The evidence of climate-forced sea level rise among the options you provided is "submerging blue islands and coastlines." Sea level rise is primarily caused by two factors related to climate change: the melting of ice sheets and glaciers, and the thermal expansion of seawater as it warms. As sea levels rise, low-lying areas, including islands and coastlines, can become submerged.
The other options—decreased temperature of oceans, temperature changes for surface currents, and increased carbon dioxide in the atmosphere—are related to climate change but do not directly indicate sea level rise.