Should the role of afforestation in climate change mitigation policy be re-evaluated?

Should the role of afforestation in climate change mitigation policy be re-evaluated?

Afforestation (planting trees) to mitigate climate change could cause warming rather than cooling globally due to non-carbon effects of land use change, according to new research from the University of Bristol.

Global land use change and its interaction with the climate system is recognised as an important component of the Intergovernmental Panel on Climate Change (IPCC)'s future climate scenarios.

New research led by T Davies-Barnard of Bristol's Cabot Institute investigated the full effects of carbon and non-carbon impacts of land use change in the representative concentration pathways (RCPs), a range of socioeconomic scenarios for future climate.  

The research team used an earth system model to investigate global temperature sensitivity to land use change in the RCP scenarios.  Their study, published in Environmental Research Letters, is the first to assess the effect of land use in both afforestation and deforestation scenarios for the RCPs.

They found that in RCP 4.5, a mid-range future climate projection that includes afforestation to help mitigate climate change, the land use change resulted in a small net positive warming.

This was primarily due to the addition of new forest in mid-latitudes, which decreased the albedo (reflectivity of the earth's surface) and increased local and global temperature.

This small net gain in could mean that RCP 4.5's universal carbon tax, a proposed mitigation policy that incentivizes growing and preserving forest, may be counter-productive with respect to climate change.

Dr Davies-Barnard said: "Without looking at the full effects of land use change, afforestation policies to reduce could actually do the opposite."

However, the researchers also recognise that and the avoidance of deforestation would undoubtedly have wider environmental benefits, such as preserving biodiversity and maintaining ecosystem services.

Dr Davies-Barnard said: "Our work shows a small warming from forest preservation and expansion, but is that really the most important thing when considering the loss of unique and irreplaceable tropical forests?"

This study has shown that non-carbon impacts of land use change make a small but important contribution which has been overlooked in the RCPs and, thus, their effects need to be considered in future .  

Incorporating land use change in mitigation policy also requires a consideration of broader environmental aims, with impacts not necessarily acting in synergy, the research suggests.


Explore further

Protecting forests alone would not halt land-use change emissions

More information: "Full effects of land use change in the representative concentration pathways." DOI: 10.1088/1748-9326/9/11/114014
Journal information: Environmental Research Letters

Citation: Should the role of afforestation in climate change mitigation policy be re-evaluated? (2014, November 24) retrieved 19 October 2019 from https://phys.org/news/2014-11-role-afforestation-climate-mitigation-policy.html
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Nov 24, 2014
Please keep the forests and grow more. We need to initiate and maintain massive reductions in human-caused greenhouse gasses and create as much absorption as possible worldwide. The heat reflective properties of forests compared to light colors may lead to incremental regional temperature upticks but this in no way counters the global greenhouse effect caused by these gases. Barren zones like the tundra and artic will continue to heat up at an incredible rate and cause the release of immense sinks of methane from permafrost. There is no masking of global warming near the arctic.

Nov 24, 2014
Imalumberjack, please grow lots and lots of trees. :)

Nov 24, 2014
Afforestation (planting trees) to mitigate climate change could cause warming rather than cooling globally
Yeah, because we all know forests are MUCH warmer than deserts in the same latitudes (sarcasm).

Nov 24, 2014
Afforestation (planting trees) to mitigate climate change could cause warming rather than cooling globally
Yeah, because we all know forests are MUCH warmer than deserts in the same latitudes (sarcasm).
@Uba
sarcasm noted... but you should really read the study
it is far more interesting than you think

and it has some interesting ideas that they worked out
such as
Whereas carbon emissions are well mixed in the atmosphere, giving them a global impact, biogeophysical effects are much more locally focused. Therefore the more important effects from LUC are likely to be regional scale, especially in mid–high latitude areas of afforestation. However, as shown here, the biogeophysical effects of LUC can still affect the global climate in the RCPs.
i thought the study was interesting and i can't wait to see some further studies on the subject

Dec 02, 2014
I do not see how the albedo effect has anything like the weight it is given in studies such as these and I am high sceptical as to conclusions so drawn. We should instead be looking in the optimal, climax vegetation for a particular location before we start messing about with affairs. Clearly forest - deciduous or conifer - are climax and so natural and sustainable over a far wider area of the globe than now found.

We must drive a century of restoration and include marginal lands the whole world over.

Chris Hemmings
O/C Five Trillion Trees

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