Was 2016 really the hottest year yet?

2016 was the hottest year for the USA, but what about the planet?

If you thought 2016 was hot, that's because it was. In fact, 2016 was the second hottest year on record for the USA.

LOS ANGELES, CA (California Network) -- As most of the nation freezes under a blanket of January snow, it's difficult to remember the warm months of summer. They did happen, and they are likely to return again, and again, and again.

According to the National Oceanic Atmospheric Administration's (NOAA)  National Centers for Environmental Information (NCEI). The average temperature for the 48 lower United States was 2.9 degrees Fahrenheit above the 20th-century average.

For the lower 48, this is the second hottest year on record since records were kept in 1880 with 2012 about a half-degree warmer (54.9F vs. 55.3F).

It is too soon to declare 2016 as the hottest year on record for the planet. And a hot year in the USA does not necessarily mean the rest of the planet is hot. The lower 48 states only comprise about 2 percent of the earth's surface area.

However, high-temperature records were routinely broken around the globe, and it is likely that 2016 will become the hottest year on record or at least one of the hottest ones to date. Temperature records have fallen for each of the three previous years.

The University of Alabama, using satellite data is already declaring 2016 to be the hottest year on record since satellite records were kept. That record only stretches back 38 years. According to the University, 2016 was just .02 degrees Celsius warmer than 1998, the previous record holder.

Regardless of temperature records, the focus for climatologists is on the trend, not the individual records. Both 1998 and 2016 were El Nino years with significant heat stored in the Pacific Ocean being released into the atmosphere. But scientists say that El Nino has only a minor impact on global temperature.

But there is a trend, which is steadily upwards. Ten of the hottest years on record all took place since 1998. Conversely, the coldest year on record is 1911. That record has not fallen for over a century.

Why are warm records falling while the cold record continues to hold? The planet is warming up. The culprit is carbon dioxide that is released by the burning of fossil fuels. We know this is the culprit because human produced CO2 has a different isotope than what nature produces. Therefore, we can measure human emissions, and when we do we find that humans are contributing to the CO2 load in the atmosphere.

The concentration of carbon dioxide continues to build in the atmosphere. If the theory holds true, then as CO2 levels rise, so too should global temperatures. So far, this is what we have been observing.

Unfortunately, the temperatures are rising faster than nature can adapt leading to the extinction of many plants and animals and putting pressure on many communities. From farming communities in Central California to Arctic villages in Alaska, the impact of climate change is becoming increasingly pronounced.

The only solution to this crisis is to act to reduce CO2 emissions as quickly as possible. Unfortunately, all plans to accomplish this goal are subject to controversy.