Climate change: More reasons for concern

Main topics

Building on IPCC’s Third Assessment Report, the conference on Avoiding Dangerous Climate Change considered three scientific questions relating to stabilising greenhouse gas concentrations in the atmosphere at levels which would avoid dangerous anthropogenic climate change.

The questions

The report addresses the following questions. Among many leading scientists that contributed were several MNP scientists; they were mainly involved in questions 2 and 3.

1. What are the key impacts for different levels of climate change?

Not surprisingly, the report concludes that impacts will change according to the extent of temperature rise.

"Above a one degree Celsius increase, risks increase significantly, often rapidly for vulnerable ecosystems and species," concludes Bill Hare from the Potsdam Institute of Climate Impact Research in Germany, who produced an overview of more than 70 studies of impacts on water resources, agriculture and wildlife. "In the one to two degree range, risks across the board increase significantly, and at a regional level are often substantial," he writes. "Above two degrees the risks increase very substantially, involving potentially large numbers of extinctions or even ecosystem collapses, major increases in hunger and water shortage risks as well as socio-economic damages, particularly in developing countries."

2. What emission pathways may lead to avoiding dangerous climate change?

"For achieving the two degrees Celsius target (EU climate policy target) with a probability of more than 60%, greenhouse gas concentrations need to be stabilised at 450 ppm CO2-equivalent or below". Thus concluded Michel den Elzen (MNP) and Malte Meinshausen (NCAR, USA), authors of chapter 31.

They explored the relationships between various climate targets, atmospheric greenhouse gas concentrations that are required for achieving these targets, and associated emission levels.

• See also their report: "Meeting the EU 2 degrees C climate target: global and regional emission implications"

3. What mitigation options exist for achieving stabilisation of greenhouse gases concentrations at low levels?

"The combined technical potential of different mitigation options seems, in principle, to be sufficient to achieve low-level stabilization. The biggest problem does not seem to be the technologies or the costs, but overcoming the many political, social and behavioral barriers to implementing mitigation options." is concluded by Bert Metz and Detlef van Vuuren (both MNP) as authors of chapter 35. They assessed available literature on the mitigation potential of technologies.

More Information on the report

• The UK government site (contains the report).
• The newsitem on the BBC site