It appears that climate engineering could buy us some time, and it is time we need if we are to make a sustainable and smooth shift away from reliance on fossil fuels. Research shows that non-fossil fuel energy sources will – based on today’s availability – get us less than halfway toward a path of stable carbon emissions by 2050, and only a tiny fraction of the way towards stabilisation by 2100.

If politicians change course and agree this December to invest significantly more in research and development, we would have a much greater chance of getting this technology to the level where it needs to be. And, because it would be cheaper and easier than carbon cuts, there would be a much greater chance of reaching a genuine, broad-based – and thus successful – international agreement.

Carbon pricing could be used to finance research and development, and to send a price signal to promote the deployment of effective, affordable technology alternatives. Investing about 100 billion dollars annually would mean that we could essentially resolve the climate-change problem by the end of this century.

Practically, his proposal summarizes his position he has previously outlined with so many words in his two books The Skeptical Environmentalist and Cool It. And his position is: yes to a carbon tax, and yes to investing on basic energy research.

For a centrist position, that’s actually not all bad. (Which is why the severity levelled against him I often find somewhat off-putting.) When the chips fall down, Lomborg sits on the right side of the argument - anthropogenic climate change is real and needs to be tackled, carbon use should be taxed (but not through carbon credits), and the extra incomes should be invested in development of durable energy.

Lomborg’s swoon with geo-engineering strikes me as somewhat new, and appears to be the product of the new heap of economists he chairs, under the name of the Copenhagen Consensus Center.

So, what is cloud whitening anyway?

Cloud reflectivity enhancement - Wikipedia, the free encyclopedia

Cloud reflectivity enhancement is also known as 'marine cloud brightening' or 'cloud whitening'. It is a geoengineering technique that works by solar radiation management. By modifying the reflectivity of clouds, the albedo of the Earth is altered. The intention is that this technique, in combination with greenhouse gas emissions reduction (and possibly other geoengineering techniques) will be sufficient to control global warming. Compared to other climate modification strategies, this technique is relatively simple and benign, being based as it is on natural processes of 'ocean spray'.

Solar Radiation Management (SRM) is only one of a number of packages that fall under geoengineering. Together with Carbon Capture, solar radiation management schemes are the most featured in the press. Probably the proposal of SRM that hits the headlines often is the one with injecting SO2 particles into the atmosphere (as first blogged at ET by technopolitical, one of those diaries that has become a staple read). There have been plenty of arguments why SO2 injection might not be the best of all ideas available, even when it is considered one of the most effective and more cheaper schemes so far proposed.

On the other hand, cloud whitening through spraying sea water might even be doable today, by the use of unmanned Rotor ships. As water droplets don’t last very long in the atmosphere, once the process of spraying is stopped, the effects will wear off quickly.

The future design of a Rotor ship? Image from Climate Change Today.

Still, the effects and results have only been preliminary researched. Initial theoretical calculations suggest that the method is, in potential, effective. From this PDF by Lenton and Vaughan (2009), on cloud whitening:

It has been argued that a 50–100% increase in droplet concentration in all marine stratiform clouds would give rise to an increase in top-of-cloud albedo of 0.02, causing a planetary albedo increase of 0.005, and that this would offset a doubling of atmospheric CO2 (Latham, 2002; Bower et al., 2006). However, an increase in planetary albedo of 0.005 gives a TOA radiative forcing of −1.71Wm−2 5 from Eq. (2), sufficient to offset the present anthropogenic radiative forcing, but not that from a doubling of CO2, as noted in the original source (Charlson et al., 1987). To offset 3.71Wm−2 from doubling CO2 requires a planetary albedo increase of 0.011 (Latham et al., 2008).

snip

Recently the numbers have been revised, considering non-overlapped marine stratiform clouds to cover 17.5% of the Earth’s surface, a required change in top-ofcloud albedo of 0.062 is estimated (Latham et al., 2008). However, the revised calcu15 lation assumes that the change in low-level cloud albedo causes an identical change in planetary albedo, which would be wrong even if the clouds were at the top of the atmosphere.

Instead they are near the surface and the change in planetary albedo could be less than 70% of the change in top-of-cloud albedo, from Eq. (6). Accounting for this, we estimate a required increase in top-of-cloud albedo of 0.091 (Table 1) across 20 all regions of marine stratiform clouds. This is a markedly larger value than the often cited 0.02, but not inconceivable given that such clouds can range in albedo from 0.3 to 0.7. The CCN source required to achieve this change in albedo needs re-quantifying.

Thus there still seems a long, long way ahead from theoretical calculations to practical execution. Even so, for Lenton and Vaughan, cloud whitening through sea level spray seems to pass, but is not considered an optimal solution. For anyone interested in geoengineering schemes, the whole article is a fine read.

But also Lomborg underlines in the editorial that he sees geoengineering as a transitional measure to overcome the gap between carbon-driven energy to durable energy, and not the end-all and be-all. Which, in my opinion, is a saner way to look at geoengineering anyway.

It will be interesting to see how prominently geoengineering projects will feature in the end text of the Climate Change Conference.