loss of biodiversity and reduced global and regional food security. Climate change policies may lead to costs that are relevant to the article 2. For example, more stringent policies to control GHG emissions may reduce the risk of more severe climate change, but may also be more expensive to implement. Projections There is considerable uncertainty over future changes in anthropogenic GHG emissions, atmospheric GHG concentrations, and associated climate change. Without mitigation policies, increased energy demand and extensive use of fossil fuels could lead to global warming (in 2100) of 3.7 to 4.8 °C relative to pre-industrial levels (2.5 to 7.8 °C including climate uncertainty). To have a likely chance of limiting global warming (in 2100) to below 2 °C, GHG concentrations would need to be limited to around 450 ppm CO2-eq. The current trajectory of global emissions does not appear to be consistent with limiting global warming to below 1.5 or 2 °C. Precautionary principle In decision making, the precautionary principle is considered when possibly dangerous, irreversible, or catastrophic events are identified, but scientific evaluation of the potential damage is not sufficiently certain (Toth et al., 2001, pp. 655–656). The precautionary principle implies an emphasis on the need to prevent such adverse effects. Uncertainty is associated with each link of the causal chain of climate change. For example, future GHG emissions are uncertain, as are climate change damages. However, following the precautionary principle, uncertainty is not a reason for inaction, and this is acknowledged in Article 3.3 of the UNFCCC (Toth et al., 2001, p. 656). Criticisms of the UNFCCC process The overall umbrella and processes of the UNFCCC and the adopted Kyoto Protocol have been criticized by some as not having achieved their stated goals of reducing the emission of carbon dioxide (the primary driver of rising global temperatures of the 21st century). At a speech given at his alma mater, Todd Stern—the US Climate Change envoy—expressed the challenges with the UNFCCC process as follows: "Climate change is not a conventional environmental issue ... It implicates virtually every aspect of a state's economy, so it makes countries nervous about growth and development. This is an economic issue every bit as it is an environmental one." He went on to explain that the United Nations Framework Convention on Climate Change is a multilateral body concerned with climate change and can be an inefficient system for enacting international policy. Because the