NEW YORK ( TheStreet) - Global greenhouse gas emissions are growing and Chinese oil and gas companies are some of the top offenders, according to a  December 2014 report by Thomson Reuters and BSD Consulting. 

The report studied greenhouse gas emissions from the world's 500 largest businesses by market cap to determine how output has "evolved" from 2010, the baseline year for calculating emission reductions, to 2013, which is the latest year with completed data.

Over the four-year period, the Global 500's greenhouse gas emissions increased by 3.1% to reach 4.96 gigatonnes per year of carbon dioxide equivalents --13.8% of global emissions. The top 20 companies emitted 2.77 gigatonnes in 2013, more than half the total.

Greenhouse gas emissions should have decreased by 4.2% for the same period "in order to have a likely probability of staying within the 2° Celsius average global temperature increase" from 2010-2050, the authors of the report note, to help reduce the impact on the world's climate. These recommendations were outlined in the 2014 United Nations Environment Programme Emissions Gap Report.

To be sure, emissions output changes can be the result of "business growth and/or the result of concerted action to become less carbon intensive," the report said. "Change in absolute emissions also can be the result of acquiring or selling part of a business, or reflect changes in GHG scope or methodology for measuring GHG."

Here are the top 20 global greenhouse gas emitters in 2013, ranked from lowest to highest. Click here to here to see the worst global warming offenders of all time, according to a scientific journal.

20. Petroloeo Brasileiro S.A. (Petrobras) (PBR - Get Report)
Brazil
Sector: Energy, Integrated Oil & Gas

Petrobras, Brazil's state-controlled oil company, emitted 73.4 million metric tons of carbon dioxide equivalent in 2013.

19. Electricite de France S.A. (EDF) EDF.PA
France
Sector: Utilities, Electric Utilities

EDF, an integrated energy company that generates electricity through nuclear, hydro, wind, solar, biomass, geothermal, fossil fuel, and marine energy sources, emitted 80.6 million metric tons of carbon dioxide equivalent in 2013.

18. Royal Dutch/Shell (RDS.B - Get Report)
Netherlands
Sector: Energy, Integrated Oil & Gas

Royal Dutch/Shell, a global group of energy and petrochemicals companies, emitted 83 million of carbon dioxide equivalent in 2013. The company has emitted more than 30 billion tons of carbon dioxide equivalent over a period of nearly 200 years.

17. POSCO (PKX - Get Report)
South Korea
Sector: Materials, Steel

POSCO, a multinational steel making company, emitted 88.1 million metric tons of carbon dioxide equivalent in 2013.

16. Lafarge S.A. LGNV.PA
France
Sector: Materials, Construction Materials

Cement company Lafarge emitted 92.5 million metric tons of carbon dioxide equivalent in 2013.

Lafarge and Switzerland-based Holcim Ltd. agreed to a $43 billion merger of equals last spring. The companies are awaiting regulatory approval to complete the deal.

15. The Southern Company (SO - Get Report)
USA
Sector: Utilities, Electric

Southern Company, the Atlanta-based utility company, emitted 102 million metric tons of carbon dioxide equivalent in 2013.

14. Holcim Ltd. HLBN.DE
Switzerland
Sector: Materials, Construction Materials

Holcim, a leading global supplier of cement and aggregates, emitted 102.1 million metric tons of carbon dioxide equivalent in 2013.

Holcim and Paris-based Lafarge agreed to a $43 billion merger of equals last spring. The companies are awaiting regulatory approval to complete the deal.

13. Nippon Steel & Sumitomo Metal Corp.
Japan
Sector: Materials, Steel

Nippon Steel & Sumitomo Metal Corp., Japan's biggest steelmaker and the world's second largest steelmaker by output, formed by the 2012 merger between Nippon Steel and Sumitomo Metal Corp. emitted 114.07 million metric tons of carbon dioxide equivalent in 2013.

12. American Electric Power Co. (AEP - Get Report)
USA
Sector: Utilities, Electric Utilities

Electric utility company, American Electric Power, delivers power to more than 5.3 million customers in 11 states. AEP emitted 115 million metric tons of carbon dioxide equivalent in 2013.

11. ENEL S.p.A ENEL.MI
Italy
Sector: Utilities, Electric Utilities

Enel S.p.A. is Italy's larger power company and the second largest utility listed in Europe. In 2013, Enel emitted 115.69 million metric tons of carbon dioxide equivalent.

10. E.ON EOAN.DE
Germany
Sector: Utilities, Multi-Utilities

E.On, based in Dusseldorf, Germany, is one of the world's largest investor-owned power and gas companies. E.On emitted 120.7 million metric tons of carbon dioxide equivalent in 2013.

9. Exxon Mobil Corp. (XOM - Get Report)
USA
Sector: Energy, Integrated Oil & Gas

While Exxon Mobil ranked No. 2 in the top global warming polluters of all-time list, the company comes in at No. 9 for its emissions in 2013, in which it emitted 126 million metric tons of carbon dioxide equivalent.

Exxon Mobil accounted for 3.22% of global emissions between 1751 and 2010, the Climatic Change report said.

8. Gazprom GAZP.ME
Russia
Sector: Energy, Integrated Oil & Gas

Gazprom emitted 131.89 million metric tons of carbon dioxide equivalent in 2013. From 1751 through 2010 (it was founded in 1989), it accounted for 2.22% of global emissions, according to the Climatic Change report.

7. Duke Energy (DUK - Get Report)
USA
Sector: Utilities, Electric Utilities

Charlotte-based Duke Energy, the largest electric power company in the U.S., emitted 136.1 million metric tons of carbon dioxide equivalent in 2013.

6. GDF Suez GSZ.PA
France
Sector: Utilities, Multi-Utilities

GDF Suez, a global energy player and an expert operator in the three key sectors of electricity, natural gas and energy services, emitted 153.3 million metric tons of carbon dioxide equivalent in 2013.

5. RWE AG RWE.DE
Germany
Sector: Utilities, Multi-Utilities

German electric utilities company RWE AG emitted 167.2 million metric tons of carbon dioxide equivalent in 2013.

4. NTPC Ltd. NTPC.NS
India
Sector: Utilities, Independent Power Producers and Energy Trader

India's largest power company NTPC emitted 200.9 million metric tons of carbon dioxide equivalent in 2013.

3. Arcelor Mittal (MT - Get Report)
Luxembourg
Sector: Materials, Steel

Steel company Arcelor Mittal emitted 207 million metric tons of carbon dioxide equivalent in 2013.

2. China Petroleum & Chemical Corp. (Sinopec) (SNP - Get Report)
China
Sector: Energy, Integrate Oil & Gas

Chinese oil and gas company, China Petroleum & Chemical Corp., emitted 249.4 million metric tons of carbon dioxide equivalent in 2013.

1. PetroChina (PTR - Get Report)
China
Sector: Energy, Integrated Oil & Gas

Oil and gas giant PetroChina emitted 310.5 million metric tons of carbon dioxide equivalent in 2013.

- Written by Laurie Kulikowski in New York.