SOME CLARIFICATIONS ABOUT CLIMATE CHANGE:

SOME CLARIFICATIONS ABOUT CLIMATE CHANGE:

Recently I have received some questions from my teen daughter about climate change and what it actually means. I realized, many of us don’t really pay attention because we assume, this will happen sometime in the far future.
However, even within this year, here in Netherlands we have already experienced some interesting variations of weather patterns. Summer weather was in April this year, and currently when it is supposed to be summer, we have spring weather.
Therefore, I feel that as an expert in development and as an environmentalist, it is necessary to clarify the issue of climate change for our own sake.
Climate change refers to the change in the statistical distribution of weather patterns over long periods of time (from decades to millions of years). The change may be in terms of weather conditions or change in the distribution of weather events. Eg. extreme weather or non occurrence of previous weather events. Changes may be for specific regions or globally , there are different processes that cause climate change: natural causes eg. Ocean currents, planetary movements, unnatural causes by human activities.
The atmosphere of earth planet consists of two layers namely the troposphere and the stratosphere.
The lowest layer (zone for weather and climate) is the troposphere. The higher layer –stratosphere- is the zone whereby there is high radiation energy from the sun, which reacts with oxygen forming Ozone – an important gas that forms a protection layer which shields living things from most of the sun’s harmful ultra violet rays that can also cause skin cancer.
To understand some of the mechanism of the climate system, we look at the positive and negative feedbacks.
As the sunlight hits the planet, some of the energy is reflected back. The amount of reflection (albedo) depends on the features of the earth surface. Forests and oceans have low albedos, while i.e snow covered surfaces have high albedos.
The ocean capacity to absorb and store the energy, postpones the fast increasing global warming. ‘Feedbacks can occur in a system when the interactions between it’s component processes respond to a change of conditions. The interaction can either augment the original change (positive feedback) or reduce it (negative feedback)’
Positive feedback eg.
Greenhouse gasses i.e (methane, carbon dioxide, nitrous oxide, ozone) emissions to the atmosphere causing an increase of global temperature leading to extreme weather changes i.e drought, damaging vegetation and reducing forest cover (absorbs CO2), adds to global warming.
Negative feedback eg.
Industrial pollution increasing sulphate aerosols (a collection of tiny liquid or solid articles dispersed in a gas, such as water droplets or dust in the atmosphere - inside or outside clouds) in the atmosphere, will have a cooling effect to the atmosphere.
Feedbacks lead to cumulative climate change eg. Oceans absorbing heat, leads to rise of sea level due to thermal expansion, the heat continues to warm the waters at deeper levels spreading wider distances i.e Artic, melting ice caps adds to the rising sea level causing multiple impacts i.e floods, death of humans, damaging heat sensitive biodiversity eg. Corals, economic loss.
Increased temperatures also leads to increased evaporation affecting the climate patterns, eg. Extreme precipitation and/or extreme droughts affecting different individual regions in different ways. Some of the impacts may have a high probability of occurring but with low hazards, and vice versa, causing changes on social variables i.e some crops/animals may not be able to survive in maximum temperatures and this will have an impact throughout the food chain.
Climate models have been used by scientists from 1979 to calculate the operational climate system while estimating the possible future climates.
However, climate science lacks the accurate recordings of past millenniums to compare with modern occurring changes thus it is difficult to know if the changes observed are a natural trend occurring over long periods of time or specific for post-industrial era.
Climate science uses sample measures eg. Rainfall measurements: ‘..even with 5 gauges, the total area over which the rain is sampled is less than one square metre’. The measurements might also be affected by wind speed/direction and/or presence of obstructions eg. Buildings.
The various stages of climate models include developing scenarios of future world population including the number, technology used, economic activities, energy uses etc. Then making projections i.e how much pollution will be caused by the population, calculate the concentration in the atmosphere, then calculating how this will influence the climate system in terms of weather elements e.g temperature, precipitation and other components including the state of the ocean, ice and vegetation cover. Lastly, climate models analyse likely impacts based on the model state of the climate system predictions.

(unfortunatelly scientific models couldn't be downloaded)


As observed, the uncertainty of climate science is based firstly on the limitation of sample data, methods of obtaining data and different interpretations made by scientists. Secondly, if even one condition within a scientific model changes eg. Energy used, positive and preventive checks and/or government policies promoting environmental sustainability, the projections made by a particular scientific model become invalid.
This is why recent projections for global temperature rise by climate models show a wide range of temperature (between 1.4 °C – 5.8 °C) over the period of 1990 to 2100.
More information can be found in the book ‘Changing environments’, Edited by Dick Morris, Joanna Freeland, Steve Hinchliffe and Sandy Smith