According to the IPCC, GHG's are well beyond the business-as-usual scenario that James Hansen and NASA identified as leading to global warming "hell" ... big problem with that though.....
This IPCC AR5 SPM chart reveals some very interesting information about greenhouse gases. The chart plots GHG group emissions over the period from 1970-2010. (chart source)
The adjacent 'C3' chart, re-plots the same information using a simple column representation, plus depicting the fitted trend growth for each GHG group's emissions.
Some key points:
1. From 1970 to 2000, total GHG emissions grew by 1.3% per year.
2. Over the period of 2000-2010, that growth increased to 2.2% per year - a robust 70% growth in the annual rate.
3. Total GHG emissions jumped significantly from 2000-2010, to a historical record, with the combined CO2 emission groups being the principal contributors.
5. Methane emissions essentially stalled over 20 years but then started to increase over the last period.
6. Fluorinated gases (hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride), which are supposed to be reduced under the terms of the Kyoto protocol, have increased by 8x since 1970 but still only represent less than one-tenth of one percent of all GHG emissions.
7. Although the growth rate of CO2 emissions from fossil fuels slowed a bit from 1980 to 1990, it's growth started accelerating during the 90's.
8. The combination of CO2 fossil fuels emissions and CO2 emissions from deforestation, forest fires and peat burning have grown from 72% of all GHG emissions in 1970 to 76% of all GHG emissions.
Clearly, and unequivocally, the GHG emissions have not only sustained the business-as-usual (BAU) growth path that so concerns prominent advocates of climate alarmism, but over the last 10 year period the 'BAU' scenario levels for the demonized CO2 have jumped significantly (see top 3 charts on this page)
A little history: The BAU greenhouse gas emissions path was made famous by NASA's James Hansen, whose 1988 Senate testimony introduced the public to the dangerous and accelerating global warming potential of Scenario 'A'. This scenario was determined/computed to be a direct result of not reducing/restraining the GHGs emissions, especially fossil fuel CO2.
From a famous 1988 peer reviewed article by Hansen et al.:
"We define three trace gas scenarios to provide an indication of how the predicted climate trend depends upon trace gas growth rates. Scenario 'A' assumes that growth rates of trace gas emissions typical of the 1970s and 1980s will continue indefinitely; the assumed annual growth averages about 1.5% of current emissions, so the net greenhouse forcing increases exponentially. Scenario 'B' has decreasing trace gas growth rates, such that the annual increase of the greenhouse climate forcing remains approximately constant at the present level. Scenario 'C' drastically reduces trace gas growth between 1990 and 2000 such that the greenhouse climate forcing ceases to increase after 2000."
Switching from that history to the present, as the IPCC documents in the latest AR5 SPM (WGIII), we are living in the emission scenario of unrestrained growth - growth beyond the feared 1988 'BAU'. Hansen defined unrestrained BAU growth of GHGs as 1.5% per year, and now the IPCC reports it's growing at a 2.2% per annum rate.
In the opinion of climate alarmist advocates, this feared 'Beyond-BAU' growth means that radiative forcings (watts per square meter) will dramatically increase, resulting in out-of-control warming, multiple positive feedback loops and ever greater and more frequent climate/weather catastrophes.
And these alarmist opinions are due to the very costly and "sophisticated" IPCC/climate agencies computer crystal balls model simulations - dominated by said CO2 and other trace GHG emissions - that have proven to be such unreliable prediction tools. Recall that those climate model temperature prediction 'Ooopsies' are a major embarrassing problem plaguing the current reliance of climate science on unproven virtual simulations.
Just to add a little more context to the 'Beyond-BAU' fears of accelerating CO2 emissions, there is this article:
"Annual carbon dioxide emissions showed a strong [2014] rise of 2.5% on 2013 levels, putting the total emitted this year on track for 40bn tonnes. That means the global ‘carbon budget’, calculated as the total governments can afford to emit without pushing temperatures higher than 2C above pre-industrial levels, is likely to be used up within just one generation, or in thirty years from now."
Finally, in the IPCC's own AR5 SPM words:
"Total anthropogenic GHG emissions have continued to increase over 1970 to 2010 with larger absolute decadal increases toward the end of this period. Despite a growing number of climate change mitigation policies, annual GHG emissions grew on average by 1.0 gigatonne carbon dioxide equivalent (GtCO2eq) (2.2 %) per year from 2000 to 2010 compared to 0.4 GtCO2eq (1.3 %) per year from 1970 to 2000. Total anthropogenic GHG emissions were the highest in human history from 2000 to 2010 and reached 49 (±4.5) GtCO2eq/yr in 2010.".....
"Without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist driven by growth in global population and economic activities. Baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 °C to 4.8 °C compared to pre-industrial levels."
Conclusion: The alarmist science community and the IPCC's worst case GHG scenarios have been attained. Yet global temperatures (i.e. accelerated warming) have not responded accordingly. As one could surmise..."something is rotten in the state of computer climate science."