Category Archives: Climate impacts

Climate, Climate impacts

14 compelling graphics from new National Climate Assessment

The federal government’s new National Climate Assessment paints a grim portrait of climate change’s impacts on the United States.

The 841-page report is full of graphics explaining how the rise of greenhouse gas emissions is already transforming the American West and the rest of the country. I’ve extracted the 14 images that I found most striking and organized them into 10 topics below. You’ll find the original captions and sources below the images, minus the footnotes. Click on images to enlarge them.

1) It’s getting hotter

Virtually every part of the country has gotten warmer in recent decades, but compare Alaska to the Southeast region.

US Temperature Change

Caption: The colors on the map show temperature changes over the past 22 years (1991-2012) compared to the 1901-1960 average, and compared to the 1951-1980 average for Alaska and Hawai‘i. The bars on the graphs show the average temperature changes by decade for 1901-2012 (relative to the 1901-1960 average) for each region. The far right bar in each graph (2000s decade) includes 2011 and 2012. The period from 2001 to 2012 was warmer than any previous decade in every region. (Figure source: NOAA NCDC / CICS-NC).

2) Precipitation trends differ by region

Looking back at the 1991-2012 period, some parts of the country have been relatively wet, but Arizona has been especially dry. Very heavy precipitation events have been on the rise.

Precipitation changesCaption: The colors on the map show annual total precipitation changes for 1991-2012 compared to the 1901-1960 average, and show wetter conditions in most areas. The bars on the graphs show average precipitation differences by decade for 1901-2012 (relative to the 1901-1960 average) for each region. The far right bar in each graph is for 2001-2012. (Figure source: adapted from Peterson et al. 2013).

Heavy precip heavy precipCaption: One measure of heavy precipitation events is a two-day precipitation total that is exceeded on average only once in a 5-year period, also known as the once-in-five-year event. As this extreme precipitation index for 1901-2012 shows, the occurrence of such events has become much more common in recent decades. Changes are compared to the period 1901-1960, and do not include Alaska or Hawai‘i. (Figure source: adapted from Kunkel et al. 2013).

3) Season variations in precipitation projections

Looking ahead, models predict that some parts of the nation will be wetter overall, and others will be drier. There are also strong seasonal differences.

US Precipitation

Caption: Projected change in seasonal precipitation for 2071-2099 (compared to 1970-1999) under an emissions scenario that assumes continued increases in emissions (A2). Hatched areas indicate that the projected changes are significant and consistent among models. White areas indicate that the changes are not projected to be larger than could be expected from natural variability. In general, the northern part of the U.S. is projected to see more winter and spring precipitation, while the southwestern U.S. is projected to experience less precipitation in the spring. (Figure source: NOAA NCDC / CICS-NC).

4) Drought becoming more common in West

The fraction of the West experiencing summer drought has been trending upward.

DroughtCaption: The area of the western U.S. in moderately to extremely dry conditions during summer (June-July-August) varies greatly from year to year but shows a long-term increasing trend from 1900 to 2012. (Data from NOAA NCDC State of the Climate Drought analysis).

5) Bleak outlook for West’s snowpack

Even in places that are expected to get wetter overall, precipitation may be more likely to fall as rain than snow, causing major declines in the West’s vital snowpack.

Snow water equivalent

Caption: Snow water equivalent (SWE) refers to the amount of water held in a volume of snow, which depends on the density of the snow and other factors. Figure shows projected snow water equivalent for the Southwest, as a percentage of 1971-2000, assuming continued increases in global emissions (A2 scenario). The size of bars is in proportion to the amount of snow each state contributes to the regional total; thus, the bars for Arizona are much smaller than those for Colorado, which contributes the most to region-wide snowpack. Declines in peak SWE are strongly correlated with early timing of runoff and decreases in total runoff. For watersheds that depend on snowpack to provide the majority of the annual runoff, such as in the Sierra Nevada and in the Upper Colorado and Upper Rio Grande River Basins, lower SWE generally translates to reduced reservoir water storage. (Data from Scripps Institution of Oceanography).

6) Less runoff and greater water stress

Melting snowpack accounts for the bulk of water in many Western rivers. Higher evaporation rates and greater water use by plants will contribute to steep declines in runoff and greater risks to the water supply

RunoffCaption: These projections, assuming continued increases in heat-trapping gas emissions (A2 scenario; Ch. 2: Our Changing Climate), illustrate: a) major losses in the water content of the snowpack that fills western rivers (snow water equivalent, or SWE); b) significant reductions in runoff in California, Arizona, and the central Rocky Mountains; and c) reductions in soil moisture across the Southwest. The changes shown are for mid-century (2041-2070) as percentage changes from 1971- 2000 conditions (Figure source: Cayan et al. 2013).

StreamflowCaption: Annual and seasonal streamflow projections based on the B1 (with substantial emissions reductions), A1B (with gradual reductions from current emission trends beginning around mid-century), and A2 (with continuation of current rising emissions trends) CMIP3 scenarios for eight river basins in the western United States. The panels show percentage changes in average runoff, with projected increases above the zero line and decreases below. Projections are for annual, cool, and warm seasons, for three future decades (2020s, 2050s, and 2070s) relative to the 1990s. (Source: U.S. Department of the Interior – Bureau of Reclamation 2011; Data provided by L. Brekke, S. Gangopadhyay, and T. Pruitt)

Water riskCaption: Climate change is projected to reduce water supplies in some parts of the country. This is true in areas where precipitation is projected to decline, and even in some areas where precipitation is expected to increase. Compared to 10% of counties today, by 2050, 32% of counties will be at high or extreme risk of water shortages. Numbers of counties are in parentheses in key. Projections assume continued increases in greenhouse gas emissions through 2050 and a slow decline thereafter (A1B scenario). (Figure source: Reprinted with permission from Roy et al. 2012. Copyright American Chemical Society).

7) Altered timing of spring snowmelt

Climate change will cause the annual surge of snowmelt to occur earlier in the year, which will force changes in how dams and irrigation are managed. Altered timing of the snowmelt will also pose challenges for aquatic species and ecosystems.

Northwest runoffCaption (Left): Projected increased winter flows and decreased summer flows in many Northwest rivers will cause widespread impacts. Mixed rain-snow watersheds, such as the Yakima River basin, an important agricultural area in eastern Washington, will see increased winter flows, earlier spring peak flows, and decreased summer flows in a warming climate. Changes in average monthly streamflow by the 2020s, 2040s, and 2080s (as compared to the period 1916 to 2006) indicate that the Yakima River basin could change from a snow-dominant to a rain-dominant basin by the 2080s under the A1B emissions scenario (with eventual reductions from current rising emissions trends). (Figure source: adapted from Elsner et al. 2010).

Caption (Right): Natural surface water availability during the already dry late summer period is projected to decrease across most of the Northwest. The map shows projected changes in local runoff (shading) and streamflow (colored circles) for the 2040s (compared to the period 1915 to 2006) under the same scenario as the left figure (A1B). Streamflow reductions such as these would stress freshwater fish species (for instance, endangered salmon and bull trout) and necessitate increasing tradeoffs among conflicting uses of summer water. Watersheds with significant groundwater contributions to summer streamflow may be less responsive to climate change than indicated here.

8) Greater wildfire activity expected

Higher temperatures and a thinner snowpack would be enough to increase wildfire risks, but climate change is also contributing to the spread of insects and diseases in Western forests and woodlands.

Northwest Forest
Caption: (Top) Insects and fire have cumulatively affected large areas of the Northwest and are projected to be the dominant drivers of forest change in the near future. Map shows areas recently burned (1984 to 2008) or affected by insects or disease (1997 to 2008). (Middle) Map indicates the increases in area burned that would result from the regional temperature and precipitation changes associated with a 2.2°F global warming across areas that share broad climatic and vegetation characteristics.101 Local impacts will vary greatly within these broad areas with sensitivity of fuels to climate. (Bottom) Projected changes in the probability of climatic suitability for mountain pine beetles for the period 2001 to 2030 (relative to 1961 to 1990), where brown indicates areas where pine beetles are projected to increase in the future and green indicates areas where pine beetles are expected to decrease in the future. Changes in probability of survival are based on climate-dependent factors important in beetle population success, including cold tolerance,102 spring precipitation, and seasonal heat accumulation.

9) Heat could hurt tourism

If it gets too hot, some parts of the country may become unappealing for tourists, which could have major economic implications.

Tourism

Caption: Tourism is often climate-dependent as well as seasonally dependent. Increasing heat and humidity – projected for summers in the Midwest, Southeast, and parts of the Southwest by mid-century (compared to the period 1961-1990) – is likely to create unfavorable conditions for summertime outdoor recreation and tourism activity. The figures illustrate projected changes in climatic attractiveness (based on maximum daily temperature and minimum daily relative hu­midity, average daily temperature and relative humidity, precipitation, sunshine, and wind speed) in July for much of North America. In the coming century, the distribution of these conditions is projected to shift from acceptable to unfavorable across most of the southern Midwest and a por­tion of the Southeast, and from very good or good to acceptable conditions in northern portions of the Midwest, under a high emissions scenario (A2a). (Figure source: Nicholls et al. 2005).

10)  Carbon emissions are climbing

The report focuses on climate change impacts, but it includes a couple of good graphics showing the rise in carbon dioxide emissions. U.S. output of greenhouse gases have increased primarily due to our expanding population and growing affluence.CO2Caption: Air bubbles trapped in an Antarctic ice core extending back 800,000 years document the atmosphere’s changing carbon dioxide concentration. Over long periods, natural factors have caused atmospheric CO2 concentrations to vary between about 170 to 300 parts per million (ppm). As a result of human activities since the Industrial Revolution, CO2 levels have increased to 400 ppm, higher than any time in at least the last one million years. By 2100, additional emissions from human activities are projected to increase CO2 levels to 420 ppm under a very low scenario, which would require immediate and sharp emissions reductions (RCP 2.6), and 935 ppm under a higher scenario, which assumes continued increases in emissions (RCP 8.5). This figure shows the historical composite CO2 record based on measurements from the EPICA (European Project for Ice Coring in Antarctica) Dome C and Dronning Maud Land sites and from the Vostok station. Data from Lüthi et al. 2008 (664-800 thousand years [kyr] ago, Dome C site); Siegenthaler et al. 2005 (393-664 kyr ago, Dronning Maud Land); Pépin 2001, Petit et al. 1999, and Raynaud 2005 (22-393 kyr ago, Vostok); Monnin et al. 2001 (0-22 kyr ago, Dome C); and Meinshausen et al. 2011 (future projections from RCP 2.6 and 8.5).

driversCaption: This graph depicts the changes in carbon dioxide (CO2) emissions over time as a function of five driving forces: 1) the amount of CO2 produced per unit of energy (CO2 intensity); 2) the amount of energy used per unit of gross domestic product (energy intensity); 3) structural changes in the economy; 4) per capita income; and 5) population. Although CO2 intensity and especially energy intensity have decreased significantly and the structure of the U.S. economy has changed, total CO2 emissions have continued to rise as a result of the growth in both population and per capita income. (Baldwin and Sue Wing, 2013).

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Climate, Climate impacts, Climate projections

Climate change and trends in the American West’s snowpack

Like anglers who can dutifully pinpoint the location of hotspots, winter sports enthusiasts know when and where to find the best snow. When conditions change in the slightest—whether in temperature, base depth, or type of snow—devotees take note. But it can be hard to tell whether conditions on the local slopes in a given season reflect mere chance or long-term changes in global climate patterns.

In a previous post, we explored how rising greenhouse gas emissions will take an economic toll on snow-dependent sports. A 2012 report by two advocacy groups, the Natural Resources Defense Council and Protect Our Winters, provided an indicator of how climate change may impact snow sports. The study estimated that the $12.2 billion winter sports industry has already felt the pinch of decreased snowpack and escalating average winter temperatures; under a business-as-usual trajectory, future scenarios appear even bleaker (see our dashboard of their data).

In this post, we dive deeper into what the science is telling us about climate-driven trends in the Western snowpack.

Snow drifts on Continental Divide
Snow drifts on Continental Divide at Monarch Mountain Ski Area. Photo by Mitch Tobin.

Observed trends in mountain snowpack

In the coming decades, changes to the West’s snowpack will create ripple effects far beyond the ski slopes. Near-term changes in the region’s hydrological cycle will impact water supplies, forest health, agricultural productivity, and the food supply. The bulk of the flow in most Western rivers comes from melting snow.

Describing changes in snow hydrology, one climate scientist framed it succinctly: “Shorter snow season, less snow overall, but the occasional knockout punch. That’s the new world we live in,” said Michael Oppenheimer of Princeton University.

To measure how the snowpack has been changing, scientists often gauge snow levels on April 1st, which is when the snowpack usually reaches its basin-wide maximum in the West. The amount of April 1st snow water equivalent (SWE) has shown a downward trend in recent decades: across the Cascades of the Pacific Northwest and in much of California, the SWE level has decreased 20% compared with 80 years ago.

Snowmelt tends to occur earlier

Scientists have shown that most of the large-scale reductions in snowpack have been related to rising temperatures. Temperatures have warmed by 2 degrees Fahrenheit in the Rocky Mountains and by 1.7 degrees in the Sierras.

According to Anne Nolin, professor of geosciences and hydroclimatology at Oregon State University, the spring snowpack has been declining by 1.5-2% per decade over the past several decades. While this amount may not sound like a steep change, it is significant enough to cause economic losses for the ski areas most vulnerable to a changing climate, such as those at lower elevations and in the warm extents of the Pacific Northwest.

Though overall projections anticipate a consistent decline in Western snowpack over the 21st century, these are difficult predictions to make given the great variability in snowfall from place to place and year to year. As winter sports fans are well aware, resorts separated by only a few miles can receive vastly different snow totals from a single storm.

Another challenge scientists face is the lack of long-term datasets. One key source is SNOTEL, which is operated by the Natural Resource Conservation Service and tracks variables such as precipitation, temperature, snow depth, and soil moisture at more than 600 sites in 13 states. However, the installation of SNOTEL began in the mid-1970s, and thirty years can be a narrow window for distinguishing between climatic changes and natural variability. For this reason, many climate scientists rely on temperature data, which tends to be less variable than precipitation data and which can reveal broader patterns based on 30-50 years of measurement.

Future trends: more rain, less snow, and earlier snowmelt

Under a business-as-usual scenario, winter temperatures are projected to warm by an additional 4-10 degrees Fahrenheit by the end of this century, which could lead to a 25-100% decline in snow depths in the West.

Snowpack loss may occur earlier

Although there is still considerable uncertainty, models predict a decrease in spring snowpack, a transition from snow to more rain, and a reduction in summertime streamflows across the West. By 2040, increased temperatures could melt most of the snowpack in the Sierras and Colorado Rockies by April 1st.

Hydroclimatic change

Mountainside winners and losers of climate change

The impacts of a changing climate will play out differently across the West. Lower elevation areas, such as the Pacific Northwest, are more sensitive to warming temperatures and may be the first locations to feel the impact of snow turning to rain. On the other hand, Colorado has some built-in resilience since it has more ski slopes above 9,000 feet than any other Western state. But over the long term, even high-elevation locations may not be immune to the impacts of a changing climate.

Elevation, latitude, and snowfall

In the near term, the first victims of climate change in the winter sports industry are likely to be the roughly 300 small mom-and-pop ski resorts. Many of these operations are situated at lower elevations and operate on slim financial margins. While megaresorts can compensate for low-snow years with extensive snowmaking infrastructure, smaller mountains may find such systems beyond their financial reach.

If mom-and-pop ski areas go under, it could have a big impact on the future of the American ski industry. These smaller resorts are sometimes referred to as “feeder breeders” because they provide an entry point for people learning to ski and snowboard before they graduate to steeper slopes on bigger mountains or in the backcountry.

While winners and losers may emerge in the near term, ultimately the entire winter sports industry could suffer if the shrinking snowpack turns skiing and snowboarding into fringe activities. “Colorado may have a strategic advantage,” said Nolan Doesken, state climatologist for Colorado, “but if there’s not a national or international interest in winter sports, it could ultimately disadvantage even Colorado. When the entire country struggles with snow and the demand for skiing is lower, the whole industry is at risk.”

Climate contradiction: more blizzards, but less snow overall

During the climate bill discussions in the Senate in 2010, climate change skeptic Senator James Inhofe (R-OK) constructed an igloo on the Capitol Lawn during the record Mid-Atlantic snowstorm, coined “snowpocalypse.” While Inhofe meant to suggest that climate change is hoax, scientists in fact have been warning for some time that a world with warming temperatures is poised to trigger more potent blizzards.

Since a warmer atmosphere can hold more moisture, it is reasonable to expect an upward trend in extreme winter precipitation, in the form of both rain and snow. During the past 50 years, the United States has seen twice as many extreme snowstorms as experienced during the previous 60 years.

“Strong snowstorms thrive on the ragged edge of temperature—warm enough for the air to hold lots of moisture, meaning lots of precipitation, but just cold enough for it to fall as snow,” said Mark Serreze, director of the National Snow and Ice Data Center. “Increasingly, it seems that we’re on that ragged edge.”

Data sources

Downloads

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Climate, Climate impacts, Recreation, Resources

Snow jobs: America’s $12 billion winter sports economy and climate change

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The author at work. Photo by Andy Tarica.
The author at work. Photo by Andy Tarica.

Full disclosure: I love to ski and snowboard, so before reading further, you should know that I’m more of a passionate participant than neutral analyst of America’s snow sports industry.

But whether you’re a ski bum, X Games aspirant, or disinterested flatlander, it’s undeniable that a ton of money is changing hands when it comes to skiing, snowboarding, snowmobiling, and other sports dependent on snow.

In the 2012/2013 season, 8.2 million Americans alpine skied at least once, 7.4 million people snowboarded, and 3.3 million people cross-country skied, for a combined total of nearly 57 million skier-visits. Snowmobiling, which is especially popular in the Upper Midwest, generated more than 7 million visits in just three states combined: Minnesota, Michigan, and Wisconsin.

To cut to the chase: if greenhouse gas emissions continue to climb, climate change is going to endanger America’s winter sports industry. Although a warming atmosphere can hold more water vapor, the precipitation will be more likely to fall as rain than snow, so even parts of the West that get wetter overall could see dramatic reductions in snowfall.

A diminished snowpack will jeopardize water supplies, increase wildfire risks, and transform entire ecosystems. Compared to these impacts, harm to ski bums and resorts may seem trivial, but in economic terms, low-snow years can devastate the tourism that some communities depend on. In the 2009/2010 season, U.S. winter sports trips generated nearly 212,000 jobs, labor income of $7 billion, and total economic value of $12.2 billion.

To illustrate what winter sports mean to the U.S. economy, I’ve created a dashboard on this page that visualizes data in a report from two researchers at the University of New Hampshire. Below is a screenshot (click to enlarge).

EcoWest winter sports dashboard

The Natural Resources Defense Council and Protect Our Winters, two advocacy groups, contracted with Elizabeth Burakowski and Matthew Magnusson to examine winter sports tourism in 38 states. The December 2012 report also estimates how much money each state lost, in jobs and economic value, in a low-snow year compared to a high-snow year.

In a future post, we’ll take a closer look at what the science is telling us about trends in the Western snowpack, but the authors of this report paint a bleak portrait of what’s to come under business-as-usual emissions scenarios:

Without intervention, winter temperatures are projected to warm an additional 4 to 10 degrees Fahrenheit by the end of the century, with subsequent decreases in snow cover area, snowfall, and shorter snow season. Snow depths could decline in the west by 25 to 100 percent. The length of the snow season in the northeast will be cut in half.

Yikes. Better seize those powder days while you can. I know I am.

Below is a summary of some visualizations from the dashboard, the original study, and other data sources.

Snow sports widespread

Here in Colorado, winter tourism is a major economic driver, and it’s no shock that we’re tops in the nation for skiing/snowboarding visits. Colorado accounted for one-fifth of ski and snowboarding visits, while one-eighth took place in California. What surprised me was that all but 12 of the 50 states have a winter sports economy (in reporting their findings, the authors did lump together some alpine powerhouses, such as Illinois and Indiana). If you factor in snowmobiling, the winter sports industry has an impressive geographic reach. In the graphic below, the circles are sized by the number of skiing/snowboarding visits and colored according to the number of snowmobiling visits.

Skiing, snowboarding, and snowmobiling days

Data from another source, the National Ski Areas Association, confirms there’s plenty of skiing and snowboarding taking place outside of the West. I grew up skiing/skidding on the icy hills of Northern New Jersey, Vermont, and New Hampshire, and I can definitively state that the skiing out West is way better, but if you look at the number of visits to U.S. resorts, the Rockies and Pacific regions only make up about 55% of the total.

U.S. skier/snowboarder visits by region

Billions at stake in winter tourism

It’s hard not to spend money while skiing and snowboarding, even if you live in Colorado. Before hitting the slopes, I’ll often fuel up my car at the gas station and fill my belly at my local greasy spoon. At the mountain, my annual ski pass helps pay for the parking attendants, lift operators, and ski patrol. Single-day lift ticket prices are north of $100 at some ski areas, which explains why “resort operations” is the biggest box in the graphic below.

Economic value added of winter tourism industryMany ski areas have villages or minor cities at their bases with restaurants, shops, hotels, and spas. Whether it’s the glitterati buying up garish outfits or local yokels like me purchasing coffee for the drive home, money is circulating in the snow-based economy. In mid-February, at Denver International Airport, the wind-chill outside may be 10-below zero, but the baggage claim is a madhouse of travelers arriving from around the globe, ready to shell out big bucks.

In some cases, entire cities owe their existence to ski areas. Here in Colorado, communities such as Vail, Aspen, Breckenridge, and Telluride are synonymous with their ski mountains. These places see plenty of visitors in spring, summer, and fall. There’s actually some controversy about resorts getting too busy during the “off season.” Even so, winter sports are the magnet for many of these communities, snow is like manna from heaven, and the financial impact of winter sports extends far beyond chic destinations to the more humble places where planes land and tourists drive through. The map below shows that every Western state has more than 1,000 jobs connected to winter sports.

Winter tourism employment

It’s important to remember that the data in our dashboard only tells part of the story. The data focuses on the local economic impact of skiing, snowboarding, and snowmobiling trips. Airline tickets are not included. Nor are the thousands of dollars that people spend on equipment and clothing. Last season, nearly $1.8 billion was spent at snow sports specialty stores on apparel, equipment, and accessories (in roughly equal proportions), according to SnowSports Industries America. Consumers spent about $750 million online on winter sports products.

Low-snow years harm industry

To gauge the impact of climate change, the University of New Hampshire researchers examined what happened to snow sports visits during low-snow years and then estimated the economic hit in the 38 states they studied. As shown below, some states appear to be more resilient than others. Colorado, California, and Utah suffered declines that were less than the national average, but other states, such as Washington, Oregon, and New Hampshire, saw skier visits fall even more than the national average.

Impact of low-snow year on state ski industries

As an example, the graphic below shows that ski resorts in Montana lost $16 million in a low-snow year and winter tourism employment declined by 188 jobs due to the 4% decline in skier visits.

Impact of low snowfall on Montana winter tourism

Industry faces questionable future

Skiing, snowboarding, and snowmobiling are certainly not without their environmental impacts. Fly west out of Denver on a clear day and you’ll see a lot of clear-cut strips marking the runs at the ski resorts. Below is a photo I snapped of Loveland Ski Area, where I wrote some of this post in between runs.

Loveland Ski Area, Colorado
Loveland Ski Area and Eisenhower Tunnel, Colorado. Photo by Mitch Tobin.

I’ve certainly done my share to cook the planet by driving into the mountains to ski and ride. A 114-mile round trip to Loveland from Denver causes my Subaru Forester to emit around 80 pounds of carbon-dioxide equivalent, according to the EPA’s Greenhouse Gas Emissions Calculator.

But for me and millions of other Americans, playing in the snow is essential to our well-being. We’ll neglect family, friends, work, the health of the planet, and other concerns in order to get our white powder fix. Call it an addiction or healthy habit, snow sports are more than fun and games: they’re also an economic engine that climate change threatens to freeze.

Data sources

Climate Impacts on the Winter Tourism Economy, a report by the Natural Resources Defense Council and Protect Our Winters, is the source for data on jobs, economic value, and snow sports visits in the 38 states.

Data on skiing and snowboarding is also available from Snowsports Industries America and the National Ski Areas Association.

Downloads

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.