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April 09, 2010

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Laura

Hi Kumar,

Thanks for investigating this issue and posting about it. Your work prompted a few questions: In the last step, why did you assume a land use change after 50 years?

Also, I wonder about the instructive benefits of a longer time frame (100 years, in your last example). I wonder if the immediacy of climate change calls for a shorter time frame, increasing the net present value of any carbon sequestering technologies. It seems like a lot of the ecological data speaks to pending "tipping points" -- that is, the consequences of climate change and increased ghg concentrations in our atmosphere will not be experienced along a linear path. Similarly, it appears as though the data agrees that acting now to avert long-term effect will "do" more than acting 50 or 100 years later.

In sum, I would like to hear your rationale for a few of your underlying assumptions. Thank you for addressing my questions, and thanks again for your posts.

Kumar Venkat

Thanks for your comments, Laura.

The land-use change after 50 years was just one of several scenarios I discussed in my original post, along with other scenarios such as 50 and 100-year production periods without land-use change.

A 100 year assessment period is normally used as a standard time frame in LCAs and GHG inventories, but it is necessary to weight the emission events (or sequestration events) so that earlier events get more weight than later events within those 100 years. If this is done right, any sequestration we accomplish today can indeed be shown to have more value than a similar action taken years into the future.

maryjane

informative.

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