"Global warming caused by human activities that emit heat-trapping carbon dioxide has raised the average global temperature by about 1°F (0.6°C) over the past century. In the oceans, this change has only been about 0.18°F (0.1°C). This warming has occurred from the surface to a depth of about 2,300 feet (700 meters), where most marine life thrives."https://www.nytimes.com/interactive/
Using https://www.nytimes.com/interactive/2017/01/18/world/how-much-warmer-was-your-city-in-2016.html#fajs :
Los Angeles was 0.9 deg C above normal.
Cape Town was 1 deg C above normal
Another problem: Land is getting less solar radiation and the lower atmosphere is heating because of the greenhouse effect: Personally I think cool roofs and cool pavements, etc, are making the situation worse. They prevent ground from getting hotter which reduces convection and makes pollution worse and rainfall less. If you increase convection with hotter surfaces you can get more clouds and clouds reduce solar energy falling on a city dramatically - you might get less than half the solar energy falling on a city if you have cloud formation. It seems that with global warming the following could be happening: With all the air pollutants put in the air by man, less solar energy is reaching the ground so the ground cannot warm up the air above it so much (this is discussed in physical geography books and so on). This reduces air temperatures near the ground and this increases relative humidity near the ground because relative humidity decreases with increasing temperatures unless moisture is added (and increases with reducing temperatures). Added to this, the lower atmosphere is warming because of the greenhouse effect. When air is heated by the ground it may rise, but it comes into contact with the heated air in the lower atmosphere and cannot rise so easily there because this air parcel heated by the ground needs to be hotter (less dense) than the surrounding air. Because of this less clouds form. To give credence to my theory look at the relative humidity near the ground and higher up in the diagram at http://www.climate4you.com/GreenhouseGasses.htm The relative humidity at ground level has remained high throughout the years but is decreasing higher up.