Earth, a bar­bie and the 40 trees

The Tribune (NZ) - - ENVIRONMENT - BY KEITH YOUNG, A ROCHA MANAWATU

The World Cli­mate mon­i­tor­ing body has an­nounced 2015 will be the hottest since metro­log­i­cal records be­gan. At­mo­spheric CO2 lev­els have now breached 400ppm (parts per mil­lion).

World lead­ers are meet­ing in Paris right now. Can they reach a mean­ing­ful ac­cord to cut green­house gas emis­sions and move the world econ­omy away from its fos­sil fuel en­ergy de­pen­dence?

What can you mean­ing­fully do to re­duce CO2 lev­els? Plant trees? Then how many? Massey Emer­i­tus Pro­fes­sor of Geography, and re­cip­i­ent of this year’s NZ Ge­o­graph­i­cal So­ci­ety Dis­tin­guished New Zealand Ge­og­ra­pher Medal, John Flen­ley, posed this ques­tion to nat­u­ral re­source econ­o­mist Dr Peter Read.

Peter’s an­swer: ‘‘Ev­ery per­son would need to plant 40 trees’’.

In his re­cently re­leased book, Trees, Trees, Trees! (ISBN 978-0-473-32489-6) Prof Flen­ley ex­plores that num­ber and its sig­nif­i­cance. His book gives a bal­anced, con­cise and un­der­stand­able ex­pla­na­tion of cli­mate change with ref­er­ences for those wish­ing to check sources.

But most im­por­tantly it ex­am­ines the ben­e­fits and costs of plant­ing trees.

John shows that if half of us liv­ing in the de­vel­oped world each planted 2400 trees then, as they grow over the next 100 years, they would re­move some 39 bil­lion tonnes of car­bon from the at­mos­phere, re­duc­ing CO2 by 16ppm. That buys some time to in­tro­duce the tech­nol­ogy and make the life­style changes needed to solve the prob­lem of in­creas­ing CO2 lev­els per­ma­nently.

Nat­u­ral for­est den­si­ties are around 1700 trees per hectare so our 2400 trees will re­quire about 1.4 hectares – an area equal to one quar­ter of the Square. Right now pub­lic plant­ing oc­curs in places such as Pit Park and Waitoe­toe Park. A con­ver­sa­tion to find more land is needed.

Can tree plant­ing alone solve our global cli­mate prob­lem?

‘‘No, it is not a com­plete so­lu­tion – but it will help.’’

PHOTO SUP­PLIED

Prof John Flen­ley and fel­low A Rocha mem­ber Steven Close check out plant­ing strate­gies that are out­lined in John’s book,

Trees, Trees, Trees!.

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