NASA scientists and an international team of researchers have found tropical ecosystems can generate significant carbon dioxide when temperatures rise, unlike ecosystems in other parts of the world.
Large cities can affect the weather as far as 1,000 miles away, say scientists, warming some areas and cooling others.
Last year was the ninth warmest since 1880, say NASA scientists, and the warmest recorded by far for the continental US.
Last year was the warmest on record for the contiguous United States, say NOAA scientists, with an average temperature of 55.3°F - 3.2°F above the 20th century average, and 1.0°F above 1998, the previous warmest year.
In a blow to those people who believe that global warming predictions are just a lot of hot air, an international team has established that predictions made 20 years ago are turning out pretty accurate.
The first detailed predictions of future temperatures across North America have been produced, using a combination of climate models and some complicated statistics.
The sky is falling - but it may be good news for the planet. New Zealand scientists say that the Earth's clouds are getting lower, in a mechanism that could help to counter global warming.
Huge swathes of the world could become too hot for human beings to survive, if current worst-case scientific projections of global warming turn out to be true.