El Nino and the Hottest Year on Record - Trend vs Variation

The announcement that 2015 was the hottest year on record came as the mid-Atlantic region of the United States began digging itself out of over two feet of snow. Climate deniers immediately screamed "See, climate change is a hoax because it snowed today...in winter." As always, deniers confuse weather with climate change.

Astrophysicist and science communicator Neil deGrasse Tyson (and his dog) addressed this in a simple stroll down the beach.

In short, weather is what happens on any given day; climate is the mean of what happens over time. The climate of Florida, for example, is generally warm and humid, even during the winter. The weather at any given time in Florida may be sunny or rainy or cloudy or cooler or hotter (sometimes within a few minutes). The weather in New England may be sunny or rainy or colder or warmer at any given time as well, but it's a sure bet that on average it will be much colder in New England during the winter than in Florida. The former is weather, the latter is climate.

Another way to think about this is as the difference between trend and variation. The Tyson video above was inspired by an earlier animated video demonstrating the two terms.

In both videos the dog represents the ups and downs of yearly climate variation while the human's walking path is the trend. The trend is the average over time (more or less); the variation is the noisy short-term departure from that trend.

Which gets us to El Nino. There has been a lot of talk about the strong El Nino we've been experiencing. Climate deniers paid by lobbying groups have argued (falsely) that we wouldn't have set a new record without it. But actual climate scientists at NASA and NOAA have shown that 2015 would have set a new record anyway; the El Nino merely increased the magnitude of the record-breaking.

“2015 was remarkable even in the context of the ongoing El Niño,” said GISS Director Gavin Schmidt. “Last year’s temperatures had an assist from El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”

El Nino, and its opposite counterpart La Nina, influence variation. As we've seen above, short-term phenomena have short-term affects on the year to year ups and downs in measurements like the global mean surface temperature (the most reported metric of climate change). Just like some days are sunny and others rainy, some years are warmer and others not as warm. That's the variation. That's the dog in the videos.

Trend is what happens over time. For the first 18 years of our lives the general trend is toward increasing height. For the last several decades, the general trend in climate has been toward increasing temperature.

That increasing trend is caused by increasing concentrations of CO2 and other greenhouse gases in the atmosphere. This CO2 comes from the burning of fossil fuels, which take carbon that has not been part of the natural cycle for millions of years and within a short period of time dumps it into the atmosphere and oceans. Since CO2 and other greenhouse gases control the temperature of the planet - keeping us about 30 degrees C more than it would be without them - adding more CO2 means more warming. Human activity has now added 40% more CO2 to the atmosphere (with even more in the oceans) than have been present in millions of years. The effects of this rise in CO2 and temperature are significant and a danger to humanity as we know it.

The bottom line is that there is the trend (CO2 and temperatures are rising over time) and variation (some years are warmer, some years are less warm). Deniers like to cherry pick "less warm" dates and create false narratives that ignore all the rest of the data. Actual climate scientists always look at the trends over time. The variations are important as well, mainly because they teach us how short-term phenomena like El Nino and La Nina influence the long-term trend. What we've learned from these variations is that CO2 is the primary driver of man-made global warming and the changes we've observed in our climate trends.

2015 Smashes Record for Hottest Year

As anticipated for many months, 2015 was the hottest year ever recorded. And not just the hottest by a slim margin...this was no "by the nose" win...2015 obliterated the previous record holder. By the way, that was 2014. NASA and NOAA jointly announced their independent findings this week. Here's the trend video:

This is no big surprise. Rising CO2 levels surpassed 400 ppm, a trend that has been taking CO2 about 40% higher than the normal range maintained for thousands of years. With CO2 as a driver, the mean global temperature trend has been staggering upward for many decades. Each decade has been warmer than the one before, and the hottest years are stacking up. The ten hottest years have all been since 1998, with 15 out of the 17 hottest years occurring since 2000.

You want a cool graphic? Check out this 15-second video that shows the record years continuing to rise.

In short, human activity is continuing to heat up the climate system.

Why was 2015 such a huge record breaker? Part of it is because of a massive El Nino event. You remember El Nino, right? The last big one was 1998, which not coincidentally is the year that the denier lobbyists cherry pick as their start date when they want to falsely claim "warming stopped" (despite the obvious fact that warming has continued, and more recently, sped up). El Ninos appear sporadically and in El Nino years we can generally expect global temperatures to be higher. La Nina years tend to tamp down increasing temperatures.

Aha! You might say (incorrectly). It's only warmer because El Nino made it warmer. Wrong. It's warmer because CO2 and other greenhouse gases are driving the warming trend in our climate. This year would have continued that trend even without El Nino. What El Nino did do was help 2015 not only break the previous record (of 2014), but smash it. Look again at the far right column in the graph above. Now look at the second from the right column - that's 2014. Normally the new records increase only incrementally over the previous record; after all, the climate is fairly stable and it takes a lot to change it. El Nino helped 1998 make a big jump, and it helped 2015 make a big jump. Based on how this year is starting out, 2016 has a reasonable chance of breaking the record for the third year in a row.

NASA and NOAA are not alone. The Met Office in the UK also reported that 2015 was the warmest year on record. The Japan Meteorological Agency is expected to report the same within the next few days.

None of this comes as a shock given that the early months of 2015 were already breaking monthly records by such a large margin that it would have taken a worldwide deep freeze for the rest of the year to not break the record. Instead we saw continued monthly record-breaking, which is why 2015 shattered the annual global mean temperature record.

Of course, denier lobbyists and their affiliated blogs have trotted out their usual non-scientists to dismiss the scientific findings with claims of worldwide conspiracies. Mostly the deniers have tried to ignore the inconvenient science and instead have focused on the snowstorm expected to hit one part of the eastern United States, as if it is somehow relevant. In other words, deniers will continue their desperate attempts to keep policy action from happening by intentionally lying about the well-known science.

But as the recent commitments in Paris demonstrate, the world has left the deniers to drown in their own buffoonish dishonesty while the rest of us take responsibility. It's on to 2016.

Climate Change Year in Review - 2015

Paris, Denial, Climate. Things heated up in climate science in 2015, and they are about to get even hotter. As The Dake Page predicted a year ago, 2015 was going to be a critical year in man-made climate change. It exceeded even those expectations.

Let's begin with the climate itself. The hottest year on record was set just last year (i.e., 2014). In 2015 that record was not just broken; it was shattered. While the December temperatures are not quite in yet, it was clear many months ago that 2015 was on a pace that would blow past 2014 easily. In short, 2015 is the new hottest year on record when it comes to global temperatures. Temperatures were helped along by a massive El Nino, which tends to pump up an already increasingly warmer climate system. With that El Nino expected to stay strong for several months more it means that 2016 could surpass 2015 to set yet another new record.

Action to deal with man-made climate change also heated up. With strong leadership by President Obama and Secretary of State John Kerry, the United States joined 196 nations around the world in coming to a substantive agreement this December in Paris. The Paris agreement is a start, even a very big start, but there is a lot of work still to be done. Even with that caveat in mind, though, the agreement is one of the most important events in history because it started the world on a path toward greater sustainability. It might, at least in some people's minds, even be the beginning of the end of fossil fuels. That seems unlikely given our fossil fuel-based infrastructure and the prevalence of petrochemical-based plastics, but it does signal a change in mindset that will lead to greater innovation and development of renewable energy sources.

Of course, climate denialism also heated up in 2015, a not unexpected reaction to finding themselves in a corner left behind by the world. American politicians are heavy into campaigning for next year's presidential elections and man-made climate change is set to play a significant role. The lines are clear - all Republican candidates deny the science; all Democratic candidates acknowledge the science. Republican politicians can't help demonstrate their dishonesty on the subject, even staging "hearings" to boost their denialism with their base rather than to inform on policy options. We'll see more of this in 2016.

The year 2015 also saw a report revealing what most scientists already knew - ExxonMobil Corporation was well aware of the role of fossil fuels in causing man-made climate change. They knew it, and then they spent millions trying to obfuscate it. And it wasn't just Exxon; all the major oil companies knew that their business model was warming the planet's climate system, and they knew this decades ago. The fossil fuel industry did the same thing that the tobacco industry did, they understood the harm they were causing but continued to deny it and misrepresent it and actively try to block policy action on it for decades, all to protect their huge profit margins.

So where do we go from here? While 2015 was a critical year in defining action, 2016 will be a critical year in defining how sustained that action will be. Not the least of the concerns is the U.S. presidential election, where the ultimate selection of the new president could have life-changing impacts on the future of both the United States and the World. More on that in the next post.