メタンの「超大量排出源」を特定、温暖化対策に寄与　ＮＡＳＡ

【ワシントンＡＦＰ＝時事】米航空宇宙局（ＮＡＳＡ）は２５日、粉じんが気候に与える影響を調べる装置を使い、メタンガスを大量排出している場所を世界各地で５０か所以上特定したと発表した。メタン発生源の特定により、温暖化対策への寄与が期待される。（写真は米ニューメキシコ州カールズバッドで観測された、全長３キロに広がるメタンガス。米航空宇宙局（ＮＡＳＡ）ＪＰＬ－Ｃａｌｔｅｃｈ提供）
　ＮＡＳＡは報道発表で、「メタンの排出抑制は、温暖化の影響を軽減するカギだ」と指摘。その上で、今回の成果について「メタンがどこで漏れているのか科学者が特定する一助になるとともに、迅速な対処方法の手掛かりを与える」と意義を強調した。
　ＮＡＳＡの「地球表面鉱物性粉じん源研究（ＥＭＩＴ）」は、大気中の粉じんが気候に与える影響を調査している。国際宇宙ステーション（ＩＳＳ）に７月に設置されたＥＭＩＴの装置は、観測対象をサッカー場ほどの範囲に絞ることが可能で、メタンの存在を確認する能力も示した。
　ＮＡＳＡによると、中央アジアや中東、米南西部で５０か所以上のメタンガスの「超大量排出源」が特定された。このうちの大半が、化石燃料やごみ、農業に関連していた。
　強力な温室効果ガスであるメタンは、世界的な気温上昇の原因の約３０％を占めている。大気中に占める割合は二酸化炭素（ＣＯ２）に比べて大幅に少ないものの、１００年単位で見ると約２８倍の温室効果がある。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2022/10/27-17:44）

NASA scientists, using a tool designed to study how dust affects climate, have identified more than 50 spots around the world emitting major levels of methane, a development that could help combat the potent greenhouse gas.
Reining in methane emissions is key to limiting global warming, NASA Administrator Bill Nelson said in a press release on Tuesday.
This exciting new development will not only help researchers better pinpoint where methane leaks are coming from, but also provide insight on how they can be addressed -- quickly.
NASA said its Earth Surface Mineral Dust Source Investigation (EMIT) is designed to foster understanding of the effects of airborne dust on climate.
But EMIT, which was installed on the International Space Station in July and can focus on areas as small as a soccer field, has also shown the ability to detect the presence of methane.
NASA said more than 50 super-emitters of methane gas in Central Asia, the Middle East, and the southwestern United States have been identified so far. Most of them are connected to the fossil-fuel, waste or agriculture sectors.
Kate Calvin, NASA's chief scientist and senior climate advisor, said EMIT's additional methane-detecting capability offers a remarkable opportunity to measure and monitor greenhouse gases that contribute to climate change.
- 'Exceeds our expectations' -
Methane is responsible for roughly 30 percent of the global rise in temperatures to date.
While far less abundant in the atmosphere than CO2, it is about 28 times more powerful as a greenhouse gas on a century-long timescale. Over a 20-year time frame, it is 80 times more potent.
Methane lingers in the atmosphere for only a decade, compared to hundreds or thousands of years for CO2.
This means a sharp reduction in emissions could shave several tenths of a degree Celsius off of projected global warming by mid-century, helping keep alive the Paris Agreement goal of capping Earth's average temperature increase to 1.5C, according to the UN Environment Programme (UNEP).
EMIT will potentially find hundreds of super-emitters ? some of them previously spotted through air-, space-, or ground-based measurement, and others that were unknown, NASA said.
Andrew Thorpe, a research technologist at the Jet Propulsion Laboratory leading the EMIT methane effort, said some of the methane plumes detected by EMIT are among the largest ever seen.
What we've found in a just a short time already exceeds our expectations, Thorpe said.
NASA said a methane plume about two miles (3.3 kilometers) long was detected southeast of Carlsbad, New Mexico, in the Permian Basin, one of the largest oilfields in the world.
It said 12 plumes from oil and gas infrastructure were identified in Turkmenistan, east of the Caspian Sea port city of Hazar.
A methane plume at least three miles (4.8 kilometers) long was detected south of Tehran from a major waste-processing complex, NASA said.