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NASA and The National Oceanic and Atmospheric Administration report the global warming trend is continuing. We discuss the findings with the Weather Underground’s Bob Henson.

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SHARMINI PERIES: It’s The Real News Network. I’m Sharmini Peries, coming to you from Baltimore. Global warming trends continued in 2017. Two new reports out, one by the National Aeronautics and Space Administration, NASA, and the National Oceanic and Atmospheric Administration, NOAA. According to NASA, global surface temperatures ranked in 2017 as the second warmest, but second only to global temperatures in 2016.
In the NOAA study, it concluded that 2017 was the third warmest year in their record keeping. The minor difference in the rankings is due to the different methods used by the two agencies to analyze global temperatures. Well what is the significance of this warming temperature pattern we are seeing? Let’s ask Bob Henson, meteorologist and journalist with Weather Underground. He is the author of The Thinking Person’s Guide to Climate Change. Good to have you on, Bob.
BOB HENSON: Very nice to be here.
SHARMINI PERIES: So Bob, NASA and NOAA reports show that 2017 is the second or the third year on record that’s been the warmest, although it was not an El Niño year. Tell us what this means.
BOB HENSON: That’s actually a pretty significant part of today’s reports. It turns out that when we have an El Niño going on, it actually warms the global atmosphere and that can be anywhere from a year to a couple of years. Just for a little background, El Niño is when there’s a warming of the ocean temperatures over the eastern tropical Pacific, kind of around the Galapagos and offshore of Peru and Ecuador.
But the warming can cover a huge area, bigger than the United States, so as that warm water sends heat into the atmosphere, it kind of propagates and reverberates around a big chunk of the globe. In addition to kind twerking weather patterns, it actually pumps heat from the ocean into the atmosphere. The opposite happens when we have La Niña going on. That’s a cooling in that same area, and the heat goes from the atmosphere more into the ocean.
That’s kind of up and down, the cycle that modulates this long-term warming we have going on, globally because of greenhouse gases. Now what we typically expect is that it will be warmer during the El Niño years, cooler during La Niña years, but the overall trend is upward. In this case, this was the warmest year we’ve ever had without an El Niño kind of goosing the temperatures.
SHARMINI PERIES: All right. When did we first see this recording breaking global temperature trend beginning?
BOB HENSON: Well it’s been going on for the better part of a century really. We had what was sometimes called the Little Ice Age, a period centered kind of in the 1700s, 1800s, where global temperatures were quite cold. That was when we had things like frost fairs on the Thames River in London because it froze over regularly. That’s when President George Washington crossed the Delaware on ice. It was just generally colder, especially in North America and Europe.
Since around 1900, it’s been warming globally and that trend has accelerated in the last 30 to 40 years. The last four years have all been the four warmest on record. We have seen another little blip upwards in this two steps forward, one step back, two steps forward process.
SHARMINI PERIES: Right. Is this sort of what scientists expected to see from the amount of say greenhouse gases that have accumulated in the earth’s atmosphere?
BOB HENSON: It is. We expected to see global temperatures rising, more or less at the rate they are now. Of course temperatures aren’t going to rise a precise amount every year. The projections that have been made through computer models that take into account the gases we put into the atmosphere and all sorts of other things, those models predicted a rise of several degrees Celsius unfolding over this current century. It could be as low as maybe two or three degrees Fahrenheit or as high as five, six, seven degrees Fahrenheit.
Now, we’ve already warmed in the last century, close to a degree and a half Fahrenheit, and if you look at how much carbon dioxide we put into the air, it’s roughly on par with what we would have expected. In a sense, what we’re getting right now is right on target with what we could expect. Now we can’t predict how these ups and downs of El Niño or La Niña will unfold. It wasn’t really foreseen that temperatures would slow down in their rise a little bit over the 2000s and then pick up again this decade.
That has a lot to do with whether heat is going mostly into the atmosphere. Well it’s always going mostly into the ocean. It’s only a small part that goes into the atmosphere and so that change in that amount going into the atmosphere is partially what gives us the blips in that up and down but mostly up curve.
SHARMINI PERIES: All right. Let’s get the crux of the issue. What are the implications of what NASA and NOAA are saying about the trends we are seeing?
BOB HENSON: Well obviously the implications are what we care about most. They’re widespread. The first and most obvious is that it’s getting warmer, so where you have things like heat waves going on, there’s going to be a tendency for those heatwaves to be worse, more intense. We do know a lot about how to cope with heat waves, especially in the United States. The death toll from heat waves has gone down in recent, last 10 or 20 years because they’ve done things like open cooling centers.
That’s a good example of adapting to climate change. Unfortunately, not all of the world is well-equipped to do that, so we can expect heat waves to take serious tolls on other parts of the world, especially. Now that’s the most obvious thing when we talk about global warming, but it actually affects precipitation as much or more than temperature. The main way it does this by kind of goosing the hydrologic cycle, so that when it rains, in many parts of the world, it’s tending to be heavier rain, but when it’s droughty, the drought can sometimes be more intense in its impacts because with higher temperatures, you’re pulling more moisture out of that dry soil. Unfortunately both ends of the hydrologic spectrum get affected. Drought impacts can be more intense and heavy rains can be more extreme and heavier.
We’ve seen some of that play out this year. The intense hurricanes, most particularly Hurricane Harvey in Texas, which produced the heaviest hurricane-related rain we’ve ever recorded in the US. At the same time you’ve had some very intense droughts going on in different parts of the world, and we have drought returning to the United States right now over the last month or two. Those are the main impacts.
There’s others. Impacts on storms intensity and so forth, but the further we get from temperature and precipitation, the harder it is to separate the signal from the noise, because you naturally have a lot of variability in things like tornadoes. It’d be very hard to suss out a climate change signal there.
SHARMINI PERIES: All right. Now, what we are seeing out in California where drought is causing wildfires, which are causing I guess more atmospheric changes and then heavy rains and mudslides, is this an implications of what NOAA and NASA is telling us?
BOB HENSON: Well California is kind of at the epicenter in the US for the kinds of drought impacts we can expect with a warming climate. California is just coming off of a vicious drought that went all the way from 2011 into 2016. Fortunately, 2016-17, that winter brought very substantial rain all over the western US.
Ironically those heavy rains helped lead to the wildfires because they fostered a growth in the underbrush that then dried out in the summer of 2017. Now it’s normal to have dry summers in 2017 in California. That’s just the way their climate works. Fortunately we’re starting to see a little more rain and snow just kicking in the last few days in California, so we may not go back into that five year drought, but all indications are that when it is dry in California, when we have the droughts like we just had for five years, then the temperatures are going to be much warmer than they have been in previous droughts.
In other words, even if the rainfall doesn’t change, the droughts are going to be more impactful, harder to deal with, harder on agriculture, harder on water storage because snow is going to disappear and melt off more rapidly. Some of it will evaporate. California has its hands full in dealing with drought, and at the same time, being ready for the occasional intense rains, where it’s for example recently burned, you can have very serious mudslides. It’s a lot to deal with and California is fortunately being very proactive in dealing with it, but that may not be the case in other parts of the southwest and other parts of the United States.
SHARMINI PERIES: Right. President Trump, of course now famously tweeted that on New Year’s Eve who wrote, good old global warming, where it is on this particular New Year’s Eve? Was that cool weather consistent with the pattern of global warming?
BOB HENSON: Well there’s some research in this area, on whether the northeast US and the Midwest are becoming prone to occasional bouts of really cold weather as a result of climate change. There’s quite a bit of debate on this within the science community. It’s not at all an accepted thing. There’s some evidence that we have tended toward patterns in recent years where it’s very warm and dry in the west and then the jet is then pushed up and then kicks down over the eastern US and brings down cold air.
We’ve had some pretty dramatic examples of that. Certainly the cold wave at the end of 2017, start of 2018, is a vivid example, and there have been a couple others, but there have also been examples of very dramatic winter warmth. March of 2012 was what we called the greater winter warm wave. Temperatures near 80 and near 90 even as far north as Michigan, which was really crazy for March. It’s not been a consistent tendency, colder warmer in the Midwest and Northeast. There have been these occasional episodes, and so researchers are trying to figure out if things like loss of sea ice in the Arctic might be related to this weirding or kinking of the jet stream, but regardless, what we do expect in the long run is winters are generally going to be warmer. We’re not going to see as many of these kinds of episodes going forward, especially looking ahead decades.
BOB HENSON: Certainly when we’re in the middle of them, they’re pretty intense and tough to deal with, but no, global change is warming the globe and warming the United States, regardless of these episodes.
SHARMINI PERIES: Right. Will the shift in changes that are taking place, will it become more difficult to predict weather patterns as the earth’s atmosphere alters and with the rising temperatures we’re seeing, in terms of modeling, because so much of our preparedness to deal with this stuff comes from the predictions.
BOB HENSON: That’s a very good point. A good example of that is in floods, where we have prepared societies in different cities for example to deal with a particular level of floodwater. Often that’s called a 100 year flood because it’s, on average, over a long, long time period, you would tend to get that amount of rain or that amount of flooding, once every hundred years.
The challenge is those statistics are assuming that the climate is stationary, right? That we have a fixed climate and those expectations aren’t going to change. In fact, we don’t have a stationary climate. We have a warming climate. That’s also leading to more extreme rainfall as we mentioned a few minutes ago. That means that what used to be a 100 year rainfall or a 100 year flood may become a 50 year rainfall or 50 year floods.
Cities are indeed going to have to look ahead and be prepared for perhaps bigger floods than they’re used to as a result of rainfall. In addition, on the coastlines, we’re talking about sea level rise, and that is obviously exacerbating storm surge as well as what we call nuisance flooding, which can just be triggered by a moon phase. All of these things are changing expectations.
Fortunately, weather itself is becoming better and better predicted. Our ability to predict storms and such as computer models improve, we can go further out into the future and have more confidence in where storms are headed and we have a good sense of the kinds of changes to expect from climate change and things like these heavier rains, more intense heat waves. In some ways, we’re better able to predict the kinds of weather and climate coming up, but that doesn’t necessarily mean it’s translating into predicting the outcomes, especially when it comes to say flooding where it’s also affected by where people live. You have all these compounding uncertainties that do make it hard to look forward societally.
SHARMINI PERIES: We’ve been speaking with Bob Henson, meteorologist and journalist with Weather Underground. He’s the author of The Thinking Person’s Guide to Climate Change. Bob, good to have you with us.
BOB HENSON: Great to be here. Thank you.
SHARMINI PERIES: And thank you for joining us here on The Real News Network.

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Bob Henson is an award-winning author and journalist on topics primarily concerned with the weather and climate change. In 2015, he joined Weather Underground as a weather and climate science blogger for the popular Category 6 blog. Weather Underground is a consumer brand owned by The Weather Company, an IBM Business. Based in Boulder, Colorado, Henson has interviewed dozens of the world's top weather and climate scientists.