New U.S.G.S. National Climate Change Viewer Focuses on Watersheds

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Home / New U.S.G.S. National Climate Change Viewer Focuses on Watersheds

Committed changes in annual mean maximum temperatures by 2050-2074 (base 1950-2005). Image by USGS. Modified by James Gibson

It seems there are two potential, but not mutually exclusive, paths that farmers and land and water managers can take in the face of climate change – namely adaptation and mitigation.

Climate Change Response Strategies

Mitigation attacks the impacts by reducing the magnitude of climate change itself through emissions reduction and geoengineering.

Supply-side and demand-side adaptation strategies, on the other hand, limit stakeholders’ vulnerability without dealing with any of the underlying causes.

In the mix is committed climate change, a condition that probably cannot be easily mitigated without controversial geoengineering measures. In the language of the IPCC, “because of past change in the atmosphere’s composition climate change continues for as long as a radiative imbalance persists and until all components of the climate system have adjusted to a new state.

Climate Change Viewer

Two USGS scientists, Steve Hostetler and Jay Alder, in partnership with the CEOAS at Oregon State University, have developed a visualization tool termed the National Climate Change Viewer (NCCV) that summarizes regional committed climate change in the United States.

The visualization tool’s purpose is twofold:

  1. To help guide farmers and land and water managers in their thinking and actions concerning adaptation and mitigation strategies.
  2. To help educators teach students about some of the implications of climate change.

The Times They Are a Changing

Thirty years ago one supply-side adaptation that drew a lot of attention was fresh water diversion. Magnificent North American plans like NAWAPA were dreamed up for the diversion of north-flowing rivers, primarily located in Canada, to supply the water-hungry southwest.

Today the strains on water supplies are still there but magnified by a new trigger, climate change. And in North America we are finding it in new areas such as the northeast and western mountain areas.

The hydrologic status quo is changing in the face of existing and projected climate changes. Glaciers are receding, stream and lake temperatures are rising, there is an increased frequency and magnitude of storm events, and an accelerated melting of permafrost and lake and river ice.

In addition, the atmospheric evaporative demand is increasing from higher temperatures, snow accumulation is increasing and snowmelt accelerating, and the timing and magnitude of stream flow is being altered.

National Climate Change Viewer Update

As the USGS explains, “The new tool gives citizens and resource managers the opportunity to look at climate-driven impacts on watersheds and map projected changes at the local, regional, state and watershed levels.”

In phase one of the viewer, information was provided on projected temperature and precipitation for the whole United States through the 21st century in 25-year periods. It also allowed the user to drill down to individual states and counties.

Phase two provides information on associated projected changes (e.g. soil-moisture storage) in 25 year periods but with a 55-year historical period (1950-2005).

Water Balance Model

The viewer is simulated by a simple water balance model familiar to students of geography.

Diagram of the water balance model used by the National Climate Change Viewer.

Diagram of the water balance model used by the National Climate Change Viewer.

The concept weighs the soil storage of water (input) from precipitation (e.g. rain, snowfall) against withdrawal by evapotranspiration (evaporation and transpiration) of the sun and plants. This is summarized as an end-of-month surplus or deficit.

Precipitation in excess of soil storage capacity becomes runoff.

Consider my part of North America, the Windsor-Detroit region in comparison with Colby, Kansas, two communities located on the fringe of the USGS’s Plant Hardiness Zone 6.

On average in Detroit-Windsor, and the county of Wayne there has been a relatively even supply of water from precipitation – it varies from close to 3 inches per month from May to August to close to 2 inches per month in January and February. The associated end-of-month soil-moisture storage levels usually show a replenishing from January to March with a significant deficit only in September. Growers, knowing this, have adapted accordingly.

In contrast, on average in hotter and drier Colby, Thomas County, Kansas, we find the soil-moisture storage is more skewed. The precipitation has been concentrated in the warmer months- the highest in May and July- and offset by high temperatures of close to 90°F. This results in significant soil-moisture deficits from as early as July through to September.

But the viewer projects significant mean changes in the soil-moisture storage numbers for both locales by the middle of the century.

Should supply-side strategies like expanding rainwater storage or building more reservoirs, or demand-side strategies like changing crop calendars or water reallocation be introduced? That’s a question for the policy makers and the Viewer is a tool they can use.

Are significant soil-moisture deficits projected for your region? The new tool will tell you.

Data Sources: CMIP5 Models

The NCCV offers the projections of 30 worldwide climate modeling centers participating in the 5th Climate Model Intercomparison Program (CMIP5) including a mean of all the models. These programs are providing climate information for the ongoing Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC).

NASA has statistically further refined the climate data to allow for high resolution regional climate change assessments down to the level of counties and watersheds.

Using maps, climographs, histograms, and tables the NCCV allows the user to visualize projected changes in climate and components of the water balance for any state, county and USGS Hydrologic Unit or watershed.

This data is averaged into four periods:

  • 1950 to 2005
  • 2025 to 2049
  • 2050 to 2074
  • 2075 to 2099
A comparison of committed climate change in Colby, Kansas and Detroit, Michigan. Image by James Gibson

A comparison of committed climate change in Colby, Kansas and Detroit, Michigan. Image by James Gibson

Climate-Driven Impacts on Watersheds

To view water balances aspects as they relate to US watersheds, a user of the NCCV would select Watersheds as the region type.

As a demonstration, I conducted a comparison of Colby, Kansas in the Smoky Hills section of the Missouri watershed, and Windsor-Detroit in the Detroit River section of the Great Lakes Watershed. It showed projected water-balance deficits in both areas with warmer annual mean and minimum temperatures.

Status of the Viewer

The NCCV and its data are already being used by federal agencies to examine the potential effects of climate change on aquatic and terrestrial ecosystems in the Greater Yellowstone Area.

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