Outline of contribution of Working Group I to IPCC Fifth Assessment Report

The assessment report of the Intergovernmental Panel on Climate Change (IPCC) was released for the first time in six years in September 2013. When the Fourth Assessment Report was published in 2007, the former US Vice President Al Gore and the IPCC were awarded the Nobel Peace Prize for their achievements in spreading knowledge and raising the alarm about climate change. Although the latest report has been received more quietly, it includes more precise predictions based on the research and data accumulated over the last six years.

The IPCC has three working groups, WG I for dealing with scientific knowledge about climate change, WG II for assessing impact, adaptation and vulnerability to climate change, and WG III for deals with measures to reduce global warming, and this report from WG I was approved at the 36th Session of IPCC. (The reports of WG II and WG III are due to be released in March and April 2014, respectively.)

According to the WG I report, past observation data shows that “the warming of the climate system is indisputable.” The global mean surface temperature went up by 0.85 °C in the period 1880 to 2012 while the global mean sea level rose by 19cm between 1901 and 2010. It is almost certain that the temperature of the upper layer of the ocean (0 to 700m below the surface) has gone up, and the polar ice sheets and mountain glaciers throughout the world are shrinking. The report judges that “it is extremely likely (95-100% probable) that human activity is the main factor” in bringing about this warming. The report also gives a future projection based on climate model simulations, warning that “the continuing release of greenhouse gases will cause further warming and changes to the climate system.” It estimates that the global mean temperature and mean sea level will rise by 0.3 to 1.7 °C and 26 to 55 cm by the end of this century compared with the end of the twentieth century if there is a small increase in greenhouse gases, and by 2.6 to 4.8 °C and 45 to 82 cm if there is a large increase. The report also anticipates changes in rainfall patterns, with greatly increased precipitation forecast for areas that are currently wet and further aridification in already dry regions. In this way, the Fifth Assessment Report demonstrates greater than ever before the seriousness of the problem of global warming.

Global warming does not equal global destruction

I teach the “Introduction to Geoscience” and “Environmental Science” courses in the Faculty of Economics, but there is something that always bothers me when I talk to my students. When I ask them why we have to prevent global warming, more than a few say that it is because global warming will destroy the earth, or that they feel sorry for other animals that will become extinct.

The earth’s environment has repeatedly undergone significant changes over the last few billions of years, with periods that were much colder than now but also periods that were warmer. In the Mesozoic period about one or two hundred million years ago, for example, the concentration of atmospheric carbon dioxide is thought to have reached several times its current level, while global average temperatures were 10 to 15 °C higher than now and there were no ice sheets anywhere on the planet. In an era so much warmer than the present day, living creatures able to adapt to the environment thrived. Dinosaurs are a perfect example of this. In other words, there is no need to worry about the earth itself being destroyed even if carbon dioxide concentrations increase and temperatures rise. In terms of modern human life, however, increased temperatures and the subsequent environmental changes pose a serious threat to our survival. We must therefore recognize that the issue of global warming is not a problem for the earth but a problem for humankind.

How Should We Approach Global Warming?

My answer to the above question of why we have to prevent global warming is “so that future human beings can continue to live a healthy and comfortable life.” Although it has been a long time since the latter part of the twentieth century saw calls for “limited growth” and the environmental problem became apparent, during that time human beings rushed ahead in their pursuit of affluence. The word “eco” has become a popular buzzword, but the fact is that most people would be unwilling to relinquish the wealth and convenience they have already tasted.

According to the IPCC Assessment Report, the earth’s climate and environment will change significantly in future if greenhouse gas emissions from human activity continue as they are, and there is a risk of the basis for human life being lost. Because of this, the United Nations Framework Convention on Climate Change (a treaty to prevent global warming) was signed and international measures for the reduction of greenhouse gas emissions have been in place. In reality, however, measures to counter the emission of carbon dioxide, the most damaging of the greenhouse gases, have not progressed much because of the link with the combustion of fossil fuels which forms the core of modern economic activity. While the gap between developed and developing nations widens, carbon dioxide emissions by emerging nations are rising steadily. To achieve a reduction in carbon dioxide emissions across the entire globe, emissions from the emerging economies of China and India must somehow be curbed, but the already rich developed nations have no right to restrict the economic development of these emerging nations. As a solution to this, the concept of decoupling is something I hope can be achieved. Decoupling means severing the connection between economic growth and carbon dioxide emissions, and it is one of the ideas proposed by the OECD and others for sustainable development. This means trying to control carbon dioxide emissions and reducing the amount of resources and energy used even at the same level of economic activity. But Japan has very advanced so-called energy saving technologies, which it should make full use of to help the rest of the world. I hope people will recognize that global warming is a problem that concerns the future of humankind, and take practical measures rather than just glossing over the issue with phrases such as “being kind to the earth.”