or stroke. We’re in the danger zone because we’ve poured too much carbon into the atmosphere, and we’re starting to see signs of real trouble: melting ice caps, rapidly spreading drought, increasingly severe weather, and on and on. We need to scramble back as quickly as we can to safety.

How do we create the political change to steer towards 350?

This year, we can create a grassroots movement connected by the web and active all over the world. We will focus on the systemic barriers to climate solutions, changing political dynamics whenever possible. At the same time, we’ll get to work implementing real climate solutions in our communities, demonstrating the benefits of moving to a clean energy economy.

If this global movement succeeds, we can get the world on track to get back to 350 and back to climate safety. It won’t be easy, that’s why we need all the help we can get.

How do we actually reduce carbon emissions to get to 350?

Make no mistake—getting back to 350 means transforming our world. It means building solar arrays instead of coal plants, it means planting trees instead of clear-cutting rainforests, it means increasing efficiency and decreasing our waste. Getting to 350 means developing a thousand different solutions—all of which will become much easier if we have a global treaty grounded in the latest science and built around the principles of equity and justice. To get this kind of treaty, we need a movement of people who care enough about our shared global future to get involved and make their voices heard.

Will this thing work? Will world leaders listen?

Only if we’re loud enough.
If we can make this number known across the planet, that mere fact will exert some real pressure on negotiators. We need people to understand that 350 marks either success or failure for these climate negotiations. It’s not an easy fight—the other side has the power of the fossil fuel industry. But we think the voice of ordinary people will be heard, if it’s loud enough. That’s all of our job—to make enough noise that we can’t be easily ignored.

Where did this 350 number come from?

Dr. James Hansen, of NASA, the United States’ space agency, has been researching global warming longer than just about anyone else. He was the first to publicly testify before the U.S. Congress, in June of 1988, that global warming was real. He and his colleagues have used both real-world observation, computer simulation, and mountains of data about ancient climates to calculate what constitutes dangerous quantities of carbon in the atmosphere.  The full text of James Hansen’s paper about 350 can be found here.

Isn’t America the biggest source of the problem? What about China and India?

Yes—America has been producing more CO2 than any other country, and leads the industrialized world in per capita emissions. Even though China now produces as much CO2 annually, the US still produces many times more carbon per person than China, India, and most other countries. And America has blocked meaningful international action for many years. That’s why many of us at have worked hard to change U.S. policy—we staged more than 2,000 demonstrations in all 50 states in 2007, and helped spur Congress to pass the first real laws to reduce CO2. Now we need help from around the world to persuade both the U.S. and the U.N. to continue the process.

China and India and the rest of the developing world need to be involved. But since per capita they use far less energy than the West, and have been doing so for much shorter periods of time, and are using fossil fuels to pull people out of poverty, their involvement needs to be different. The West is going to have to use some tiny percentage of the wealth it built up filling the atmosphere with carbon to transfer technology north to south so that these countries can meet their legitimate development needs without burning all their coal. A great resource for thinking about these questions is the paper prepared by the Greenhouse Rights Network, which can be found here.

350 is just a number. Wouldn’t “Climate Emergency” or “Clean Energy Now” be a better call to action?

350 translates into many languages—numerals are among the few things most people around the world recognize. More to the point, 350 tells us what we need to do. Far from boring, it’s the most important number in the world. It contains, rightly understood, the recipe for a very different world, one that moves past cheap fossil fuel to more sensible technologies, more closely-knit communities, and a more equitable global society.

And what about all the other targets people are aiming for?

Here’s Bill McKibben’s response to this question:

The question of what target to aim for in the fight against global warming has always been vexed, and for one simple reason: filling the atmosphere with carbon is at base a huge experiment, one we’ve never conducted before. It’s always been tough to judge exactly where the danger lies.

At first in the late 1980s and early 1990s, the number we routinely used was 550 parts per million CO2—mostly because it was double the pre-Industrial Revolution concentrations and hence easy to model. But it became something of a red line through dint of sheer repetition—I remember writing an op-ed for the New York Times excoriating the Clinton administration for hinting that it might be okay to go past a 550 ceiling. As time went on, it became clearer that the dangerous thresholds lay somewhere lower, and we began to use—almost interchangeably—450 parts per million, or 2 degrees Celsius. Science doesn’t actually know if 450 ppm and 2 degrees are the same thing, and no one knows how much change they would produce. Again, these were guesses for the point at which catastrophic damage would begin—they were more plausible, but still not based on actual experience. They also reflected guesses of what was politically possible to achieve. They were completely defensible, given the lack of data (though the 2C target was always problematic strategically since Americans don’t use centigrade measurements and hence have no real idea what 2 degrees Celsius means.)

In the summer of 2007, though, with the rapid melt of Arctic ice, it became clear that we had already crossed serious thresholds. A number of other signs pointed in the same direction: the spike in methane emissions, likely from thawing permafrost; the melt of high-altitude glacier systems and perennial snowpack in Asia, Europe, South America and North America; the rapid and unexpected acidification of seawater. All of these implied the same thing: wherever the red line for danger was, we were already past it, even though the atmospheric concentration of CO2 was only 390 parts per million, and the temperature increase still a shade below 1 degree C. In early 2008, Jim Hansen and a team of researchers gave us a new number, verified for the first time by real-time observation (and also by reams of new paleo-climatic data). They said that 350 parts per million CO2 was the upper limit if we wished to have a planet “similar to the one on which civilization developed and to which life on earth is adapted.” That number is unrefuted; indeed, a constant flow of additional evidence supports it from many directions. Just this week, for instance, oceanographers reported that longterm atmospheric levels above 360 ppm would doom coral reefs worldwide.

It is, therefore, no longer possible to defend higher targets as a bulwark against catastrophic change. The Global Humanitarian Forum reported recently that climate change was already claiming 300,000 lives per year—that should qualify as catastrophic. A new Oxfam report makes very clear the degree of suffering caused by the warming we’ve already seen, and adds “Warming of 2 degrees C entails a devastating future for at least 600 million people,” almost all of them innocent of any role in causing this trouble. If the Arctic melts at less than one degree, then two degrees can’t be a real target. This is simply how science works. New information drives out the old.

You could, logically, defend targets like 450 or 2 degrees C as the best we could hope for politically, especially if you add that they represent absolute upper limits that we must bounce back below as quickly as possible. But even that is politically problematic, because it implies—to policy makers and the general public—that we still have atmosphere left in which to put more carbon, and time to gradually adjust policies. We don’t—not with feedback loops like methane release starting to kick in with a vengeance. It is, we think, far wiser to tell people the best science, in part because it motivates action. It’s the difference between a doctor telling you that you really should think about changing your diet and a doctor telling you your cholesterol is already too high and a heart attack is imminent. The second scenario is the one that gets your attention.

A number of small island nations and less developed country governments have joined leaders like Al Gore in enunciating firmly the 350 target, and equating it with survival. Climate coalition groups like TckTckTck have also endorsed the target, as have a growing coalition of hundreds of organizational allies.

Here’s the important thing to remember: arguing for 350 is not making “the perfect the enemy of the good.” It’s making the necessary the enemy of the convenient. We were aware that we wouldn’t get an agreement in Copenhagen that rapidly returns us to 350—even if we do everything right it will take decades for the world’s oceans and forests to absorb the excess carbon we’ve already poured into the atmosphere. But that’s why we’ve got to get going now—and at the very least we have a number to explain why the agreement that did emerge is insufficient and needs to be revised quickly and regularly. We can use it to make Copenhagen a real beginning, not an end for years to come the way Kyoto was.

In the end, everyone needs to remember that the goal at Copenhagen was not to get a “victory,” not to sign an agreement. It’s to actually take steps commensurate with the problem. And those steps are dictated, in the end, by science. This negotiation, on the surface, is between America and China and the EU and India and the developing world; between industry and environmentalists; between old and new technology. But at root the real negotiation is between human beings on the one hand, and physics and chemistry on the other. Physics and chemistry have laid their cards on the table: above 350 the world doesn’t work. They are not going to negotiate further. It’s up to us to figure out, this year and in the years ahead, how to meet their bottom line.

Why another organization—there are already too many things going on!

It’s true, there are lots of organizations and individuals working hard to solve the climate crisis. This is great news—it means that we don’t really need to build a movement from scratch because it’s already bubbling up all over the world.

Our hope is that we can shine a spotlight on the work of existing organizations, highlighting everyone’s incredible work and knitting these many efforts together for a powerful and unified call to action—a call that is global, scientific, and specific. By providing a common platform with the 350 target, we can help to stitch together a whole that is truly greater than the sum of its parts, a diverse movement that speaks with one collective voice.

Do you measure 350 in CO2 or CO2e?

First, let’s define the term: CO2e is a calculation used by climate scientists to account for other greenhouse gases—like methane—that contribute to climate change. It converts those gases to “equivalent carbon dioxide,” and is often used by scientists and policy makers to offer a single metric that can be used for all greenhouse gases.

The initial catalyst for the 350 campaign was James Hansen’s landmark paper. “Target CO2: Where Should Humanity Aim?” In this paper, Dr. Hansen identifies 350 ppm as the upper boundary for CO2 concentrations — not CO2e.

Hansen focused on CO2 as the key greenhouse gas because it is the most prevalent in our atmosphere, has the longest life-cycle, meaning we’ll be dealing with the consequences of our actions today for over 100 years, and it is most integrated into industrial economies. In other words, cutting CO2 is the key challenge in combatting global warming, and will be the key feature of any international climate treaty.

Since formed a year ago, two things have led 350 supporters to take other greenhouse gases into account and start seeing 350 ppm in terms of CO2e. First, we’ve seen the impacts of climate change happening even more quickly than predicted. Just in 2009 there have been increased floods across Southeast Asia, a key ice bridge in the arctic melted years ahead of schedule, and places like Australia continue to be ravaged by drought. Scientists are increasingly focused on the role of potent, short-term greenhouse gases, such as methane (which is 25 times as potent as CO2—though there’s far less of it). As we think about how to combat climate change in the short term, taking these gases into account makes more and more sense.

Second, as the 350 movement has grown more and more of the groups involved, particularly groups in developing countries, do work that focuses on greenhouse gases other than CO2. These include large scale meat production or improper waste management, both leading sources of methane, industrial production of CFCs and other dangerous chemical pollutants, and more. Many of these pollution sources have profound local impacts on humans and the environment, as well as being contributers to climate change.

These considerations have led to see the 350 ppm target not only in terms of CO2, but CO2e. On a technical level, this becomes a more ambitious target, incorporating other greenhouse gases. On a practical level, it signifies the same priorities 350 has embodied all along. Any climate target lower than where we are right now—be it 350 CO2e, 350 CO2, or anything else—represents a transformative shift in how the world operates. Targets of 350 CO2 and 350 CO2e—both greenhouse gas concentrations significantly lower than current levels—have the same essential policy implications: we will STOP burning coal and other fossil fuel and we will START rolling out clean energy and other sustainable development strategies around the world.

Either way you slice it, in terms of CO2 or CO2e, 350 is the mark of a completely new direction—and the movement that will get us there.