Greenhouse Planet - Lewis Ziska ***

The message of this book is interesting, and one I've rarely seen discussed - I would definitely have given it more than three stars if it wasn't for the extremely irritating writing style (more on that later). What Lewis Ziska does is to bring to the forefront an aspect of climate change that pretty much goes under the radar: its impact on plant growth.

Mostly leaving aside the impacts of drought, wildfires and flash flooding, Ziska homes in on the implications that increased carbon dioxide levels have on plant biology. We all know that plants use the carbon dioxide in the air to get the carbon needed for growth - and that increased CO₂ levels can have an effect on that growth. But what's startling is both the lack of research into what the impact of higher carbon dioxide levels are - and the range of effects it is likely to generate (mostly negative).

Perhaps the most frequent comment of the good scientist is 'It's more complicated than we thought,' - and that's certainly the case here. Some have pointed to the positive benefits for agriculture of having more CO₂ in the atmosphere. And up to a point those benefits exist. However, Ziska makes clear that it would be extremely over-simplistic to think that this is a universal benefit. Arguably, the two most significant findings here are that not all species of the same crop react the same way to increased carbon dioxide levels, and that weeds, on the whole, get more benefit than crop plants - so the impact of higher CO₂ on a field of, say, rice or wheat, can be to reduce the crop yield because there is so much more competition from weeds.

An important point that Ziska makes is the relative lack of research into this, in part because it falls between two stools. The agricultural funders point to the climate people, who then refer you back to the agricultural sources. It is particularly strange, as Ziska says, that there has been hardly any research into finding which strains of crop plants benefit most from having more carbon dioxide available, so that appropriate choices can be made. Hopefully the book will help turn this round.

So far, so good. But there are some issues with the writing. Ziska uses an extremely heavy-handed folksy style with far too many rhetorical questions along the lines of 'Rice is often a staple food for the poorest people - and they will be the ones most impacted. Yeah, but those of us who don't eat a lot of rice won't be affected, right? Wrong...' The single (quite small) page with that one in contains two other rhetorical questions and a passing 'Hmm'.

This is also a very US-centric book for a worldwide problem. Although Ziska does refer to other countries (as in those rice-heavy locations), the examples are very much driven by America's distinctive approach to farming (and its plant life such as poison ivy). And then there's a near-obsession with one phrase that I've never heard used by climate change deniers: 'CO₂ is plant food'. The entire book pivots on countering the use of this phrase to suggest that climate change is just fine. 

I accept some have said this, but certainly in Europe it's not something that you often come across. Even if people do make this argument, it's hard to see how it somehow would counter the impact of sea level rise, droughts, wildfires, flash floods, mass migration and more. It might be catchphrase with a certain kind of American conservative, but it's not got any traction in the world at large. All it does in this book is get in the way of the important stuff.

What we have here is by no means all bad, then - and highly recommended if you want to learn more about the impact of CO₂  on plant growth, and the implications of yet another impact of climate change. But it could have been better.

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Review by Brian Clegg - See all Brian's online articles or subscribe to a weekly digest for free here