"Hot" days in Boulder highlight concerning warming trend
Rising average temperatures have wider implications for Boulder, as residents try to adapt to recent, dramatic weather shifts that have been facing the area. While breaking record highs, Boulder also is dealing with a growing fire season.
While Colorado is best known for its winter landscapes, the state, including Boulder County, is endeared as a summer destination. This is partly connected to Boulder’s climate, which offers an escape from the heat and humidity of other parts of the country. For example, Chautauqua started as a retreat offering respite from the heat of Texas summers.
But all of that may be changing, as average temperatures in Boulder County rise (Figure 2) and days above 90-degrees Fahrenheit become more frequent (Figure 1). Here we present 30 years of temperature data, rigorously collected by Boulder climatologists Matt Kelsch and John Brown, that highlight some concerning warming trends for Boulder County.
Rising temperatures, especially in summer months, can cause many different stresses, including heat-related illnesses for humans, rising water demands, crop losses within the agricultural sector, lengthening fire season, negative impacts on tourism, and greater pressures on species with low tolerance to heat. All of these consequences of rising temperatures place greater stress on local public health and businesses.
However, it remains unclear how much this warming trend is connected to climate change, and how long the trend may hold. Continuing to collect reliable data will be the key to understanding what these patterns mean for Boulder and will provide us with a better platform to guide policy and public advocacy.
explore the data
Hot days (above 90°F) in Boulder, from 1990 to now.
Figure 1. The number of days above 90°F in Boulder, measured daily and summed per year, from 1990 to 2020. We can see natural, cyclical behavior for these average maximum temperatures (temperatures that rise and fall periodically). However, we can also see a warming trend (represented by the black dashed line) with the number of days with greater than 90°F temperatures generally rising over time. Source: Data provided by Matt Kelsch, Associate Scientist IV at the University Corporation for Atmospheric Research (UCAR) and John Brown, NOAA’s Earth System Research Lab.
Monthly heat in Boulder, from 1991 to 2019
Figure 2. Average maximum temperatures, by month, from 1991 to 2019. Each vertical bar is divided into lots of little rows or horizontal bands, with each band showing the average maximum temperature (in °F) for that month in a single year. The bottom band of each vertical bar is the year 1991 and the top band of each vertical bar is 2019. On this graph, the higher the average temperature, the wider and darker are the bands in each vertical bar. Temperature fluctuations are what you might expect, with warmer months in summer and cooler months in winter. November is a great example of the type of variability we see in Boulder, with some years being quite cool (light peach, narrow bands) and other years being quite hot (orange to red, wide bands). Source: Data provided by Matt Kelsch, Associate Scientist IV at the University Corporation for Atmospheric Research (UCAR) and John Brown, NOAA’s Earth System Research Lab.
Wildfires in Boulder, Colorado / Unsplash
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Looking forward, how can we address human-caused changes in climate? And how can we adapt to the changes on the horizon?
Reduce carbon emissions
The main strategies to combat warming trends at the global scale are to reduce emissions of carbon dioxide related to human activities and to increase the amount of carbon stored or sequestered in our natural ecosystems. Emissions reductions can result from decisions and policies related to key energy, manufacturing and agricultural industries.
We can also each shift personal decisions that affect our daily emissions. Taking a measured approach to shifting our daily behaviors, such as driving fuel-efficient vehicles, cycling instead of driving, outfitting our homes and businesses with energy-saving appliances, using public transit when possible, and staying up-to-date on consumer products that contribute to climate change, can all have lasting impacts.
As residents of Boulder County, we can contribute to the development and implementation of policies at the local, state, and national levels that tackle emission sources that contribute to the rise in greenhouse gases. For example, the city of Boulder’s Climate Mobilization Action Plan and Boulder County’s Climate Action initiatives provide excellent guidance for actions to reduce emissions, such as reducing fossil fuel use in transportation, increasing energy efficiency, and reducing waste that ends up in landfills.
Enhance carbon storage
We can also contribute to efforts to enhance the carbon storage capacity of our natural ecosystems, often referred to as Natural Climate Solutions. Organizations in the city and county of Boulder have programs aimed at increasing carbon stored by soils on farmland as well as soils that support forests, wetlands, and grasslands. We can support policies and programs that advocate for the avoidance of land conversion as well as the restoration of degraded habitats to maintain or increase carbon storage in our natural ecosystems.
Adapt to changing conditions
As humans on a warming planet Earth, we need social action plans in place for adapting to the warmer temperatures that we will see in the years to come. This means designing infrastructure to navigate the rise in heat-related illness and educating the public about the elevated health risks. It is also crucial to streamline our cooling systems (for manufacturing/energy plants and A/C and refrigeration methods we use in our own homes) that are pushed to greater extremes during warmer months.
