A goal of a 50% reduction in global greenhouse gases emissions by 2050, with an 80% reduction by developed countries (hereafter referred to as the G8 Goal), was proposed at the G8 Summit held in L’Aquila, Italy, in July 2009. Here we analyze the scientific and political implications of the G8 Goal and its equity and feasibility by examining four greenhouse gas emissions scenarios. Our results show that (1) the goal to keep atmospheric CO2 concentration of <450 ppmv, stated by G8 nations, can only be achieved under the scenario of a steady, linear emissions reduction by all countries and simultaneously meeting the G8 Goal during the period 2005-2050; (2) under the G8 Goal, the carbon emissions quota for developing countries would not meet their carbon emission demands even if very strict reduction regimes are followed, with a gap of up to >1/3 of emissions demand in the next 45 years; and (3) under the G8 Goal, the cumulative per capita emissions during the period of 2006-2050 for developed and developing countries will be 81 t C and 40-47 t C, respectively, with the former doubling that of the latter, implying that the historical disparity of carbon emissions between developed and developing countries would be widened. Historically, the cumulative per capita emissions from developed countries are 12 times of those from developing countries. We therefore conclude that (1) the G8 Goal seeks to impose binding reduction targets on developing countries that will impede their industrialization process and cause conflicts among developing countries in the allocation of carbon emission rights; (2) the G8 Goal will not only widen the existing disparities of historical carbon emissions between developed and developing countries, but also generate new inequalities in the rights of carbon emissions; and (3) the 450 ppmv threshold of atmospheric CO2 concentration control, which is the basis for the G8 Goal, is impractical and impossible, and should not be accepted as the foundation for international climate negotiatio
Global surface temperature has dramatically increased in the past decades.It is critical to evaluate such a change using appropriate approaches.The previous studies for assessment of the change usually used overall trends of temperature series(i.e.slopes of simple linear regression of temperature versus year based on a least-square analysis) for entire study period.Temperature trends,however,differ among different periods,i.e.there are often breakpoints in the temperature series.Therefore,the overall linear trend of a temperature series may conceal some of the temporal characteristics of the temperature change.To precisely characterize the temporal and spatial patterns of air temperature change in China,we analyze the annual mean temperature series between the year of 1961?2004 for 536 meteorological stations across China,using piecewise linear regression approach.We found remarkable breakpoints in the annual mean temperature during the study period across the country.The annual mean temperature started to increase in 1984 at a rate of 0.058°C/a at the country level.The year when warming started appeared to be gradually later from the north to the south:temperature increased since the 1970s in the north(north of 40°N),and did not rise until the 1980s in most areas of the south(south of 40°N),with warming starting in 1983 in the Tibetan Plateau.The trends in annual mean temperatures showed a large spatial heterogeneity across China:a relatively small rising with a rate of 0.025-0.05°C/a in the Sichuan Basin,Central China and South China;the greatest increase in some parts of northwest China(i.e.Xinjiang) with up to a rate of 0.1°C/a;and rising at a rate of >0.05°C/a for most regions of the country.The feedbacks of cold waves and snow may be responsible for such regional differences in the timing and rates of warming in China.
