A summary of: "The Earth Transformed: Trends, Trajectories, and Patterns" by Meyer and Turner.

The beginning of the previous century foresaw a rosy future, with no limit to environmental capacities to absorb the impacts of economic progress. However, while this thoughtless outlook was acted upon right into the nuclear age, it has proven to be wrong.

There are two truly global systems in our particular environment, that is in our biosphere. They are:

1. The atmosphere: the classic example of changes in a global system are the effect of greenhouse gases on the atmosphere causing global warming, and the ozone depletion from CFC's in the stratophere.

2. The oceans.

If an environmental change occurs locally, but is sufficiently widespread spatially in impact, it may be considered a global phenomenon. These "globally cumulative" changes include deforestation and loss of fish stocks.

Some global and local environmental changes are not manmade, but result from natural fluctuations. For example, marine fish populations which suffer spontaneous collapse from natural cycles, and desertification such as has occurred in the North African Sahel zone since the last Ice Age.

Sometimes data is unreliable and does not reflect reality. Politically suppressed bad news results in false optimism. China has, in the past, reported successful reforestation when in fact forest cover in Sichuan was actually down to 12.6 percent from 19 percent over the past forty years. Due to this type of reporting, sound analysis can be wasted on unsound methodology, and result in false conclusions. The indices of change would suggest at least four things:

1. Human activities are equal or greater than natural forces as driving change in the environment.

2. Most such activities are recent.

3. Acceleration of human impact has not always been the case.

4. Human impacts have expanded in variety and character from involving surface resources to now affecting material and energy flows in the biosphere. Some of the changes in our biosphere since preindustrial times which are related to human activity include the following:

-The world forest cover has been depleted by 20 percent.

-In addition to that, the greenhouse gases have increased: CO2 by 25 percent, chiefly by the mineral fuel consumption of the industrialized world, and methane by 100 percent due partly to the increased cultivation of rice in the developing world.

-Also, we are introducing entirely synthetic organic chemicals into the environment which are having an effect, locally at least, on the reproductive processes of many species of wildlife.

-The measures of trace pollutants are accelerating.

-The use of fresh water by humanity has increased four hundred percent since 1950.

When taking the meaning of global change into consideration, the bottom line is concern over economic and social consequences, not concern over biological change in the biosphere per se. For instance, the impact of drought caused by global warming is local, and my be coincident with improved conditions elsewhere (northwards). A more alarming consequence than drought will be sea level rises great enough to sink the world's seaports and the all important coastal settlements where so many of the world's people now live.

While the people of the industrialized north may be able to respond to sea level rises, the poor of the third world will not be able to mount an effective response.

For instance, while Rotterdam may be able to protect itself, at great expense, from a rise of five metres, there are many south pacific atolls inhabited today which will become merely undersea hazards to navigation after such a sea change.

There are four "Nature Myths" which, depending upon the one we subscribe to, will colour our response to the global changes taking place. They are:

1. Natural systems are resilient and self-correcting (the Gaia hypothesis) therefore little need for restraint in exploiting the environment is called for.

2. Natural systems are resilient within limits, little affected by shocks, therefore there is need only for enough caution to avoid willfully triggered disaster.

3. Natural systems are inherently fragile, likely to react to mild pressures causing imbalance and therefore there is a need for extreme caution to avoid disasters.

4. Natural systems are capricious and unpredictable, like the eruption of long quiet volcanoes and the devastation of large meteor impacts, therefore disaster is inevitable and regulation futile.

All of these four opinions are possibly reflecting the social status of those who hold them, since in their own way these opinions of the natural order of the world in which we live allow to some degree either egalitarian or elitist stances towards nature, mitigating on the one hand, or dismissing on the other, our potential entrepreneurial engagement with the resources of the planet.

Human impact on the environment may be a result of population, resource use per capita, and technology (Erlich and Holdren's 1971 PAT formula). However, regional impacts are often actually a result of institutional policy, the political structures, trade relations and even of belief systems (attitudes). At a subglobal level these forces overshadow the PAT drivers of change.

The impact of change on food supply and economies are severest for the tropical world, and there is found the least capacity to respond to such change. The "Project on Critical Environmental Zones" examined 9 regions in the world and found that the worst was that of the Aral Sea bordering Kazakhstan and Uzbekistan. Water drawn off from tributary rivers drained the Aral Sea itself, salinity increased, fish died off, the ports were left high and dry, miles from the waterfront, and airborne salts poisoned agricultural land. Serious human health problems were found to have resulted from salts, fertilizers and pesticides.

Also found endangered, in addition to Africa's Lake Chad which is well documented, are the Basin of Mexico, The Sundaland of Indonesia/Malaysia, the Ukanbani in southeast Kenya, the Ordos Plateau of north China, all being regions where the trajectories of environmental change put sustainability of human use into question. Amazonia, the Llano Estacado and finally, the North Sea Basin are also areas of extreme concern because of the rapid change which has occurred in those environments since the turn of the previous century.

The lessons to be learned here include:

1. There are lanrge regions where environmental degradation jeopardizes livelihood, change outstripping our ability to adapt.

2. Management response is inadequate: a do-nothing response often being the preferred one.

3. Global problems require negotiations and agreements among many nations, complicating any response.

In conclusion, by humankind altering the physical conditions of the environment, we have inherited an "earth transformed". The 21st century will see no frontiers left, all lands being formally managed. Will it actually be possible to manage our only collective home, planet earth?