Category Archives: greenhouse gas emissions

Climate change: how did we get here, and why is it so hard to fix? (Part 1)

Activities that cause emissions are ubiquitous, diverse and deeply embedded in modern life.  The world’s energy system is huge and long-lived.  This makes emissions tough to deal with. 

This post is the first of two stepping back a little from the specific topics I usually cover to take a very high level look at why the climate change problem is so hard to fix.  This first post looks at how we got here and (at a very high level) the physical and engineering challenges of addressing the climate change problem.  The next post will consider some of the political and psychological barriers to greater action.

The consequence of industrialisation

The world’s climate was remarkably stable from before the birth of agriculture, some 8-10,000 years ago, until very recent times[1].  Human civilisation grew up in a stable climate, and knew nothing else, despite the calamities caused on occasions by storms, floods, drought, and so forth.

Industrialisation changed this.  There is no single year that definitively marks the beginning of industrialisation, but 1776 probably as good a reference point as any.  It was an eventful year, with the US Declaration of Independence giving history one of its most famous dates, while elsewhere the first edition of Adam Smith’s Wealth of Nations was published and the Bolshoi Theatre opened its first season.  But in the long view of history perhaps more important than any of these was that James Watt’s steam engines began to power industrial production[2].  This, more than any other event, marks the beginning of the industrial era.

In the nearly two and a half centuries since 1776, world population has grown by almost a factor of about 10.  Economic output per person has also grown by a factor of about 10.  Taking these two changes together, the world’s economic activity has increased by a factor of about 100.  This has put huge stresses on a range of natural systems, including the atmosphere[3],[4].

The increase in the use of fossil fuels has been even greater than the increase in industrial activity.  Around 12 million tonnes of fossil fuels, almost entirely coal, were burnt each year before 1776[5].  Today the world burns about 12 billion tonnes of fossil fuels each year, an increase of a factor of 1000[6].

This huge increase in the burning of fossil fuels is now – together with deforestation, agriculture and a few other activities – changing the make-up of the atmosphere on a large scale.  This in turn, is changing the world’s climate.   Within a single human lifetime – just one percent or so of the time since the birth of agriculture – changes to the climate are likely to be much greater than human civilisation has ever before experienced.  The consequences of these changes are likely to be largely harmful, because manmade and natural systems are largely adapted to the world we have, not the one we are making.

The characteristics of the systems that have led to these changes also make the problems hard to address.

The scale of emissions is huge …

The scale of CO2 emitted from the energy system is vast, around 36 billion tonnes p.a.  If this were frozen into solid form as “dry ice” it would cover the whole of Manhattan Island to the depth of about two thirds of the Empire State building.

The system that generates these emissions is correspondingly huge.  The world’s energy system cost tens of trillions of dollars to build, and is correspondingly immensely expensive to replace.

The diversity and dispersion of emissions makes the problem more challenging …

The problem is worse even than its scale alone suggests.  It would be simpler to deal with emissions if they were all in one place, whether Manhattan or elsewhere, and in solid form.  Instead emissions are dispersed across billions of individual sources around the world.  And they come from many different types of activity, from transporting food and powering electronics to heating and cooling homes and offices.  There is no single technology doing one thing to be replaced, but a wide diversity of technologies and applications.

And once emissions get into the atmosphere the greenhouse gases are very dilute.  Carbon dioxide makes up only 400 parts per million (0.04%) of the atmosphere.  Among other things this makes capture of CO2 once it has got into the atmosphere difficult and expensive.

And assets producing emissions are very long lived …

Energy infrastructure often lasts many decades, so changing infrastructure tends to be a long term process, with premature replacement expensive.  And on the whole the existing system does its job remarkably well.  Some political considerations aside, there would be little need for very rapid changes to the system if it were not for climate change and other forms of pollution.

Energy is central to modern life …

Finally it’s not possible to simply switch off the world’s energy system because it is essential to modern life.  Hurricane Sandy disrupted much of New York’s energy system, and the consequences of that gave an indication of how quickly modern life collapses without critical energy infrastructure.

These physical characteristics of the problem are compounded by the political and psychological obstacles to change at the necessary scale.  I will return to these in my next post.

Adam Whitmore – 22nd May 2017


[1] This climatically stable period since the end of the last ice age between 11,000 to 12,000 years ago is referred to as the Holocene.  Agriculture started not long after the ice sheets retreated and the world warmed.  Human activity has now led to a new period, referred to as the Anthropocene.

[2]  The first use of the Watt engine to provide the rotary power, which was crucial for factories, was a little later in 1782 at the Soho manufactory near Birmingham.



[5]Reliable data is obviously hard to come by that far back, but See Energy for a Sustainable World: From the Oil Age to a Sun-Powered Future By Vincenzo Balzani, Nicola Armaroli .  They estimate 10 million tonnes in 1700 and 16 million tonnes by 1815.  The majority of the increase would have been in the later part of this period.  See also Socioecological Transitions and Global Change, edited by Marina Fischer-Kowalski, Helmut Haberl, who quote estimates of 3 million tonnes p.a. in 1700 in the UK, a large proportion of the world total at the time, with little increase to 1776.  This consumption included a few primitive, inefficient steam engines, used mainly for pumping water from coal mines themselves.  The Newcomen steam engine required such large quantities of coal that it was rarely economic to site it away from coal mines.  The Watt engine was more than twice as efficient.

[6] My estimate of the total mass of coal, oil and gas, based on data in BP statistical review of World Energy.