Ole! Spanish Greenhouses Make Climate Less Caliente

Greenhouses in southern Spain could be responsible for lowering the local temperature

By Rachel Durfee Posted 10.14.2008 at 5:10 pm 2 Comments

Spanish Greenhouse iStockPhoto

The southern coast of Spain is known for hot parties, hot food, and hot people. But one thing it may soon be known for is cooling the climate. The southeastern region of Almeria is home not only to paella and flamenco but also to the world's largest expanse of greenhouses. The roofs on these "hot houses" reflect incredible amounts of sunlight – so much, in fact, that scientists now say they could be responsible for lowering the local temperature.

Today, 26,000 hectares of Almeria's semi-arid pasture land is dominated by greenhouse horticulture in a constant change-over that has been occurring since the 1970s to improve the region's agriculture. Using satellite data, scientists from the University of Almeria identified differences in surface radiation (how much heat is emanating from the ground) and albedo (the ability to reflect sunlight) between the greenhouse-covered land and the natural, semi-arid land. Simultaneously, they compared temperature trends inside the region with those throughout Spain. The results showed that in Almeria, air temperature has cooled by an average of 0.3 degrees Celsius per decade since 1983. The rest of Spain, however, has experienced temperatures rise 0.5 degrees Celsius. It seems the white roofs dotting the region are good for more than just an iconic photograph: they are also the key to the cooling temperatures.

The researchers believe that this relatively simple technology (reflective roofs) could be applied to similarly semi-arid regions throughout the world and have the same effect.

Southern Spain: It's so hot, it's cool.

Via Environment.NewScientist.com

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2 Comments

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idratherbegolfi...

from Plymouth, WI

10/14/08 at 6:45 pm

This is remarkable, I've always wondered what the effect would be on global temperature if we all painted the tops of our buildings white, instead of black or gray, which of most them are. White obviously reflects much larger amounts of solar energy than black Could solving the warming really be as simple as reflecting more light back into space? Realistically, I think it could be a solution, if we are unable to solve the output of CO2 in time. It's times like these I wish I had a climate simulator on hand to calculate the effect.

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mioffe_2000

10/24/08 at 6:59 pm

1. Clouds reflect huge parts of solar energy back to space: thick clouds-75-90%, thin clouds-30-50%;
2. Forests contain much more carbon than does grass and they also absorb more sunlight and produce more water vapor, which affect cloud formation.
3. Water vapor is one of the lightest gases and has tendency to go up to cloud level. Water has another properties it takes a lot of energy to evaporate water. Evaporation of water will cool air temperature. Despite that water vapor is greenhouse gas, it tendency to go up bring them on cloud level, where distances between molecules bigger and heat will go to space more easily than on ground level. No others greenhouse gases have these properties. Of course, reduction of carbon dioxide in the air will cool the Earth. Water vapor will also cool the Earth. We need increase evaporation of water. It is significantly cheaper then efforts to reduce greenhouse gases.
4. Sun is the best source of energy to evaporate water from growing trees, and not only will cool the air of Earth but also produce the cheapest, really “green” source of energy, which can be used in any time during hundreds of years.
5. White fresh snow reflects to space 75-95% of Sun radiation. White cars, houses, roads will do the same.

Tim Flannery wrote that only new forests collect carbon also absorbing sunlight to grow and produce water vapor. Trees are the best and cheapest pumps in the world. They use Sun energy to evaporate huge amount of water. It is the cheapest way to cool the air of the Earth. Drop of rain on cloud level is the cleanest and the best solvent of carbon dioxide.
Increasing of evaporation of water will do more to reduce carbon dioxide in the air than any attempt of conservation energy.