Regions of the world that exhibit significant warming over recent decades is likely the result of a robust urban heat island effect - South Korea's warming climate provides evidence
Read here. The global warming that has happened in recent past is due to a combination of factors, both man-made and natural. The natural production of warming is a result of the ongoing expected rebound from the Little Ice Age, solar/cosmic influences and normal climate cycles/oscillations.
The human influence on global warming takes many forms, including the result of human CO2 emissions. What has been well known and established long ago is that urban areas are warmer than rural areas - this human condition on the climate is referred to as the 'urban heat island' effect. The robustness of this human effect has been confirmed by new peer reviewed research by scientists analyzing South Korea's temperatures since 1954.
"The cities that show great warming due to urbanization are Daegu, Pohang, Seoul, and Incheon, which show values of about 1.35, 1.17, 1.16, and 1.10°C, respectively. The areas that showed urban warming less than 0.2°C are Chupungnyeong and Mokpo. On average, the total temperature increase over South Korea was about 1.37°C; the amount of increase caused by the greenhouse effect is approximately 0.60°C, and the amount caused by urban warming is approximately 0.77°C.”" [KIM Maeng-Ki, KIM Seonae 2011: Journal of Atmospheric Environment]
FWIW, the determination of the UHI impact was accomplished by only analyzing temperature data and population statistics. The authors apparently did not attempt to identify any non-human influences on climate.