Climate Sense

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Observing and understanding the ocean

Dr P. Bernal, Executive Secretary, The Intergovernmental Oceanographic Commission,

and Assistant Director-General, United Nations Educational, Scientific and Cultural Organization

he ocean plays a key role in regulating the climate system:

capturing, transporting and releasing vast quantities of

heat, the ocean serves as the memory of climate, influ-

encing patterns of drought and flood over land. The ocean is

inexorably rising, expanding in volume as it warms, and from

the landlocked ice that melts into it.

Permanently absorbing nearly two billion tons of human-generated

carbon from the atmosphere every year – and therefore reducing the

speed of change – the ocean has already spared us from catastrophic

climate change. Eventually the ocean will absorb most of the addi-

tional carbon civilization produces. However this is happening at

the expense of the health of the ocean. A direct consequence is the

growing acidity of the ocean, and the impact this has on ocean life

and ecosystems.

The ecological services the ocean provides are fundamental to

the maintenance of life on Earth. This makes the ocean the ultimate

global commons, because all humankind has a stake in preserving a

healthy, functioning ocean.

But many questions remain unanswered:

• How will the ocean capacity to absorb carbon evolve?

• What will the impact be on marine ecosystems?

• Are there tipping points in ocean circulation that by locking the

climate system in a different equilibrium could lead to sudden

changes in patterns of drought and rainfall over land?

• How are human stresses on the marine environment exacerbated

by climate change?

In the past decade, we have started to systematically observe the

ocean for the first time in history. In May 2009, 8,132 automated

platforms collected data from the ocean. The Argo Project has

seeded the ocean with more than 3,000 robotic floats evenly distrib-

uted across the globe. These floats park at a depth of 2,000 metres,

rising once every ten days to the surface, measuring physical prop-

erties on their way up and transmitting their data by satellite once

at the surface.

Today satellites measure the surface of the ocean with great preci-

sion. They record changes in temperature that set the atmosphere

in motion, measure the height and shape of the sea surface which

reveals the speed and direction of the currents below, and derive the

strength of the wind on its surface from observing and quantifying

the waves it whips up. Around the world tide gauges record changes

in sea level with high precision for climate monitoring, and with

high speed for tsunami alerts. The data are used for climate monitor-

ing, research and forecasting, but also to support weather and ocean

forecasts, as well as hazard warnings. Without ocean information

it is impossible to predict seasonal rainfall anomalies, the appear-

ance of El Niño, or the extent of local sea-level rise. We

would have difficulty predicting the amount of carbon

in the atmosphere, and how fisheries will evolve under

the effects of climate change.

The Intergovernmental Oceanographic Commission

(IOC) recently reported to the state parties of the

United Nations Framework Convention on Climate

Change that this success in expanding ocean observa-

tions rests on tenuous ground. While many nations

contribute to sea level measurements along their

coasts, only a limited number of nations contribute

much to the satellite and in situ observing systems. On

the satellite side, many of the ocean observing devices

are launched as part of ‘research missions’, and the

transition from these ad hoc missions to a long-term

sustained monitoring effort has been extremely difficult

to achieve. The European Union has made good strides

into making commitments to sustaining essential ocean

climate observations from space. But too many of these

observations rely on research-based voluntary support

structures that were never meant to sustain an observa-

tion and information system over the long-term. Until

now following a policy of ‘business as usual’, nations

of the world are not rising to the challenge of building

perennial structures to monitor the ocean, a key part of

the climate and life support system of the Earth.

These observations have been crucial in improving

the scientific understanding and our ability to better

predict the global climate system. In 2007 the Fourth

Assessment Report of the Intergovernmental Panel on

Climate Change categorically stated that climate change

was ‘unequivocal’, based in part on the assessment of

nearly 300 scientific papers written by oceanographers

drawing on these new ocean observations. They noted

evidence that the average temperature of the global

oceans has increased, and that the ocean has been

absorbing more than 80 per cent of the heat added to

the climate system.

We also know that many centuries of change in the

climate are already in the pipeline and will take place

based solely on past emissions from human activities

thus far since the beginning of the industrial age. So

even if strong controls on emissions are negotiated,

human populations, and particularly those in the devel-

oping world, will have to adjust to a changing climate,

with different patterns of rainfall and drought and rising

sea levels. It seems obvious that to underpin these diffi-

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