Climate change: Trees to the rescue

Andreas Wilson-Späth

“Stop worrying about climate change already! Some clever engineer or science boffin will come up with a technological solution to the problem well before we burn the planet to a crisp.” That’s what some of my friends say when I mention global warming and its likely consequences.

Among the supposed silver bullets that will end the crisis are so-called low, zero or negative emissions technologies (for example ways to remove and store the CO2 generated by coal-fired power plants) and geoengineering (large-scale methods of taming the climate, for instance by stripping CO2 out of the atmosphere in bulk or shielding the earth’s surface from solar radiation).

If you, like my friends, have got your hopes pinned on these, I’ve got some bad news for you.

Humans have been unintentionally practicing geoengineering for centuries, pumping all manner of pollution into the environment without knowing the impact of these actions. Turns out it’s much harder to deliberately fix the resulting problems than it was to accidentally cause them to begin with. Like a varsity student faced with the messy aftermath of an epic house party, we’re still in the process of discovering this truism.

In what is perhaps the most comprehensive assessment of geoengineering options to date, a group of experts working under the auspices of the US National Academy of Sciences recentlypublished two reports that pour cold water on any hopes for a quick and easy techno-fix.

Here are some of the key findings:

- While some proposed geoengineering methods may be of some use in the future, they are not ready for deployment yet and will never be fix-it-all solutions to climate change. We still know way too little about their effectiveness and a lot more research, including small-scale, outdoor experimentation, is necessary.

- Most of the proposed techniques are prohibitively expensive and many come with considerable risks of detrimental side effects and “unanticipated, unmanageable and regrettable consequences”.

The authors of the reports warn that using geoengineering to fiddle with the global climate on the basis of our current scientific knowledge would be “irrational and irresponsible”.

A working paper published by researchers at the University of Oxford’s Smith School of Enterprise and the Environment comes to very similar conclusions, suggesting that geoengineering and negative emissions technologies may only reach some degree of maturity and effectiveness by 2050.

But it’s not all doom and gloom. The Oxford scientists point out that our most efficient, cost-effective, simple and appropriate option for sequestering carbon from the atmosphere is rather well established: planting trees.

They estimate that a hectare of forest can trap around 3.7 tonnes of CO2 every year at a cost (less than US$100 per tonne) that beats all of the proposed high-tech alternatives. In addition, planting trees comes with a number of bonus ecosystem benefits, including the provision of wildlife habitat, the prevention of erosion and improved soil quality. The US National Academy of Sciences reports concur: reforestation is the cheapest and most readily available route to take at this point in time.

So here’s to all the treehuggers who work hard to prevent deforestation, the treeplanters who toil equally hard to bolster the world’s tree population, and, of course, to the ecowarriors who encourage us to reduce global greenhouse gas emissions in the first place.

- Andreas is a freelance writer with a PhD in geochemistry. Follow him on Twitter:@Andreas_Spath