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We come across two different uses of the term CO2 emissions (and concentrations), and different definitions, and different metrics of CO2 emissions weight, making 'CO2 emissions' very confusing.

CO2 equivalent​
CO2 equivalent, which is higher than CO2, is mainly used by the IPCCin assessments. ​

CO2 emissions (just CO2) and CO2 equivalent emissions (CO2e/CO2eq)​
CO2 equivalent includes the other main GHGs, like methane and nitrous oxide, expressed in terms of an equivalent amount of CO2 in terms of surface warming effect. So CO2 eq is considerablyhigher than CO2. CIO2 eq. accounts for seven GHGs in all.

​The others like HFCs include the most potent and long lasting GHGs. They are artificial 'man-made' chemicals used in industry emitted in the tiniest amounts.

Kyoto CO2 eq GHGs​

1. ​Carbon dioxide (CO2) 
2. Methane (CH4) 
3. Nitrous oxide(N2O) 
4. Hydrofluorocarbons (HFCs) 
5. Perfluorocarbons (PFCs) 
6. Sulfur hexafluoride (SF6) 
7. Nitrogen trifluoride (NF3)

​There are also two different definitions of CO2 eq. 

In addition to the above, some agencies, like the EU, roll in the cooling effect of sulfate aerosol emissions making their CO2 eq. some what lower.

Burning fossil which fuels emits ​CO2 also releases air pollution aerosols (tiny particles suspended in the air (lower atmosphere). Black carbon (soot) is one which has a surface warming effect, second only to CO2. The largest source is from burning forests. Other sources are burning fossil fuels particularly diesel, wood stoves and cooking with wood. 
Black carbon is not accounted for in any CO2 eq. definition.

Others emissions are acid aerosols notably sulfates, that is surface cooling.
This is not a good thing because fossil fuel burning has to ​stop (zero carbon) and that will unmask
​​the hidden warming of cooling aerosols. 

Damage to human health
​​​​As well as the main source of global warming greenhouse gases fossil fuels
are the main source of toxic air pollution. Over recent as air pollution effects
​on health have been researched more and more population health damaging
​and ​lethal effects have been found and confirmed.

The fossil fuel world economy ​is responsible for an estimated
​5 million deaths a year

Climate change is causing an estimated 400,000 deaths a year (DARA 2012)​​


Other fossil fuel emissions to remember​​

It must not be assumed that ​CO2 is the only global warming
​fossil combustion emissions. 
There are actually a lot of greenhouse emissions​ from
​burning fossil fuel emissions. 

Having to end all fossil fuel combustion to achieve 
​the zero carbon energy world has many other human population
​and economic benefits.




Greenhouse Gases, CO2, CO2e, and Carbon:  
What Do All These Terms Mean? 2012 Ecometrica
Since 1750 the human race has been responsible for a staggering 2,000 gigatonnes of carbon dioxide emissions.

​​2015 CO2 emissions from fossil fuel combustion  ​and cement manufacture were 35.7 Gt CO2 (GHlobal Carbon project) ​1 GtC = (109 tonnes C = 3.67 Gt carbon dioxide.

Chart of global CO2 emissions from fossil fuels & CO2 atmospheric concentration 1860 to 2015
Chart of CO2 emissions by country and per capita 2013 ​ 

Emissions from 1750
Emissions from 1990
​Global Carbon Project
Since 1750 to 2013  CO2 emissions have been increasing at an exponential (accelerating   rate).

From 2014 fossil fuel C22 emissions have practically stopped increasing, but all projections  are for CO2 emissions to carry on increasing.​​
CO2 is mainly being emitted by fuel combustion (wood, peat, coal, oil, natural gas methane)

By far the most CO2 is being emitted by burning fossil carbon as fuel.

Using electricity emits CO2 , unless from hydro or clean renewable energy.
Nuclear fission energy is assessed as low carbon by the IPCC (full life cycle)​​.​

T​​ransportation emits COP2 by burning gasoline. Electric 
vehicles are a source of CO2 emissions unless the electricity is from hydro or clean renewables. 
The manufacture of cement (burning limestone) emits CO2. ​
The full life cycle of the new clean renewables though is not zero carbon though- e.g. it takes a lot of steel and concrete to manufacture and erect a large wind turbine. Wind energy does not have enough energy density to manufacture wind turbines.
Modern construction is a source of CO2 from the steel and concrete. ​

Deforestation emits CO2 from the forest floor, which is then not recycled by the standing forest​.
Forest fires emit CO2 which are increasing due to global surface warming.  ​
CO2 is also emitted ​by drought due to the rapid decay of plants, including crops. 
Slash and burn agriculture in general emits CO2​.
​Modern agricultural lands emit and take up a large amount of CO2 that is actually estimated to be about in balance (IPCC AR4).

The IPCC refers to CO2 emissions from agriculture and deforestation as 'land use change'.
21 Mar 2016 Human carbon release rate is unprecedented in the past 66 million years-
research indicates the present CO2 emission rate is 10 times faster ​than the past 66 M years.

Emissions from EDGAR