IPCC SRES scenarios - consequences of climate change
By S.M. Enzler MSc
Projections of consequences of climate change
According to the IPCC SRES scenarios, climate change will be noticeable by various impacts. Temperatures and precipitation will change, sea levels will rise and droughts and floods will occur more frequently (figure 2).
Figure 2: integrated framework of climate change by IPCC
Temperatures have been rising by 0,6 +/- 0,2 degrees Celcius in the past century. The largest temperature rises were in 1910-1945 and after 1975. According to projections by the IPCC in 1996 the average global air temperature will be 1oC higher by 2040 if no additional steps are taken to reduce emissions of CO2 and other greenhouse gases. By 2100 temperatures will increase by another 1,5oC. Even if current-day greenhouse gas emissions would suddenly stop earthly temperatures would still rise at least 0,5 oC, before stabilizing in 2050. This applies to any of the IPCC scenarios (figure 3). The total amount of global rainfall will increase. However, there will be regions that will receive less rainfall than before the changes took place. Annually, the number of days of intense rain showers or very high temperatures will both increase.
There is large uncertainty in the amount of warming that would result from a stabilization of greenhouse gas emissions. In figure 3, the CO2 stabilization level is depicted.
Temperature increase will probably be greater close to the polar regions. It is possible that polar ice melting causes the Northwest Passage to be usable for commercial transport. It has been predicted that by 2090 the entire North pole may be completely free of ice.
Temperature change has an impact on precipitation rates. In subtropical areas monsoon rains will be heavier. There will also be more heat waves in summer and fewer prolonged cold periods in winter. Frost-free growing seasons at northern latitudes will be enhanced, but increased flooding in winter and drought in summer will negatively affect crop growth.
Sea level rise
The IPCC predicts that sea levels will rise by about 18 cm by 2040 and by about 48 cm by 2100 in the most extreme case (figure 4). This regards the globalized human wealth scenario.
Sea level rise is stated to be caused by thermal expansion of seawater (figure 5), storm surges and rising and falling of land in coastal regions. The sea level rise may seem small, but there are countries where the larger part of the population currently lives on land that will be flooded if these projections are correct. Moisture changes will occur fast compared to changes in the past, and consequentially ecosystems will be destabilized (figure 2).
Droughts and floods
As was mentioned before, temperature and sea level change cause the frequency of droughts and floods to increase. More people will experience flooding of their lands and homes (figure 6) and extreme drought will negatively influence crop yield.
The predictions made by climate models of the IPCC have shown that CO2 concentrations, and consequentially sea levels and temperatures will continue to rise long after emissions are cut back (figure 7).
Climate change influences many other environmental issues, such as air quality, water quality, desertification, biodiversity, forestation and stratospheric ozone depletion. It is important that these issues are dealt with in an integrated framework. The issues are al interconnected and therefore need to be considered interchangeably.
The work field that integrates causes and impacts of environmental issues and policy measures (solutions) is called Integrated Environmental Assessment (IEA), a subdivision of the work field of Environmental Systems Analysis. This is a type of Environmental Science that applies many different tools, including environmental models, environmental impact assessment and environmental indicators, to describe and find solutions for environmental problems.
IPCC scenario presentations à http://www.ipcc.ch/present/graphics.htm
RIVM, the Netherlands à file:///D:/Data/Temporary%20Internet20Files/Content.IE5/K5W3OJCV/IMAGE_model%5B1%5D.ppt
Sorrell, S., Emissions Trading After Kyoto. Introduction to Environmental Economics of Science and Technology Policy Research, 2004 à http://www.sussex.ac.uk/Users/prpp4/lec8.ppt
Summary of the 1996 SRES report à http://www.grida.no/climate/ipcc/emission/014.htm