a thirty year period and we have gained 1/2 a degree that is statistically within no dicernable change

Again there is 7% more carbon in the atmosphere since 1971 so a portion of that perhaps as high as 3% could be mans release. so we need to clean up our emissions. When carbon hits 550 ppm approximately in 200 years without doing anything the northern tree line will be 25 to 30 miles further north and will act as a carbon sink. to cycle it back down because by then peak oil will have been long past and coal itself will be extremely scarce

The ultimate objective of the UNFCCC is to stabilize GHG concentrations in the atmosphere to avoid climate change (UNFCCC, 1992). Due to scientific uncertainties in the climatic system the concentrations level to be stabilized has not been unambiguously determined yet (Metz and van Vuuren 2006). However, there is a general understanding among the scientific community that atmospheric concentrations of CO2 may need to be contained below 450 ppm to avoid the “dangerous interference” mentioned in the UNFCCC text (Kopp 2004). If non-CO2 GHGs are also included, the concentrationss level would be 550 ppm CO2eq. Non-CO2 GHGs would have significant impacts on global warming because of their much higher rediative forcing (or global warming potential) compared to CO2 (IPCC 2007). Moreover, their inclusion provides flexibility to reduce the costs of stabilizing the GHG concentrations (e.g., Weyant et al. 2006).

However, non-CO2 GHGs are often excluded from most existing studies because of lack of data (Sarofim et al 2004). This study too does not include non-CO2 GHGs because neither historical nor forecasts of these gases are available to the details needed here.

To stabilize atmospheric CO2 concentrations at 450 ppm level, global CO2 emissions must decline before 2030 (Grubb et al 2006; Stern 2006). The Fourth Assessment Report of IPCC concludes that to stabilize CO2 concentrations between 400 --- 440 ppm level, global CO2 emissions should start declining by 2020; to stabilize CO2 concentrations between 440 --- 485 ppm level, global CO2 emissions should start declining by 2030 (IPCC 2007). To achieve this level of stabilization, stringent mitigation targets and wider participation, including non-Annex I countries, might be required.

In this study, we have developed two scenarios for the near-term (i.e., until 2030) targets for CO2 emissions reductions in line with long term stabilization of CO2 concentrations at 450 ppm level. While developing these scenarios we followed two principles. First, Annex I countries’ historical emissions are primarily responsible for the hitherto build up of GHG concentrations in the atmosphere. Secondly, non-Annex I countries share in the total CO2 emissions is continuously increasing and will surpass to that of Annex I countries within a few years. By 2030, non-Annex countries would contribute 55 percent of the global CO2 emissions (EIA, 2007b). It is unlikely to get global emissions declining before 2030 unless non-Annex I countries’ total emissions start declining. We therefore consider two scenarios for non-Annex I countries’ total emissions15 : stabilization of their total CO2 emissions at the (i) 2020 level and (ii) 2030 level16. In the case of Annex I countries, their emissions paths are assumed to follow the targets as specified below in both scenarios:

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This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO2 concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.