We've just about run out of time to keep the rise of global temperature below 2 degrees Centigrade (3.6 degrees Fahrenheit). The world promised to do it back in 2010. But it hasn't acted. This is your moment, as a Global Citizen, to raise your voice to head off disastrous climate change.
The 2-degree limit is the last guardrail for a safe global climate. If temperatures shoot beyond 2 degrees, it's quite possible that natural feedbacks - melting ice sheets, drying rainforests, release of greenhouse gases from the melting tundra - could carry the world to runaway climate change. Such major climate disruptions would put sustainable development and the end of poverty out of reach. Even 2 degrees C is enough to create chaos in many parts of the world: higher sea levels, more floods, droughts, ocean acidification, heat waves and extreme storms.
The 2-degrees C limit was adopted by all governments in 2010. Since then emissions have kept on rising, and we are running out of time to stay within 2-degres. More precisely, we are running out of our planet's carbon budget, that is, the amount of carbon we can burn and still remain below 2-degrees C. In just a few years we'll lose the remaining chance to keep the Earth's temperature below the 2-degree C limit.
Yet, we can still succeed -- if all major economies of the world begin to take strong and consistent actions to decarbonize their national energy systems in three main ways: shifting to low-carbon electricity; moving from fossil fuels to electricity in vehicles and buildings; and massive gains of energy efficiency. A fourth main global pillar is to shift from deforestation to reforestation and to reduce emissions from agriculture. These transformations are deep, but they are feasible and will not only protect the climate but also boost prosperity if we apply our efforts and ingenuity to the effort.
Now you can stand up and make your voice heard. Many of the world's leading scientists and climate experts have put forward a statement to global leaders for delivery at the United Nations Climate Summit on September 23. Here is your chance to add your name with these illustrious signatories by clicking here and adding your own name to the statement.