Illustration: Ruth Bowers
Our world is unsustainable right now in the way it operates. Our
incipient macroeconomic recovery is very fragile and will be
unsustainable unless we have what we promised we would have but do
not yet have - a green recovery. We will not even be able to manage
a short-term macroeconomic recovery unless we integrate strategies
for climate change mitigation and adaptation into our macroeconomic
Humanity faces a dire and growing crisis. Sustainable
development is truly the fundamental challenge of today's world:
how to combine economic growth with environmental sustainability,
including the mitigation of human-induced climate change.
Technological advances in the past - such as the mobilization of
fossil fuels and the spectacular increases in food production
flowing from improved plant breeding techniques - have both raised
our living standards and imposed unanticipated and unwanted side
effects on the environment. All technological solutions are
imperfect. We must be agile in adjusting to the unanticipated
consequences, rather than giving up on the benefits of advanced
Nobel laureate Paul Crutzen, one of the three atmospheric
scientists who discovered the ozone-depletion effect of
chlorofluorocarbons (CFCs), has coined the phrase "anthropocene"
for the current period of the Earth's history. By this new term,
which is Greek for "human-made epoch", Crutzen means that humanity
has seriously disturbed many critical Earth systems. Crutzen should
know, since he helped to discover how humanity had accidently
overtaken the natural process of ozone creation in the stratosphere
through the use of CFCs. Ironically, the ozone-depletion effect was
not even suspected at the beginning of the 1970s, at a time that it
was already quite far advanced.
There are no doubt many more such surprises to be uncovered, or
learned the hard way, because we are likely unaware of some of the
serious damage that humanity is inflicting on the planet. The size
of the human population - 6.8 billion people - and the scale of
economic activity - US$ 10,000 output per person - is now so vast
that anthropogenic (human-made) interference in the Earth's natural
systems is vast and still poorly understood.
Humanity is now demanding so much food, including feed grain for
livestock, that humanity as a whole is now directly or indirectly
appropriating around 40 per cent of all the photosynthesis
occurring on the planet. We're commandeering the photosynthesis in
our croplands and in our pasturelands, and we've eliminated the
photosynthesis in the places now under our buildings, streets and
other human-built structures.
With so much photosynthesis being commandeered by humanity, it
is no surprise that much less food and habitat is available for
other species. Our huge appetites are therefore inducing dramatic
population declines and even the extinction of the flora and fauna
on which we depend. The pollinators are disappearing, whole classes
of amphibians are disappearing, fisheries around the world are
We're also fundamentally interfering in the hydrologic cycle
through the extensive damming of rivers, preventing many of the
largest rivers from even reaching the sea. A significant part of
the groundwater used for irrigation around the world is being
discharged faster than it's being recharged. The water table is
falling sharply in India, China and parts of the United States.
Our glaciers are retreating. Some precipitation in the mountains
never turns to snow anymore because of the warming, and that means
we get winter run-off of the water, rather than snowpack which
melts in the spring and summer. As a result, the run-off is
occurring before the crops can develop.
To produce food, humans are now putting more nitrogen on the
land in the form of chemical fertilizer than is naturally fixed by
normal biological and physical processes. This heavy deposition of
nitrogen is contributing to the emission of nitrous oxide into the
atmosphere, a greenhouse gas, and to the massive discharge of
nitrogen into rivers. The result is that nitrogen accumulates as a
nutrient in the mouths of the great rivers, causing eutrophication
and then hypoxia - dead zones - in more than 100 estuaries around
the world. We are killing off one of the most important and
productive of the Earth's ecosystems.
We have, of course, also raised by one-third the carbon
concentration in the atmosphere from about 280 parts per million of
CO2 in the pre-industrial era, to about 389 parts per million now.
And carbon dioxide, of course, is the main greenhouse gas, the main
anthropogenic cause of climate change, and also the main cause of
the acidification of the oceans. Dr James Hansen, my colleague at
Columbia University and the American Government's leading climate
scientist, says that we've already passed into the danger zone,
what is called "dangerous anthropogenic interference in the climate
system", in the UN Framework Convention on Climate Change.
Much of the CO2 emitted into the atmosphere today will remain
there for centuries, causing climate change that will affect future
generations for centuries as well, unless we learn to reverse the
rise in CO2 through some deliberate processes. Moreover, as we
clean up air pollution, it is likely that we will remove
particulate pollution which is currently masking some of the
greenhouse gas effect. Ironically, lower pollution - which we need
for human health - could thereby expose us to a burst of further
Climate change will mean more droughts, more floods, loss of
irrigation water, more intense rainfall, more extreme hurricanes
and much more, of course with a high degree of variation around the
globe. Higher temperatures will also likely mean the decline of
crop yields in many places, notably in the tropics, because of
What I have described would be true even if we stopped further
economic growth, and stabilized the magnitude of the anthropogenic
effects. Yet economic growth is bound to continue, because of both
higher incomes in the developing countries and a rising
Suppose that the rich world stayed where it is right now in
terms of GNP [gross national product] per person and the developing
world catches up over time (as the emerging markets are now doing).
What would that mean for total output in the world? With the rich
world at US$ 40,000 per capita and the world average income at US$
10,000 per capita, full catching up would mean a four-fold increase
in world GNP, assuming no growth of population.
Of course the world's population is growing as well - to about
9.2 billion people by 2050, or another 40 per cent, according to
the UN's "medium" forecast. If we combine a population increase of
40 per cent and a four-fold increase in per capita income in the
world, we would experience a nearly six-fold increase in world
output! Yet today's economic production is already environmentally
unsustainable. How could the world ever succeed in raising world
income six times?
One possibility is that the world economy stops growing. The
results could be calamitous if various regions suffered a sharp
fall of living standards. We notice that no politician is winning
office in the US or Europe promising to cut living standards
The other way to combine economic growth and sustainability is
through technological change. Consider the famous IPAT equation:
I = P x A x T. In this equation, I signifies the
total impact of humans on the environment; P is world population; A
is the level of economic activity; and T is a measure of the
average environmental impact of technology. If population (P) and
per capita income (A) are both rising, then the environmental
impact will also rise unless T goes down, meaning that we reduce
the environmental impact of our technology systems.
We should of course redouble our efforts to stabilize the
population. Countries with rapidly growing populations can achieve
rapid voluntary reductions of fertility. The level of fertility
(five or six children per woman in much of rural Africa) could push
sub-Saharan Africa's population from 800 million to around 1.7
billion by 2050. Africa would suffer enormously. Neither the
economy nor the environment could support that size of population.
The key path to lower fertility is well known. Family planning and
contraception should be available to all households. Girls should
be enabled to stay in school, rather than being forced to marry at
a young age. Women should be empowered to choose to have smaller
families. And child mortality should be reduced, so that families
know with very high likelihood that their children will survive, so
that they thereby have the confidence to stick with smaller
Yet population stabilization will not be enough. We need also to
reduce T. We simply cannot go on with the internal combustion
engine, coal-fired power plants and the current ways that we grow
and eat our food. The planet will not accept a big increase in
world incomes with today's technologies.
What new technologies are needed? When we look at greenhouse gas
emissions, the biggest single emitting sector is agriculture (plus
changes in land use related to agriculture). We need to slow and
then to reverse deforestation, use fertilizer more precisely and
take other measures to reduce the greenhouse gases in agriculture
(e.g., conservation agriculture). The other major emitting sectors
are power generation, transport, industry and buildings (commercial
and residential). We will need new technologies in all of these
We will need a variety of low-carbon methods to produce
electricity. One promising category is renewable energy: wind,
solar and geothermal. Another is nuclear power, though we will need
stringent safeguards to ensure that nuclear fuels are well
Another promising approach is carbon capture and sequestration:
using fossil fuels safely by collecting the carbon dioxide from
combustion and putting it safely into geologic storage under the
The decisions to pursue such alternative methods are societal
rather than merely commercial. Markets and society have to make
choices together. We need cooperation to achieve major changes in
Talking about the problem does not solve it. In the whole world
we don't yet have one full-scale coal-fired power plant that is
capturing and sequestering its carbon dioxide, even though the
engineers and scientists have been advocating the testing of this
approach for more than a decade.
One way to speed the adoption of low-carbon alternative energy
sources is to tax carbon emissions or to subsidize low-carbon
energy, or both. Straightforward carbon taxes are much more
manageable than complicated cap-and-trade systems.
A massive technological changeover requires a complex set of
policies: research and development [R&D], demonstration
projects, regulations, feed-in tariffs, subsidies for consumers for
low-emission technologies, carbon taxes and other tools. We need a
systems approach to technological change, not simply one or two
The way we structure the global climate negotiations is
currently not helpful. Climate change should not be viewed as a
poker game where each country holds its cards close to the vest and
bargains with the other countries.
The climate change challenge is the most complex engineering,
economic and social problem that humanity has ever had to face
together. We should be problem-solving together. All cards should
be on the table. We should be discussing what to do - and how to do
it - for solar energy, nuclear energy, electric vehicles,
sustainable agriculture and more. We should be designing global
demonstration projects and major international R&D efforts. We
should be addressing the solutions sector by sector. Then we'd
start getting somewhere.
We need a process that includes not only diplomats but also
engineers, scientists and hydrologists. We need a new kind of
process. Among other things, the UN Framework Convention on Climate
Change secretariat needs a standing technical body presenting
options and estimated costs of alternative strategies.
Finally, let me emphasize again: we need to make progress fast.
The Earth is under unprecedented stress. We have no time to lose.
And when we act, we need always to keep the needs of the poorest of
the poor paramount. They are dying each year by the millions, of
chronic under-nutrition, preventable and treatable diseases, unsafe
drinking water and natural hazards without proper infrastructure.
In short, millions are dying each year because of their poverty -
and our neglect - and climate change (caused disproportionately by
the rich world) will make it worse, until we act decisively.
In the end, we need global cooperation. We need to remember the
common stakes of all humanity. We need to heed the eloquent and
historic words of John F. Kennedy, as he called on his countrymen
to be brave in the pursuit of peace:
"So let us not be blind to our differences, but let us direct
attention to our common interests and to the means by which those
differences can be resolved. And if we cannot end now our
differences, at least we can help make the world safe for
diversity. For in the final analysis, our most basic common link is
that we all inhabit this small planet. We all breathe the same air.
We all cherish our children's future. And we are all mortal."
This is an edited version of the 14th Raúl Prebisch Lecture.
Presented at the Fifty-sixth session of the UNCTAD Trade and
Development Board, Geneva, 15 September 2009.