Well essentially if the electricity is got from a green renewable source. It essentially eliminates the production of carbon dioxide which essentially just takes the iron oxide, produce iron on the cathode and oxygen on the anode.
That is a big question, because in an iron blast furnace essentially the reactions take place in three dimensions. So you've got these gas flowing particles and they get reduced all over the surface. The description of the process is that you have a liquid pool and that's essentially two-dimensional, so the mass of material produced per square metre is much less. So there are lots of challenges.
「Nature Podcast, 9 May 2013」Derek Fray @ the University of Cambridge
電気分解を使って鉄を生成する方法のメリット・デメリット。鉄の生成にも多くのCO2排出を伴う。
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SEJ has been applied extensively in volcanology and in the nuclear sector, and more recently in and ecology.
If contributions from glaciers and ice caps (12.4 ± 4 cm) and thermal expansion of the ocean (14–32 cm) are taken into account, we’re looking at a range in SLR of 33–132cm by 2100, according to Bamber and Aspinall.
「Quantifying uncertainty on thin ice」Nature Climate Change 3, 311–312 (2013)
専門家が考える、将来の海水準上昇予測を定量化する新手法の紹介。
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Climate anomalies have already had a detectable impact. Satellite observations and data from CO2 measurement towers suggest that extreme events reduce plant productivity by an average of 4% in southern Europe and 1% in northern Europe, says Reichstein. That lowers annual carbon uptake by 150 million tonnes — equivalent to more than 15% of Europe’s annual man-made CO2 emissions. The most extreme events can turn forests and grasslands from carbon sinks to sources. In 2003 alone, a record-breaking heatwave in Europe led to the release of more CO2 than is normally locked up over four years.
Lack of water makes plants less capable of fending off pathogens and insects. After the 2003 heatwave, caterpillars devastated Mediterranean oak forests near Montpellier in France. Researchers have presumed that this triggered a large carbon release, but such responses are hard to predict.
The world’s soils contain almost 100 gigatonnes of carbon — twice as much as the entire atmosphere. Just a 10% increase in soil-respiration rates, says Bahn, would release more CO2 in a year than humans pump out.
「Wild weather can send greenhouse gases spiralling」Nature (09 April 2013)
ヨーロッパにおいて、異常気象が陸上炭素循環にも大きな影響を及ぼしている可能性が示されている。
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Developers of the €3.5-million (US$4.5-million) project say that the P2G technology is an ideal way to cope with the unreliable nature of solar and wind power. During sunny or breezy days, excess electricity can be used to make methane, which can be stored and then burned to generate power when the winds fail or the days turn dark.
But the economic challenges are daunting, with the total costs of the Energiewende estimated to top !1 trillion. Europe’s deep financial crisis looms large over a project of that scale, warns Roger Pielke Jr, an environmental-policy researcher at the University of Colorado Boulder. “The German public has so far shown great willingness to pay for the transformation, but there will be limits to that willingness, especially if the economic climate gets rougher.”
The primary motivation for the Energiewende is to combat climate change. By 2020, Germany aims to cut its greenhouse-gas emissions by 40% below 1990 production levels, and it hopes to achieve a reduction of at least 80% by 2050. The government set those goals in 2005, but the targets became much more ambitious in the aftermath of the Fukushima nuclear accident in Japan in March 2011.
Germany is subject to the vagaries of outside forces, such as the rapid expansion of natural-gas production in the United States, which has curbed domestic demand for coal. Excess US coal is now heading to Europe, helping to fuel a resurgence of coal use in the United Kingdom and Germany, among other countries. With Germany’s imports of low-cost coal rising, the country’s greenhouse-gas emissions increased by almost 2% in 2012 — bucking a long-term decline.
The government intends to have one million battery-powered cars on German roads by 2020, but experts view that goal as unrealistic. The industry lacks the capacity to produce that many electric cars, and motor-loving Germans have not shown much desire for them. The new Audi and similar models may turn more heads, because consumers can switch to normal fuel if they are running low on natural gas and cannot find a specialized refuelling station. That option is not available to owners of batter-powered vehicles that run low on charge.
「Germany’s energy gamble」Nature (10 April 2013)
ドイツのエネルギー政策’Energiewende’の紹介。エネルギーをメタンガスとして貯蓄し、再生可能エネルギーの欠点を補う試みも始まっている。
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They find that coral reefs in the western tropical Pacific Ocean are likely to be among the first to succumb to global-warming-induced increases in water temperatures, whereas coral reefs in other places, such as near the high-latitude limits of their range, may hang on for a few more decades. Unfortunately, coral reefs in these higher-latitude environments may be the first to succumb to ocean acidification.
These findings therefore suggest that if we aim to protect any coral reefs, the RCP2.6 pathway must be viewed as an upper bound on permissible greenhouse gas concentrations. However, many see the emissions associated with RCP2.6 as ‘unrealistically’ low. If this view is correct, then the only ‘realistic’ scenario is one in which we kill off all coral reefs.
After previous mass extinction events — preserved in the geological record — it took many hundreds of thousands of years before coral reefs became common once again. Such evidence suggests that the decisions we make over the next years and decades will affect the marine environment for hundreds of thousands of years to come.
「Coral ‘refugia’ amid heating seas」Nature Climate Change 3, 444–445 (2013)
温暖化する海域の中には、サンゴの消失が遅れる海域が少なからずあるかもしれず、そうした海域こそ集中的に保護する必要がある。
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But although fossil fuels can be replaced, at some cost, by carbon-neutral alternatives, we will continue to depend on managing Earth’s land surface for food and fibre.
しかし、化石燃料はある程度のコストを払えばカーボン・ニュートラルな代替物に置き換えることは可能であるが、我々は食糧と繊維のために地球の陸地を管理することに依存し続けるのである。
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They find that coral reefs in the western tropical Pacific Ocean are likely to be among the first to succumb to global-warming-induced increases in water temperatures, whereas coral reefs in other places, such as near the high-latitude limits of their range, may hang on for a few more decades. Unfortunately, coral reefs in these higher-latitude environments may be the first to succumb to ocean acidification.
These findings therefore suggest that if we aim to protect any coral reefs, the RCP2.6 pathway must be viewed as an upper bound on permissible greenhouse gas concentrations. However, many see the emissions associated with RCP2.6 as ‘unrealistically’ low. If this view is correct, then the only ‘realistic’ scenario is one in which we kill off all coral reefs.
After previous mass extinction events — preserved in the geological record — it took many hundreds of thousands of years before coral reefs became common once again. Such evidence suggests that the decisions we make over the next years and decades will affect the marine environment for hundreds of thousands of years to come.
「Coral ‘refugia’ amid heating seas」Nature Climate Change 3, 444–445 (2013)
温暖化する海域の中には、サンゴの消失が遅れる海域が少なからずあるかもしれず、そうした海域こそ集中的に保護する必要がある。
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But although fossil fuels can be replaced, at some cost, by carbon-neutral alternatives, we will continue to depend on managing Earth’s land surface for food and fibre.
しかし、化石燃料はある程度のコストを払えばカーボン・ニュートラルな代替物に置き換えることは可能であるが、我々は食糧と繊維のために地球の陸地を管理することに依存し続けるのである。
「Plant a tree, but tend it well」Nature 498, 47–48 (06 June 2013)
新たに生育する植物が吸収できる炭素の量は栄養の量に制限される。
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It has long been debated — including at the Conference of the Parties in Doha last December — whether industrialized countries responsible for historical emissions should continue to bear the largest proportion of mitigation costs in the future. The most contested view is that poor and emerging economies are increasing carbon emissions and therefore should intensify their efforts to mitigate.
「先進国がこれまでのCO2排出の責任を負い、将来の削減コストについても大部分を負担するべきか否か」については、昨年12月のドーハにおける会合を含め、長いこと議論されてきた。もっとも論争されている観点は、「貧困国・発展途上国はどんどんCO2を排出しているため、削減する努力を強化すべきである」というものである。
The international community has to support developing nations as poverty undoubtedly increases susceptibility to climate-related risks. But vulnerability to climate change has several dimensions that depend on a combination of economic and social factors.
貧困は気候に関連したリスクを確実に大きくするため、国際社会は発展途上国を支援しなければならない。しかし、気候変化に対する脆弱性は社会・経済的要因の組み合わせに依存するいくつかの次元を持っている。
「Positive intentions」Nature Climate Change 3 (6) (June 2013)
Bohnにおける気候変化に関する国際会議を受けて。
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The fastest emissions growth last year occurred in Brazil’s energy sector, although it is still eco-friendly compared with the energy sectors of most other major economies. Brazil boasts the world’s most advanced bioethanol industry, and produced roughly 85% of its electricity from hydropower in 2010. But Brazil has increasingly turned to fossil fuels to drive an ever larger share of its economic growth in recent years. Emissions from the energy sector increased 21.4% between 2005 and 2010, translating to an increase of 399 million tonnes of CO2.
“This is the key to fixing international diplomacy — we need a few big emitters to demonstrate credibly how successful international coordination would tangibly lead to extra efforts,” says Victor. “Brazil, as a big emitter and an emerging country, is in a special position to do that.”
「Brazil reports sharp drop in greenhouse emissions」Nature NEWS (05 June 2013)
ブラジルは森林破壊の削減によって排出量を大幅に削減できたが、一方で農業・エネルギー部門の排出は増加しており、将来の課題も多い。
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Researchers say that China has reasons beyond climate change to implement emission caps. In the past few years, rampant air pollution has caused increased public resentment and social unrest across the country.
中国には気候変化以上に排出量制限を設けるのに足る理由がある、と研究者は言う。過去数年間に、猛威を振るっている大気汚染が人々の怒りを買っており、国家に対する社会的不安が増加している。
Kelly Sims Gallagher, an expert on energy and environmental policy at Tufts University in Medford, Massachusetts, says that an ambitious emissions cap from China “would send a strong political signal to the world” and would make it easier to pass more aggressive climate legislation in the United States, where there is strong political resistance to national climate regulations.
エネルギー・環境政策の専門家であるマサチューセッツ州MedfordのTufts大のKelly Sims Gallagherは、「中国における野心的な排出量制限は世界に強い政治的メッセージを送ると思われ、国家的な気候調節に対して政治的な強い反発があるアメリカ合衆国においても、より意欲的な気候法案が通りやすくなるかもしれない。」と述べる。
「China gets tough on carbon」Nature (13 June 2013)
中国がキャップ・アンド・トレードを導入することをうけて。
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Recent abrupt changes, such as the green revolution and China’s rapid industrialization, differ substantially from the pace of previous changes, such as agricultural practices, which evolved over centuries and thus allowed species and species interactions to coevolve. The systems resulting from those gradual changes maintained an equilibrium that benefits conservation, sustainable production, and cultural ecosystem services. To protect future human civilizations from the effects of the Anthropocene, we should work to decelerate change to gain time for evolution and prevent break- downs in ecosystem services.
「The Age of Man: Outpacing Evolution」Science (14 June 2013)
人類の時代（Anthropocene）の定義を巡る議論。
