That is up from the pre-industrial level of 280ppm, a considerable increase.
So to the vital question of when we might reach 2˚C above pre-industrial levels in other words how much time do we have to curb our excess emissions? Warming is directly related to the quantities of greenhouse gases there are in the air, the chief of which is carbon dioxide.Ĭoncentrations of carbon dioxide in the atmosphere are already at 382 parts per million (ppm). By any standard, if you care about the future of the human race, it is too close for comfort.
In fact the 2˚C threshold is much closer than almost anyone outside the specialist scientific community is prepared to acknowledge. So the key question is how close are we to a 2˚C rise, and when will we get there? The first thing to admit is that nobody knows for sure, but many who understand the science say the answer to this twin question is, first, that we are already very close, and second, we might get there terrifyingly soon. It will affect many species' survival prospects, including our own. Some scientists estimate that when the temperature reaches an extra 2˚C above that equilibrium the earth's natural systems will be in serious trouble. The danger grows with the increase in average temperature above what is called the pre-industrial level - the mid-18th century. New information makes clear that reaching the tipping point is a much more immediate threat than was previously thought. Beyond that, as unwelcome changes in the earth's reaction to extra warmth continue, it is theoretically possible to trigger runaway climate change, making the earth's atmosphere so different that most of life would be threatened.Īs with a lot of climate science, what used to be theory is now being seen in practice on the ground. The tipping point in many scientists' view is the 2˚C rise that the EU has adopted as the maximum limit that mankind can risk. Once the temperature rises a certain amount then all the ice caps will melt. This is where a small amount of warming sets off unstoppable changes, for example the melting of the ice caps. The phrase "tipping point" is heard a lot more from scientists. Plants and trees that take carbon dioxide out of the atmosphere die back, creating a vicious circle as the climate gets hotter and hotter. As the atmosphere heats up, more greenhouse gases are released from the soil and seas. Runaway climate change is a theory of how things might go badly wrong for the planet if a relatively small warming of the earth upsets the normal checks and balances that keep the climate in equilibrium.
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