Parliaments and Climate Change: an Introduction to the Science

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Parliamentarians need not be environmental experts to develop a strong legal framework for tackling climate change, or to carry out their relevant budgeting and oversight tasks.  That being said, a basic understanding of the science behind climate change is helpful when taking parliamentary action.  When assessing proposals or preparing budgets, parliamentarians benefit from understanding what key factors are driving climate change, and how its impacts are likely to affect his or her region or country.  Being comfortable with the subject will also help when trying to convince fellow parliamentarians to support proposals, or when talking to constituents who may be skeptical or unsure about the need for action. 

Climate Change: Additional Resources

This page offers a brief introduction to the science behind climate change.  For more information and updates, please take a look at the AGORA Climate Portal’s resources and news feed.  You may also want to consult the work of the Intergovernmental Panel on Climate Change, which provides extensive reports on trends, projections and impact of climate change.  

Finally, for more information on climate change and an overview of relevant knowledge networks, programmes and organizations, please visit our page on additional resources.

Understanding climate change

The term ‘climate change’ refers to a significant and lasting change in weather patterns for temperatures, precipitation levels and wind.  It is important to understand that weather systems know a considerable amount of natural variation: no two days are the same, and a limited number of ‘extreme weather events’ such as record temperatures, periods of drought and floods can and do occur within this standard range. 

We speak of climate change only when we observe changes that fall outside of that natural variation - in other words, changes that indicate a departure from the established weather system.  These changes can take the form of higher or lower average indicators (for example a regional temperature rise), but may also include significant increases in extreme weather events such as floods, droughts and heat waves. 

Climate change has historically been caused by a number of factors such as large volcanic eruptions, plate tectonics and variations in solar radiation.  The changes observed today, however, are almost certainly linked to human activity.  In its most recent Assessment Report (AR5), approved by nearly 200 countries in September 2013, the Intergovernmental Panel on Climate Change  states that “It is extremely likely (with 95%-100% certainty) that human influence has been the dominant cause of observed warming since the mid-20th century.” 

‘Human influence’ here points primarily to the increase in carbon dioxide emissions and their impact on the Greenhouse Effect.  The Greenhouse Effect refers to the layer of natural gases that envelop the earth, trapping heat from the sun’s radiation and thereby keeping the Earth at a relatively steady and ‘comfortable’ temperature.  Following the spike in carbon dioxide emissions since the industrial revolution, primarily due to the burning of fossil fuels, this layer is trapping more and more heat, leading to increases in global temperatures.



Contrary to popular belief, most of this global warming (an astonishing 93,4%) is not going into the atmosphere but into the oceans. Professor Hans Joachim Schellnhuber CBE, Director of the Potsdam Institute for Climate Impact Research, explains that “if the additional heat absorbed by the Earth’s oceans since the 1950s would be released, the atmosphere would warm by about 36°.  It’s a tremendous time bomb, slumbering in the oceans.”  In other words, climate change is already reaching far beyond the extreme weather events and temperature rises that have been experienced recently.  Only decisive action can halt further escalation of these developments.   

The impacts: 21st century projections 

Rising emissions have contributed to global warming, rising sea levels, increased ocean acidification, loss of summer ice in the Arctic, extreme weather patterns, increased severity and frequency of droughts and storms, and greater temperature extremes.  A business-as-usual scenario would see global temperature increases of around 4% by the end of this century, creating a vastly different habitat for all life on earth. 

The points below sum up some of the key projected impacts we can expect with a 4° increase, taken from the related World Bank Report.  They illustrate quite clearly how climate change may impact your country and constituents, and why urgent action is required.

  • CO₂ Concentration and Ocean Acidification: Carbon emissions are absorbed by the oceans, increasing the water’s acidity levels.  At the current rate this process is expected to destroy most coral reefs and significantly harm animals that live in shells, such as crabs and oysters.  This has important consequences for marine life.  Many other animals depend on these smaller ones for their survival, and endangering them will endanger the rest of the food pyramid – including the more than 1 billion people who depend on fish for their protein.  Those depending on fishing for their livelihood will also face serious consequences: many oyster farms, for example, are already struggling to keep afloat as their harvests are increasingly disappointing.  Finally, coral reefs form an important natural barrier against rising tides and floods; their disintegration and eventual disappearance will further increase the vulnerability of coastal populations.  
  • Droughts and Precipitation: Modeling projects that, in a warmer world, wet areas will become wetter and dry areas will become drier.  In terms of regional projections this means that there will be an increase in rainfall in the tropics and in mid to high latitudes, and a decrease in the subtropics.  Rainfall during extreme precipitation events is also expected to increase by a further 20 percent in a 4° temperature rise scenario.  For the latter, the strongest increases were found for South Asia, Southeast Asia, western Africa, eastern Africa, Alaska, Greenland, northern Europe, Tibet, and North Asia. 
  • Tropical Cyclones: While it remains difficult to project whether the frequency of tropical cyclones will rise or remain the same, the intensity of such cyclones is projected to increase.  This, in combination with increased population pressure and economic growth, makes that larger numbers of people and greater amounts of wealth will be exposed.  For more detailed projections, please consult the IPCC’s Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change.      
  • Sea-Level Rise:  Projecting sea-level rise is extremely difficult, complex and controversial.  As the earth’s sea level is not flat, some regions will see bigger sea level rises than others.  The IPCC report suggests that above-average rises can be expected along the northeastern North American and eastern Asian coast, as well as the Indian Ocean.  Given the considerable number of large coastal cities in these regions, the risk of extreme floods and weather events, combined with dense populations and often inadequate planning, leaves these cities highly vulnerable.  For many low-lying areas, such as the Pacific Small Island States, sea-level rises will lead to increased flooding, land erosion, and the degradation of fresh ground water resources. 

It is worth noting that, in the months since the publication of the latest IPPC publication, new findings estimate sea-level rises which at a faster rate and at higher levels than those of the AR5 report. 

Sectoral impacts

The climate change impacts noted above have critical consequences on all aspects of human life and development.  For an overview of key sectoral impacts, please consult the publication below.

Turn down the heat: why a 4 warmer world must be avoided

This report spells out what the world would be like if it warmed by 4 degrees Celsius, which is what scientists are nearly unanimously predicting by the end of the century, without serious policy changes. 

The 4°C scenarios are devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher malnutrition rates; many dry regions becoming dryer, wet regions wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity in many regions; increased frequency of high-intensity tropical cyclones; and irreversible loss of biodiversity, including coral reef systems.

To read the full report, please click here.