By: Jill Johannessen
Last year we were struck by heat records brought to us by the mass media. The heat records, as well as the heat wave in southern Europe in 2003, are no coincidence according to Solomon, but are more likely than not linked to a global warming trend. She claims that heat waves like the one in 2003 will occur more often if we continue to emit greenhouse gases at present rates and that at the end of the century this could be common.
Eleven of the last 12 years rank among the 12 warmest years since the instrumental record of global surface temperature started in the 1850s. - The statistical probability for this to be a random chance is very small – if purely random it’s less than 1:100 000, says Solomon.
- If we force the climate, we will get a response
The last fifty years comprise the warmest period in at least 1300 years and the rate of warming is accelerating. A crucial difference now compared to warmer periods of the distant past is that the warming now is happening at a much faster rate and across the globe. In the ocean, warmer temperatures have been measured down to 3000 meters. The IPCC report concludes that it is very likely that human activity resulting in increasing emissions of greenhouse gases is causing most of the warming. Atmospheric concentrations of carbon dioxide, methane and nitrous oxide have risen dramatically since the industrial revolution (see figure below). The level of CO2 is now about 30 percent higher than before industrialization, and has not been higher in 650 000 years as determined from ice cores. But how do we know that this increase is not due to natural factors?
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Figure1. Record high CO2 concentrations: Carbon dioxide is the anthropogenic greenhouse gas with the greatest impact on the climate system. The figure shows a significant increase in the concentration of atmospheric CO2 the last 50 years. Furthermore, it shows that the development in modern time is distinct different than the development before the industrialization. (Source: IPCC report 1, 2007, revised by Norwegian Pollution Control Authority). |
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- While past climate variations were due to changes in the earth’s position relative to the sun – which also caused changes in the level of CO2 concentrations in the atmosphere – CO2 and other greenhouse gases are now the driving force for climate change. The solar irradiance hasn’t changed much. Actually, if we account for only the natural factors, then we should have experienced a slight cooling since 1980 due to the effect of volcanic eruptions, Solomon explains.
What stands out as the most important finding in the report?
- For policy makers the Fourth Assessment Report is a strong statement that the warming we have observed the last 50 years is very likely to have been induced by human activity. Even though scientists involved with climate research have known this for quite some time, the scientific community has come to a better understanding of the earth system; also how higher temperatures affect other climate variables and patterns, such as precipitation, wind patterns and sea-level rise.
Sea-level rise is a serious threat
There is a great uncertainty tied to how fast the Greenland ice sheet will melt. Under previous warm periods, for instance last interglacial period 125 000 years ago, reductions in ice volume in Greenland and possibly Antarctica led to a 4-to-6 meter sea-level rise compared to today’s level.
- Sea-level rise is a very serious issue that we have to deal with. We know that the sea level is rising and will continue to rise, but we don’t know exactly how fast. Even without taking into account the sea-level rise related to melting of the Greenland ice sheet, we still have to prepare ourselves for that the face of the planet is changing. Sea-level rise can be expected to affect many countries across the world. For a country like Bangladesh it is critical as one meter sea-level rise will affect millions people.
Does this report undermine all doubts about climate change to be driven by human activities?
- It is extremely unlikely that it is not due to human activities; there is no other credible explanation for the recent warming. But, I think we have to accept that people realize this at a different speed. No matter how strong the evidence will be, there will always be some doubters. Even today, you find people who don’t think smoking is causing health problems. Take for example medical care. When a drug is tested it is not 100 percent certain that the drug will not have unusual side effects in some people, or that it works exactly the same way for everybody taking the drug. Some people view this as proof it doesn’t work – but of course for the overwhelming majority it does. A team of qualified experts makes an assessment about the usefulness of the drug based on careful study, and that’s a service to society.
Fearing the consequences for Africa
The IPCC report part 2 states that poor countries in Africa and parts of Asia will face the most serious consequences of climate change. Solomon stresses that she fears what might happen if we are not able to control the emissions.
- My biggest fear for the near-term is problems related to drought, in particular for Africa. For instance, in Sahel, south for Sahara, which is semi-dry land, people already feel the consequences of soil that is becoming too dry for farming.
Though Solomon has great concern for Africa, she will not comment on whether the Western world has a moral responsibility to help these countries. - It is not up to me as a scientist to take on a political or a philosophical role, she states.
A hot issue in the USA
The attention given to climate change issues has been massive the last year worldwide. Do you feel that we stand in front of a change of course now?
- There has been a tremendous advance in public understanding of climate change in the US. People are starting to ask questions; economists have started to analyse the cost of climate change, social scientists want to know the effects of climate change on societies, politicians ask what we can do about it and how to prepare for changes that are inevitable. The industry tries to analyse challenges and new possibilities as a result of adaptation strategies to climate change. Climate change has become a big issue with both democrats and republicans, which is quite remarkable.
IPCC has now released three reports from the Fourth Assessment Report. What impact do you think these reports have had - in USA and elsewhere?
- I think there are several factors contributing to the increased attention to climate change issues. First of all, people are starting to see the warming, and effects of a warmer climate are becoming evident. Second, better observations of the climate worldwide and improved climate models have contributed to greater accuracy and more certain conclusions that the climate change we are observing is due to human activity. Third, scientists have also become better in educating the public on issues concerned with climate change. Last, but not least reporters have increased their understanding and thereby become better equipped to report about climate change issues.
Solomon also thinks that former Vice President Al Gore’s movie has played an important role in people’s awareness of the issue. While his movie is more of a personal statement, the IPCC report is an academic statement. As such, the two complement each other.
More than 30 000 comments
Even though there is a mix of factors that have contributed to the attention given climate change issues, Solomon feels that this report has a special value for politicians and decision-makers to make informed decisions. She is encouraged by the outcome of the report. It is a robust source for an issue of such great concern.
- In science, there are many voices, which can be confusing for non-experts. The IPCC report states what is the status and current level of a broad agreement. It represents a consensus of understanding, which involves a long and broad process of assessing hundreds of studies. While a paper in a peer-reviewed journal is reviewed by 2-3 experts, the IPCC assesses peer-reviewed papers involving hundreds of reviewers. The process is transparent and includes two rounds of comments for researchers and governmental experts. In total, the first report received more than 30 000 comments, to which each have been responded. This process makes the IPCC report a very robust document, which serves a special function for non-experts who are not in a position to sort though all this information themselves.
- We have to be patient
The US has been criticized for not taking part in the Kyoto Protocol. Do you think sustainable development is possible unless USA joins when new international agreements are to be negotiated?
- Any international agreement will be most effective if everybody joins. However, a lot of things are happening in the US too. California and states in the east coast like Massachusetts and New York are going in the forefront in order to reduce the emissions. 150 cities, including Seattle, have decided to take local action towards reduction of CO2 emissions.
China, India, Brazil and Mexico are all increasing their CO2 emissions rapidly due to expanding economic development. How do you think we should face this problem?
- How the world deals with this problem also depends on how Western industrialised countries are able to join up with developing countries in sharing solutions and mutual agreements.
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Susan Solomon (picture), the leader of Working Group 1 of the Intergovernmental Panel of Climate Change, is widely recognized as one of the leading scientists in the field of atmospheric science and for her groundbreaking work on the Antarctic ozone hole, which she received the National Medal of Science, the United States’ highest scientific honour. - One thing that I have learned is that scientists need to be clear and patient. It can take several years from a result to be published to general acceptance, she concludes. (Photo: Jill Johannessen) |
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