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INTRODUCTION

Global warming is the increase in the average temperatureofEarth's near-surface air and oceans

since the mid-20th century and its projected continuation. According to the 2007 Fourth

Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface

temperature increased 0.74 0.18 C (1.33 0.32 F) during the 20th century.[2][A]Most of the

observed temperature increase since the middle of the 20th century has been caused by

increasing concentrations of greenhouse gases, which result from human activity such as the

burning offossil fuel and deforestation.[3]Global dimming, a result of increasing concentrations

of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the

effects of warming induced by greenhouse gases.

Global warming harms all aspects of surface and underwater plant life. Plant life on earth is

altered by the elevated temperatures caused by global warming. So, how does global warming

affect plants? The answer is fairly simple. Higher temperatures and other climate changes

decrease the amount of rain and water plants receive, as well as elevating sea temperatures. This

can cause droughts and increases the risk for wild fires. The effect of global warming on plants is

caused by numerous factors.

Effect of global warming on plants

Plants can easily be affected by even a gradual increase in temperatures. Small shifts in climate

changes can harm a number of plant species. The plants of the mountain and Polar Regions are

especially at harm from global warming. As ice in these areas melt, the plants are endangered

because the ground becomes warmer than the usual temperature the plants are accustom to.

While some plants are able to adapt to the temperature changes, many are not able to do so.

Consequences for Plant Life

Over the past decade, global warming has increased the number of forest fires, affecting

numerous areas of the world. This is caused by record high temperatures and drought. In return,

these fires add to the greenhouse gases in the atmosphere.

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As temperatures in regions begin to rise, plants are beginning to grow in other areas they are

normally not found in. They are trying to adapt to the global warming changes. The growing

seasons for many plants are becoming altered as the temperatures change. As the temperature

changes, many plants and not capable of reproducing, causing many numbers of plant species to

become limited. The same thing occurs with underwater plant life. The higher water temperature

limits plants ability to thrive and reproduce.

Results of Global Warming

As a result of all the changes caused by global warming, the risk of wild fires increases. Larger

wild fires are being recorded, as well as more acres of land are burning. Droughts are beginning

to effect areas that normally do not see drought. This causes many plants to not receive the water

and nutrients they need to survive.

If global warming continues, many growing seasons can become permanently changed.

Precipitation patterns can begin to change, harming plant life. Heat waves can begin to last

longer causing many plants to die. Frost days can also begin to last longer, harming a wide

variety of plant species. Plants can begin to be threatened by a lager number of predatory insects.

If the effect of global warming on plants continues, the food supply for many humans and

animals can start to diminish from the harm done to plants. As the temperatures rise, more and

more plant species will begin to be threatened. This will cause a chain reaction for all aspects of

the planet.

Climate model projections summarized in the latest IPCC report indicate that the global surface

temperatureis likely to rise a further 1.1 to 6.4 C (2.0 to 11.5 F) during the 21st century. [2] The

uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse

gas concentrations and the use of differing estimates of future greenhouse gas emissions. An

increase in global temperature will cause sea levels to rise and will change the amount and

pattern ofprecipitation, probably including expansion of subtropical deserts.[4] Warming is

expected to bestrongest in the Arctic and would be associated with continuing retreat of glaciers,

permafrost and sea ice. Other likely effects include changes in the frequency and intensity of

extreme weather events, species extinctions, and changes in agricultural yields. Warming and

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related changes will vary from region to region around the globe, though the nature of these

regional variations is uncertain.[5]As a result of contemporary increases in atmospheric carbon

dioxide, the oceans have become more acidic; a result that is predicted to continue.[6][7]

1880-2009 global mean surface temperature difference relative to the 19611990 average

Comparison of ground based (blue) and satellite based (red: UAH; green: RSS) records of

temperature variations since 1979. Trends plotted since January 1982.

Mean surface temperature change for the period 2000 to 2009 relative to the average

temperatures from 1951 to 1980.[1]

The scientific consensusis that anthropogenic global warming is occurring.[8][9][10][B] Nevertheless,

politicalandpublic debate continues. TheKyoto Protocol is aimed at stabilizing greenhouse gas

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concentration to prevent a "dangerous anthropogenic interference".[11] As of November 2009, 187

states had signed and ratifiedthe protocol.[12]

GLOBAL WARMING

Temperature changes

Two millennia of mean surface temperatures according to different reconstructions, each

smoothed on a decadal scale, with the actual recorded temperatures overlaid in black.

Evidence for warming of the climate system includes observed increases in global average air

and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

[13][14][15][16][17] The most common measure of global warming is the trend in globally averaged

temperature near the Earth's surface. Expressed as a linear trend, this temperature rose by

0.74 0.18 C over the period 19062005. The rate of warming over the last half of that period

was almost double that for the period as a whole (0.13 0.03 C per decade, versus 0.07 C

0.02 C per decade). The urban heat island effect is estimated to account for about 0.002 C of

warming per decade since 1900.[18] Temperatures in the lowertroposphere have increased

between 0.13 and 0.22 C (0.22 and 0.4 F) per decade since 1979, according to satellite

temperature measurements. Temperature is believed to have been relatively stable over the one

or two thousand years before 1850, with regionally varying fluctuations such as the Medieval

Warm Periodand the Little Ice Age.[19]

External forcings

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External forcing refers to processes external to the climate system (though not necessarily

external to Earth) that influence climate. Climate responds to several types of external forcing,

such as radiative forcing due to changes in atmospheric composition (mainly greenhouse gas

concentrations), changes in solar luminosity, volcanic eruptions, and variations in Earth's orbit

around the Sun.[31]Attribution of recent climate change focuses on the first three types of forcing.

Orbital cycles vary slowly over tens of thousands of years and thus are too gradual to have

caused the temperature changes observed in the past century.

Greenhouse gases

Greenhouse effect schematic showing energy flows between space, the atmosphere, and earth's

surface. Energy exchanges are expressed in watts per square meter (W/m2).

Recent atmospheric carbon dioxide (CO2) increases. Monthly CO2 measurements display

seasonal oscillations in overall yearly uptrend; each year's maximum occurs during the Northern

Hemisphere's late spring, and declines during its growing season as plants remove some

atmospheric CO2.

Thegreenhouse effectis the process by which absorption and emission ofinfrared radiation by

gases in the atmosphere warm a planet's lower atmosphere and surface. It was proposed by

Joseph Fourierin 1824 and was first investigated quantitatively bySvante Arrhenius in 1896.[32]

The question in terms of global warming is how the strength of the presumed greenhouse effect

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changes when human activity increases the concentrations of greenhouse gases in the

atmosphere.

Naturally occurring greenhouse gases have a mean warming effect of about 33 C (59 F).[33][C]

The major greenhouse gases are water vapor, which causes about 3670 percent of the

greenhouse effect; carbon dioxide (CO2), which causes 926 percent; methane (CH4), which

causes 49 percent; and ozone (O3), which causes 37 percent.[34][35][36] Clouds also affect the

radiation balance, but they are composed of liquid water or ice and so have different effects on

radiation from water vapor.

Aerosols and soot

Ship tracksover the Atlantic Oceanon the east coast of the United States. The climatic impacts

from aerosol forcing could have a large effect on climate through the indirect effect.

Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's

surface, has partially counteracted global warming from 1960 to the present. [54] The main cause

of this dimming is aerosols produced by volcanoes andpollutants. These aerosols exert a cooling

effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel

combustionCO2 and aerosolshave largely offset one another in recent decades, so that net

warming has been due to the increase in non-CO2 greenhouse gases such as methane.[55]

Radiative forcing due to aerosols is temporally limited due to wet deposition which causes

aerosols to have an atmospheric lifetime of one week. Carbon dioxide has a lifetime of a century

or more, and as such, changes in aerosol concentrations will only delay climate changes due to

carbon dioxide.[56]

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In addition to their direct effect by scattering and absorbing solar radiation, aerosols have

indirect effects on the radiation budget.[57] Sulfate aerosols act as cloud condensation nuclei and

thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar

radiation more efficiently than clouds with fewer and larger droplets.[58] This effect also causes

droplets to be of more uniform size, which reduces growth of raindrops and makes the cloud

more reflective to incoming sunlight.[59] Indirect effects are most noticeable in marine stratiform

clouds, and have very little radiative effect on convective clouds. Aerosols, particularly their

indirect effects, represent the largest uncertainty in radiative forcing.[60]

Solar variation

Solar variation over thirty years.

Variations in solar output have been the cause of past climate changes.[64] The effect of changes

in solar forcing in recent decades is uncertain, but small, with some studies showing a slight

cooling effect,[65] while others studies suggest a slight warming effect.[31][66][67][68]

Greenhouse gases and solar forcing affect temperatures in different ways. While both increased

solar activity and increased greenhouse gases are expected to warm the troposphere, an increase

in solar activity should warm the stratosphere while an increase in greenhouse gases should cool

the stratosphere.[31] Observations show that temperatures in the stratosphere have been cooling

since 1979, when satellite measurements became available. Radiosonde(weather balloon) data

from the pre-satellite era show cooling since 1958, though there is greater uncertainty in the early

radiosonde record.[69]

A related hypothesis, proposed by Henrik Svensmark, is that magnetic activity of the sun deflects

cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect

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the climate.[70] Other research has found no relation between warming in recent decades and

cosmic rays.[71][72]The influence of cosmic rays on cloud cover is about a factor of 100 lower than

needed to explain the observed changes in clouds or to be a significant contributor to present-day

climate change.[73]

Feedback

Feedbackis a process in which changing one quantity changes a second quantity, and the change

in the second quantity in turn changes the first. Positive feedbackamplifies the change in the first

quantity while negative feedbackreduces it.

Climate models

Calculations of global warming prepared in or before 2001 from a range of climate models under

the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions and

regionally divided economic development.

The geographic distribution of surface warming during the 21st century calculated by the

HadCM3 climate model if a business as usual scenario is assumed for economic growth and

greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 C

(5.4 F).

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The main tools for projecting future climate changes are mathematical models based on physical

principles including fluid dynamics, thermodynamics and radiative transfer. Although they

attempt to include as many processes as possible, simplifications of the actual climate system are

inevitable because of the constraints of available computer power and limitations in knowledge

of the climate system. All modern climate models are in fact combinations of models for

different parts of the Earth. These include an atmospheric model for air movement, temperature,

clouds, and other atmospheric properties; an ocean model that predicts temperature, salt content,

and circulation of ocean waters; models for ice cover on land and sea; and a model of heat and

moisture transfer from soil and vegetation to the atmosphere. Some models also include

treatments of chemical and biological processes.[74] Warming due to increasing levels of

greenhouse gases is not an assumption of the models; rather, it is an end result from the

interaction of greenhouse gases with radiative transfer and other physical processes .[75]Although

much of the variation in model outcomes depends on the greenhouse gas emissions used as

inputs, the temperature effect of a specific greenhouse gas concentration (climate sensitivity)

varies depending on the model used. The representation of clouds is one of the main sources of

uncertainty in present-generation models.[76]

Attributed and expected effects

Global warming may be detected in natural, ecological or social systems as a change having

statistical significance.[84] Attribution of these changes e.g., to natural or human activities, is the

next step following detection.[85]

Natural systems

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Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s

measurements began that allow the monitoring of glacial mass balance, reported to the WGMS

and theNSIDC.

Global warming has been detected in a number of systems. Some of these changes, e.g., based on

the instrumental temperature record, have been described in the section on temperature changes.

Rising sea levels and observed decreases in snow and ice extent are consistent with warming. [17]

Most of the increase in global average temperature since the mid-20th century is, with high

probability,[D]atttributable to human-induced changes in greenhouse gas concentrations.[86]

Even with current policies to reduce emissions, global emissions are still expected to continue to

grow over the coming decades.[87] Over the course of the 21st century, increases in emissions at

or above their current rate would very likely induce changes in the climate system larger than

those observed in the 20th century.

Ecological systems

In terrestrialecosystems, the earlier timing ofspring events, and poleward and upward shifts in

plant and animal ranges, have been linked with high confidence to recent warming.[17] Future

climate change is expected to particularly affect certain ecosystems, including tundra,

mangroves, and coral reefs.[87] It is expected that most ecosystems will be affected by higher

atmospheric CO2 levels, combined with higher global temperatures.[89] Overall, it is expected that

climate change will result in the extinction of many species and reduced diversity of ecosystems.

[90]

Social systems

There is some evidence of regional climate change affecting systems related to human activities,

including agricultural and forestry management activities at higher latitudes in the Northern

Hemisphere.[17] Future climate change is expected to particularly affect some sectors and systems

related to human activities.[87] Low-lying coastal systems are vulnerable to sea level rise and

storm surge. Humanhealth will be at increased risk in populations with limited capacity to adapt

to climate change. It is expected that some regions will be particularly affected by climate

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change, including theArctic,Africa, small islands, and Asianand African megadeltas. In some

areas the effects on agriculture, industry and health could be mixed, or even beneficial in certain

respects, but overall it is expected that these benefits will be outweighed by negative effects. [91]

Responses to global warming

Carbon capture and storage (CCS) is an approach to mitigation. Emissions may be sequestered

from fossil fuel power plants, or removed during processing in hydrogen production. When used

on plants, it is known asbio-energy with carbon capture and storage.

Mitigation

Reducing the amount of future climate change is called mitigation of climate change. The IPCC

defines mitigation as activities that reduce greenhouse gas (GHG) emissions, or enhance the

capacity of carbon sinks to absorb GHGs from the atmosphere.[92] Many countries, both

developing and developed, are aiming to use cleaner, less polluting, technologies.[45]:192 Use of

these technologies aids mitigation and could result in substantial reductions in CO2 emissions.

Policies include targets for emissions reductions, increased use of renewable energy, and

increased energy efficiency. Studies indicate substantial potential for future reductions in

emissions.[93] Since even in the most optimistic scenario, fossil fuels are going to be used for

years to come, mitigation may also involve carbon capture and storage, a process that traps CO2

produced by factories and gasorcoalpower stations and then stores it, usually underground.[94]

Adaptation

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Other policy responses include adaptationto climate change. Adaptation to climate change may

be planned, e.g., by local or national government, or spontaneous, i.e., done privately without

government intervention.[95] The ability to adapt is closely linked to social and economic

development.[93] Even societies with high capacities to adapt are still vulnerable to climate

change. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs

of future adaptation are not fully understood.

Another policy response is engineering of the climate (geoengineering). This policy response is

sometimes grouped together with mitigation.[96] Geoengineering is largely unproven, and reliable

cost estimates for it have not yet been published.[97]

UNFCCC

Most countries are Parties to the United Nations Framework Convention on Climate Change

(UNFCCC).[98] The ultimate objective of the Convention is to prevent "dangerous" human

interference of the climate system.[99] As is stated in the Convention, this requires that GHGs are

stabilized in the atmosphere at a level where ecosystems can adapt naturally to climate change,

food production is not threatened, and economic development can proceed in a sustainable

fashion.

Views on global warming

Per capita greenhouse gas emissionsin 2000, including land-

use change.

Total greenhouse gas emissions in 2000, including land-use change.

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There are different views over what the appropriate policy response to climate change should be.

[106][107] These competing views weigh the benefits of limiting emissions of greenhouse gases

against the costs. In general, it seems likely that climate change will impose greater damages and

risks in poorer regions.[108]

Politics

Developing and developed countries have made different arguments over who should bear the

burden of costs for cutting emissions. Developing countries often concentrate on per capita

emissions, that is, the total emissions of a country divided by its population.[109] Per capita

emissions in the industrialized countries are typically as much as ten times the average in

developing countries.[110]

Public opinion

In 20072008 Gallup Polls surveyed 127 countries. Over a third of the world's population was

unaware of global warming, with people in developing countries less aware than those in

developed, and those in Africa the least aware. Of those aware, Latin America leads in belief that

temperature changes are a result of human activities while Africa, parts of Asia and the Middle

East, and a few countries from the Former Soviet Union lead in the opposite belief.[116]

Other views

Most scientists accept that humans are contributing to observed climate change.[44][119] National

science academies have called on world leaders for policies to cut global emissions.[120] However,

some scientists and non-scientists question aspects of climate-change science.[121][122]

Etymology

The term global warmingwas probably first used in its modern sense on 8 August 1975 in a

science paper by Wally Broecker in the journal Science called "Are we on the brink of a

pronounced global warming?".[133][134][135] Broecker's choice of words was new and represented a

significant recognition that the climate was warming; previously the phrasing used by scientists

was "inadvertent climate modification," because while it was recognized humans could change

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the climate, no one was sure which direction it was going. [136] The National Academy of Sciences

first usedglobal warmingin a 1979 paper called the Charney Report, it said: "if carbon dioxide

continues to increase, [we find] no reason to doubt that climate changes will result and no reason

to believe that these changes will be negligible." [137] The report made a distinction between

referring to surface temperature changes as global warming, while referring to other changes

caused by increased CO2 as climate change.[136] This distinction is still often used in science

reports, with global warming meaning surface temperatures, and climate change meaning other

changes (increased storms, etc..)[136]

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EFFECT ON PLANTS

You may think that global warming is caused by carbon dioxide emissions from burning fossil

fuels, industry and the like, but did you know that methane is a potent greenhouse gas- second to

carbon dioxide?

The world's annual methane production at present is around 600 million tonnes, tripling the

concentration of methane in the atmosphere over the last 150 years. Researchers have recently

discovered that plants release 10 to 30 percent of the world's methane and the recent increase in

methane concentrations in the atmosphere results mainly from human activities and agricultural

activities, which normal global conservationist would consider totally harmless.

In the last few years, much research has been focused on the biosphere and how gases released

from the biosphere exchange with the atmosphere and influence climate. What has recently been

found from this research goes against what has been previously assumed- organic gases released

by plants contain methane. Methane is best known as an imported energy source but only part of

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the methane uptake in the atmosphere, is due to industrial activities connected with energy

production and use. This would therefore suggest that the main reason for this high increase in

methane concentration is from 'biogenic' sources- mainly rice cultivation and large areas of plant

coverage such as the Amazon.

If this discovery wasn't surprising enough, it was also discovered that the formation of the

methane is not hindered by the presence of oxygen. It was previously assumed that biogenic

methane is formed anaerobically via micro-organisms. In this way, acetate or hydrogen and

carbon dioxide are turned to methane- this takes place during the anaerobic decomposition of

organic material. Therefore the methane was thought to come from dead plant material.

However, the research concluded that plants themselves produce methane in a normal

oxygen-rich environment. It turned out living plants let out 100-1000 times more

methane than dead material. This increased further when the plants were exposed to

sunlight. It is still unclear what processes are involved in the production of the methane

but scientists believe the reaction mechanism cannot be explained with current plant

knowledge.

It seems odd that such a basic discovery should come only now- 20 years after the

methane cycle was investigated. Its obvious why really- all sources of information said

that biogenic methane could only be produced anaerobically so there was no reason why

anyone should look any further!

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With the total amounts of methane produced a year approaching 240 million tonnes, the

percentage of methane produced by plants is nearing 30% , two thirds of which comes

from tropical areas where the most amount of biomass is located (this is immediate

evidence for why there appear to be high methane concentrations over rainforests as

shown by satellite imaging). These figures are set to rise if current rates of intensification

in farming increase as with the global population on the rise and the need for more

farming, these new findings may have important implications for how policymakers

address climate control.

But is there anyway of controlling these emissions?

There is no way in which we can catch the methane released to burn so could we just

chop down all the trees in the rainforest? This would mean more paper and would act as a

biogenic fuel source. But at the heart of this is a vicious cycle- rainforests act as a major

carbon dioxide sink and oxygen source as well as major areas of biodiversity and

habitats. Seeing as carbon dioxide is even worse for the atmosphere in global warming

terms, this wouldn't be a wise decision.

There is also the great degree of production of methane from cattle ranching. These cows

produce thousands of tonnes a year of methane- all of which is released into the

environment. Reducing the amount of livestock and degree of agriculture is no easy task

with the demand for food as high as it is, and set to rise. There may be no answer to this

rather new but surprisingly serious problem but it is definitely something for climate

control agencies to take note of.

So what is next to come? A related question is what role the biosphere has played in

methane production over the history of the Earth and what kind of influence the rise in

global temperatures and carbon dioxide emissions have on the production of methane

from plants. The answer to these questions will provide better understandings in the

feedback mechanisms between climate change and greenhouse gas production.

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his warming is in addition to carbon dioxide's better-known effect as a heat-trapping greenhouse

gas. For scientists trying to predict global climate change in the coming century, the study

underscores the importance of including plants in their climate models.

"Plants have a very complex and diverse influence on the climate system," says study co-author

Ken Caldeira of Carnegie's Department of Global Ecology. "Plants take carbon dioxide out of the

atmosphere, but they also have other effects, such as changing the amount of evaporation from

the land surface. It's impossible to make good climate predictions without taking all of these

factors into account."

Plants give off water through tiny pores in their leaves, a process called evapotranspiration that

cools the plant, just as perspiration cools our bodies. On a hot day, a tree can release tens of

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gallons of water into the air, acting as a natural air conditioner for its surroundings. The plants

absorb carbon dioxide for photosynthesis through the same pores (called stomata). But when

carbon dioxide levels are high, the leaf pores shrink. This causes less water to be released,

diminishing the tree's cooling power.

The warming effects of carbon dioxide as a greenhouse gas have been known for a long time,

says Caldeira. But he and fellow Carnegie scientist Long Cao were concerned that it is not as

widely recognized that carbon dioxide also warms our planet by its direct effects on plants.

Previous work by Carnegie's Chris Field and Joe Berry had indicated that the effects were

important. "There is no longer any doubt that carbon dioxide decreases evaporative cooling by

plants and that this decreased cooling adds to global warming," says Cao. "This effect would

cause significant warming even if carbon dioxide were not a greenhouse gas."

In their model, the researchers doubled the concentration of atmospheric carbon dioxide and

recorded the magnitude and geographic pattern of warming from different factors. They found

that, averaged over the entire globe, the evapotranspiration effects of plants account for 16% of

warming of the land surface, with greenhouse effects accounting for the rest. But in some

regions, such as parts of North America and eastern Asia, it can be more than 25% of the total

warming. "If we think of a doubling of carbon dioxide as causing about four degrees of warming,

in many places three of those degrees are coming from the effect of carbon dioxide in the

atmosphere, and one is coming from the direct effect of carbon dioxide on plants."

The researchers also found that their model predicted that high carbon dioxide will increase the

runoff from the land surface in most areas, because more water from precipitation bypasses the

plant cooling system and flows directly to rivers and streams. Earlier models based on

greenhouse effects of carbon dioxide had also predicted higher runoff, but the new research

predicts that changes in evapotranspiration due to high carbon dioxide could have an even

stronger impact on water resources than those models predict.

"These results really show that how plants respond to carbon dioxide is very important for

making good climate predictions," says Caldeira. "So if we want to improve climate predictions,

we need to improve the representation of land plants in the climate models. More broadly, it

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shows that the kind of vegetation that's on the surface of our planet and what that vegetation is

doing is very important in determining our climate. We need to take great care in considering

what kind of changes we make to forests and other ecosystems, because they are likely to have

important climate consequences."

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Documents

Effect of Global Warming on Plant = 13.11