Sep 18, 2013 - 9:21am
You can download this media brief and related infographics at the bottom of this page.
On September 27th, the Intergovernmental Panel on Climate Change (IPCC) releases the Fifth Assessment Report of its working group on the science of climate change. It is six years since the last report was released.
Reports on the impacts of climate change and options to reduce emissions will be released in March and April 2014 respectively.
Thousands of scientists from the world’s leading research bodies, including the CSIRO, together with thousands more expert reviewers, contribute to the assessment of climate science by the IPCC.
The reports of the IPCC set the context in which international climate negotiations take place, national climate policy is developed, and many firms make long-term investments.
Largely based on the work of the IPCC, over 190 governments including China, USA and Australia, have agreed that the world should avoid a 2°C increase on average global temperature. As the advanced economy most exposed to climate and extreme weather impacts, this goal is in our national climate interest. The Coalition Government agrees with this goal and, along with the ALP, has committed to reducing emissions by 5–25 per cent on 2000 levels by 2020. Only the 25 per cent target is consistent with global action to avoid a 2°C increase itself likely to represent dangerous climate change.
This brief outlines some of the likely consequences projected for Australia from unchecked climate change.
What is the latest IPCC report likely to say?
While the new IPCC report is yet to be released, it is based on publicly available scientific research, and will almost certainly reconfirm and even reinforce the scientific view expressed in the last report in 2007. In fact, the science and the conclusions drawn by the IPCC have continued to strengthen since their first report in 1990 (Table 1). The science tells us that:
- The world is warming. The mean global temperature has risen by almost 1°C since pre-industrial times, with increasing temperatures over land and sea. Whilst the rate of warming has not been the same everywhere (it appears to be higher in Australia, for instance), the land has warmed more quickly than the sea surface. (See below for responses to questions about rates of warming and other recent questions). The temperature is rising in the oceans, down to several hundred metres, with about 92 per cent of the extra heat energy trapped by greenhouse gases absorbed by the oceans.
- Melting glaciers and ice sheets, sea-ice retreat, and rising and warming sea levels are among the many signs of climate change.
-The melting of glaciers and ice sheets in the last decade is now several times faster than it was in the 1990s.
-The rate of Arctic sea-ice retreat has doubled since AR4 in 2007, and thick multiyear ice is retreating even faster—a rate unprecedented in at least the last 2,000 years.
-Sea-level rise has accelerated almost twice as fast from 1993–2010 as compared to 1901–2010.
-The oceans are becoming more acidic as more and more carbon dioxide is absorbed, threatening coral reefs and fisheries, and the jeopardizing $6.5 billion in yearly tourism revenue from the Great Barrier Reef.
- Carbon pollution is causing climate change. The warming cannot be explained by natural causes alone. There is now overwhelming evidence that the warming observed in the 20th and 21st centuries is caused mainly by emissions of carbon dioxide and other greenhouse gases, principally from the burning of fossil fuels and deforestation.
- Carbon pollution is already dangerously high. The atmospheric concentrations of carbon dioxide, methane, and other greenhouse gases are now higher than at any time in human history, and at any time for at least 800,000 years. In May this year, the concentration of carbon dioxide in the air reached 400 parts per million (ppm) —around 40 per cent higher than before the Industrial Revolution. When CO2 levels were last this high, 3 to 5 million years ago, the mean global temperature was around 3°C higher than today, the sea level was up to 40 metres higher, and the Greenland ice sheet was impermanent.
What are the likely risks and impacts of climate change in Australia?
Download the full media brief below for tables on the likely risks and impacts of climate change on Australia as a whole and each state.
The tables give examples of observed and predicted impacts and risks associated with climate change across Australia. The points are drawn from assessments and studies by CSIRO, the Climate Commission, the Bureau of Meteorology, the Garnaut Review, and the 4th Assessment Report of the IPCC (2007).
FREQUENTLY ASKED QUESTIONS
Has global warming stopped or ‘paused’?
No. The average temperature of the land and seas continues to rise. The rate of temperature increase at the surface, however, appears to have slowed since the late 1990s, but the oceans continue to warm as predicted. The oceans absorb more than 90 per cent of the extra heat trapped by rising carbon pollution.
The rate of surface warming from 1998–2012 was 0.05 ºC per decade. But over the entire period from 1951 to 2012, it was 0.12 ºC per decade. Other aspects of the climate system (Arctic sea ice loss, ocean temperature rise, glacier melt, etc) show no slowdown.
The cause or causes of the recent slowdown in air temperature increases are the subject of active research, particularly on the way the oceans absorb heat, as well as the effect of aerosols, and other factors. It is important to understand that these factors are likely to be short-lived and scientists believe that the warming will quicken again. Changes in the rate of warming are well within the bounds of normal variability.
Scientists have adjusted their estimates of climate’s sensitivity to rising carbon dioxide levels; does this mean the situation is less urgent?
No. Because the scientific understanding of climate change has grown, there has been a revision of the estimate of the likely range of temperatures when the climate reaches a new equilibrium, with the lower-end slightly lower, from 2ºC to 1.5ºC.
This means that, at the time the level of CO2 in the atmosphere has doubled—between 2050 and 2070—the mean surface temperature will be less than 0.1ºC different to the previous estimate.
Crucially, even if we cease to emit carbon pollution at the point of doubling the warming would continue and could be higher than previously thought, new estimates suggest.
Emissions are currently on track to push warming well over the 2ºC internationally agreed danger mark, and past 3ºC above the pre-industrial average.
The UK Met Bureau concludes that neither the recent warming slow down nor the adjustment to climate sensitivity estimates "materially alter the risks of substantial warming of the Earth by the end of this century".
How does the IPCC work?
The IPCC’s job is to carefully summarize the state of scientific understanding of climate change. It does not carry out new research nor does it monitor climate-related data. It meets in plenary sessions about once a year to decide on the work plans of the Working Groups and the Task Force on National Greenhouse Gas Inventories, and to agree on report content.
The Working Groups are: 1. Physical Basis of Climate Change; 2. Climate Change Impacts, Adaptation, and Vulnerability; and 3. Mitigation of Climate Change.
Hundreds of the world’s top scientists work to develop the IPCC Assessment Reports by critically analysing and synthesizing the available peer-reviewed and publicly available scientific literature.
Drafts are then reviewed extensively by other scientists and by a wide range of interested parties. Reports developed by each of these bodies go through an extensive, multi-level review process. Reviewers typically represent more than 150 countries as well as a wide range of organizations, including public agencies and NGOs.
Note that, by the time scientific material has been collated, reviewed, and synthesized into an IPCC report, some of it may well be out of date.
Because the IPCC is an intergovernmental body, governments as well as experts review its reports. As drafts are prepared and finalized, comments received from both are taken into account by lead authors, leading to refinements where appropriate.
Following criticisms in 2010, IPCC procedures were reviewed by the InterAcademy Council and a number changes were made to improve procedures, governance, management, conflict of interest policy, and communications.
Hasn’t the IPCC got it wrong before?
Overall, the IPCC assessment reports reflect the state of scientific knowledge very well. If anything, they tend to be quite conservative in some of their conclusions. Following the publication of the 4th Assessment Report in 2007, two legitimate scientific errors in thousands of pages (the first concerned the speed at which glaciers in the Himalayas might retreat; the second projections of the extent of flooding in the Netherlands) were discovered, as well as several manufactured ones. These became the focus of campaigns to undermine public confidence in climate science.
The errors did not undermine the remainder of the findings of the IPCC and were promptly corrected in any case. Science is self-correcting; conspiracy theories are not.
It is worth putting these errors into perspective:
- Assessment reports are published every six or seven years, with the drafting process taking about three years.
- Each report of the three IPCC 2007 working groups is 900-plus pages long. The next report is likely to be of a similar length.
- The reports were written by 450 lead authors and 800 contributing authors, whose work underwent review by more than 2,500 experts, who submitted around 90,000 comments on drafts—all of which are on the public record.
It is not surprising that a few errors emerged from such a lengthy, cumbersome process, involving so many people, each volunteering their time over several years. Rather, it is surprising that there were not more mistakes and, more importantly, that so many experts could agree on so much.
Can we avoid a 2ºC rise in mean global temperature?
Given the will to act, yes. In the past few years we have seen a growing number of credible assessments (beginning with the IPCC’s own assessment in AR2, and Treasury modelling more recently) say that it’s technically and economically doable to keep warming below 2ºC.
Keeping under the two-degree wire does require a mix of measures, including strong incentives for clean energy and energy efficiency, including price and limits on pollution, clean energy targets, carbon capture and storage, and regulations. It is critical that we start now: modelling of future warming and emissions show that global pollution needs to peak by 2020. To be effective, all emitters, including Australia, need to pull their weight.
The problem of climate change is not, principally, one of economics or technology, or even physics, but of political, community and business leadership.For more information
John Connor | CEO, The Climate Institute | 02 8239 6299
Kristina Stefanova | Communications Director, The Climate Institute | 02 8239 6299