Overview

The fuss over change

On a global scale, surface temperatures have risen by about 0.6 degrees Celsius in the last 150 years. By the end of this century, temperatures are predicted to increase even further by about 1.4 to 5.8 degrees Celsius. The untrained eye, the person who has lived through the vagaries of the seasons will wonder what all the fuss is over climate change. After all, temperatures can and do shift much more dramatically than the change being described above.

The swings in temperature are certainly more dramatic when measured over brief periods of time and short distances. Thus, for instance, during typically cold and dry months, the mercury can oscillate by as much as 10 degrees in just one day. But when measured over decades or centuries, temperature is less fidgety, varying only by as much as 8 degrees, and this over thousands of years. On such a long term, large geographic scale, temperature does not seem to change considerably. This has been evident at least in the last 20,000 years.

Which is why upon closer examination of the historical record and of the global extent of the change, the temperature shifts that have been observed and predicted are considered to be substantially rapid and therefore potentially dangerous. This widespread surge in warming has consequences as well on the amplitude of changes in rainfall and wind patterns, sea level, and extreme events such as typhoons. The changes therefore are worth all the fuss and concern because they do pose a serious threat to life and its various support systems, most of which have evolved largely out of a benignly varying climate through the ages.


Reasons for the warming

Contrary perhaps to common intuition, the sun alone is not enough to warm our planet. If this star were the only source of warmth, the earth would be shivering in subzero temperatures. The only reason it does not freeze over is because of the presence of certain gases in our atmosphere that have a remarkable property of preventing the warmth at the earth's surface from escaping into space. This atmospheric blanket of gases is able to contain the warmth that sustains life much in the same way a greenhouse is able to keep interior temperatures warm enough for its resident plants to grow and flourish (see greenhouse effect). These so-called greenhouse gases or GHGs are the natural thermostat of our planet.

The fact that global surface temperatures have been observed to be rising dangerously in the last 150 years has led science to consider the many possible reasons for this trend. The present diagnosis is that aside from fluctuations in solar intensity and sea surface temperatures, it is also the rapid increase in GHG levels in the atmosphere that is behind this planetary fever as well.

Many of these GHGs arise naturally from the regular breathing of our planet but it is only in recent years that the evidence has become clearer: GHGs released from our agricultural, industrial and urban activities far outpace these natural sources. Moreover, current scientific assessments point to the increasing likelihood that the warming of the last 50 years can be attributed to these human activities.

Because the feverish pace at which we are growing is not about to change, and because these GHGs do not readily disappear in our atmosphere, what we have wrought by our rapid, GHG-fueled economic growth, what we may have begun is dangerous climate change.


Our response

Averting climate change is complex because the problem is more than a scientific and environmental issue. The rapid increase in GHG emissions in the last century is difficult to check because, historically at least, these emissions are primarily tied to the economic growth of nations. As such, political, social, cultural, and equity issues often come into play when addressing this issue.

Despite this complexity, we can no longer afford to postpone substantial reductions in emissions that are urgently needed to stabilize GHG levels in the atmosphere. The solution demands no less than a global effort that is integrated with the growth and development of communities and nations. It can only be lasting if it is governed by the principles of stewardship, accountability, and equity. It will be effective only insofar as climate protection strategies and measures are readily translated to the local level.

Our response must be drawn from an adequate grasp and engagement in four areas that are critical to addressing this global issue:

Science
Adaptation
Mitigation
Policy

Science covers the scientific basis of the problem and the geophysical impacts associated with the problem of climate change.

Adaptation focuses on the vulnerability of various sectors to climate change impacts as well as on the adaptation measures that are needed to cope with the change.

Mitigation deals with the effort to reduce the net release of GHGs to the atmosphere and all that this effort entails.

Policy discusses the spectrum of decisions, strategies, and rules that are needed to initiate and implement climate response measures.