If we halt deforestation, will we ensure a healthy future planet? If we cut fossil fuel emissions by a quarter, can we maintain a steady global temperature and keep sea levels from rising? If we reduce carbon emissions by half, will we be on track for a sustainable tomorrow?
When dealing with a system as large and complex as planet Earth, it can take years or even decades before we start to see the effects of our actions. Clearcutting a forest today won’t make it any warmer tomorrow, just as planting a forest today won’t lower the temperature the day after. But, as we have seen over the past century, these actions will impact the health of our environment over time. The question is, by how much?
Climate Interactive, a group that specializes in climate modeling, has developed an online tool to answer exactly that question. Their C-Learn Climate Simulation tool helps people to understand the long-term climate effects of our actions. Users can input their own fossil fuel emissions rates and then see how those changes will be reflected in temperature change, sea level rise, and atmospheric carbon concentration over the next century. The simulation allows users to tailor emissions rates to three regions so that developed countries, large and rapidly developing countries, and smaller countries developing more slowly can all have different targets. In addition, it allows users to set global deforestation and afforestation rates.
The C-Learn tool suggests 350-450 ppm as a target range for atmospheric CO2 concentrations and 1.5-2 degrees C as a target cap for temperature change. But what kind of emissions reductions will we need to reach those goals?
To begin, let’s look at a “Business as Usual” simulation, in which current emissions and growth patterns remain unchecked. Clearly, we’ll need to make some real changes in order to keep our planet healthy, since these numbers are nowhere close to our target–and they’re still rising.
What if we try some moderate emissions reductions? The graphs below show a 40% reduction in emissions in developed countries, a 20% reduction in rapidly developing countries, and a 10% reduction in countries developing more slowly. For each group, reductions are based on 2005 emissions levels and are set to start in the year 2020.
These moderate emissions reductions really made an impact! Now, instead of 976 ppm in the Business as Usual scenario, the atmospheric CO2 concentration in 2100 is projected to be only 533 ppm. We can see a similarly encouraging reduction in the global temperature increase over time. Even so, these reductions aren’t enough to land us within our targets, and, although both graphs display much gentler slopes, neither has leveled off.
Is it even possible to reduce our emissions enough to reach a steady state within our CO2 and temperature goals? What if we try a simulation with much larger emissions cutbacks? The following graphs result from a scenario with 99% emissions reductions from 2005 levels in all countries, starting in the year 2020. That’s like cutting all emissions almost in half.
Alright, so it can be done! These more extreme emissions reductions have successfully brought both CO2 concentrations and global temperature change to well within the target zone. According to the simulation, CO2 levels in 2100 would be 422 ppm, and the temperature would be 1.7 degrees C over pre-industrial levels. Additionally, both graphs appear to have stabilized at these levels.
Certainly, this scenario is not the only one that will allow us to achieve our emissions goals, but it’s a start.
Now it’s your turn to ask the “what if” questions. What other scenarios can you make that will allow us to live within Earth’s limits? What do you think is the optimal scenario? There are many more combinations to try, more inputs to adjust, and more graphs and data to review. Explore the C-Learn Climate Simulation tool for yourself, and tell us below what emissions goals you think we should be aiming for. With the Rio +20 Conference coming up next week, the time to start working towards our targets is now!
