by Christina Hulbe
Last Friday, the Intergovernmental Panel on Climate Change, Working Group Three: Mitigation, issued the summary for policy makers (pdf) of their final report. A webcast of the press conference is here. Mitigation means, specifically, efforts to stabilize or reduce greenhouse gas concentrations in the atmosphere (or to otherwise manipulate Earth's temperature).
After the break, I'll outline findings that the working group evaluates as "high agreement" and "much evidence." Some seem obvious (emissions have increased) but many are not, and many address topics in the ongoing discussion about how people and governments should respond to global warming.
Before that, I'd like to emphasize a few themes from the report. First, technologies already exist to accomplish meaningful greenhouse gas (GHG) stabilization goals. Second, the costs of mitigation are manageable (estimates range from small gains in GDP to costs in the few percent of GDP range). Third, there are significant co-benefits to mitigation, including economic growth in some sectors, public health, and energy & food security.
* Global greenhouse gas (GHG) emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. Over that time interval, the growth in emissions from various sources are as follows:
* energy supply sector increased by 145%
* direct emissions from transport 120%,
* industry 65%
* land use, land use change, and forestry 40%
Between 1970 and 1990:
* direct emissions from agriculture grew by 27%
* direct emissions from buildings grew by 26% (remained at
approximately 1990 levels since then) though buildings have a large
share of the emissions growth from electricity use
* With current mitigation policies and related sustainable development practices, global GHG emissions will continue to grow over the next few decades
cost of GHG mitigation
* As energy demand increases, it is often more cost-effective to invest in improving end-use energy efficiency instead of investing in increasing the energy supply
* Returning global energy-related CO2 emissions to 2005 levels by 2030 would require a large shift in the pattern of investment in energy production but the net additional cost is estimated to range from negligible to perhaps 10%
* Economic analyses that assume a multi-gas approach (more than just CO2) and inclusion of carbon sinks generally yield lower net costs than CO2-only scenarios
GHG emissions mitigation strategies are affordable and have many co-benefits
* There are economically viable mitigation strategies, that can offset the projected growth of global emissions or reduce emissions below current levels
* In addition to reducing emissions, energy infrastructure investments in developing countries, upgrades of energy infrastructure in industrialized countries, and policies that promote energy security have (region-specific) co-benefits including air pollution abatement, balance of trade improvement, provision of modern energy services to rural areas, and employment opportunities
* Near-term health co-benefits from reduced air pollution may offset a substantial fraction of mitigation costs (in all regions studied for the AR4)
* Employing energy efficiency technologies for new and existing buildings can reduce CO2 emissions by about 30% by 2030 and yield a net economic benefit. Barriers to such changes include availability of technology, financing, and governmental policies but there are also large co-benefits including improvements to indoor and outdoor air quality and energy security.
* The economic benefits in GHG mitigation are predominantly in energy-intensive industries but by-and-large, these industries are not taking advantage of mitigation options. Key barriers are slow rate of capital stock turnover, lack of financial resources, limited access for small and medium-sized businesses to appropriate support.
* Forest-related mitigation can reduce emissions and increase CO2 removal at low cost with substantial co-benefits. The co-benefits include income generation, biodiversity and watershed conservation, and renewable energy supply. About 65% of the mitigation potential is in the tropics and about 50% of the total mitigation potential lies in reducing emissions due to deforestation.
* Post-consumer waste is a small part of the global GHG emission but mitigation strategies here can have a positive effect at low cost with public health and environmental protection co-benefits.
* Geoengineering approaches (orbiting reflectors, iron fertilization of the ocean) are largely speculative and untested, and may have unanticipated side-effects. Reliable cost estimates are not available. (The working group classifies this as medium agreement, limited evidence.)
the big picture
* Mitigation strategies adopted in the next two to three decades will have a large impact on our ability to achieve lower atmospheric GHG stabilization levels (and thus lower net warming).
* GHG stabilization can be achieved with currently available technologies (and more expected to be commercialized in the next few decades).
* quoting the report: "Making development more sustainable by changing development paths can make a major contribution to climate change mitigation, but implementation may require resources to overcome multiple barriers. There is a growing understanding of the possibilities to choose and implement mitigation options in several sectors to realize synergies and avoid conflicts with other dimensions of sustainable development."