Content-Weak vs. Strong sustainability | eePRO @ NAAEE

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Content-Weak vs. Strong sustainability

This is from a FB group ( that I started, but it seems to be my own journey. In this part I am concerned about how economics relates to the valuation of natural systems. In the second posting I will bring the importance home with an example from climate change.

Did you know there are different types of sustainability (weak and strong)? Which do you believe and what type of sustainability is taught in your school system or where you work? See below for differences. These two approaches yield different economic valuations of the natural world. A chart for the two types is reproduced from the second source two simplify the distinction. I think the current thought in environmental science favors strong sustainability. Even the UN has a mixture of different strong and weak emphases in the classes and policies they offer. Why it matters is if the goal of your org or educator is weak, well you may think things are going to be just fine when in reality they may not be and much more sacrifice may be required to achieve the safe stable world we need to provide for our children. My message isn’t that I am right and you are wrong. It is that you should think about what you believe our future should be and make sure that the institutions that are around you and part of your life promote reasonable ideas about human sustainability for you and your children. I know I am going to look at where I volunteer and what the sustainability goals of those orgs are.

Comparison of strong vs. weak from UN PDF

I have finished the Michael Mann Climate Change class on ( I highly recommend the class. SDG academy is a provider of UN classes and sustainability. For the unwary the UN sponsors classes that have both types of sustainability goals strong and weak. The ones where policy is analyzed after the environmental science tend to advocate hard sustainability. One of the important topics that I have glossed over in the past is climate sensitivity-what will be the earth’s average temperature rise with a doubling of CO2. We are in an ice age which has warm periods (like present interglacial) as the atmospheric CO2 cycles between 200-260 ppm. 260 ppm (preindustrial) is an interglacial. Today’s CO2 level is roughly 415 ppm. About climate sensitivity in lecture 4.6 Michael Mann presents the information below.
“This is why I am advocating strong sustainability. “Now implicit in the traditional definition of climate sensitivity is the so called Charney notion of climate sensitivity. The concept envisions the equilibrium sensitivity of Earth's climate to CO2 forcing in terms of the equilibrium response of the climate system to a doubling of CO2 concentrations that includes all fast feedbacks. That is to say changes in water vapor, clouds, sea ice, and perhaps even small ice caps and glaciers. The implicit in this definition becomes apparent as soon as we start to think of the lasting multi-century impacts of anthropogenic climate change. The fast feedbacks do not, for example, include the slow retreat of the continental ice sheets, or the slow response of Earth's surface properties and vegetation. For example, boreal forests slowly expand poleward as the climate warms. Accounting for these slow feedbacks leads to the possibility that the equilibrium long-term response to anthropogenic greenhouse gas emissions is larger than the IPCC projections we have focused on up to now. This more general notion of climate sensitivity is typically referred to as earth system sensitivity. There is good evidence from long-term geological records of climate change that these slow feedbacks do indeed matter, and that the ultimate warming and associated changes in climate might be substantially larger than what is implied by the simple Charney definition of sensitivity implicit in the IPCC projections. For both the mid Pliocene period, roughly 2.8 million years ago, and the mid Miocene period, about 15 million years ago, global mean temperatures appear to have been warmer than would be expected from even the upper range of the estimated Charney sensitivity, which is roughly 4 and 1/2 degrees celsius for CO2 doubling. That suggests an earth system sensitivity that could be substantially higher than the standard Charney estimate of climate sensitivity. Study using climate models that incorporate these slow feedbacks, find that the Earth's system sensitivity is indeed substantially greater than the nominal Charney sensitivity, roughly 50% higher. Thus a stabilization of CO2 levels at twice pre-industrial levels over the next century might lead to a warming of 3 degrees Celsius over the next one to two centuries, but an eventual warming closer to four and a half degrees Celsius, once the land surface and vegetation and ice sheets have equilibrated to the new climate. A process that could take a thousand years, but perhaps substantially less.”