Trends in Daily Solar Radiation and Precipitation Coefficients of Variation Since 1984
As anyone who lives on Earth can attest, weather is rarely “average.” However mild or extreme a climate may be, it can be relatively warm one day and cool the next; clouds appear or the sun breaks through; precipitation, if it occurs, tends to do so in bursts. Yet many climate models focus on “average” weather for a particular time and place, something that occurs only rarely in the real world.
This question is important because climate change has the potential to not only increase median temperatures, but also alter weather patterns. Averages and extremes can remain the same even as variability increases — more sunny days, more rainy days — and this can have significant effects on the environment. For example, plants have evolved to expect a certain pattern in weather variability, and a change in that pattern could have serious consequences.
A 2011 study from Princeton University in the online journal of the American Meteorological Society, “Trends in Daily Solar Radiation and Precipitation Coefficients of Variation Since 1984,” looks at the possibility of changes in the variability of daily sunshine and precipitation over time. The study was based on data from NASA’s International Satellite Cloud Climatology Project and the University of Maryland’s Global Precipitation Climatology Project.
Key findings include:
- Statistically significant changes in solar radiation variability were found across 35% of the planet since 1984.
- Tropical Africa and Southeast Asia showed large increases in sunshine variability. “These increases in solar radiation variability were correlated with increases in precipitation variability and increases in deep convective cloud amount.”
- Data indicates that tropical South America has seen correspondingly large changes in solar radiation variability mainly from December through February.
- Changes in climate variability can have consequences for any process that depends on regular climate variability, including solar energy production and plant photosynthesis. Other impacts could include soil moisture and runoff, carbon sequestration and mosquito populations, which can affect disease outbreaks.
“Given the large number of processes that are nonlinearly sensitive to climate, improving our understanding of current and future high-frequency variability should be a high-priority area of research,” the scholars conclude.
Tags: global warming, Africa, Asia
Read the issue-related New York Times article "A Warming Planet Struggles to Feed Itself."
- If you were to revise the article based on knowledge of the study, what key changes would you make?
Read the Princeton University study “Trends in Daily Solar Radiation and Precipitation Coefficients of Variation Since 1984.”
- Summarize the study in fewer than 40 words.
- Express the study's key term(s) in language a lay audience can understand.
- Evaluate the study's limitations. (For example: Do the results conflict with those of other reliable studies? Are there weaknesses in the study's data or research design?)
- Write a lead (or headline or nut graph) based on the study.
- Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
- Interview two sources with a stake in or knowledge of the issue. Be prepared to provide them with a short summary of the study in order to get their response to it. Write a 400-word article about the study incorporating material from the interviews.
- Spend additional time exploring the issue and then write a 1,200-word background article, focusing on major aspects of the issue.