How can the human population explosion be curbed?

Obviously this is an extremely sensitive and political issue but the facts are simple – there are too many people in the world for the finite number of resources it holds. This issue must be raised fearlessly if the world is to survive as we know it. More people will only impact the earth further.

What are the consequences of land cover and land use change for human societies and the sustainability of ecosystems?

The environment of the Earth has many close connections and relationships with human activity. It is also now more widely recognized that a profound transformation of the Earth’s environment is taking place and that many of these changes are the result of human action. Growing world population and increasing wealth are driving demands for more food production. Croplands and pastures occupies today roughly 40% of the land surface and global land cover and is according to the Millennium Ecosystem Assessment (MA) the main modification humanity makes to land cover, and therefore a main driver of ecological change, and biodiversity loss at the global scale.

Current trends in land use allow humans to appropriate an ever-larger fraction of the biosphere’s goods and services while simultaneously diminishing the capacity of global ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and mediate infectious diseases…
Modern landuse practices, while increasing the short-term supplies of material goods, may undermine many ecosystem services in the long run, even on regional and global scales. Confronting the global environmental challenges of land use will require assessing and managing inherent trade-offs between meeting immediate human needs and maintaining the capacity of ecosystems to provide goods and services in the future. Assessments of trade-offs must recognize that land use provides crucial social and economic benefits, even while leading to possible long-term declines in human welfare through altered ecosystem functioning.
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How many humans can the earth system sustain under different scenarios of “development status” that exist in current societies?

There is a need to link current limits in natural systems (e.g. freshwater resources, agricultural productivity, natural versus altered habitats, ability of ecosystems to tolerate pollutants, etc) to the size of the human population, recognising that the earth system does not have infinite resources. This can help contextualise current conflicts, anticipate future ones and indicate limits to growth that should inform all individuals. This is a politically-sensitive topic that needs to be addressed from local to global scales in order to understand the consequences of global change in the future.

Where and how will population pressure and climate change affect the availability of freshwater for human needs and diverse ecological communities?

Regional patterns of population pressure and human demands for freshwater will likely interact with the effects of climate change to alter the distribution and availability of freswater across the face of the globe. Humans and freshwater/estuarine ecosystems will both suffer. We need to be able to predict the effects of climate change on freshwater resources in order to understand how humans and ecosystems will be threatened by lack of adequate freshwater, and by loss of the ecological goods and sevices provided by rivers and estuaries (e.g,. fish, fibres, flood mitigation).

How can the future growth of settlements in the third world (Africa) be sustainable and planned?

The recent UN-HABITAT (2008) report on rate of urbanization said that the number of people of living in urban areas will more than double its 2007 level of 373.4 Million by 2030. Unlike in the developed western world where the urbanization process is taking place within a planned environment, in Africa the cities are growing without any plan or pattern. Slums are in the increase all over the cities of Africa with its attendant consequences of crime, poverty and health problems which has the capacity to truncate any global effort to make our earth a better and safer place. We must therefore address the root causes of unplanned growth and institutionalize community planning so that each community within and outside the cities of Africa and other developing countries would see the beauty of planning so that the towns are not only planned but provision are made for conservation and environmental protection.

How can we develop empathy for a global environmental system?

In the past conflicts and wars were mainly about self-determination and food (18th and 19th Century) and space and resources (19th and 20th Century). Looking to the future and the 21th Century we will see more and more conflicts due to the overuse of environmental resources and systems. We are now living in the Anthropocene and human interference is reaching into nearly every natural system. This will lead to major changes in those systems with possible catastrophic consequences. The increasing world population will become more vulnerability to environmental threads.

Since the 1960s an environmental movement has established. Notable cornerstones are the book “Silent Spring” by Rachel Carson and the foundation of the “Club of Rome”. Only a small percentage of the western world population is aware of their environmental impact yet. It will be a major task for the 21th Century to establish a global awareness and empathy for nature. This is not anymore a blurred hippie idea, but a necessary step to enable a global sustainable development. We will have to achieve that every person realizes the environmental consequences and systemic impact of its action.

The question is, in which way can Earth System Research contribute to this.
Education and outreach need to be enhanced. Research results need to be translated to the public in a comprehensive way.

Current trajectory of human action is not sustainable at a global scale: how can scientific understanding of complex systems and human perturbations devise sustainable development pathways across the scientific, policy and resource management divide, particularly at the regional level where most decisions are taken?

During the last 50 years the human population has risen from to 2,5 to over 6 billion. The use of land, water, minerals and other natural resources has increased almost ten-fold over the last two hundred years and approximately 50% of the ice-free land surface has now been significantly modified by humans and most of the rest is managed for human purposes. This phenomenon, which has obvious implications, creates the need to study the interactions, which occur on different temporal and spatial scales, affecting the biosphere and which are particularly susceptible to human actions, especially the efforts to provide a growing human population with food, energy, shelter and employment.

A global change research perspective which places primary emphasis on the global scale often misses a vast amount of work, frequently done under other guises, which is directly relevant to the study of global change phenomena. Such work is crucial for understanding the underlying processes which when aggregated constitute global change. Ultimately global change research will provide much of the underlying scientific understanding of complex systems and human perturbations that is required to devise sustainable development pathways at regional level. The drive for sustainability – the desire to make the development of the growing ‘human enterprise’ more compatible with the natural evolution of the Earth system – gives global change research its most fundamental rationale and connection to applications in policy and resource management. Where global change research is weak – application of the work through interaction with the policy and resource management sectors, sustainable development science is strong; and where sustainable development work is often weak – understanding the fundamental dynamics of complex environmental systems, global change research is strong. Clearly, the two fields of enquiry should work in much closer harmony in the future.

How can we establish and maintain a sustainable relationship between humans and the rest of the living world?

This is without doubt the most important and challenging question that has ever faced our species.

Our present use of the planet is not sustainable. Achieving “a sustainable relationship between humans and the living world” will require a huge intellectual, scientific, technological and social effort.

Whatever sustainable means, maintaining the current number of humans is not an option, and we cannot continue to extract services from the natural world at the rate we do today. Stopping soil erosion is not enough; nor stopping climate change; nor is stopping the fragmentation of habitats or the damming of rivers. Sustainability is not just a matter of making sure that the rate of use does not exceed the rate of replenishment. We must reverse many trends, overhaul our organisations and the way we do things, and considerably improve the processes we use to grow and prepare food, clothes, and other material goods, and to transport them and us around the place.

If we are to meet this grand challenge one thing is essential: the contribution of science in all its many flavours.

Understanding how to establish and sustain a balanced relationship between humans and the rest of the living world will certainly need reductionist, rational, value-free and quantitative knowledge of the natural world and its interaction with our activities. But it will also require holistic, partly intuitive, ethical and qualitative knowledge, accumulated empirically over a long time and through learning by doing.

Let us direct every effort towards understanding, and increasing the capacity to understand, our living planet as a single, complex entity.

We need many more socio-ecologists out there doing anthro-geo-physiological fieldwork. We also need philosophers and communicators and people who delight in studying and understanding complex, interacting, self-regulating, far-from-equilibrium, self-organising, ambiguous, borderless systems.

Let us learn how to expect the unexpected.

How can semi-arid agrosystems adapt to expected changes in climate and anthropogenic forcing?

Due to growths in water scarcities and population needs, agrosystems in semi-arid region have to increase their agronomic performances in terms of water use efficiencies and yields, where both can be regarded at the scale of regional watersheds that include several compartments (shallow and deep aquifers, crop mosaics, hydro-agricultural constructions) in relation with distribution of blue and green water. Decision support systems for the benefit of stakeholders have to be strengthened by relying on biophysically based modeling platform that encompass the aforementioned compartments and the related water flows. This requires first parameterizing and calibrating the modeling platform components, where the use of remote sensing if of prime interest for constraining models in a spatially distributed manner, and then setting up realistic scenarios from the calibrated modeling platforms. In this context, special efforts have to be made over relief areas, where hilly structures allow water harvesting for irrigation purposes, and therefore the maintaining of agricultural populations along with their economical activities.

Local carrying capacity and sustainability: to what extent can “reduce, recycle and re-use” help to re-define constraints on population growth? To what extent is globalization contributing to carrying capacity in the short-, medium- and longer- terms?

Such answers might help people understand their profound dependence on ecosystems for their survival and thus perhaps influence policy.