IPCC 4^th Report - Main findings

Climate Change (CC) issues are presented widely in media these days and frequently the same messages (facts) are used by NGOs in their campaigns or school teachers in their teaching process. CC related campaigns or teaching are sometimes ending with a bit of frustration (another bad news issue) or reluctance how the public can stop the CC or influence the whole process. INFORSE member NGOs have the unique position here because their activities are primarily oriented on sustainable energy development and are offering the solutions to the threat of CC. What is really needed for NGOs and teachers is to get the scientific knowledge of CC in a relatively simple way which can be used as the support for argumentation towards sustainable energy development. This report is targeted at exactly this goal: providing the NGOs and teachers with the CC knowledge based on latest scientific data which can be helpful in their daily work. The content of this document is based on The IPCC 4th Assessment Report (AR4).

Why IPCC 4^th Report and why the NGOs should use IPCC facts?

There are many papers, reports and news published daily on CC issue. Despite the fact that majority of them are fully in line with the latest scientific data there are some of them which are trying to present CC in just the opposite way. Unfortunately even some politicians are influenced by these confusing facts and thus they contribute to confusing the public.

United Nations (UN) is aware of this situation which lasts for many years and in order to reduce the confusion they supported to establish the Intergovernmental Panel on Climate Change (IPCC) which now has the scientific credibility and capacity to provide up to date data. The IPCC was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization and has a long history of publishing its reports on CC. This year (2007) they produced the 4^th report which is the basis for the information provided below. It is also important to note that the IPCC does depend on consensus and it means that they have to be quite cautious in what they say.

Climate change is now a fact recognized by scientists and the governments. Thus all relevant scientific information should be the starting point for INFORSE member NGOs in order to link their efforts oriented on renewables with climate change issues.

Who is behind the IPCC:

The IPCC has the highest international credibility in terms of CC science. IPCC reports are written by teams of authors, nominated by governments and international organizations. They come from universities, research centers, business and environmental associations from all over the world. More than 800 contributing authors and more than 450 lead authors were involved in the writing of the AR4. Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information. More than 2500 scientific expert reviewers were involved in the two-stage scientific and technical review process of the AR4. As usual the government officials were involved in work on the summary reports, but the scientist (authors), who are not paid for this, had the final word over the thousands of pages of texts.

Structure of IPCC 4th Assessment Report :

The IPCC 4th Assessment Report (AR4) summarized the scientific results related to causes and consequences of climate change accumulated since 1950. AR4 consists of four volumes covering the results of different working groups (WG):

WG 1: "The Physical Science Basis"
WG 2: "Impacts, Adaptation and Vulnerability"
WG 3: "Mitigation of Climate Change"
"The Synthesis Report"

WG 1 Report, "The physical science basis", assesses the current state of knowledge about the natural and human drivers of climate change, reflecting the progress of the climate change science in the observation of the atmosphere, the Earth's surface and oceans. It provides a paleoclimatic perspective and evaluates future projections of climate change.

Working Group 2 Report addresses "Impacts, Adaptation and Vulnerability": It provides a detailed analysis of observed changes in natural and human systems and the relationship between those observed changes and climate change, as well as a detailed assessment of projected future vulnerability, impacts, and response measures to adapt to climatic changes for main sectors and regions.

Working Group 3 Report on "Mitigation of climate change" analyses mitigation options for the main sectors in the near term, addressing also cross sectorial matters such as synergies, co-benefits, trade-offs, and links with other policy objectives. It also provides information on long term mitigation strategies, for various stabilization levels, paying special attention to implications of different short-term strategies for achieving long-term goals.

AR4 "Synthesis Report" is an overall scientific view on climate change that integrates and synthesizes all information from the three volumes around 6 topics areas.

For each report a Summary for Policymakers (SPM) is included. The SPM therefore represents the point of agreement: participating governments acknowledge that there is enough scientific evidence worldwide to support the document's statements. Thanks to the depth of its scientific work and to the value of its intergovernmental nature, IPCC work is very much policy relevant. Its assessment reports played a decisive role in inducing governments to adopt the United Nations Framework Convention on Climate Change and the Kyoto Protocol. However, IPCC is neutral with respect to policy and its assessment reports are not policy prescriptive.

What are the most important results of the report?

The Physical Science Basis - Observations

Carbon dioxide, methane and nitrous oxide levels have increased significantly over pre-industrial levels due to human activities. Carbon dioxide due to fossil fuel burning and land use change, methane and nitrous oxide due to agriculture. The global mean concentration of CO2 was 379 ppm in 2005 compared to 280 ppm in pre-industrial time.

Source: IPCC AR4. 2007

IPCC observed that :

• the global average, surface temperatures have increased by about 0,74°C over the past hundred years (between 1906 and 2005) and warming continues at about 0,13 C per decade.
• The warming was not steady. In recent years it seems to be accelerating (see the figure). The warmest years on the record were 1998 and 2005 and 11 of the 12 warmest years ever have occurred in the last 12 years (1995 to 2006). Warming, particularly since the 1970s, has generally been greater over land than over the oceans.
• Sea level is rising now about 3,1mm per year.
• The long term climate changes are underway around the world.

Source: IPCC AR4. 2007

Impacts and Projections

Temperatures

The global climate temperature will likely increase by 2,4 – 6,4 (relative to 1980-1999 temperatures).For the next two decades, a warming of about 0,2°C per decade is projected for a range of emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0,1°C per decade would be expected. Since IPCC’s first report in 1990, assessed projections have suggested global average temperature increases between about 0,15°C and 0,3°C per decade for 1990 to 2005. This can now be compared with observed values of about 0,2°C per decade, strengthening confidence in near-term projections.

It is expected that we will experience:

• Warmer and fewer cold days and nights over most land areas
• Warmer and more frequent hot days and nights over most land areas
• Warm spells/heat waves. Frequency increases over most land areas
• Area affected by droughts increases

See level rise

Sea level rise is expected to reach 0,26 – 0,59 m at 2090-2099 relative to 1980-1999. There is strong evidence that global sea level gradually rose in the 20th century and is currently rising at an increased rate, after a period of little change between AD 0 and AD 1900. Sea level is projected to rise at an even greater rate in this century. The two major causes of global sea level rise are thermal expansion of the oceans (water expands as it warms) and the loss of land-based ice due to increased melting. Thermal expansion alone would lead to 0,3 to 0,8 m of sea level rise by 2300 (relative to 1980–1999). The IPCC concluded that there is no solid scientific understanding of how rapidly the vast stores of ice in polar regions will melt, so their estimates on new sea levels were based mainly on how much the warmed oceans will expand, and not on contributions from the melting of ice now on land. Nevertheless they estimate that the anthropogenic warming and sea level rise would continue for centuries due to the time scales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.

Contraction of the Greenland Ice Sheet is projected to continue to contribute to sea level rise after 2100. Snow cover is projected to contract. Widespread increases in thaw depth are projected over most permafrost regions. Sea ice is projected to shrink in both the Arctic and Antarctic. In some projections, arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century.

It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent.

Observations of Greenland and Antarctica have forced IPCC to conclude that there is a 50% chance that widespread ice sheet loss "may no longer be avoided" because of greenhouse gases in the atmosphere. Such melting would raise sea levels by four to six meters. It would cause "major changes in coastline and inundation of low-lying areas" and require "costly and challenging" efforts to move millions of people and infrastructure from vulnerable areas. The previous report (AR 3), concluded that the chance of such an event was "not well known, but probably very low". Areas such as the Maldives can be hardly hit and low-lying countries such as the Netherlands and Bangladesh, as well as coastal cities including London, New York and Tokyo, can face frequent flooding.

Storms

Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical sea surface temperatures. There is less confidence in projections of a global decrease in numbers of tropical cyclones.

Precipitation

Increases in the amount of precipitation are very likely in high latitudes, while decreases are likely in most subtropical land regions (by as much as about 20% in 2100). Heavy precipitation events are also expected. Frequency (or proportion of total rainfall from heavy falls) increases over most areas. Intense tropical cyclone activity increases are also expected.

Other impacts

The IPCC also mentioned a new chemical consequence of the buildup of carbon dioxide in oceans: a drop in the pH of seawater as oceans absorb billions of tons of carbon dioxide, which forms carbonic acid when partly dissolved. This could have an impact on some kinds of corals and plankton.

Uncertainties

There are still some open questions remaining about the speed and extent of some impending change. These uncertainties are related to the future pollution trends, size of population and the complex relation between the greenhouse emissions, clouds, pollution, the oceans and other factors, which both emits and soaks up greenhouse gases.

Confidence level

It is very unlikely that the 20th-century warming can be explained by natural causes. The late 20th century has been unusually warm. Palaeoclimatic reconstructions show that the second half of the 20th century was likely the warmest 50-year period in the Northern Hemisphere in the last 1300 years. This rapid warming is consistent with the scientific understanding of how the climate should respond to a rapid increase in greenhouse gases like that which has occurred over the past century, and the warming is inconsistent with the scientific understanding of how the climate should respond to natural external factors such as variability in solar output and volcanic activity.

Source: IPCC AR4. 2007

Mitigation - Technology

In the chapter related to key mitigation technologies IPCC mentioned for energy sector following options :

• improved supply and distribution efficiency;
• fuel switching from coal to gas;
• nuclear power;
• renewable heat and power (hydropower, solar, wind, geothermal and bioenergy);
• combined heat and power and also
• applications of Carbon Capture and Storage.

In the transport sector the main options are :

• more fuel efficient vehicles;
• hybrid vehicles;
• cleaner diesel vehicles;
• biofuels;
• shifts from road transport to rail and public transport systems;
• non-motorised transport (cycling, walking).

There are also other sectors covered like buildings, industry, agriculture etc.

IPCC mentioned that the renewable energy generally has a positive effect on energy security, employment and on air quality. Given costs relative to other supply options, renewable electricity, which accounted for 18% of the electricity supply in 2005, can have a 30-35% share of the total electricity supply in 2030 at carbon prices up to 50 US dollars per ton of CO2 equivalent.

It is important to note that nuclear industry welcomed AR4, which endorses nuclear energy’s status as one of a range of “commercially available climate change mitigating technologies”. The IPCC said nuclear energy is likely to increase its share of the global electricity market from 16 to 18 percent by 2030, given costs relative to other supply options at carbon prices up to 50 US dollars per ton of CO2 equivalent. AR4 said that issues such as safety, waste and weapons proliferation continue to be constraints for the nuclear energy industry.

Conclusions

For the first time it was concluded that global warming is "unequivocal" and that human activity is the main driver, "very likely" causing most of the rise in temperatures since 1950. It was also said that the average temperatures would probably increase by 4 deg. Celsius during this century if emissions continue to rise. Even under its most optimistic scenario, based on a declining world population and a rapid switch to clean technology, temperatures are still likely to rise by 1,8 deg. Celsius.

The IPCC also said that the world is already committed to centuries of warming, shifting weather patterns and rising seas, resulting from the buildup of gases in the atmosphere that trap heat. But it was also mentioned in the AR4 that the global warming can be substantially slowed by prompt action.

AR4 is the first IPCC report in which the scientists declare with near certainty (more than 90 percent confidence) that carbon dioxide and other greenhouse gases arising from human activities are the main cause behind the global warming since 1950. In previous IPCC report published in 2001 (AR3), the scientists put the confidence level at between 66 and 90 percent.

AR4 also concluded that if carbon dioxide concentrations in the atmosphere reach twice their pre-industrial levels, the global climate will likely warm by 2,4 – 6,4 (relative to 1980-1999 temperatures). Sea level rise is expected to reach 0,26 – 0,59 m at 2090-2099 relative to 1980-1999).

Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century. The rising temperatures could force hundreds of species to become extinct and trigger conflicts in countries struck by droughts and severe flooding.