Tell me why we’ve got Human Impacts on Weather and Climate.

Actually, that is a book that’s co-authored by my father, and in my book, The Climate Fix, the first chapter is entitled Dinner Table Climate Science and I explain how growing up I was taught all sorts of things by my father, who was a leading atmospheric scientist, and his colleague, Bill Cotton. They worked together at Colorado State for several decades and they have written this book that provides a thorough and comprehensive look at human influences on the climate system, which includes carbon dioxide but goes far beyond just carbon dioxide. If people want to understand the issue of climate change it’s important to understand the diversity of influences that people have on the climate system. You could point to the Intergovernmental Panel on Climate Change Survey, but that’s a monumental tome that is not really written for the layperson.

We have monumental tomes on the site.

Well, I would have a hard time recommending a thousand-page academic survey.

I would have a hard time reading it. But this one is readable, is it?

Yes. It’s not written for the broad public, but anyone could pick it up and learn something important about the climate system and why it is so complicated to make accurate predictions and the wide range of influences we have.

What are some of the human impacts on weather and climate, apart from the obvious ones?

A lot of attention is paid towards carbon dioxide but there are other greenhouse gases, such as nitrous oxide and methane, and then there are trace gases, some of which are human produced, like chlorofluorocarbons and their derivatives that also have effects.

How do we produce those?

Sometimes they are waste products from producing refrigerants, some of them are the refrigerants themselves.

You mean the chemicals that make refrigerators work?

Right. And there’s an irony, which of course there always is in human actions, that some of the chemicals that are problematic from the standpoint of their climate influence, were introduced as a solution to chemicals that ate away at the ozone layer in the 70s and 80s that led to the Montreal Protocol. So one generation’s solution became the next generation’s problem. When we burn anything it releases particulates into the atmosphere which scientists call aerosols, and these can change the amount of sunlight that hits the earth and they can precipitate out and, for example, change the colour of snow.

Oh God, really?

Yes. This can lead to accelerated melting and can change the reflectivity of the snow. When people change the land surface, by turning forests into crop land, they can change weather patterns that have a regional and, perhaps, global effect.

So it sounds as if we can’t do anything without changing the climate.

Well, people have a big footprint on planet earth and Mike Hulme, the author of another book I’m recommending, eloquently explains that climate change is not a problem that can be solved but it’s one that we can manage for better or worse.

How Many People Can the Earth Support?

This book is from the middle of the 90s and it’s a fantastic book because the title is very provocative and, if you’re concerned about our impact on the planet, one of the things you want to understand is why there are so many of us and how many people can actually inhabit the earth in a sustainable way.

How many can? We had a book called Feeding The Ten Billion on the site recently.

The answer that Cohen comes up with is something between a hundred million and a hundred billion and the reason why it’s such a large range is that he says it depends on which kind of world you want. A lot of the choices we make with environmental impact are now choices we make consciously. We can ask what kind of world we want.

But we’re very unlikely to decide not to have children. It’s such a mammalian instinct. If everybody alive has a child we’ll hit an unsustainable point quite soon.

This is one of the issues that Cohen comes up with. The definition of what’s sustainable may not be governed by hard physical limits but by the world we wish to inhabit.

So we could sustain a huge number but it would be horrible?

Right. But again that puts it well into the realm of society and politics. One of the interesting things about population is that efforts to explicitly manage global population have fallen out of favour and predictions now are for the world population to peak and then actually decline without coercive policies.

Why? Are we all going to be wiped out by a meteorite?

No. The assumptions are that as people get wealthier they have smaller families and in some places, like Germany, Sweden, Italy, people are reproducing at a rate lower than the replacement. In Sweden and Germany the government is creating tax incentives to get people to have more children, an irony that wouldn’t have been envisioned 30 years ago.

So we might not have to panic?

Certainly not. There are things that we control and things that we don’t and right now it seems that global population is outside of direct control. The idea is that if you empower women and we see a growth in prosperity we will see a slower population growth.

Seeing Like a State.

This is a book that talks about the perils and limitations of policy wonk hubris – the idea that we are capable of large-scale top-down designs on society to have specific effects. It goes through a number of cases, such as urban planning, where the most well-intended thoughtful interventions don’t lead to the desired effect and sometimes have exactly the opposite effect. I would say an example would be global population policies, such as the Chinese one-child policy. It’s a good lesson for people thinking about climate change, whether to create a global policy for carbon dioxide emissions – we’ve seen that lead to corruption and mischievous accounting rather than emission reduction.

Sorry, do you mean people shouldn’t try to reduce global warming because it will do it by itself?

No, not at all. We should be trying to reduce it, absolutely, but to think that we can do it comprehensively with a single treaty or a large-scale policy instrument may be fanciful thinking. He talks about urban planning and efforts to manage agriculture. I give a simple example in my own book, which is the introduction of cane toads into Australia. They had cane beetles that ate sugar cane and led to crop damage and loss of revenue, so someone had a bright idea that they would introduce these toads that like to eat cane beetles. The idea was that here’s a natural intervention. But it turned out that the toads didn’t prefer to eat the beetles but they found other delicious things to eat in Australia and they didn’t have any predators. So now if you go to Australia there are 300 million cane toads. Intervening in complex systems can lead to negative outcomes that are wholly unexpected. The Global Carbon Market sounds great on paper but may in fact be counterproductive. More direct, simple approaches focusing on cause and effect would be more effective. If we’re really worried about burning fuel that produces carbon dioxide, we should come up with energy sources that don’t produce carbon dioxide.