Key issues on debating about global warming are reviewed：①Does the global warming pause? The answer is not sure. The HadCRUT3 data show that the temperature during 1999-2008 increased only a little (0.07℃/10a), but this decade is still the most warmest one among the last 30 years. However, the data from NASA GISS indicate that the temperature increased in the same period is  higher (0.19℃/10a). Thus, global surface temperature in recent years oscillates on  a warm level. However, natural variability needs to be taken into consideration.②Does the global warming be caused fully by anthropogenic factors? The answer is no. ENSO, solar activity, volcanism, and thermohaline circulation can also exert impact in some extent on climate change, though the morden global warming may be mostly attributed to the increasing of greenhouse effect. However, the natural factors may sometimes overwhelm the anthropogenic effect in the interannual to interdecadal time scale. Specially, the solar activity factor should be given more attention. ③Does the impact of global warming become more evident recently? The answer is yes. New observational datas indicate that the melting speed of glaciers and ice caps and rising speed of sea level in recent years have exceeded the related projections by IPCC 4th Assessment Report. Accordingly, the updated projection of the future sea level also increases.