IPCC’s latest report on Climate Change – summary part 2

After looking at historical emissions trends, the report then looks at future greenhouse gas (GHG) emissions trends and considers a series of scenarios around economic growth, global population growth, development of new technologies and their uptake. These were developed separately by the Special Report on Emission Scenarios.

The scenarios are:

A1. There is rapid economic growth with global population growth which peaks mid-century declining thereafter. The theme of this scenario is that the regions of the world converge, economically, scoially and culturally, and there is a substantial reduction in regional differences in per capita income.

This splits into 3 groups that describe alternative technological change to energy systems:

A1F1. Fossil fuel intensive.
A1T. Non-fossil energy sources prevalent.
A1B. A balance across a range of energy technologies.

A2. This scenario considers a very heterogeneous world with an emphasis on self-reliance and preservation of local identities. A slow convergence of fertility patterns leads to continuing population growth and technological change is more fragmented and slower than in other scenarios.

B1. Similar to A1 but with rapid changes to economic structures towards a service and information economy, with less material intensity and the introduction of clean and resource efficient technologies. The emphasis is on global solutions to sustainability, including improved equity, but without additional climate initiatives.

B2. Like A2, this scenario describes a world with local solutions to sustainability. It has continuously increasing population growth, at a lower rate than A2, intermediate levels of economic development, and less rapid and more diverse technological changes than the A1 and B1 scenarios.

Estimates of GHG emissions for the years 2030 and 2100 were developed from these scenarios, and have since been updated. Both are included in the graph (and make it a bit confusing!). The year 2000, on the left of the graph, is taken as the baseline.

You can click on the graph to open it in a new window.




The general consensus in the report is that with current climate change mitigation policies and related sustainable development practices, GHG emissions will continue to grow over the next few decades.

As can be seen from the above graph, these scenarios lead to a wide range of projected emissions. These range from an increase of 9.7 Gigatonnes (CO2 equivalent) from the year 2000 baseline by 2030 to 26.7 Gigatonnes (CO2 equivalent) by 2030 - respective a 25% and 90% increase.

By the year 2100, there is a huge variation in GHG emissions between scenarios due to different ways of mitigating them. In the next blog, I'll look at what the report says about mitigating GHG emissions, the sectors where this can be achieved and the costs.