기후변화 대응 해법은 ‘나무에 있다"...옥스포드대 Could planting trees help ease carbon budgets?
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사람들이 기후변화대응에 대해 얘기할 때 종종 비행기가 화학물질을 대기 중에 살포하거나, 고층건물의 이산화탄소를 구름에 흡수시켜야 한다는 생각을 한다. 그러나 옥스퍼드 대학에서 나온 새 보고서 ‘Stranded Carbon Assets and Negative Emissions Technologies’는 기후변화에 대응하는 방법이 복잡하지 않다고 말한다. 사실 방법은 이미 모두가 알고 있다. ‘나무심기와 토양개량’이다. 이 두 기술에 대해 보고서는 ‘후회하지 않을 것’이라고 말한다. 식재와 토양은 적은비용이 들고, 약간의 추가 위험이 있다 해도 대기를 이롭게 하기 때문이다. 보고서는 지금부터 2050년 사이, 가장 유망한 기술로 나무와 바이오 숯을 꼽았다. 산림경영은 인간이 자신의 환경을 형성한 가장 오래된 방법 중 하나이기 때문에 의미있는 해결책이라고 한다. 바이오 숯은 식물과 나무, 농경지 폐기물을 진공상태에서 태워서 생성된 고탄소물질로 이산화탄소를 빨아들이는 특징이 있다. 바이오 숯을 땅 속에 묻으면 이산화탄소 흡수와 동시에 토양에 영양을 공급할 수 있다. 또한 보고서는 ‘네거티브 배출기술(Negative Emissions Technologies, NET)’에 대해 언급했다. NET는 기후변화의 최악을 늦추기 위한 방법이며, 지구 평균기온 섭씨 2도 이내로 억제하는 국제목표를 충족하기 위한 여러 도구 중 하나로 봐야한다는 것이다. 옥스퍼드 보고서의 저자는 “이산화탄소가 필연적으로 방출되는 속도에 대항하려면 글로벌 에너지, 농업 시스템 규모의 노력과 인프라가 필요하다”며, 조림이 성공하기 위해서는 세계적인 지원이 필요하다고 말했다. 전지은 기자 · 라펜트 |
By Will Nichols Planting forests, adding lime to oceans, and improved soil management techniques are among the so-called Negative Emissions Technologies (NETs) that could help buy the world extra time to tackle climate change. But it would be "foolish" to assume these measures can outweigh the climate impacts associated with continuing to burn fossil fuels, Oxford University researchers have today warned. The latest report from the university's Stranded Assets Programme details how deploying NETs could save around 120 GtCO2 by 2050, extending by 11 to 13 per cent the nominal global carbon budget required to deliver a 50 to 80 per cent change of limiting average warming to 2C. The vast majority of the saving could come from afforestation, soil carbon improvements, and biochar processes, whereby wood is burnt at high temperatures with limited oxygen to produce a char that can be added to soils, effectively trapping carbon, the report states. These 'no-regrets' NETs have low upfront costs, co-benefits such as enhanced soil fertility, and are not subject to the policy and technical uncertainties affecting other emission reduction technologies, most notably carbon capture and storage (CCS), the paper says. It says such no-regrets options could be used to minimise residual emissions from 'stubborn' emitters such as the agriculture and aviation sectors, adding that companies should work together to maximise their deployment. There is a chance that the global carbon budget could be extended by as much as 140 per cent, the paper adds, but it warns this would require the world to have already started to roll out NETS and CO2 storage infrastructure "on an improbably massive global scale". It adds that NETs should not be considered an easier option than reducing current emissions - uncertainties remain around the costs, potential, and environmental effects of carbon capture, ocean liming or extracting CO2 from the air, known as direct air capture (DAC), the report notes, while the costs are unlikely to be any lower than cutting emissions in the first place. "Combined with the potentially high costs and energy requirements of several technologies, and the global effort needed to approach the technical potentials discussed previously, it is clear that very large-scale negative emissions deployment, if it were possible, is not in any sense preferable to timely decarbonisation of the energy and agricultural systems," the report says. And the researchers are very clear that successful NETs deployment does not offer a safety net for carbon-intensive assets. They say operating a fossil fuel intensive sector alongside a large-scale negative emissions sector is an "extremely unlikely" scenario, and as such the risk of high-carbon assets becoming stranded as a result of climate change policies and alternative clean technologies remains acute. "While 'no-regrets' negative emissions could help address carbon pollution from 'stubborn' difficult to mitigate sources like agriculture and aviation, it would be foolish for owners or operators of carbon-intensive assets to assume negative emissions will 'save the day' or change the risks they face from climate change," said Ben Caldecott, co-author of the report and director of the Stranded Assets Programme. "Successful NETs deployment would not mean business-as-usual - they might address risk on the one hand (by potentially extending carbon budgets), but they create it on the other (through new and uncertain costs). There must also remain a very clear preference for timely mitigation over negative emissions as there are significant dangers associated with tipping points - once alternative earth system states have been realised, we may not return to where we started even if carbon concentrations are reduced successfully." The paper comes as US coal prices dropped to their lowest level in six years, with prices not far from the $42.20 per tonne recorded during April 2009 when the global economy was in the midst of financial crisis. Plunging oil prices and a 44 per cent drop in natural gas prices have encouraged power generators to shift away from burning coal, although falling demand in China, the world's biggest consumer and producer of coal, is also starting to bite. Meanwhile, in the past week US petroleum producers have reportedly taken 94 oil drilling rigs off the market, the biggest one-week decline since 1987, as the inhospitable investment environment for fossil fuels continues. With economic and climate factors lining up to erode the investment case for dirtier power sources, news that NETs will not be able to award the sector a get out of jail free card when it comes to carbon emissions only adds to the sense of a global industry that is yet to come to terms with the huge stranded asset risks it now faces. http://www.businessgreen.com/bg/analysis/2393189/could-planting-trees-help-ease-carbon-budgets |
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