The United States has only 4% of the world population, and 
emits  25% of the world's CO2 emissions (year 2005).

SORTED  BY  CO2 Emissions Per Person (Grouped by Country)
Country GDP CO2 emissions GDP per Emissions Area  Population CO2 emissions per person
(in millions of US Dollars) (in thousands of metric tons) (in thousands of US Dollars per metric ton) (in sq. mi.)   (in thousands of metric tons per person)
Panama 14351 6255 2.294 177 20,579 0.30395
Qatar 31550 36450 0.866 4,416 885,359 0.04117
Trinidad and Tobago 13558 41217 0.329 1,980 1,065,842 0.03867
United Arab Emirates 103006 94163 1.094 32,000 2,602,713 0.03618
Bahrain 11781 21327 0.552 257 698,585 0.03053
Kuwait 61469 59879 1.027 6,880 2,418,393 0.02476
Luxembourg 35620 9442 3.773 998 474,413 0.01990
United States 12438873 5872278 2.118 3,718,691 298,444,215 0.01968
Australia 692436 356342 1.943 2,967,893 20,264,082 0.01758
Canada 1098446 517157 2.124 3,855,081 33,098,932 0.01562
Singapore 116326 57471 2.0241 267 4,492,150 0.01279
Saudi Arabia 284895 340555 0.837 756,981 27,019,731 0.01260
Estonia 12310 15943 0.772 17,462 1,324,333 0.01204
Norway 285604 55461 5.15 125,181 4,610,820 0.01203
Finland 204385 62659 3.262 130,558 5,231,372 0.01198
Czech Republic 125709 114563 1.097 30,450 10,235,455 0.01119
Republic of Ireland 206467 43187 4.781 27,135 4,062,235 0.01063
Israel 122987 66312 1.855 8,019 6,352,117 0.01044
Russia 755437 1432513 0.527 6,592,735 142,893,540 0.01003
Netherlands 629391 162739 3.867 16,033 16,491,461 0.00987
Germany 2906658 804701 3.612 137,846 82,422,299 0.00976
Kazakhstan 51876 147921 0.351 1,049,150 15,233,244 0.00971
Oman 25038 30118 0.831 82,031 3,102,229 0.00971
Japan 4799061 1203535 3.987 145,882 127,463,611 0.00944
South Korea 720772 446190 1.615 38,023 48,846,823 0.00913
United Kingdom 2295039 543633 4.222 94,525 60,609,153 0.00897
Greece 230684 94117 2.451 50,942 10,688,058 0.00881
Denmark 265934 47620 5.585 16,639 5,450,661 0.00874
Libya 32962 50418 0.654 679,358 5,900,754 0.00854
Cyprus 17144 6671 2.57 3,571 784,301 0.00851
New Zealand 107670 33995 3.167 103,737 4,076,140 0.00834
South Africa 226486 345382 0.656 471,008 44,187,637 0.00782
Austria 318343 63701 4.997 32,382 8,192,880 0.00778
Poland 312257 296398 1.054 120,728 38,536,869 0.00769
Slovenia 35106 15310 2.293 7,827 2,010,347