Climate Change LucilaInstituto “Santa Cruz” – Buenos Aires, Argentina
What is it?• Climate change is any change in global temperatures and precipitation over time because of natural variability or to human activity. It is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions, or in the distribution of weather around the average conditions.
Causes• Climate change is caused by factors that include oceanic processes, variations in solar radiation received by Earth, plate tectonics and volcanic eruptions, and human-induced alterations of the natural world; these latter effects are currently causing global warming, and "climate change" is often used to describe human- specific impacts.• On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions.
Glaciers• As temperatures warm, glaciers retreat unless snow precipitation increases to make up for the additional melt; the converse is also true.• Glaciers grow and shrink because of natural variability and external forcings. Variability in temperature, precipitation, and englacial and subglacial hydrology can strongly determine the evolution of a glacier in a particular season.
Vegetation• A change in the type, distribution and coverage of vegetation may occur given a change in the climate. Some changes in climate may result in increased precipitation and warmth, resulting in improved plant growth and the subsequent sequestration of airborne CO2. A gradual increase in warmth in a region will lead to earlier flowering and fruiting times, driving a change in the timing of life cycles of dependent organisms. In reverse, cold will cause plant bio-cycles to lag. Larger, faster or more radical changes, however, may result in vegetation stress, rapid plant loss and desertification in certain circumstances.
Precipitations• Changes in rainfall and other forms of precipitation will be one of the most critical factors determining the overall impact of climate change. Rainfall is much more difficult to predict than temperature but there are some statements that scientists can make with confidence about the future.
Global sea level change• Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average. More recently,altimeter measurements — in combination with accurately determined satellite orbits — have provided an improved measurement of global sea level change. To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, and nearshore archaeological remains.
Global temperature rise• All three major global surface temperature reconstructions show that Earth has warmed since 1880. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. Even though the 2000s witnessed a solar output decline resulting in an unusually deep solar least in 2007-2009, surface temperatures continue to increase.
Warming oceans• Ocean temperatures are rising. When heat enters the atmosphere of the Earth from the Sun, is stored in the ocean, land and atmosphere. The ocean, which covers 70% of the planet, stores about 90% of the Earths heat.
Contraction of ice sheets• The Greenland and Antarctic ice sheets have decreased in mass. Data from NASAs Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers of ice between 2002 and 2005.
Artic sea ice decline• Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.
Extreme events• The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.
Ocean acidification• Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent. This increase is the result of humans emitting more carbon dioxide into the atmosphere. The amount of carbon dioxide absorbed by the top cape of the oceans is increasing by about 2 billion tons per year.
Droughts• Drought and climate change should rethink the management of water resources in the Mediterranean areas.• Even a moderate rise in average temperatures translates into a much higher frequency of extreme events that cause enormous damage, as drought
Floods• The direct effect of climate change on the frequency and intensity of rainfall results in floods of great magnitude.• Climate warming has caused the increased intensity of floods in the northern hemisphere during the second half of the twentieth century.
IPCC prediction• The Intergovernmental Panel on Climate Change (IPCC) predicts that increases in global mean temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase.
Here is a picture of the global climate change recent impactsPhenomena Likelihood that trend ocurred in late 20th centuryCold days, cold nights and frost lessfrequent over land areas Very likelyMore frequent hot days and nights Very likelyHeat waves more frequent over mostland areas LikelyIncreased incidence of extreme Likelyhigh sea levelGlobal area affected by drought Likely in some regionshas increasedIncrease in intense tropical Likely in some regionscyclone activity in North Atlantic
Here is a picture of the global climate change future trendsPhenomena Likelihood of trendContraction of snow cover areas, increasedthaw in permafrost regions, decrease in Virtually certainsea ice extentIncreased frequency of hot extremes,heat waves and heavy precipitation Very likely to occurIncrease in tropical cyclone Likely to occurintensityPrecipitation increases in highlatitudes Very likely to occurPrecipitation decreases in subtropicalland regions Very likely to occurDecreased water resources in manysemi-arid areas, including western High confidenceU.S. and Mediterranean basin