Weather, Climate Variability, and Climate Change
By Lareef Zubair (International Research Institute for Climate Prediction)
The air around the earth is a very thin envelope, which we call the atmosphere. The density of this envelope of air decreases from about one kilogram per square kilometer at the earth’s surface to about one-tenth of a kilogram at an altitude of 20 kilometers. Above altitudes of 20 km, it continues to diminish rapidly with distance from the earth. The sun influences the atmosphere by radiative heat. Because of the way the earth rotates on its axis and the way it rotates around the sun, there are seasonal and diurnal (night and day) variations in the atmosphere. Diurnality and seasonality are important characteristics of the atmosphere.
Definitions
- Weather is the current or ongoing state of the atmosphere and is generally predictable up to 10 days in advance
- Climate is the long-term average of the weather over many years
- Climate change is the long-term change in the average state of the climate. It can be predicted, but such predictions are speculative
- Seasonal climate variability comprises the departures from the average state of the climate due to shifts in ocean or land conditions. It may be predictable up to one year in advance
Climate change
There is scientific consensus that the climate is changing, both on a global and on a regional scale. There is a risk that climate change can upset ecological systems that have adapted to environmental niches. The causes of climate change include disturbance in energy balances due to anthropogenic (caused by humans) pollution such as burning fossil fuel. Uncertainty and risk are inevitable in dealing with climate change. Human-induced climate change is also accompanied by equity and moral issues: Who is causing climate change and who pays for the consequences?
Coping with climate variability
The ability to predict climate variations on a seasonal or inter-annual scale presents communities with the opportunity to develop their adaptive capacity. Decision-making is often driven by short-term concerns, and it is thus more feasible to focus on climate variability than on long-term climate change. Developing the capacity and expertise to deal with climate variability also helps prepare communities to deal with the long-term effects of climate change. Measures to adapt to climate variability are needed immediately. Their efficacy can be tested, and such measures, when well formulated and well presented to the public, are likely to enjoy wide community acceptance. The capacity to undertake climate assessments, predictions, and adaptation measures should be developed regionally. To improve capacity, pilot studies are needed that call on expertise from multiple sectors.
What can we do?
- Improve understanding of climate and its relationship to our societies and environment. Improve understanding of climate change, its current and potential effects, and the vulnerability of communities to its impact.
- Develop strategies to adapt to and mitigate the effects of climate change. Following the precautionary principle, formulation of adaptation and mitigation strategies need not wait for perfect scientific evidence of climate change. In 1998, the Science and Environmental Health Network defined the precautionary principle as follows: “When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of an activity, rather than the public, should bear the burden of proof.”
- Build capacity and develop resiliency on a regional basis
- Adopt no-regrets policies as a first step. These are policies that will generate net social benefits whether or not there is climate change.
Summing up
While maintaining pressure to develop mitigation strategies, communities need to prepare to adapt to the effects of climate variability and climate change that cannot be avoided or mitigated. To achieve this goal, policymakers and the general public need to develop a good understanding of climate and the effects of climate change. Information on climate change and climate variability is needed at the local and regional level. This information must include a comprehensive perspective from multiple sectors, such as health and agriculture. Understanding the vulnerability of the environment and of human society is as critical as understanding climate. Data on projects where climate information was used to develop mitigation and adaptation strategies would provide a particularly important component of the information base. In improving the collection, analysis, and use of appropriate information, it will be important to support the entry and work of young people in the field of climate-environment-health interactions, particularly in the tropics.
Group discussion
Following the 1997–1998 El Niño event, there was massive coral bleaching in the Indian Ocean. Research findings would be useful on whether and how quickly coral reefs were recovering. There are also reports of excess plankton bloom, but these might be due to poor land use rather than climate change. Summertime radiation is much stronger in the Southern Hemisphere than in the Northern Hemisphere because during the Southern Hemisphere summer the earth is closer to the sun. No one has established any significant relationship between the 11-year sun-spot cycle and any climate effect on earth. If there is any effect, it is probably not discernible because other factors are more important.