The challenges and opportunities facing the world as a result of climate change have been distilled into a concise and sobering guide by the Intergovernmental Panel on Climate Change (IPCC). This fourth IPCC report raises serious concerns of species extinction as well as arguing strongly in favor of stepping up support and action on adaptation to the effects of global warming. — ScienceDaily (Nov. 20, 2007)
Earth & Climate
Consensus of scientists regarding global warming
Scientific opinion on climate change
Instrumental temperature record
IPCC Report on Climate Change - 2007
The guide, officially known as the Summary for Policy Makers, underlines the urgency to act to reduce greenhouse gas emissions alongside the economic costs of a transition to a low carbon society.
It also argues strongly in favour of stepping up support and action on adaptation.
"Neither adaptation nor mitigation alone can avoid all climate change impacts. However, they can complement each other and together can significantly reduce the risks of climate change," says the report by the IPCC, a panel jointly established by the UN Environment Programme (UNEP) and the World Meteorological Organisation (WMO).
It also highlights five "reasons for concern" which are now stronger than before. This is because scientists now conclude that they may happen at lower increases in temperature or because the risks may be larger than had previously been supposed.
These include the impacts on species and biodiversity hotspots as temperatures rise including polar and high mountain communities and ecosystems.
The report says that around 20 per cent to 30 per cent of the plant and animal species assessed are likely to be at increased risk of extinction if global average temperatures exceed 1.5 degree C to 2.5 degree C over late 20th century levels.
The report also points to the likelihood of "irreversible" impacts. For example if temperature increases exceed about 3.5 degrees C, between 40 per cent and 70 per cent of the species assessed might be at increased risk of extinction.
Increases in sea surface temperatures of about one-three degrees C are projected to result in more "frequent coral bleaching events and widespread mortality."
There is also concern over the oceans and seas becoming more acidic as they absorb rising levels of carbon dioxide and the impacts on "marine shell-forming organisms" like coral reefs.
Other reasons for concern focus on the risks of extreme weather events with higher confidence in the projected increases in droughts, heatwaves and floods as well as their adverse impacts.
The report also flags up concern that the poor and the elderly in low-latitude and less-developed areas including those in dry areas and living on mega-deltas are likely to suffer most.
There is high confidence that by mid-century "many semi-arid areas, for example the Mediterranean basin, western United States, southern Africa and northeast Brazil, will suffer a decrease in water resources due to climate change."
The IPCC summary also expresses concern that any benefits linked with climate change will be gone after more modest temperature rises. The guide, launched after five days of discussions in the Spanish city of Valencia, will be essential reading for delegates attending the upcoming UN climate convention meeting in Bali, Indonesia.
Concern is also raised that new observations linked with the Greenland and possibly Antarctic ice sheets may mean that the rate of ice loss will increase above previous forecasts.
Achim Steiner, UNEP Executive Director, said: "This is perhaps the most essential reading for every person on the planet who cares about the future. In this Summary, the hard science has been distilled along with evidence of the social and economic consequences of global warming but also the economic rationale and opportunities for action now."
"While the science will continue to evolve and be refined, we now have the compelling blueprint for action and in many ways the price tag for failure-from increasing acidification of the oceans to the likely extinctions of economically important biodiversity."
"The momentum on climate change in 2007 has been nothing short of breathtaking and in no small measure due to the series of assessments from the IPCC. Today's final synthesis report translates the complex science into a lingua-franca so that governments meeting in Bali can not only understand the challenge but be empowered to act collectively on a decisive post 2012 emission reductions regime," he added.
"This pocket guide for policymakers is also more than that. It is also a citizens guide for engaging political leaders, their members of parliament, local authority officials the chief executive officers of national corporations in a public debate on what needs to happen next," added Mr Steiner.
Michel Jarraud, Secretary-General of the WMO, said: "The science of climate change has been finally and forever heard in 2007 as a result of the painstaking and transparent assessments of the IPCC. Agreement on the climate assessments should stimulate action to protect lives and property against natural hazards and to reduce risks of economic setbacks and conflicts over water, food and energy."
"Now that the issue of climate change is established and recognized, observational and research efforts should be increased, rather than reduced. Because societies need more detailed information about anticipated impacts at regional and local levels for responding and adapting to climate change," he said.
"Individuals, enterprises and civil society cannot adapt autonomously without reliable information and projections, especially since they should make some of their investment choices well before the effects of climate change are fully visible. They should have access to scientifically credible and adequate information on climate, from prediction on the likely timing, extent and effects of climate change, to knowledge of drought and flood resistant crops and new crop planting techniques," said Mr Jarraud.
The summary makes a strong link between climate change and the wider challenges facing in particular developing countries a result of issues like poverty, unequal access to resources, conflict and disease.
On an optimistic note, the summary point out that combating climate change does not have to damage or derail economies.
"There is high agreement and much evidence of substantial economic potential for the mitigation of global greenhouse gas emissions over the coming decades" if governments adopt the right policies and incentives, it says.
Bringing down global carbon dioxide emissions to 2005 levels by 2030 will require a big shift of investment patterns -- "although the net additional investment required ranges from negligible to five to 10 per cent," concludes the report.
The IPCC estimates that biggest prospect for emissions cuts comes from buildings, followed by industry and energy supply, agriculture and forestry under a variety scenarios based on the market price of carbon.
Adapted from materials provided by United Nations Environmental Programme.