350 FAQs

To preserve our planet, scientists tell us we must reduce the amount of CO2 in the atmosphere from its current level of 410 parts per million to below 350 ppm. But 350 is more than a number—it’s a symbol of where we need to head as a planet.

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 with us.

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. The planet is in its 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. We need to scramble back as quickly as we can to safety.

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

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.

350 Bay Area is approaching this movement on the regional level, to make sure we are doing our part. We must engage Bay Area residents and our elected leaders to put lowering carbon emissions at the top of their agendas.

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.

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.