Dispelling the notion that urban “green” spaces help counteract greenhouse gas emissions, new research has found — in Southern California at least — that mowing and other lawn maintenance emit much larger amounts of greenhouse gases than the well-tended grass sequesters.
Turfgrass lawns remove carbon dioxide from the atmosphere through photosynthesis and store it as organic carbon in soil, making them important “carbon sinks.” However, greenhouse gas emissions from fertilizer production, mowing, leaf blowing and other lawn management practices are four times greater than the amount of carbon stored by ornamental grass in parks, a new study shows. These emissions include nitrous oxide released from soil after fertilization. Nitrous oxide is a greenhouse gas that’s 300 times more powerful than carbon dioxide, the Earth’s most problematic climate warmer.
“Lawns look great — they’re nice and green and healthy, and they’re photosynthesizing a lot of organic carbon. But the carbon-storing benefits of lawns are counteracted by fuel consumption,” says Amy Townsend-Small, Earth system science postdoctoral researcher at University of California, Irvine. Townsend-Small is the lead author of the study, which has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union (AGU).
The research results are important to greenhouse gas legislation being negotiated, Townsend-Small says. “We need this kind of carbon accounting to help reduce global warming,” the lead author says. “The current trend is to count the carbon sinks and forget about the greenhouse gas emissions, but it clearly isn’t enough.”
The following image shows the temperatures over the course of the year, with one line per decade (values are averaged), per continent. The color scale goes from light green (1900s) to dark green (2000s). The reason for going by decade here is that there are considerable yearly fluctuations that make this chart nearly unreadable if done at that level.
Some interesting patterns emerge here. While it’s not possible to see exactly which lines are which decade (the colors are too similar, and there is too much overplotting), this is really more about trends, which are quite apparent.
All continents except for South America show darker colors at the top, meaning that temperatures get warmer for most of the year. Africa gets warmer summers but cooler winters: note the dark green lines at the bottom of the pack on each end. The two regions in the southern hemisphere are clearly visible because they have their minima in the middle of the year.
South America has a pattern that looks very similar to Africa, with warmer summers and colder winters (just at different times of the year). The Pacific and Asia have darker colors at the top and the bottom because they had some colder years in the 1970s and 1980s. These outliers do not invalidate the general trend, though.
"a temporary laser light marker system that accurately maps a hypothetical barrier network to protect bay area cities from rising waters caused by climate change."
or to paraphrase - if you are below the green laser line and there isn’t a barrier, you are most likely under water.
I regard the picture as an ecosystem in which all the elements are interrelated, interdependent, perfectly balanced, without trimming or unutilized parts; and herein lies the lure of painting; in a world of chaos, the picture is one small rectangle in which the artist can create an ordered universe.
- Charley Harper