AS countries have developed and economies and populations have expanded, more and more greenhouse gases have been released into the atmosphere.
The concentration of carbon dioxide has risen as global average temperatures have increased. Although Zimbabwe and the rest of Africa have not contributed significantly to greenhouse gases, Africa is experiencing unprecedented climate change that is likely to lead to a crisis of human survival and national development.
Among its other impacts, climate change has resulted in declining water resources and water quality, reduced agricultural productivity, damaged infrastructure, loss of lives and ecosystems as well as degradation.
Aggravated by its geographical position in the semi-arid belt of Southern Africa, and its reliance on rain-fed agriculture and other climate-sensitive options, Zimbabwe has not been spared the impairment of climate change.
The livelihoods of millions of Zimbabweans depend on vulnerable natural resources and their depletion as a result of climate change will lead to further poverty and set back the country’s efforts to achieve sustainable development.
For these reasons, it is important to understand climate change and take remedial measures to climate-proof our African ecosystem.
The earth’s climate has been changing for millions of years.
But it is changing faster today than it has for thousands of years, largely due to greenhouse gas emissions caused by human activities.
Climate change is defined as, “…the long-term change (over decades or centuries) in the earth’s climate caused by the release of greenhouse gases – notably carbon dioxide and methane – that trap heat in the atmosphere. These gases can be released through natural causes or human activities.”
Among other factors, climate change brings about measurable changes in temperature and rainfall or wind patterns, which occur over several decades or longer.
The gases in the earth’s atmosphere act like a greenhouse – they allow the sun’s short-wave radiation to pass through, but restrict long-wave radiation (heat) from escaping back into space. The gases trap the heat, causing temperatures in the atmosphere to rise.
The atmosphere maintains the planet about 15°C warmer than it would otherwise have been. Without the natural greenhouse effect, the earth would be too cold for life.
While some scientists and meteorologists believe it to be a natural phenomenon linked to the rotation of the earth and volcanic activity, most agree that human activities, such as the burning of coal or oil (fossil fuels), for industry and transport and producing electricity (Hwange Power Station), release noxious gases into the atmosphere.
Large-scale commercial agriculture and forest clearing also contribute to gas emissions.
These have caused excessive gases to build up in the atmosphere, causing the planet to heat up too much and too fast, an effect known as global warming.
The gases that trap this heat are called ‘greenhouse gases’.
To understand climate change, we must first understand the difference between weather, climate and climate variability.
In Zimbabwe, the climate is typically warm, sunny and dry with hotter temperatures usually between mid-August and November and cooler temperatures between May and mid-August. Zimbabwe’s seasonal rainfall occurs between mid-October and mid-March.
Weather is the state of the atmosphere — such as temperature, humidity, wind and air pressure — at a given time and place.
Weather can change from day-to-day and from hour-to-hour.
One day may be sunny, the next windy and the next, rainy.
In some places, the weather can change so rapidly that we experience several types of weather in a day.
Climate describes the average weather conditions that occur in a particular place or region over at least 30 years.
Zimbabwe has seasonal rainfall that typically occurs between mid-October and mid-March.
Statistically, from a weather station in Zimbabwe, it is highly likely that in a 30-year record, any day in June, the weather will be cold and dry, whereas in December it is likely to be hot and wet
Similarly, any day in June in a 30-year record shows a high chance that the weather will be cold and dry, whereas in December it is likely to be hot and wet.
Climate variability refers to non-permanent and shorter-term changes (those that occur daily, seasonally, annually, inter-annually or over several years), including the fluctuations associated with El Niño (dry) or La Niña (wet) events.
In one climate cycle (30 years), it is possible to have a cooling trend lasting up to 10 years followed by warming trend of maybe three years, then a drying trend for five years.
A country with an unusually wet rainfall season (such as those in Zimbabwe in 1999/2000 and 2016/2017) may be experiencing climate variability.
It would be incorrect to conclude that the climate has changed to one of heavy rainfall based on one season’s rainfall.
It is normal for a climate to vary across time and space.
Zimbabwe’s rainfall varies according to the time of year and between years.
Some years are wet; others have droughts, with more recent years becoming drier.
Temperature averages and extremes of hot and cold also vary naturally while some seasons and years are hotter and colder than others.
Globally, the climate is being observed and monitored by the World Meteorological Organisation (WMO) through national meteorological services such as the Zimbabwe’s meteorological services, which have records of more than 100 years of weather observations. These are complemented by research institutions and remote sensing satellites, radars, buoys and terrestrial equipment.
In 1988, the UN Environment Programme (UNEP) and the WMO established the Intergovernmental Panel on Climate Change (IPCC) to assess the scientific, technical and socio-economic information relevant to the understanding of climate change; its potential impacts and options for adaptation and mitigation.
The Inter-governmental Panel on Climate Change (IPCC) is a group of thousands of scientists from across the world which, under the co-ordination of the UN, produces reports assessing global knowledge and evidence about climate change. The IPCC is central to any climate interventions and finance across the globe.
The IPCC reports have become the scientific basis for global climate negotiations, vulnerability assessments and the introduction of the Intended Nationally Determined Contributions (INDCs).
In 2014 it published its Fifth Global Assessment Report.
Regrettably, although African countries bear the brunt of climate change, the previous five IPCC Assessments failed to adequately address the continent’s needs because governments and scientists in developing countries were poorly represented at IPCC forums.
Most models describing the climate system have shown that the very rapid changes recorded in the past century were caused by human activities.
The heating of the atmosphere disturbs the climate system, the global energy balance and hydrological cycles.
This leads to many other changes, including increases in extreme events such as heat waves, erratic rainfall, violent storms, intense tropical cyclones and the melting of ice packs on mountains and snow caps at the north and south poles.
Global warming also affects ocean and wind currents, leading to changes in rainfall patterns and increases in extreme weather events, including storms, floods, forest fires and droughts.
Every living thing on earth will be affected by climate change, but the regions that will experience the most impacts are in the developing world; many, such as Zimbabwe, are in the tropics and sub-tropics where temperatures are already high.
These countries, especially in Africa, with low adaptive capacity and whose populations rely on livelihoods like agriculture, fishing and forestry that draw on natural resources are sensitive to climate and are extremely vulnerable to the impacts of climate change including hunger, poverty and disease.
It is, therefore, vital that we all fully understand climate change and realise its severity.
Dr Michelina Andreucci is a Zimbabwean-Italian researcher, industrial design consultant and is a published author in her field. For views and comments, email: email@example.com