What if... we all ate organic?

If you've spent five minutes in the aisles at M&S, you'll know that organic food is big business. 'It's better for the environment' claim the marketers, 'It's healthier' and 'think of all those poor animals'. But is it worth splashing extra cash on organic? What would happen if everyone decided it was?

It's worth giving a little thought to the huge benefits industrial agriculture has brought to the world. At the turn of the 20th century, an agricultural apocalypse was looming. ‘unless the chemistry world manages to turn the nitrogen of the air into fertilizer' German chemist Karle Engler told the British Association for the Advancement of Science in 1898 'the western world will starve’.

A few years later Fritz Haber and Carl Bosch came up with a method for the industrial scale production of ammonia, the basis of modern fertilisers. It's difficult to overstate the impact of the Haber-Bosch process. Since 1950 the relative abundance of cheap food has allowed global populations to expand from 2.5 billion to today's seven. Without it, you probably wouldn't be here reading this article.

But intensive agriculture has many side effects. Fertilisers and pesticides can contaminate hydrological and ecosystems in unexpected ways. It is here that organic agriculture, with its reduced reliance on chemicals has clear advantages. You might have also seen claims that organic food is healthier. But extensive studies have found that organic food offers no additional nutritional value. And whilst it might expose you to less pesticides, the levels of pesticides permissible in our food in the UK are so tightly controlled, they pose no measurable risk to health.

Now remember - this blog is about climate change! So does organic food produce fewer greenhouse gases? The evidence is often conflicting but overall the balance seems to point to yes. Nitrate fertilisers used in industrial farming are broken down by bacteria in the soil, which release nitrous oxides into the atmosphere. And the techniques used in organic farming mean that carbon is held, or sequestered, in the soil for longer, keeping it out of the atmosphere.

Comparing emissions across types of agriculture is tricky. Different values are arrived at depending on whether you're calculating emissions per kg of produce or per hectare of land. And figures vary wildly depending on whether you've accounted for the sequestration effects of organic farming or not.

An eight year study by scientists at Michigan State University to measure gas fluxes from agriculture found that, once sequestration effects were taken into account, emissions from organic were 64% lower. Modelling studies show similar reductions. So, if we take the most optimistic predictions, emissions from agriculture could reduce by 64% if we all ate organic (or about 9% of total emissions). But this is likely to be a long way off the actual figure. Far more research is needed to establish the true impact of going organic. 

Comparison of soil carbon gains and losses in different farming systems in long term field experiments
Source: Low Greenhouse Gas Agriculture, FAO (2009)

What is clear is that the social implications would be huge. The reduced yields of organic compared to industrial farming mean it's unclear whether it's even possible to feed the global population entirely on organic. And food prices would undoubtedly rise. In a world where nearly a billion people go hungry, I think we're best sticking to industrial practices for the foreseeable future.

What if... we all drove electric?

You might have spotted stories in the press lately stating that electric vehicles are worse for the environment than conventional ones. This isn’t what we've been led to believe. So is it true? And if so, what would happen if we all switched to electric cars tomorrow?

The reports stemmed from a study by the Norwegian University of Science and Technology that looked at the lifecycle impacts of electric cars against conventional ones. Lifecycle analyses look at stages in a cars life, from manufacture to disposal, and calculates the environmental impact in each. Impact includes both greenhouse gas (GHG) emissions and environmental contamination from toxic materials released into the environment.

Globally 13% of GHG emissions are from transport of which 6% are from road vehicles

Source: IPCC 2007 Assessment report

This is a blog about climate change so I don’t want to dwell on environmental contamination issues which, whilst I would never suggest are unimportant, are a separate issue to the greenhouse gas emissions that warm the globe. In short, electric vehicles were found to cause much more contamination of freshwater and ecosystems due to the higher concentrations of copper and aluminum involved in their manufacture... Bad news.

But what about climate change? The report found that the global warming impact of manufacturing electric vehicles was roughly twice that calculated in previous reports.  But by far the biggest source of greenhouse gas emissions in an electric car's lifetime come from driving it (the usage phase).

This is counter-intuitive. Electric cars, which have no exhaust, should perform much better here. But if the electricity used to power the cars comes from fossil fuels, then each unit of electricity used driving will have associated GHG emissions.

Electric car manufacturers Tesla claim their Roadster model has zero emissions. But does it really?

In Europe, where use of renewables is comparatively high, electric cars have a 10% - 24% lower global warming impact than conventional cars over the average lifetime distance of 150,000km. Use the car for longer and the reduction increases. The opposite is true for shorter distances.

But if all the electricity to power the car comes from coal, the situation changes. Suddenly electric cars have a 17% - 27% bigger global warming impact. In a world where 64% of electricity is produced from fossil fuels (compared with 50% in Europe), if we all switched to electric cars tomorrow, the impact on GHG emissions would be much smaller than one might expect.

So if you live in China, I wouldn't run out and buy an electric car. But you might consider it if you're from the EU. And as the global energy mix becomes more reliant on renewables in the future, investing in an electric car will become increasingly sensible. The Smith School, a University of Oxford research centre founded by ex-chief government scientist David King recently published a future transport roadmap stating that electric vehicles should play a vital role in reducing future GHG emissions from transport. And the UK government's chief climate change advisory group, the Committee on Climate Change, state that it will be impossible to meet emissions targets from road vehicles without using electric cars.

Might be time to start browsing those showrooms.

What if... all flights were grounded?

I thought I'd make my first post about the event that inspired this blog. In April 2010 the Eyjafjallajökull Volcano in Iceland erupted, spewing millions of tonnes of ash into the air. The ensuing ash cloud which engulfed northern Europe forced twenty countries to close their airspace, grounding hundreds of thousands of flights.

What was bad news for tourists was a once in a lifetime opportunity for scientists. Previously they could only postulate the effects of such a large scale change to aviation – now they could observe it firsthand.  David McCandless produced this marvelous diagram for his information is beautiful website  to illustrate the carbon dioxide offset by all those grounded flights. He references his sources here.

Let's take the idea one step further. Instead of European flights, what would be the impact of grounding all the flights in the world? (on a side note, the video below- an animation of all the flights in the world - makes fascinating viewing).

Each year, 165 member countries report their greenhouse gas emissions the United Nations Framework Convention on Climate Change. The World Resources Institute (WRI), a global environmental think tank, compile this data to produce a comprehensive database of global emissions. According to the WRI, 1.6% of global greenhouse gas emissions are from aviation. So the impact of not flying would be relatively small right?

Not quite. Aviation emissions have a threefold effect. Firstly, there's the direct emissions. Next, the high concentrations of nitrous oxides emitted by planes induce the formation of ozone, another greenhouse gas, which causes further warming. Finally, aircraft contrails - water vapour tracks drawn in their wake - are thought to induce clouds which further enhance warming. Once these two additional effects are taken into account, the IPCC estimates aviation accounts for 3.5% of total global emissions.

It's still only 3.5% - so why all the fuss about aviation?

It's because of the rate at which aviation emissions are increasing. The aviation industry has grown 9% year on year since 1960. So stop aviation now and you'll be stubbing out a major future emissions source.