United Nations Environment Programme

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Tool 6: Climate change and the greenhouse effect

The effects of climate change
The environmental effects of climate change are numerous and difficult to predict. When climate change first came on the political agenda in the late 1980s, there was a heated debate about its’ effects. However, the majority of scientists and experts – and virtually every government – acknowledge that climate change is real and that the issue needs to be addressed. The questions now are what to do and how and when to do it.

Effects on nature:
A wide range of impacts of climate change on the natural environment have already been observed by scientists and researchers. Some impacts include: shrinking of glaciers; thawing of permafrost; changes in the patterns of freezing and earlier break-up of ice on rivers and lakes; lengthening of mid- to high-altitude growing seasons; shifts in plant and animal ranges; declines of some plant and animal populations; and changes in the timing of biological production patterns such as flowering of trees, emergence of insects, and egg-laying in birds.

Estimated long-term effects of rising average global temperatures include:

  •  Sea level rise, with an average of 9 to 88 cm, which will have impacts such as floods, threatening low-lying lands.
  • Increased precipitation in some regions and decreased precipitation in other parts. Unfortunately, rain will decrease in typically semi-arid and arid areas.
  • Vegetation zones will shift, endangering many species. Adaptation to rapid changes will not be possible for many species.
  • Frequency and intensity of storms and other weather phenomena will increase as “more energy” comes into the climate system (see Figure 2 below).
  • Irreversible damage to natural ecosystems such as coral reefs, atolls, mangroves, tropical forests, polar and alpine ecosystems, prairies, wetlands, and glaciers.

Figure 5: The cost of extreme weather events between 1950 and 1998. Source: IPCC

Effects on human societies:
The effects on nature listed above will also have enormous and possibly catastrophic effects on human societies. Estimated effects include:

  • Food security will be affected, especially for people living in vulnerable areas, as agricultural production is affected by changing climate.
  • Fresh water resources will be affected and decrease in vulnerable areas and increase in other areas.
  • Heat waves will increase cardiovascular (heart and lung system), respiratory and other diseases.
  • Infrastructure built for stable climate conditions and designed to cope with expected rain levels will become vulnerable to flooding and landslides, such as houses in close proximity to rivers, as well as bridges and roads.
  • Tropical cyclones are expected to become more destructive in some areas.
  • People in vulnerable areas who are dependent on nature for their livelihoods will suffer most, as they tend to have little resources to adapt.
  • Vector-borne diseases, such as malaria and cholera, are expected to increase and spread.

The Kyoto Protocol
In 1992, a global convention on climate change was signed under the auspices of the United Nations, with the long-term aim of protecting the global climate.

A number of highly controversial issues - such as the causes of climate change and the severity of its expected effects - has surrounded the climate change debate. To address this, an independent scientific body was established - the Intergovernmental Panel on Climate Change (IPCC) - to examine assess these issues. The IPCC is made up of scientists from around the world, and has so far made three major assessments; the IPCC is currently working on a fourth assessment, as new evidence is gathered. According to the IPCC, the concentration of CO2 in the atmosphere should not exceed 550 ppm in order for global communities to adapt to resultant effects. In order to not exceed 550 ppm, countries must cut global CO2 emission by approximately 50% by 2050 and by 90% by 2100.

In 1997, a binding commitment was signed on greenhouse gas emissions - the Kyoto Protocol - which sets specific targets for the reduction of CO2 and other greenhouse gases by the year 2012. This Protocol is only the first step toward climate protection: a new commitment for the post-2012 period is currently under negotiation.

For more info on climate change >> www.ipcc.ch,