Gases such as water vapor, methane, carbon dioxide, methane, ozone, nitrous oxide, and fluorine-containing compounds are called “greenhouse” gases because they trap heat and warm the planet’s surface. Some of these gases are generated naturally, and some through human activities. The natural greenhouse effect has been good to us, warming the atmosphere near the ground to a comfortable 15°C (59°F) on average. Without it, the average temperature would be closer to -18°C (0°F) and far less hospitable to life.
But the artificial component of the greenhouse gases currently in our atmosphere appears to be carrying this warming effect too far, threatening significant disruption to our climate with consequences to our health, agriculture and, as ice shelves melt and the oceans expand, our coastlines. It could also disturb weather patterns significantly, causing drought or flooding in important farming regions. It is widely accepted in the science community that increased amounts of certain greenhouse gases in the troposphere are promoting a general increase in its temperature, especially at high latitudes. Warming of the climate system is evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level. Unless the warming trend is abated, many scientists fear that temperatures will rise 1.4 to 5.8 Celsius degrees (2.5 to 10.4 Fahrenheit degrees) by the end of this century.
TES is measuring the gases pertinent to global warming and will contribute to a long-term global greenhouse gas inventory, by measuring tropospheric water vapor, methane, and ozone, all of which have an impact on climate change, as well as additional gases important to tropospheric chemistry, such as carbon monoxide.
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TES measurements let us quantify the greenhouse gas impact of tropospheric ozone. In analysis published in Nature Geosciences (PDF, 1.5 MB), we reported that tropospheric ozone, in clear sky, traps an average of 0.48 W/m2 of outgoing long wave radiation. This is the combined effect of man-made and natural ozone. With TES observations, we can see the spatial and seasonal patters of the absorption. It is interesting to note that ozone is less important as a greenhouse gas in the tropics, because water vapor absorbs so much of the outgoing radiation
For further information, see also:
- The role of ozone in climate forcing and feedback
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Greenhouse gases contribute to global warming by trapping some of the energy that Earth radiates after being warmed by the sun. TES scientists are currently able to calculate how much energy is trapped at various altitudes by ozone and they’re in the process of doing the same with water vapor, the most abundant greenhouse gas. Upcoming work with TES data may similarly reveal the effects of methane.