19-1 How Might the Earths Temperature and Climate Change in the Future
Weather and Climate Are Not the Same Weather is short term changes in the atmospheric variables like wind, temperature, precipitation and barometric pressure in a certain area over a period of hours or days. Climate is the average weather conditions of the earth or of a particular area. Temperature and precipitation that is measured over a long period of time. The time can range from decades to centuries to thousands of years.
Climate Change is Not New Over the past 3 billion or more years, the planets climate has been altered by a lot of things. These factors include changes in the suns output of energy, impacts by large meteorites that throw large amounts of dust into the atmosphere, and slight changes in the earths orbit around the sun. The climate on earth is also affected by global air circulation patterns that reflect incoming solar energy and helps to cool the atmosphere, various concentrations of the different gases that make up the atmosphere and the changes in ocean currents. The atmosphere has had long periods of global cooling and global warming over the past 900,000 years. These cycles of freezing and thawing are called glacial and interglacial periods.
The Climate and Our Lives and Economics Depend on the natural Greenhouse Effect Greenhouse effect affects the earths climate because it warms the earths lower atmosphere and surface. About 1% of the earths lower atmosphere is made up of greenhouse gases, especially water vapor (H2O), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Heat radiated into the atmosphere by the earth causes molecules of these gases to vibrate and release infrared radiation with an even longer wavelength into the lower atmosphere. As this radiation interacts with molecules in the air, it increases their kinetic energy and warms the lower atmosphere and the earths surface, which over time affects the earths climate. It is thought that without the natural greenhouse effect, earth would be frigid and uninhabitable place.
19-2 What Are Some Possible Effects of a Warmer Atmosphere
Enhanced Atmospheric Warming Could Have Serious Consequences Most historic changes in the temperature of the lower atmosphere took place over thousands of years. What makes the current problem urgent is that we are faced with a rapid projected increase in the average temperature of the lower atmosphere during this century. This is probably going to quickly change the mild climate that we have had for the past 10,000 years. What we are facing is very rapid climate change. These changes will affect where we can grow food and how much we can grow. It will also affect what areas will have problems with increased drought and which will have increased flooding. It will also affect what areas people and wildlife can live.
More Ice and Snow Are Likely to Melt Climate models project that the worlds polar regions will be most affected by climate change because of the warming of the climate. The ice and snow in these areas help to cool the earth by reflecting solar energy. When the ice and snow melts it exposes darker land and sea areas. These areas reflect a lot less sunlight and absorb more solar energy. The atmosphere above the poles would warm faster. Mountain glaciers are important to the water cycle because they store water as ice during cold wet seasons and release it slowly to streams during warmer dry seasons. If these glaciers continue to shrink people in many countries could be faced with major water, power and food shortages.
Severe Drought Is Likely to Increase Drought happens when evaporation from increased temperatures exceeds precipitation for a long period of time. Southern Australia has experienced a severe drought for a decade, and the western United States is experiencing its worst drought in 500 years. A 2007 study by climate researchers at NASAs Goddard Institute for Space Studies predicts that by 2059 up to 45% of the worlds land area could be experiencing extreme drought. When droughts increase and spread it affects the growth of trees and other plants, the growth declines. When the forests and grasslands dry out the chances of wildfires increase and this adds CO2 to the atmosphere. Other problems caused by drought are declining stream flows and less available surface water. It will also cause water tables to fall with more evaporation. This will get worse because farmers will irrigate more to make up for drier conditions. It will cause the lakes, reservoirs and inland seas to shrink. Some of these effects will probably going to accelerate atmospheric warming and lead to even more drought.
19-3 What Can We Do to Slow Projected Climate Disruption
Dealing with Climate Disruption Is Difficult One of the main things we can do is do everything we can to avoid any and all climate tipping points. The climate tipping points are points where natural systems can change beyond a chance to go back. The problem is global. Dealing with this threat will require international cooperation. The problem is a long-term political issue. Voters and elected officials generally respond better to short- term problems than to long- term threats. Most of the people who could suffer the most serious harm from projected climate disruption during the latter half of this century have not been born. The projected harmful and beneficial impacts of climate disruption are not spread evenly.
Prevent and Reduce Greenhouse Gas Emissions Preventions- Cut fossil fuel use. Shift from coal to natural gas. Improve energy efficiency. Shift to renewable energy resources. Transfer energy efficiency and renewable energy technologies to developing countries. Reduce deforestation. Use more sustainable agriculture and forestry. Put a price on greenhouse gas emissions. Reduce poverty. Slow population growth Reduce- Remove CO2 from smokestack and vehicle emissions. Store CO2 by planting trees. Sequester CO2 in soil by using no-till cultivation and taking cropland out of production. Sequester CO2 deep underground. Sequester CO2 in the deep ocean. Repair leaky natural gas pipelines and facilities. Use animal feeds that reduce CH4 emissions from cows
Collect Greenhouse Gas Emissions and Stash Them Somewhere One way is to increase the uptake of CO2 by starting a global tree-planting program. Restore wetlands where they have been drained for farming. Wetlands are good at taking up CO2 and provide other natural services. Another way is to plant plants in large areas of degraded land. Plants like perennial plants that are fast growing and remove CO2 from the air and store it in the soil. Another way is to help the natural uptake and storage of carbon by preserving natural forest. Seeding the oceans with iron to promote the growth of more marine algae and other phytoplankton. Marine algae and phytoplankton absorb large amounts of CO2 from the atmosphere as they grown. Remove CO2 from the smokestacks of coal-burning power and industrial plants to store it somewhere. This is called carbon capture and storage.
19-4 How Have We Depleted Ozone in the Stratosphere and What Can We D About It
Our Use of Certain Chemicals Threatens the Ozone Layer Around 95% of the suns harmful ultraviolet radiation is kept from reaching the earths surface by a layer of ozone in the lower stratosphere. The ozone depletion in the stratosphere is a serious threat to humans, animals and plants that use the sunlight to support earths food webs. CFCs, more commonly known as Freons, was thought to be a dream chemical. It is odorless, nonflammable, nontoxic and chemically unreactive. Because it is very inexpensive to manufacture it was used a lot as coolants in refrigerators and air conditioners, as a cleaner for electronic parts like computer chips, propellants in aerosol spray cans, as gases used to make insulation and packaging and fumigants for granaries and ships cargo holds. It was proven in 1974, by chemists Sherwood Rowland and Mario Molina, that CFCs are chemicals that destroy protective ozone in the stratosphere. These are not the only ozone depleting chemicals though. Some of the others are methyl bromide which is a fumigant, hydrogen chloride which is released in the stratosphere by space shuttles, halons and hydrobromoflurocarbsons, used in fire extinguishers and some cleaning solvents.
Why Should We Worry about Ozone Depletion? Ozone depletion should be a concern for us because there are many problems that can be caused by this. This will cause worse sunburns, eye cataracts and increased skin cancers. The increase in UV radiation could destroy phytoplankton. Phytoplankton plays an important role in removing CO2 from the atmosphere.
We Can Reverse Stratospheric Ozone Depletion A lot of researchers think that we should stop producing all ozone-depleting chemicals. Even if we did it would take a long time for the earths ozone layer to recover the levels of ozone it had years ago. The goal of the Montreal Protocol was to cut emissions of CFCs by about 35% between 1989 and 2000. After getting news that seasonal ozone thinning above Antarctica representatives from 93 countries had more meetings in 1992 and adopted the Copenhagen Protocol. This accelerated the phase-out of key ozone- depleting chemicals. Finally companies and nations agreed to work together to solve this global problem. If nations keep following agreements on stratospheric ozone the levels should return to 1980 levels by 2068.
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