The Full Picture

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Understanding the coupled human-environmental

Earth system: science without borders

Kevin Noone, International Geosphere-Biosphere Programme (IGBP)

n enduring legacy of the Apollo space programme of the

1960s is the iconic ‘Earthrise’ image of our planet taken

from the perspective of a tiny spacecraft in orbit around the

moon. It was the first time that millions of humans had the oppor-

tunity to see our home planet as a single entity. They got a glimpse

of a connected system that transcended the political, social,

economic and even scientific boundaries humans have projected

onto it. Continents, oceans, clouds, and the fantastically thin shell

that is our atmosphere all appeared together as a beautiful whole.

From a scientific perspective, these images helped to stimulate us

to rediscover the science of the Earth system.

The Earth system has been connected on a planetary scale since life

first appeared on it more than three billion years ago. Ever since, the

Earth has existed as a highly coupled, interdependent system of compo-

nents and processes, all of which operate on a multitude of temporal

and spatial scales. Throughout most of our history, humans have only

viewed and experienced the Earth system on small scales: through the

prism of our villages and settlements, and later our cities and nations.

Even though humans have transformed the environment in very impor-

tant ways throughout history, it has only been in the last century or so

that human activities have begun to match (and often exceed) the

natural forces that regulate the Earth system. Recent ice core data show

that current levels of carbon dioxide and methane are well outside the

range of natural variability over the last 800,000 years.

Roughly half of the world’s ice-free land surface has been altered by

human actions. Humans now fix more nitrogen than nature does.

Particles emitted by human activities alter the energy balance of the

planet, as well as having adverse effects on human health. These may

seem unrelated issues; however, over recent decades we have gained a

deeper understanding of the degree to which all of these separate issues

are linked. The Earth system is very complex with myriad feedbacks,

and has exhibited rapid, global-scale responses to changes in environ-

mental conditions. Humans, rather than simply affecting or being

affected by the natural environment, are a central component in the

Earth system. Within the Earth system, there are feedbacks and tele-

connections that operate on a planetary scale, and in which humans are

directly involved.

Bridging the spatial and temporal scales of the different interacting

processes in the Earth system and putting together the many different

disciplines (from both natural and social sciences) is a huge challenge

for the scientific community.

For the global change research community, a further challenge is to

present research results in more accessible and informative ways to

stakeholders, particularly those concerned with sustainable develop-

ment. We are frequently expected to answer questions on

the effects of global change on regional and even local

scales. Stakeholders seek strategies to deal with future

environmental change, most often with a place-based

perspective. This is particularly important for the devel-

oping world, since the capacity to adapt to local or regional

changes driven by global factors is often limited.

The need to understand how the natural world works

has not diminished, but in fact underpins the answers to

questions of sustainable development. We must continue

to concentrate on first-class science involving the inter-

actions and feedbacks between biological, chemical and

physical processes and human systems. However, scien-

tists, resource managers and policy makers require a

common understanding in order for their interactions to

be mutually beneficial.

The kinds of questions now being asked of the research

community have changed over the last decades, and reflect

the increasing appreciation of the interconnectedness of

the Earth system. In the past, many scientific questions of

societal importance could be successfully addressed by

concentrating on either individual, or a small number of

the components of the Earth system, even though answer-

ing the questions still required international,

interdisciplinary collaboration. For instance, finding out

what caused the development of the Antarctic ozone hole

required international collaboration among atmospheric

chemists and meteorologists.

In contrast, the kinds of questions now being asked of

the scientific community show the increasing need for

a more holistic approach. Questions such as: can global

warming, urban-industrial emissions and land cover

changes influence the Asian Monsoon circulation? How

will changes in precipitation patterns caused by global

warming influence water management policies, on

regional and local scales? What will be the consequences

of large-scale land use and ecosystem changes caused

by moving towards biofuel production? What are the

impacts of the predicted climate changes on food

production and human security? What role does urban-

ization play in the health effects of air pollution? Do

megacities play a role in affecting the energy balance of

the planet and in the hydrological cycle? What form of

carbon sequestration scheme will have the smallest

negative impact on the earth system?

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