Climate Math: 2 = 350 = 40

There are more and more numbers associated with various climate change policies, depending on the time frame for the goals, on the types of goals (greenhouse gas reductions, expansion of renewable energies, financial support), and on the parties that suggest the goals. It therefore is becoming more and more difficult to understand what in the world various parties are talking about and which numbers one should support.

But if one looks beyond the confusing mess of numbers, there are three numbers that stick out as being the most important of all. That is, those numbers are most important if you are concerned about the long-term safety for all people of the world and less concerned about the short term profits of  a few. Any politicians who truly have our long term safety in mind, must have a goal that includes each one of these numbers or stricter measures. Anything less ambitious is maybe well meant by people who do not truly understand the urgency of the problem, but insufficient.

Two of those numbers you are already well familiar with if you have read our journal for a while (for additional information on them please go to my previous article on Safe boundaries for humanity).

These numbers are:

Two, as in two Degree Celsius. This number expresses the increase in global temperature since pre-industrial times that must not be transgressed. If global temperature increases by more than two degrees, then – so most climate scientists agree – several tipping points in the earth’s system are likely to be passed, causing irreversible changes in the earth’s climatic systems. Positive feedback loops would cause a temperature increase that is far beyond today’s estimates. Right now, global temperatures have already increased by about 0.9 degrees Celsius, and about 0.6 degrees are in the pipeline due to the time lag between greenhouse gas emissions and warming. So there is extremely little wiggle-room left.

More than 90 countries actually demand that global warming be limited to 1.5 degrees. Less warming would maximize our chances to avoid irreversible catastrophic changes to our climate system, and is therefore a great idea. But unfortunately, so far this goal gets no support from industrialized nations and is very unilkely to be met.

Remember, two degrees Celsius is a number we never want to reach nor pass.

350, as in 350 ppm. This number expresses the concentration of carbon dioxide in the atmosphere below which we must return to. It refers to the number of CO2 molecules per one million other molecules in the air. Today, we have about 387 ppm. Before the onset of industrialization and during the last 800,000 years, CO2 concentration never exceeded 280 ppm. So we have done a pretty amazing job in adding CO2 to the atmosphere in very little time. However, it IS possible to return to a safe concentration below 350 ppm within this century. But this requires immediate effective actions, such as the phase-out of all coal fired power plants that cannot capture and sequester CO2 within the next 10-20 years.

Remember, 350 is a number that we MUST reach within this century to stay below a warming of two dergree Celsius.

based on these requirements, another number comes into play. Maybe this number is more important than either of the numbers above, as this number has to be reached within just 11 years. Short term goals are absolutely essential for our success, as they are the ones that show us the path that is immediately before us. They can quickly indicate if we are acting effectively or not. And we can judge the effectiveness of our political leaders within a single legislation period.

This additional number is 40, as in 40%, the percentage by which greenhouse gas emissions need to be reduced by 2020. In the last IPCC report, scientists suggested that we need emission reductions of 25-40% by 2020. However, since then scientists have realized that our climate is changing faster than expected and that we are getting closer to tipping points than we assumed just two years ago. It is therefore a matter of urgency to reduce the likelihood of failure as much as possible, and therefore need to go with the highest possible target. A new group has formed to press for this target: 40inCopenhagen.org.

Remember, 40 is a target we must reach within 11 years.

In summary: 2 = 350 = 40

That is: to avoid a global warming by more than 2 degrees Celsius we need to reduce our current atmospheric CO2 concentration from 387 ppm to at most 350 ppm within this century. To ensure we are on the right path, the first step has to be a reduction in greenhouse gas emissions of 40 percent by 2020.

Now, let’s get to work!

Maiken Winter

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