Climate change in the Rogue Valley
Years ago we heard the claim: "People always talk about the weather, but nobody ever does anything about it." No longer is this the case.
Although counties in the Rogue Valley are not suffering from climate change like the 50 percent of counties in the nation declared disaster areas, for those of us with eyes, ears and a mind open enough to see, climate change is here and now. For Republicans, Democrats and Independents alike, the impact of droughts, wildfires and storms can be devastating.
This is the first of three articles exploring the likely Rogue Valley future over the next century; it sets the scene and identifies temperature projections.
The basics of climate change are simple and uncontroversial:
1) All objects emit radiation; hotter objects — like suns — emit short wavelength visible radiation while cooler bodies — like planets — emit longer wavelength heat.
2) When visible wavelength radiation is absorbed by our planet, it turns to longer wavelength heat which radiates back out.
3) This heat is intercepted by gas molecules in our atmosphere, some gases absorbing more than others.
4) Planets like Venus with a higher density of these gas molecules are hotter than those like Mars with lower densities.
5) Without these gases in our atmosphere, our global temperature would probably be too cold to support life as we know it.
6) Increasing the density of these gases in our atmosphere increases the temperature.
7) Although carbon dioxide is not the most effective heat-retaining gas, it is present in a much higher density and has a longer life span in the atmosphere than methane, oxides of nitrogen and water vapor.
The 18th century Industrial Revolution resulted in humans burning fossil fuels (initially coal, later oil and gas) at an increasing rate. Additionally, with improved mechanization. more rapid and extensive forest clearing and burning became possible as we turned standing trees into carbon gas.
Globally, we have seen a warming of about 1.5 degrees Fahrenheit over the past century with the greatest heating occurring since the 1970s. Climate scientists worldwide have been exploring the trends in greenhouse gas emissions over the past century and projecting what future emissions might cause under a wide range of scenarios. These scenarios make different assumptions about our global population and energy consumption patterns.
Models that assume we will continue behaving as we have in the past are called business-as-usual models. Given our lack of response so far, this is the most reasonable assumption upon which to base future projections.
Of course, if we act to address the issue by reducing greenhouse gas emissions, projections based on this scenario will be high. On the other hand, if we actually increase the rate at which we emit these gases, the projections will be overly optimistic; outcomes will be worse than projected.
Once we acknowledge that climate change is happening, we might reasonably ask what the consequences will likely be where we live. Fortunately, a glimpse of our Rogue Valley future can be found in a 2008 report released by the Geos Institute. The projections are based on three global models using the business-as-usual scenario. The Mapped Atmosphere, Plant, Soil Systems team from the Northwest Research Station of the U.S. Forest Service provided the local scale projections analyzed in that report.
Compared with 1961-1999 conditions, projections focus on 2035-2045 and 2075-2085. The average projected warming for 2035-2045 is 2 to more than 3 degrees, and for 2075-2085, 4 to 8 degrees. But seasons vary; thus 2035-2045 winters will likely warm just 1.5 to about 3 degrees while summers will probably be 2 to 4.5 degrees hotter compared with that baseline. Meanwhile, 2075-2085 winters will likely be 3.5 to 6 degrees hotter with summers some 5.5 to nearly 12 degrees hotter. Notably, August by 2075-2085 could be as much as 15 degrees warmer than historic records.
As critical as are temperature averages, heat extremes and heat waves may be more important. As the century unfolds, we will likely see many more days — and extended periods — with the temperature exceeding 95 and even 100 degrees. These periods will pose threats not just for human health but also to many of our crops. Each 1 degree average increase in temperature decreases crop productivity substantially, but more importantly, more heat waves may well cause severe crop losses — important not only for the farmer but also for the population that consumes the crops.
The next article will discuss precipitation and water availability patterns along with other major climate change consequences. The final article will explore what is happening locally and what the imperatives are by way of response.
Alan Journet, a retired ecologist, lives in the Applegate Valley. He offers presentations on aspects of climate change and is one of a group of local residents establishing a grassroots Rogue Valley climate protection organization. He can be reached at firstname.lastname@example.org.