Research press release


Nature Communications

Climate sciences: Estimating the effects of solar geoengineering on tropical cyclone frequency



これと似た結果が成層圏エアロゾル注入についても予想されるため、この方法の影響評価は参考になると考えられる。そのため、Anthony Jonesたちの研究グループは、大気と海洋を完全に結合した大循環モデルを用いてシミュレーションを行い、半球の成層圏エアロゾル注入が北大西洋の熱帯低気圧の頻度に及ぼす影響を調べた。その結果分かったのは、エアロゾルを北半球で注入すると、北大西洋の熱帯低気圧の頻度が低下し、南半球で注入すると、北大西洋の熱帯低気圧の頻度が上昇する可能性があることだった。これに対して、2070年に成層圏エアロゾル注入を突然中止すれば、熱帯低気圧の活動が当初の状態に逆戻りすると考えられている。


Solar geoengineering methods that inject aerosols into the atmosphere may have regionally diverging effects on tropical cyclone frequency, suggests a modelling study in Nature Communications. These results suggest the uncertain effects of solar geoengineering - a proposed approach to counteract global warming - should be considered by policymakers.

A solar geoengineering approach known as stratospheric aerosol injection is expected to effectively cool the Earth’s surface by reflecting some sunlight before it reaches the surface. Observations of volcanic eruptions, which are the natural analogue of stratospheric aerosol injection, suggest that aerosol enhancements modulate tropical cyclone activity: eruptions in the northern hemisphere decrease North Atlantic tropical cyclone activity, and those in the southern hemisphere enhance it.

As similar outcomes are expected for stratospheric aerosol injection, it would be informative to assess the implications of this approach. Thus, Anthony Jones and colleagues run simulations with a fully coupled atmosphere-ocean model to investigate the effect of hemispheric stratospheric aerosol injection on North Atlantic tropical cyclone frequency. They find injections of aerosols in the northern hemisphere would decrease North Atlantic tropical cyclone frequency, while injections contained to the southern hemisphere may potentially enhance it. However, abrupt cessation of injections in 2070 would rapidly lead to a rebound of tropical cyclone activity to its base state.

The authors caution that while tropical cyclone activity in the North Atlantic could be suppressed by northern hemisphere injections, this would, at the same time, induce droughts in the Sahel. Therefore, unilateral geoengineering to control the climate response of a particular region should be considered carefully, as this approach may have negative effects elsewhere.

doi: 10.1038/s41467-017-01606-0

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