Global dimming

GLOBAL DIMMINGPRESENTATION BY: SIBTAIN ALI 11-env-94

Another human-made, environmental threat, deserves attention and concern, an important but little-known environmental issue, impactful on Earths hydrological and biological systems1Points to be discussedIntroduction to global dimmingImpacts of global dimmingRemedial measures and preventionsubstantial and growing impact on the living Earth2

What is global dimming?Global dimmingis the gradual reduction in the amount of global direct irradiance at the Earth's surface.

Gradual reduction in the amount of solar radiation causing a cooling effect.

Decline of sunlight reaching the Earth surface.

This reduction of heat reaching the earth is known as Global Dimming3Global Dimming(contd)Systematic measurements initiated in 1950s revealed that the average amount of sunlight has markedly decreasedDubbed as GLOBAL DIMMING by an English scientist Gerry Stanhill in 2001.Measurements, concludes that the reduction has globally averagedper year, equivalent to areductionof 2.7- 4% per decade.Their effects are complex and vary in time, location, and altitudethermopile pyranometers: use to measure solar radiation.This amount of reduction might seem small but the consequences may not belarge impact on Earths biospheres4Pollutants causing global dimmingBurning of fossil fuels and Biomass produce pollutants i.e.Sox's ,smoke, soot, ash and other pollutants.

Due to human activities, pollution is shielding the oceans from the full power of the Sun,naerosolsolid or liquidparticlessuspended in air or other gaseous environment.Aerosolsvary in size and composition5Sulphate AerosolsFossil fuels, factories ,volcanoic ash ,burning coal, decomposition of sulphur containig gases i.e carbonyl sulfide

Contrails causing heat reflectionDuring the aftermath of the September 11, 2001, all commercial flights were grounded for the next three days and it was found that the temperature rose by some 1 degree centigrade in that period of 3 days.

(the vapor from planes flying high in the sky) were seen as another significant cause of heat reflection.

7Phenomenon of global dimmingPollutants and aerosol particles enter the atmosphere and causing the formation of brown and polluted clouds.Water dropletsare seeded by air-borne particles, Polluted air results in clouds with larger number of droplets than unpolluted clouds.

released a huge quantity ofaerosol particlesthat reflect incoming sunlight right around the planet's northern hemisphere. Consisting of a mixture of exhaust fumes, smoke and dust it reduces global warming by reflecting sunlight back into space and shields us from some of the sun's radiation.8Phenomenon of global dimming(Cont.)Makes those clouds more reflective. More of the suns heat and energy is therefore reflected back into spaceAerosols and other particulates absorbsolar energyand reflect sunlight back into space.

Larger deeper longer lasting cloudsthese clouds cool the Earth during the day with their shadows but trap heat like a blanket at night. Pollution can cause clouds from late afternoon thunderstorms to last long into the night rather than dissipate, causing warmer nights.9

Impacts Of Global Dimming

Global dimming has tragic and devastating effects on the earths environment and living beings. The pollutants causing global dimming also leads to acid rain, smog and respiratory diseases in humans.It is impactful on Earths hydrological and biological systems.

adisturbanceis a temporary change in average environmental conditions that causes a pronounced change in anecosystem.11CHANGE IN RAINFALL PATTERNScientists believe that the reflection of heat have interfered with the hydrologic cycle which have made waters in the northern hemisphere cooler. As a result, reducing evaporation and less rain has formed crucial rainfall has failed to arrive over the Sahel inNorthern Africa.

Researchers have long thought that smaller droplets start a chain reaction that leads to bigger, longer-lasting clouds: Instead of raining down, the lighter droplets carry their water higher, where they freeze. The freezing squeezes out the heat the droplets carry with them and causes the thunder cloud to become draftier.12Massive famines and droughtsseverityBetween 1970sand 1980s, massive famines werecausedby failed rains.Reduction in the amount of rain reaching certain parts of the globe, resulting in drought and famine situations. This has tragic consequences like miserable lives and deaths due to starvation.

Dry spell, a prolonged period of abnormally low rainfall, leading to a shortage of wate13

Billions Are Likely To Be Affected In Asia

Scientists said that the impact of global dimming might not be in the millions, but billions. The Asian monsoons bring rainfall to half the worlds population. If this air pollution and global dimming has a detrimental impact on the Asian monsoons some 3 billion people could be affected.

Clouds become less trnaslucent or their ability to reflect the light increasesharmful,damaging and injurious effectsasia comprises of the 60 percent of world population.14Global Dimming Hiding The True Power Of Global Warming

The positive aspect of global dimming is that it covers the drastic effects of global warming.Global dimming has led to an underestimation of the power of global warming.Both of them can prove fatal for our environment and need to be solved togetherIt is also difficult to place the effect of the two, and find a balance point that will bebeneficialfor human and its environment.In order to cater the damaging effect of both the issues.15Affects photosynthesis in plantsGlobal dimming is also believed to cause heat waves and runaway fires. Also, decrease in sunlight or solar radiation will negatively impact process of photosynthesis in plants. Due to inadequate sunlight and improper solar radiation, the process of solar radiation will be adversely affected.16Climate change and agriculture Reduction of global temperature can affect agriculture :The potential forsoils to support agriculture anddistribution of land use will be influenced bychanges in soil water balance.Influence the productivity of vegetable and food production.Fieldcrops will be particularly affected by temperature changes.

HEALTH PROBLEMSThe pollutants that lead to global dimming also lead to various human and environmental problems, such as smog, respiratory problems, and acid rain.The impacts of global dimming itself, however, can be devastating.Particulate matterreleased during the burning of fossil fuels demonstrates serious health risks to humans, causing respiratory conditions, as well asenvironmental problemsdue to the formation of smog and acid rain.Fine particles can also penetrate indoors. Many scientific studies have identified a relationship between elevated levels of fine particles and increased illness and premature death from heart and lung disorders, such as asthma and bronchitis.18

REMEDIAL MEASURESReduce the emission of soot, ash, sulphur, particulate matter and other toxic particles entering into the atmosphere .

Reducing the emmissnons and ultimately avoiding the formation of polluted clouds20How can we reduce these emissions?Control devices at industries stacks.Create set of laws and ensure their implementation.Limit the use of aerosol spraysGas emitting from factories can be controlled to acceptable levels.

Industrial scrubbers substantial env polices must be createdbeyond a tolerable limit must be charged, Ultimately reduces global dimming21Balance both Global warming and Global dimming can be kept in control.

Spread awareness about global dimming in every part of world.

It is essential to maintain a balance b/w cooling and warming particles.Education on this topic is important because few people even know that global dimming exists and that it is a hazardous environmental issue. By spreading awareness, more people can take action and prevent even harsh effects of global warming.22Optimal use of Green Technology displacing fossil fuels and reducing by products i.e sulphate aerosols etcThese include:Photovoltaic (PV) solar powerWind energy HydroelectricityGeothermal energy Biomass energy

Green technology definitionThere are many sources of clean energy23Protect our natural resources such as forest, oceans and snow capped mountains.

Trees help to trap and hold particle pollutants (dust, ash, pollen and smoke) that can damage human lungs. They absorb CO2and other dangerous gasses and, in turn, refill the atmosphere with oxygen. Trees remove gaseous pollutants by absorbing them through the pores in the leaf surface. Particulates are trapped and filtered by leaves, stems and twigs, and washed to the ground by rainfall.

24According to the U.S. EPA saving energy can reduce emissions. Because most energy sources require burning fossil fuels, the less energy you use, the greener you are.

THINGS YOU DO AT HOMEUse compact fluorescent bulbs Reduce the usage of refrigerants and air-conditionersuse microwave instead of ovensKeep the air filters clean from the furnace Try walking, biking and use public transportation.

Instead of standard tubelights.

26Buy energy-efficient appliances with the "Energy Star" labelCharge batteries rather than throw them away.Avoid using plastic bags

These will require less energy to do job, meaning lower bills and less fossil fuels being burned.4. Use reuseable bags, boxes, or just carry your items27HISTORIC EVENTS RELATED TO GLOBAL DIMMINGBY:m. USMAN SALEEMHISTORY:An ancient concept.21st Century Research related to global dimming.Air pollution main cause.Extent differs regionally (1961-90).Dropping the planets temperature by more than a degree Celsius (James Hansen).

1. LAKI ERUPTION COOLS EUROPE:1783-------Benjamin Franklin took a step forward.Studied Volcanic eruption in Laki .Devastating impact on Icelandic population.During peak episodes of the event, large portions of Iceland were covered by fine volcanic ash and haze (gases and aerosols).Caused a drop in global temperatures, as sulfur dioxide was ejected into the Northern Hemisphere. Caused crop failures in Europe and, Ultimately caused famine.

2. Dinosaurs Extinction TheoryEarly 1980sGiant Asteroid hit the earth and debris were sent into the atmosphere (Walter and Luis Alvarez,1980)Cooled the planet and killed off the dinosaurs.Volcanic eruptions clouded the skies (another leading theory).But, the basic mechanism of global cooling was the same.Aroused public awareness about climatic changes.Encouraged scientists to explore global dimming.

313. Ice Cores Reveal Past Trends 1970s 1980sMassive volcanic eruptions of dust and sulfuric acid had triggered climate cooling (GRIP).Sulfuric acid and other small particle sulfates persist in the stratosphere for years.Sulfate aerosols (natural/anthropogenic) ------ main culprits in climate cooling

ice cores contain an abundance of information aboutclimate. Inclusions in the snow of each year remain in the ice, such as wind-blowndust,ash, bubbles of atmospheric gas and radioactive substances. The variety of climaticproxiesis greater than in any other natural recorder of climate, such astree ringsorsediment layers. These include (proxies for) temperature, ocean volume, precipitation, chemistry and gas composition of the lower atmosphere, volcanic eruptions,solar variability,sea-surface productivity, desert extent and forest fires.324. Dimming recognized worldwide 1980s:22% dimming observed in Israel between 1950 to 1980 (Gerry Stanhill).It hardly made a splash in scientific community.But others also determined reduction in sunlight.9 % in Antarctica, 10 % in areas of the U.S., 16 % in parts of Great Britain, and almost 30 % in Russia.He coined the term GLOBAL DIMMING.Human activities and pollution the main cause.

5. Indian Ocean Study 1990s (project indoex)$25 million multinational study spanning four years.led by Veerabhadran Ramanathanthe sunlight reaching the ocean in the northern regions cut down by more than 10%.Cause two miles thick pollutant layer.Toxic mix of soot, sulfates, and other pollutants directly blocked sunlightAlso spawn clouds that reflected the sun's energy back to space.

This 2001 satellite image captures the toxic aerosol haze blanketing northern India and Bangladesh, south of the Himalayan Mountains.

34REFERENCEShttp://www.planetextinction.com/planet_extinction_global_dimming.htmhttp://prezi.com/oadh3917u8jj/global-dimming/http://www.theguardian.com/environment/2013/sep/30/owen-paterson-minister-climate-change-advantageshttp://www.sciencedirect.com/science/article/pii/S0168192300002410http://www.climatechangesask.com/html/learn_more/Solutions/GeoEngineering/Solar_Radiation_Management_/Global_Dimming/index.cfmhttp://www.geoengineeringwatch.org/global-dimming-2