1998 was the hottest year of the millennium. The 6 hottest years on record have occurred during the 1990s. Temperatures have risen about 0.6 degrees centigrade since 1860 when records began
The distressing effects of extreme weather events have been illustrated only too clearly by recent floods in China, Bangladesh, Europe, Venezuela and Mozambique, famine in Sudan, and Hurricane Mitch in Central America. Such events have killed thousands of people, displaced millions and caused massive financial losses
Studies have indicated that an increase in global temperature may lead to an increase in both the frequency and the intensity of future El Niņos. Robert May, UK Government Chief Scientific Advisor said that "if global warming continues, perturbation to weather systems like this are likely to become more common"
Extreme weather events could become more common if we fail to take action to cut emissions of greenhouse gases now.
It is no longer a question of whether the earth's climate will change but when, where and by how much." John Robert T. Watson, Chairman of the United Nations Inter-Governmental Panel on Climate Change, 1999.
During the closing decades of the 20th century record breaking temperatures and a run of extreme weather events rang the alarm bells. The trend is continuing into the 21st century and this briefing catalogues some of the extreme weather events that have occurred during the last few months, along with signs in the environment that our climate is really changing. Man-made emissions of greenhouse gases are agreed to be the key contributing factor to climate change. The most important of these gases is carbon dioxide which is released when fossil fuels - coal, oil, gas - are burnt.
The 1990s were not only the warmest decade of the 20th century but also of the millennium [2]. In addition to this trend of higher temperatures we can also expect increases in the following:
- intense precipitation
- long dry spells
- frequency of hurricanes
- extremely high temperature events
Furthermore, there is the possibility of unpleasant surprises, as the response of the climate system to radiative forcings could be non-linear, with quite irregular changes such as fluctuations in the behaviour of El Niņo, one of the main drivers of climate variability, and stagnation of the Ocean Conveyor Belt.
The economic costs of climate change are now recognised. In November 1998, the Worldwatch Institute and Munich Re - the world's largest reinsurer - issued a report which assessed the total losses, worldwide, from storms, floods, droughts, and fires for the first eleven months of that unusual year. The staggering sum, at that time, was a record $89 billion: nearly 50 percent higher than the previous record of $60 billion in 1996. In addition to material losses, these weather-related events had taken an estimated 32,000 lives, while displacing 300 million people from their homes: more than the populations of Canada and the United States combined. [4] The insurance industry is certainly worried about the soaring costs of severe weather damage and is already refusing cover for various weather events in certain regions.
We cannot say for certain that individual events are the direct result of human influence on the climate, but they do show how vulnerable we are to climate changes and highlight the inadequacy of existing coping strategies. Reflecting on actual recent events brings home the immediacy of climate change amid the understandable preoccupation with what lies ahead.
Dramatic as such crude statistics are, they hardly begin to describe the devastating impact that individual weather events can have on the lives of the people affected - or indeed, the scale of the problem if governments do not act to limit future climate change.
Obviously, there are many uncertainties associated with climate modelling, and so far, not one single extreme whether event can be directly attributed to climate change. But in light of the evidence that climate change is happening already, and the knowledge that weather extremes pose real risks to human life and economic well-being, predictions should not be taken lightly. The extreme weather events which have characterised recent trends have all too often been a source of misery to many. Major cuts in greenhouse gas emissions are needed urgently to slow down climate change and eventually stabilise concentrations of greenhouse gases in the atmosphere.
WHAT ABOUT EL NIŅO?
The El Niņo Southern Oscillation (ENSO) is a naturally occurring phenomenon. Weakening easterly trade winds result in higher sea temperatures in the tropical pacific, and cause major changes in global weather patterns. El Niņos are set in motion at irregular intervals, altering the course of weather and climate, around the world, for up to a year or so. The most recent were in 1982-83, 1986-87, 1990-95, and 1997-98. The record-breaking and long-lasting El Niņo of 1997-98 began in April of the first year and persisted until May of the next. During this period, extreme weather events were reported from around the world.
The 1997-98 El Niņo almost certainly contributed in establishing 1998 as the world's warmest year on record. The most severe drought of the 1997-1998 El Niņo struck Indonesia, with the result that many of the fires commonly set to clear land for agriculture raged out of control for weeks on end. So much ash was carried into the air that respiratory problems were reported as far as 1000 km (about 600 miles) away, and the loss of visibility was held responsible for the crash of a commercial airliner. El Niņo-related drought and associated wildfires continued into 1998 in Brazil, Mexico, and Florida. As expected with El Niņo, flooding hit Peru and Ecuador but also Chile, and coastal fisheries were disrupted. [4]
Predictions about future El Niņos are hard to make, but the probability that they will be of increased intensity and frequency due to higher global temperatures might spell out more misery for many of the world's nations.
CONCLUSIONS
Recent years have seen a number of 'floods of the century' and the hottest year on record. In the short-term it is difficult to distinguish between natural variability and climate change, so it is not possible to definitely link a specific weather event (or sequence of events) to climate change. However, there are indications that the human footprint on the climate system is becoming increasingly visible. The IPCC said in 1996 that recent changes in climate are "unlikely to be entirely natural in origin".
The next IPCC assessment report (third assessment report, TAR), due out in spring 2001 is expected to produce more evidence.
It is clear however, that climate change threatens more frequent and extreme weather events such as those experienced recently and catalogued in this briefing. Droughts, floods, cyclones and storm surges, with knock-on effects for ecosystems, fires, pests outbreaks, human health, our settlements and food security, might increase in frequency and intensity. For millions, this could mean homelessness, missing relatives, crop failure, famine, disease or death. It is the poor countries which are likely to suffer most. The industrialised countries, having polluted the atmosphere with greenhouse gases over the last century, will also be hit. But they will be much more able to react to extreme weather events and to protect their people.
Avoiding such an outcome will require deep cuts in emissions of greenhouse gases now.
