Conclusions of Working Group III of AR4


As I wrote here on Friday, below is a short version of the Summary of Policymakers of the third Working Group of AR4. Those pages concern the mitigation of climate change. We will see it is still time to act and hope remains.

The summary for Policymakers of Working Group III of the Fourth Assessment Report of the International Panel on Climate Change was released on May 4th.

Below are the most interesting quotes as well as some comments or explanations from me.

Global greenhouse gas (GHG) emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. (…).Between 1970 and 2004, global emissions of CO2 , CH4 , N2O, HFCs, PFCs and SF6 , weighted by their global warming potential (GWP), have increased by 70% (24% between 1990 and 2004), from 28.7 to 49 Gigatonnes of carbon dioxide equivalents (GtCO -eq).

The emissions of these gases have increased at different rates. CO2 emissions have grown between 1970 and 2004 by about 80% (28% between 1990 and 2004) and represented 77% of total anthropogenic GHG emissions in 2004.

Page 1

As we can see with the above figures anthropic GHG emissions are booming. According to the authors, the main causes of this explosion are the energy supply sector with an increase of 145 percent as well as the transport sector with an increase of 120 percent.

Afterwards, the authors make an important statement :

With current climate change mitigation policies and related sustainable development practices, global GHG emissions will continue to grow over the next few decades.

Page 3

After some pages other statements are worthy :

Both (…) studies indicate that there is substantial economic potential for the mitigation of global GHG emissions over the coming decades, that could offset the projected growth of global emissions or reduce emissions below current levels.

Page 10

On page 16, some strong arguments to climate change mitigation are proposed. On top of obvious benefits, the IPCC noted that stopping climate change would have :

near-term health co-benefits from reduced air pollution as a result of actions to reduce GHG emissions can be substantial and may offset a substantial fraction of mitigation costs

On a financial basis :

Including co-benefits other than health, such as increased energy security, and increased agricultural production and reduced pressure on natural ecosystems, due to decreased tropospheric ozone concentrations, would further enhance cost savings.

as well as :

Integrating air pollution abatement and climate change mitigation policies offers potentially large cost reductions compared to treating those policies in isolation.

Insulation of housings is to me a huge source of CO² emissions savings and the IPCC did a declaration that reinforces my position :

Energy efficiency options for new and existing buildings could considerably reduce CO² emissions with net economic benefit. Many barriers exist against tapping this potential, but there are also large co-benefits (…). By 2030, about 30% of the projected GHG emissions in the building sector can be avoided with net economic benefit.

Page 18

This IPCC summary also reports the following :

Geo-engineering options, such as ocean fertilization to remove CO² directly from the atmosphere, or blocking sunlight by bringing material into the upper atmosphere, remain largely speculative and unproven, and with the risk of unknown side-effects. Reliable cost estimates for these options have not been published.

Geo-engineering is a little bit sci-fi to be applied as the main solution to climate change. If this interest you, I will propose an article on this topic as I got some articles on that.

This paper presents two parts, before 2030 and afterwards. Below is their introduction to the long term part :

In order to stabilize the concentration of GHGs in the atmosphere, emissions would need to peak and decline thereafter. The lower the stabilization level, the more quickly this peak and decline would need to occur. Mitigation efforts over the next two to three decades will have a large impact on opportunities to achieve lower stabilization levels .

Page 21

A concrete solution is provided to force people to turn to cleaner ways :

Policies that provide a real or implicit price of carbon could create incentives for producers and consumers to significantly invest in low-GHG products, echnologies and processes. Such policies could include economic instruments, government funding and regulation (high agreement, much evidence).

Page 28

This report also notes the following statement :

Government support through financial contributions, tax credits, standard setting and market creation is important for effective technology development, innovation and deployment. Transfer of technology to developing countries depends on enabling conditions and financing (high agreement, much evidence).

One of the conclusions is :

The literature identifies many options for achieving reductions of global GHG emissions at the international level through cooperation. It also suggests that successful agreements are environmentally effective, cost-effective, incorporate distributional considerations and equity, and are institutionally feasible.

Page 31

Source :

  • Working Group III Summary for Policymakers, released on May 4th by the IPCC. | Direct download

I will release on Wednesday an article on the main solutions proposed by the IPCC.

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