32 No. 4
Perspectives on Chemistry and Global Climate Change
by Fulvio Zecchini and Pietro Tundo
Global warming is one of the most appropriate case-studies to introduce to students since it involves extensive problem-based learning and class discussion. In order to understand such phenomenon, students must explore several aspects of chemistry, physics, and biology in a holistic and multidisciplinary fashion.
A number of IUPAC projects are focused on educating students and the general public about the central role of chemistry in understanding and devising countermeasures to the global warming phenomenon. The Organic and Biomolecular Chemistry Division’s Subcommittee on Green Chemistry has completed three projects concerning the translation, updating, adaptation, and distribution of a monograph on global climate change for secondary schools. Read more in the side article Teaching About the Role of Green Chemistry.
Another IUPAC project, entitled Visualizing and Understanding the Science of Climate Change (2008-043-1-050), is currently underway. A project of the Committee on Chemistry Education, it treats the topic from a different perspective using Internet-based communication/educational tools. (Read more here.)
A Timely Topic
Based on data from the Intergovernmental Panel on Climate Change (IPCC Report 2007), there is firm evidence of global warming, and proof that human activity is the major cause. According to the panel, mean global surface temperature has increased by 0.7 °C ca. from 1906–2005. In recent decades, glaciers have begun melting faster all over the world, and the snow cover has been shrinking in the Northern Hemisphere. Model-based estimates of sea-level rise for the decade 2090–2099 range from 0.18 to 0.59 metres compared to the average for 1980–1999.
It is widely accepted by the scientific community that global warming is caused by the emission of anthropogenic greenhouse gases (GHGs) into the atmosphere. In 2007, the IPCC completed an analysis of 2004 climate data and found that CO2 remains the most prevalent GHG, accounting for 76.7% of emissions (56.6% derived from the use of fossil fuels, 17.3% from deforestation, and 2.8% from other sources), followed by methane, 14.3%; nitrous oxide, 7.9%; and F-gases, 1.1%. In terms of the human contribution, the major impact comes from energy usage, 25.9%; followed by industry, 19.4%; forestry, 17.4%; agriculture, 13.5%; transport, 13.1%; residential and commercial buildings, 7.9%; and waste and wastewater, 2.8%.
Within such a framework, it is obvious that the solution to global warming lies in international politics, since the two most effective counteractions would be to switch to alternative energy sources as soon as possible and to immediately discontinue deforestation. From a practical point of view, the solution must be a mix of countermeasures (political and scientific) and adaptation/
mitigation (society and economics).
The most recent international event on climate change was the Copenhagen conference held in December 2009. Its most significant result was that all major industrial countries, including USA and China, agreed that action is necessary immediately. Such was the core philosophy of the Kyoto Protocol, whose provisions in terms of GHG reductions have not been met on a global level.
According to the Stern Review on the Economics of Climate Change, inaction will have a major negative impact on the world economy, costing 5%–20% of global annual GDP. Conversely, the cost of reducing GHGs by 75% by 2050 is estimated at 1% of global GDP. Such a cut would result in a CO2 concentration of 550 ppm. The concept is reported in The European Commission’s white paper “Adapting to Climate Change: Towards a European Framework for Action” makes the same general argument about inaction/action costs.
Progress on reducing GHGs has been limited following the Kyoto Protocol since several countries do not agree on specific countermeasures, although all nations acknowledge that the main solution remains abating emissions of CO2. In this context, the European Commission has set two targets for the European Union in its “Communication 20 20 by 2020”: a reduction of at least 20% in GHGs and the production of 20% of energy from renewables. The targets are intended to limit temperature increase to 2 °C. In parallel, the USA is adopting diverse initiatives such as the Mandatory Reporting of GHGs Rule, to report emissions and collect data for future policy decisions, and The Climate Change Technology Program, to foster novel technologies for the reduction of GHGs. Hopefully, some concrete decisions will be taken at the forthcoming international UNFCCC meeting in Bonn (June 2010) and during the COP-16 in Cancun (December 2010).
Simplified scheme of the carbon cycle. (Institute for the Application of Calculations, National Research Council, Napoli, Italy). Figure 3.9 reproduced from Il Cambiamento Globaled del Clima.
The Role of Green Chemistry
From a scientific point of view, some countermeasures are quite simple to imagine: the use of fossil fuels is the major concern, but technically speaking their complete substitution is not achievable at present. Photovoltaic and wind power are sustainable ways to produce energy, but the energetic yield per used surface of such technologies is too low, being insufficient for most civil and industrial applications. On the other hand, Green Chemistry can provide significant contributions to the abatement of CO2 emissions. Following are just a few of the many ways Green Chemistry can help:
- creation of new products/processes/catalysts to reduce energy consumption and by-products/waste production
- development of products/processes/catalysts that don’t use halogens or volatile organic solvents
- implementation of highly efficient processes
- use of CO2 as a C1 building block
- generation of H2, bio-hydrogen, from biomasses
- valorization of biomasses in bio-refineries
- syntheses of biodiesel from exhaust oils or from algae, bio-ethanol from lignin/cellulose biomasses
- creation of polymers from renewables
- use of novel materials for photovoltaic panels and fuel cells, and the improvement of battery capacity for electric vehicles
- improvement of catalytic converters for vehicles
Independence from fossil fuels still seems far off: on the one hand, we need more time, on the other hand, action is needed now. Some scientists recently proposed to adopt some extreme geo-engineering measures at a global level in order to actively capture CO2 or to reflect part of the solar radiation. With respect to the last solution, Tom Wigley and Paul Crutzen (Nobel Prize in Chemistry in 1995) have proposed the deliberate periodic introduction of sulphate particles, aerosols, or precursors (dimethyl sulphide, sulphur dioxide, carbonyl sulphide, or hydrogen sulphide) in the atmosphere, in order to form reflecting/diffracting sulphate aerosols. If this were economically viable, Wigley thinks we could have a 20-year period during which the warming should be balanced by the reduced incoming radiation, allowing us more time to find proper long-term solutions.
Clearly, there are many aspects of chemistry that relate to climate change. For this reason, many if not most divisions of IUPAC are involved in the issue. Educational projects, such those discussed in this article, not only help make students better stewards of the planet, but they help develop the next generation of scientists and chemists who will, in all likelihood, still be developing solutions to this global problem.
Pietro R. Tundo <[email protected]> and Fulvio Zecchini <[email protected]> are both at the Università Ca’ Foscari di Venezia, in Venezia, Italy. Tundo was president of the IUPAC Division on Organic and Biomolecular Chemistry for 2008–2009.
last modified 28 June 2010.
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