A climate change primer: changes to environment and ecosystems
Climate change is being driven by the build-up of greenhouse gases in the atmosphere, mainly due to human activities.
Higher greenhouse gas levels are causing an enhanced greenhouse effect, leading to a global rise in temperature.
Higher temperatures are melting ice caps and, with thermal expansion of oceans, raising sea levels.
Significant changes to weather patterns are expected - more severe storms, more rain in wet areas, less rain in dry areas.
Other factors affect climate over differing timescales, including solar activity, ocean currents and other natural cycles. The factors are being swamped by the effects of greenhouse gases.
Climate changes are profoundly affecting the Earth’s environment and ecosystems. These effects are made worse by other forms of environmental degradation.
Glossary
Greenhouse gases: Atmospheric gases that trap heat. The most important are:
- water vapour (has the biggest greenhouse effect but levels are relatively stable)
- carbon dioxide (CO2)
- methane (present at lower levels than carbon dioxide but has much stronger greenhouse effects)
- lower-atmosphere ozone.
Other chemicals, such as nitrous oxide and CFCs, are also greenhouse gases but are present at low levels.
Ocean conveyor/thermohaline circulation/meridional overturning circulation: Global-scale ocean currents, including the Gulf Stream, which keeps the UK’s climate relatively mild. Although some have suggested these could disappear, drastically lowering temperatures in the UK, this is currently thought unlikely.
El Niño-Southern Oscillation: Large-scale sea surface and atmosphere fluctuations that have significant impact on climate in the southern hemisphere. El Niño means ‘the little boy’ or 'Christ child', as its effects are generally seen at Christmas time. A cold phase during each El Niño episode is known as La Niña (‘the little girl’).
Acidification: Carbon dioxide dissolving in the oceans forms carbonic acid, lowering pH.
Troposphere: The layer of the Earth’s atmosphere closest to the ground. Where greenhouse gases are found. Ozone in the troposphere contributes significantly to global warming.
Stratosphere: The layer above the troposphere. Ozone in the stratosphere is protective.
Sunspots: Regions of relatively low temperature on the surface of the sun. Sunspots rise and fall in a cycle lasting about 11 years; their numbers also vary over long timeframes. Sunspots seem to affect the Earth’s climate - not because less solar energy hits the Earth (sunspots affect less than 0.5% of the sun’s output) but possibly through their impact on cosmic rays and cloud cover. Sunspot activity is factored into models of climate change and its effects are thought to be small compared with those of greenhouse gases.