Our directory of things of interest

Unnatural Climates

  • Written by  Chris Caseldine
  • Published in Opinions
Unnatural Climates ahupepo
08 Jul
Whether anthropogenic climate change began over 8,000 years ago or within the last few centuries, our inadvertent experiment in climate geoengineering is now not only discernible in its effects, but is also providing major challenges for ourselves and future generations

Whatever action we take, from managing greenhouse gas emissions to active solar radiation management, it will have climate consequences. It’s therefore appropriate to ask two fundamental questions related to climate as a context for current and future actions: 1. What is or would be ‘natural’ climate, without human interference? 2. What sort of climate is the objective of intervention by whatever chosen method?

Establishing the character of ‘natural’ climate is made difficult by our potential influence over the Holocene, especially if we have indeed had a long Anthropocene with human changes in greenhouse gas emissions over several millennia. However, from our study of the Holocene and earlier interglacial climates it is possible to infer the climatic results of the continuing interplay between the changing astronomical position of the Earth, solar irradiance variations and episodic volcanic activity.

By running these natural variations forward in time we can project a future pattern of climate variations over future decades, centuries and millennia assuming we were not here. This is, of course, of little value for our immediate concerns but provides a context for current debates – there is for instance the possibility that we may have been heading close to a tipping point for Ice Age inception prior to greenhouse gas use, and given the impact of CHCs and their like we now have the technology to offset any future glacial threat.

Defining ‘natural’ climate is however tricky in deciding what criteria to use. Over a millennial time scale it is probably best to consider GHG concentrations as they best define previous glacial/interglacial changes; any drop below ca. 270ppm CO2 would be likely to take us out of an interglacial. As we head into concentrations well in excess of those experienced for several millions of years, a ‘natural’ climate seems a long way off.

Climate stability is a difficult concept to define, and even more difficult to achieve

Mean temperatures at various spatial scales provide another approach using the Holocene as a template, the range of temperatures providing a ‘natural’ envelope. This has the advantage that it accords with the messages coming from the IPCC and other bodies of a need to restrict temperatures to no more than 1.5°C as in the Paris agreement.

Increasingly though messages are couched in terms of avoiding dangerous climate change and the need to return to some stable climate state. The Holocene is seen as a period of stable climate, lacking abrupt change and periods of climate getting out of control. Climate stability is, however, a difficult concept to define, and even more difficult to achieve. While it is likely that a loss of Polar ice would lead to potentially unstable global climate, there is a danger in assuming that without us global climate was rather akin to the Garden of Eden and somehow ‘safe’. We need to recognise the still uncertain and variable climate that occurs with or without human activity.

The difficulty of deciding how to define ‘natural’ climate means that when we examine the objectives of organisations and individuals in terms of climate it is not surprising that they are expressed in varying ways. Whether expressed in terms of greenhouse gas emissions or global temperatures, or as climate we do not want to experience, the objectives can appear vague. As the various sides of the climate debate become more entrenched, the terminology inevitably mirrors this, with the idea of there being a climate solution for instance, implying that if only we do A or B climate will return to ‘natural’ and hence be a beneficial and well-behaved part of the Earth system.

‘Natural’ climate is not benign; from a human perspective the climate of the Holocene within which civilisations developed has been one that human societies have coped with and at times benefited from. It has also been a period when extreme climate events have affected, and continue to influence the way we live. To anyone suffering droughts, hurricanes or floods, climate is still a problem and it is here that the promises of climate geoengineers add a further complication. Climate geoengineering, especially the quick fix of solar radiation management, offers a way to offset greenhouse gas influences and manage (stabilise?) climate. If it were used and successfully limited warming without any of the perceived associated risks, then important ethical questions would remain. Extreme climate events are part of our Holocene climate experience and can have devastating impacts on human societies. Once we manage our climate to keep it as ‘natural’ as possible, however defined, then why should we not use such interventions to make life easier for those suffering from climate disasters? ‘Natural’ climate comes with many risks for humans, it is not a perfect world.

Chris Caseldine is Emeritus Professor at the Centre for Geography, Environment and Society at the University of Exeter

This was published in the July 2016 edition of Geographical magazine.

Related items

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe Today

Adventure Canada


Aberystwyth University University of Greenwich The University of Winchester




Travel the Unknown


Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    The Air That We Breathe
    Cities the world over are struggling to improve air quality as scandals surrounding diesel car emissions come to light and the huge health costs of po...
    Diabetes: The World at Risk
    Diabetes is often thought of as a ‘western’ problem, one linked to the developed world’s overindulgence in fatty foods and chronic lack of physi...
    The Nuclear Power Struggle
    The UK appears to be embracing nuclear, a huge U-turn on government policy from just two years ago. Yet this seems to be going against the grain globa...
    The true cost of meat
    As one of the world’s biggest methane emitters, the meat industry has a lot more to concern itself with than merely dietary issues ...


NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in OPINIONS...


Would North Korea give up its nuclear weapons? Would an…


It’s time to tackle the hidden superbug menace in India’s…


Earlier this month, an international sustainability conference brought together 400…


On the Southern edge of the remote Kongsfjorden (King’s Fjord)…


Exploring outdoors and in different places is important throughout our…


Something has gone badly wrong with our planet’s oceans. If…


Taking a wider look at Brexit from a geography standpoint


The blockade of imports into Qatar by its Gulf neighbours…


Is it time for a new and radical approach to alleviating…


Plastic-free aisles in our local supermarkets may just be key…


As reports of tourists being fed dog meat in Bali…


The idea of rewilding boar into the UK’s landscapes is…


2017 is the Chinese year of the chicken. This year, the…


Despite the many claims of authenticity, modern filmmaking is still…


With medical (and especially dental) tourism on the rise, Vitali…


More drugs than you might think are derived from, or…


The growth of cities is one of the defining challenges…


On a long-awaited return to Ukraine, Vitali Vitaliev finds a…


The world is changing, but one thing stays the same…


We live in an age where awe and wonder at the…