mendations by producing status reports on the im- To avoid such temperature increases, greenhouse gases
pacts of vanishing sea ice, possible meltdown of the must be stabilized at a level below a doubling of pre-in-
Greenland ice sheet, and on changes in permafrost. A dustrial levels. Achieving this means that no later than
study on adaptation challenges will also be carried out 15 to 25 years from now emissions will have to stop
with the aim of enhancing the adaptive capacity of Arc- increasing and start decreasing significantly – to about
tic residents. 10–50 per cent of currents levels by 2050
2
. In the longer
term, emissions must be cut by as much as 70–80 per
Options to mitigate climate change cent in order to stabilize the Earth’s climate system.
One of the main conclusions of the fourth IPCC as- Recent comprehensive assessments and reports
2,3,4
indi-
sessment report is that it is very likely (more than 90 cate that such emission cuts can be achieved over the next
per cent) that most of the global warming during the few decades without significant welfare losses. The cost is
last 50 years is due to the observed increase in human- estimated to be less than 2 per cent of the gross domes-
made greenhouse gas concentrations, and that contin- tic product (GDP), well below the rate of growth in the
ued greenhouse gas emissions at or above current rates economy. Many of the needed technologies exist, and the
would cause further warming and induce many changes potential for improving them and developing new tech-
in the global climate system during the 21st century that nologies is high. It is the sum of many small and medium
would very likely be larger than those observed during contributions to reductions in emissions through the use
the 20th century
1
. of several different kinds of technologies for energy effi-
ciency, renewable energy, and carbon capture and storage
Today, the CO
2
level in the atmosphere has increased by (CCS) that is likely to constitute the solution in the end.
40 per cent over pre-industrial levels. Under a business-
as-usual scenario for emissions from human activities, At the political level, there is a wide variety of policies,
a doubling will occur in 50–80 years, depending on the measures and instruments that could be applied to
rate of increase in emissions and how much nature will stimulate the use of alternative existing technologies,
absorb, which would most probably lead to a global tem- improve them and develop new technologies. According
perature increase of 3 ºC. to the IPCC
2
, “A positive ‘price of carbon’ would create
incentives for producers and consumers to significantly
A global temperature increase of more than 2–3 ºC will invest in lower carbon products, technologies and proc-
constitute dangerous climate change with unacceptably esses.” A carbon price of US$20–50 per tonne of CO
2

high risk of: equivalent could largely decarbonise power generation
Significant negative impacts on global food production and make many mitigation options in the end-use sec-
and water supply; tors attractive
2–4
. A uniform carbon price must be global-
Large-scale changes in ecosystems and biodiversity ly accepted to ensure equal conditions for competition
that will negatively affect ecosystem services; in a globalized economy. In addition, incentives related
Melting of parts of the Greenland and Antarctic ice to direct governmental funding and regulations are re-
sheets with subsequent devastating sea-level rise; quired. For example, the development of new technolo-
Irreversible abrupt climate changes, such as large- gies will depend on large-scale governmental funding of
scale changes in ocean currents. research and development.
CHAPTER 9 POLICY AND PERSPECTIVES 219