Sunday, April 5, 2009

Climate Change: Adaptation vs Mitigation

There is a substantial risk that the continued release of greenhouse gases into the atmosphere will cause a range of adverse impacts including global warming, sea level rise, intensification of storms, changes in historical patterns of rainfall (and drought), threats to endangered habitats and the possible spread of infectious diseases.  Even if the countries of the world agree to take aggressive steps to stabilize or reduce CO2 emissions over the next twenty to fifty years, there is still a strong possibility that the cumulative effects of past greenhouse gas emissions will cause sea level to rise and storms to intensify for at least the next several decades, and probably longer.   Think about the worst storm you or your family can remember and the damage it caused.  What if storms like that occurred every ten years instead of every 100 years? 

Given such risks, it makes sense to search for low-cost ways of reducing CO2 emissions. Collectively, such steps fall under the heading of mitigation. We also need to be thinking about how to reduce the severity of whatever impacts do occur. These are generally called adaptation measures.   In the same way that cities and towns plan ahead for natural disasters like earthquakes, they should take steps to deal with the risks posed by climate change and sea level rise. This is particularly true for coastal communities.

There is a consensus building approach to managing the risks associated with climate change. First, coastal communities need to forecast the likely impacts of sea level rise, storm intensification, changes in rainfall patterns, and potential public health threats. They need to identify the ways in which their community is vulnerable. While this is not easy to do, most communities have documentation of the worst storms that have occurred in their area and the damage they did.  If there are photos, these can provide particularly useful evidence of what a two foot or an six foot rise in sea level might mean.  Communities can use various computer-based forecasting and scenario-casting tools to anticipate the risks that they face. Then, they need to inventory their options.  What can they do to protect themselves?  Our team at MIT ( has identified five types of responses:  reduce the vulnerability of the built environment by removing certain important structures from harm's way or protecting them in place by adopting new building or land use codes; protect water and waste water infrastructure by increasing water supplies and decreasing demand; protect wetlands and wildlife by preserving existing assets and enhancing their resiliency; preserve farm and forest land in the same ways; and invest in public education (including emergency preparedness, evacuation strategies, and civil defense). Once a community has an inventory of policy options, it needs to organize a public forum to consider which options make the most sense from a risk management standpoint. A lot of groups and individuals will need to be involved in joint fact finding and collaborative problem solving. (Professional facilitation can make the job easier).   Finally, communities need to enhance their adaptive management capabilities.   That means clarifying which agencies and organizations have responsibility for monitoring risks and implementing risk management strategies given new information.  

These are not merely technical tasks, they involve political choices, particularly about what money to spend and what added restrictions to impose on private property holders.  Such decisions can't be left to experts.  Communities must engage representatives of all relevant stakeholding groups in making these hard choices.  And, since we are talking about very complex "socio-ecological systems," nobody is going to get it right the first time.  A process of continuous public learning and adjustment will be required.

The global battle goes on over who should pay for mitigation and whether we can restrict
CO2 emissions while simultaneously encouraging economic growth in the developing world and economic recovery in the developed nations. Whatever these decisions, however, there is a high likelihood that we have already begun to feel the effects of climate change.  We can not ignore the risks (think Katrina and what happened when that city's infrastructure was overwhelmed). A consensus building approach can make it easier to reach fair, efficient, stable and wise agreements about how best to adapt.