Rules for Geoengineering the Planet

The 2015 Paris climate agreement was a major milestone, but the truth is, achieving its ambitious goal of keeping temperatures to within 1.5 °C to 2 °C of preindustrial levels would require rates of mitigation far in excess of what’s been achieved—or even what’s been planned.

Because of this, more people are contemplating geoengineering—notably solar radiation management, which involves reflecting a portion of the sun’s radiation back into space. The idea raises many questions. We don’t know how effective it would be, and we don’t fully understand its potential impacts. There are also ethical issues about its use and its governance.

We need to acknowledge that the aggregate environmental and socioeconomic risks of solar radiation management would probably be small in comparison with the benefits of reducing global temperatures. But those benefits and harms would be unequally spread among regions of the world, and between current and future generations.

Read the observations of Janos Pasztor on MIT Technology Review - “Rules for Geoengineering the Planet.”

The World Passes 400 PPM Threshold. Permanently

In the centuries to come, history books will likely look back on September 2016 as a major milestone for the world’s climate. At a time when atmospheric carbon dioxide is usually at its minimum, the monthly value failed to drop below 400 parts per million.

That all but ensures that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists.

Because carbon pollution has been increasing since the start of the Industrial Revolution and has shown no signs of abating, it was more a question of “when” rather than “if” we would cross this threshold. The inevitability doesn’t make it any less significant, though.

September is usually the month when carbon dioxide is at its lowest after a summer of plants growing and sucking it up in the northern hemisphere. As fall wears on, those plants lose their leaves, which in turn decompose, releasing the stored carbon dioxide back into the atmosphere. At Mauna Loa Observatory, the world’s marquee site for monitoring carbon dioxide, there are signs that the process has begun but levels have remained above 400 ppm.

Read Brian Khan’s story on Climate Central - “The World Passes 400 PPM Threshold. Permanently.”