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Severe Heat, Drought and Wildfires: State Climatologist on Colorado's 'New Normal'

Nolan Doesken has been studying Colorado's weather for 35 years. He explains his job, and what's ahead for his state because of climate change.

Aug 22, 2012
NASA satellite image taken in July of Colorado's Waldo Canyon fire

Colorado is the kind of place where you can play softball in shorts in 70-degree weather in the morning, then bundle up and brace for a blizzard by nightfall. The state's weather is so variable that one winter will leave a giant snowpack in the Rockies, and the next, like the last one, will be bone dry and prime the forests for devastating wildfires when the summer heat arrives.

Even in a relatively quiet year, Colorado's weather keeps the state climatologist, Nolan Doesken, very busy. This year, with a prolonged drought, record-breaking heat in the spring and early summer, and massive wildfires in June, Doesken has been going nonstop for months.

Doesken has been studying the state's climate since 1977, when he arrived at Colorado State University's Colorado Climate Center in Fort Collins. He was appointed state climatologist in 2006 and is a former president of the American Association of State Climatologists. Over the years he has not only recorded his state's wild extremes, he's also been in the middle of some, including a rainstorm that dumped 14 inches in a day, and an early fall snowstorm that left him stranded in a car on a highway.

InsideClimate News spoke via email with Doesken about his job.

ICN: You've been watching Colorado's climate for decades. Has it changed noticeably since you started?

Doesken: The most notable change that has been evident over the past 20 years has been warmer temperatures at most times of the year, but particularly a lack of extreme wintertime cold waves. Some of our mountain valleys used to see temperatures below 40 degrees Fahrehneit fairly regularly, a few times every few years. Now we've only seen those conditions once or twice in the past two decades. We had been seeing a lot of hot temperatures but without extreme heat waves—although this year we got the extreme heat wave, similar to what we had back in 1934 and 1954 but had not seen for many, many years.

We haven't seen any systematic changes toward wetter or drier—or greater extremes in storms and precipitation—or at least not yet.

ICN: How much of Colorado is under severe drought?

Doesken: Nolan DoeskenNolan Doesken100 percent of our state is currently assessed as being in severe, extreme or exceptional drought. Most of our mountains had much below average winter snow followed by an unusually warm and dry spring and a blistering hot summer. A few local areas have enjoyed beneficial rains during the past seven weeks thanks to the summertime North American monsoon. Fortunately, that put a damper on wildfires that were raging in many parts of the state in June.

ICN: Is this unprecedented?

Doesken: We had similar conditions back in 2002, 1977, 1954 and 1934. This year was so hot that conditions were on their way to being as bad or worse than in those famous droughts, but the July rains really helped, especially in the mountains.

ICN: What are some of the less-obvious impacts of drought that might escape the average person?

Doesken: There are areas of the state that rely on groundwater for water supplies. During drought, the depletion of groundwater is accelerated, and that can have significant long-term impacts.

This year we had so much forest fire smoke (a drought impact) and ash in the air that it clogged some air filters on air conditioners resulting in more maintenance and repairs.

Drought is a slow disaster that actually has apparent impacts on mental health for those who are facing economic hardship or those who are living with the constant stress from potential wildfire. Drought really wears on you.

ICN: How many heat records have been set in Colorado this year? Has this been the state's hottest year so far?

Doeksen: Quite a few, but we only track the "new records" for selected stations that have very long and consistent climate data. So far (counting August) 7 out of 8 months this year have been warmer than average over many areas of Colorado. For most of the state, this will be the warmest Jan.-Aug. on record.

ICN: Has there been a big change in the nighttime lows Colorado has been experiencing in recent years?

Doesken: Yes. Overnight lows have been showing a warming trend in the past 20 to 30 years. Interestingly, this year it has been the daily highs, more so than the lows, that have been unusually high.

ICN: What has been the most memorable weather event in the state since you've been there?

Doesken: I can describe many, but the two most impacting for me personally both occurred within three months of each other in 1997. First, in late July we had a highly localized summer storm here on the west side of Fort Collins. When it was all said and done, over 14" of rain fell near our office (CSU Foothills campus). That is close to our annual average and more rain than we get in many years. Flood waters claimed five lives right in town. The campus was pummeled, and had close to $200 million in property damage. The very next night a similar—but larger in area—storm dropped similar amounts of rain in an area of northeastern Colorado. We dropped all of our other work and dedicated several months to documenting these storms.

Then in October 1997, a ferocious early-season blizzard plastered Colorado. For the first time in my life, I spent a night stranded in a car with my boss (I was the assistant state climatologist at that time) and his wife along I-25 north of Denver. Some were stranded for two days on the road to Denver International Airport. I believe eight people lost their lives and close to 30,000 cattle died. Although the storm was well forecast by the NWS, people just weren't ready for something so severe so early in the season.

ICN: What are some things about Colorado's climatology that aren't generally known?

Doesken: There are little "banana belts" tucked into the mountains here and there where local wind patterns create areas that are much milder than surrounding areas. The best known is [the town of] Palisade, where canyon winds created a climate very suitable for growing peaches, wine grapes, etc.

ICN: Colorado's weather seems to change rapidly and drastically much of the year. Can you give a few of the more extreme examples of that rapid change?

Doesken: There are plenty of examples, but some that stand out are our spring storms such as Easter Sunday back in 1987 where the temperature [in] April soared into the 80s during the day, then a strong cold front came through that brought a cloud of dust that set off people's in-house smoke alarms, then came thunder and lightning, and by evening it was snowing hard.

We also have very large changes (as do areas in other low-humidity, high-elevation western states) in temperature that occur just on clear, dry days.  Some of our mountain valleys in Colorado can see 50-60 degree temperature swings on clear days, especially at this time of year.

ICN: What changes do you see ahead for the state because of climate change?

Doesken: Darn good question. It is fairly clear that warmer weather, similar to what we've experienced so far this year, is a part of our future. Of and by itself, that has ecological consequences. Precipitation is much harder to predict [because] we already see huge year-to-year variations in precipitation. So when we hear a forecast saying, "precipitation will become more variable in the future," I almost chuckle.

Even if precipitation stayed about the same, on average, as it is now, warmer temperatures generally mean more evaporation in an interior, low-humidity climate like ours, and that would mean reduced surface water supplies. Since there is already abundant evidence that we have had drier times in Colorado than what we've become accustomed to the past 150 years, such as extensive sand dunes over parts of eastern Colorado, we know that a drier future is an uncomfortable possibility.

ICN: The wildfires that Colorado has seen this year and in recent years: Are they the new normal?

Doesken: Just as drought has been a regular visitor, there has been plenty of fire in the past. What is different is that prior to the 1960s or so, we haven't had so many people living in and near the forests, and there haven't been so darn many dead trees as we have now. Not every year will have the hot, dry springs like we had this year, but every year will have hot, dry summers with lightning to trigger fires—so yes, we'll see plenty more fire in the years ahead.

ICN: What are the main elements that have made the fires so severe?

Doesken: The incredibly warm, dry March set the stage this year—and got the fuels dried out earlier.  No prolonged cool/damp weather in April, May or early June simply set the table.  It was so dry that many of us expected even more and potentially larger fires than what occurred, based on the severity of drought and fuel moisture.  Fires that start early—May or June—are much more likely to be accompanied by periods of strong winds (that's when the real trouble comes) than fires that start in July or early-mid August when environmental winds are lighter.

There is some evidence that lower elevation snowpack may be retreating earlier in the spring than previously, but variability still wins the day, making trends hard to track. In 2011, northern Colorado's snowpack was deep and persisted well into the summer.  In 2012, the snowpack was shallow and melted very early. Ecologists are very convinced that climate has already changed dramatically in the Rockies, but the evidence from snowpack data is not totally compelling. Remember, Colorado is the highest elevation state by far, and as a result our snowpack trends are a bit different than areas with lower-elevation mountains/valleys. Even in warm years, our mountain snowpack stays well below freezing throughout the winter months. So we keep our eyes on spring.

ICN: With everything that's happened in Colorado in recent years, do you still encounter a lot of skepticism about climate change? If so, how do you respond?

Doesken: Indeed. I've been a skeptic myself at times. It's OK to be skeptical, and I tell people that. Most scientists are or should be skeptical and then let the evidence shape their knowledge and understanding. I know that climate models aren't perfect, but they are useful. I point people to the model experts and the IPCC [Intergovernmental Panel on Climate Change] reports.

In my presentations—and I give more than 50 talks a year to diverse audiences—I emphasize observations: what we know in our own state from what we have observed over the past century and beyond. I show the seasonal cycles, the spatial patterns and the year-to-year variations. Colorado is not the center of the universe, but our temperature patterns do match with North American and global climate trends relatively well, so the data do show warming.

Trends in temperature are the easy ones. Do we think we know where temperatures are going? Yes. For much of the country and world, there is a discernible and upward trend in temperatures.

Do we think we know where precipitation is going? No.  …When it comes to precipitation it will likely be many decades before a trend emerges from the huge natural variability, if there is a trend. ... In Colorado, there is so much inherent variability that it would take decades to detect a trend. We get our moisture from many different directions. We may see competing and opposite trends in the future. You can find a precipitation trend in New England, but it's hard to find a clear trend in other parts of the country.

ICN: In years like this, it seems like the state climatologist would be very much in demand. How does your life change? Are you busier now than ever?

Doesken: Yes, drought and heat draw more lasting attention to climate and climate impacts than anything else we see, at least in our part of the country. Workdays are longer, media requests are much more numerous and demanding, and speaking invitations are endless in times of drought.

ICN: Can you trace your involvement in climatology to some event in your life?

Doesken: I happened to grow up in a state, Illinois, that had a very active state climatologist who wrote articles about recent climatic conditions that were printed in our local paper every month. I delivered newspapers in my small town, Royal, Ill., population 200, and often stopped to read those articles even when I was in grade school. I thought that looked like a really fun job. Also, my father was an informal "weather observer" and he kept a personal journal for many, many years where he recorded things like daily high and low temperature, precipitation, general weather conditions. He always let me look at those journals, and my friends and I began doing "statistics," calculating things like the chances for getting precipitation on Christmas or the 4th of July, average high and low temperatures, etc.  We had a lot of fun in our early teenage years playing with climate statistics. One of my friends also became a meteorologist.

ICN: Do you get ribbing from people who sort of half-seriously blame you for extreme weather conditions?

Doesken: Always. It's been amusing over the years as people have come to associate climate and climatologists with climate change. Many people now think that all climatologists are focused solely on climate change. Little do they know that we've been around since the 1800s and have plenty of important work to do tracking climate and providing information for decision-makers.

Travel anywhere and you'll see roads, bridges, homes, fields, power lines, communications systems, etc. etc. Everything is, or should be, designed, built and maintained with background climate information in mind. The efficiency of power transmission is affected by temperature and precipitation. Water supply and delivery is incredibly closely tied to climate variations. The potential for renewable energy is related to obvious climate factors. Agricultural production, etc.  We were busy before climate change was an issue, and now we're busier and in the limelight, positively or negatively.

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