You can find more posts on climate change science, policy, and news on Climate 411.
Transitioning to a clean, low-carbon economy brings a lot of benefits: new jobs, cleaner air and improved public health are just a few examples. Here's another reason why we need to act now to cut emissions and stop global warming:
Even with immediate, aggressive, and sustained cuts in greenhouse gas emissions, damage to fragile ecosystems is virtually certain, and the Greenland ice sheet is still at risk.
Follow me over the fold for a graph that says it better than I can:
Analysis by Environmental Defense Fund with the MAGICC/SCENGEN climate model, version 5.3.
The black curve shows the best estimate of future warming under a scenario in which global emissions:
• Peak and begin to decline in 2020
• Are reduced 50 percent below today's levels around 2060
• Fall 80 percent below today's levels by 2100
The orange shading shows the 90 percent confidence interval around the warming estimate.
The brackets on the right side show the estimated range of warming that could cause severe damage to Arctic, alpine, and coral ecosystems, the total disintegration of the Greenland ice sheet, and the partial disintegration of the West Antarctic ice sheet. The higher temperature goes within or above a bracket, the more likely are big changes in the corresponding Earth system.
(Why the ranges? Why can't scientists say for sure what will happen, even with a single emissions scenario? I explained the reasons for uncertainty in climate predictions in an earlier diary.)
The take-home message
Even in this best-case scenario, fragile Arctic, alpine and coral reef ecosystems will likely suffer severe damage. (A glimmer of hope, though: by reducing other stresses, we can help coral reefs increase their resilience to warming - for example, see this blog post and this research.)
There's also a small chance - even in this scenario - that temperature could rise enough to trigger the irreversible meltdown of the Greenland ice sheet, causing an eventual 23-foot rise in sea level. The probability is small (i.e., the overlap between the orange warming band and the Greenland bracket is narrow), but it's still there.
As Dr. Stephen Schneider has said, risk is probability times consequences. The consequences of a 23-foot sea level rise are enormous, and the probability, though small, is greater than zero even with aggressive action. The longer we wait, the greater the risk. We must act now to cap greenhouse gas emissions.
Further Reading
• Reasons for hope in our race to reinvent energy
• As always, the IPCC report, particularly WG1 Ch. 10 and WG2 Ch. 19
• All about climate models in general (here and here), and the MAGICC/SCENGEN climate model in particular
• You can find more posts on climate change science, policy, and news on Climate 411.