Effect of Climate change

Introduction

Climate change 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 (i.e., more or fewer extreme weather

events). Climate change is caused by factors that

include oceanic processes (such as oceanic

circulation), 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.

Scientists actively work to understand past and

future climate by using observations and theoretical

models. Borehole temperature profiles, ice cores,

floral and faunal records, glacial and periglacial

processes, stable isotope and other sediment analyses,

and sea level records serve to provide a climate record

that spans the geologic past. More recent data are

provided by the instrumental record. Physically

based general circulation modelsare often used in

theoretical approaches to match past climate data, make

future projections, and link causes and effects in

climate change.

Terminology:

The most general definition of climate change is a

change in the statistical properties of the climate

system when considered over long periods of time,

regardless of cause. Accordingly, fluctuations over

periods shorter than a few decades, such as El Niño, do

not represent climate change.

The term sometimes is used to refer specifically to

climate change caused by human activity, as opposed to

changes in climate that may have resulted as part of

Earth's natural processes.  In this sense, especially in

the context of environmental policy, the termclimate

change has become synonymous with anthropogenic global

warming. Within scientific journals, global

warming refers to surface temperature increases

while climate change includes global warming and

everything else that increasing greenhouse gas levels

will affect.

Causes:

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.

Factors that can shape climate are called climate

forcings or "forcing mechanisms". These include

processes such as variations insolar radiation,

variations in the Earth's orbit, mountain-

building and continental drift, clouds and changes

in gas concentrations. There are a variety of climate

change feedbacks that can either amplify or diminish

the initial forcing. Some parts of the climate system,

such as the oceans and ice caps, respond slowly in

reaction to climate forcings, while others respond more

quickly.

Forcing mechanisms can be either "internal" or

"external". Internal forcing mechanisms are natural

processes within the climate system itself (e.g.,

the thermohaline circulation). External forcing

mechanisms can be either natural (e.g., changes in

solar output) or anthropogenic (e.g., increased

emissions of greenhouse gases).

Whether the initial forcing mechanism is internal

or external, the response of the climate system might

be fast (e.g., a sudden cooling due to

airborne volcanic ash reflecting sunlight), slow

(e.g. thermal expansion of warming ocean water), or a

combination (e.g., sudden loss of albedo in the arctic

ocean as sea ice melts, followed by more gradual

thermal expansion of the water). Therefore, the climate

system can respond abruptly, but the full response to

forcing mechanisms might not be fully developed for

centuries or even longer

Internal forcing mechanisms

Natural changes in the components of Earth's climate

system and their interactions are the cause of internal

climate variability, or "internal forcings." Scientists

generally define the five components of earth's climate

system to

include atmosphere, hydrosphere,cryosphere, lithosphere 

(restricted to the surface soils, rocks, and

sediments), and biosphere.

External forcing mechanisms

Variations in CO2, temperature and dust from

the Vostok ice core over the last 450,000 years

Orbital variations

Slight variations in Earth's orbit lead to changes

in the seasonal distribution of sunlight reaching the

Earth's surface and how it is distributed across the

globe. There is very little change to the area-averaged

annually averaged sunshine; but there can be strong

changes in the geographical and seasonal distribution.

The three types of orbital variations are variations in

Earth's eccentricity, changes in the tilt angle of

Earth's axis of rotation, and precession of Earth's

axis. Combined together, these produce Milankovitch

cycles which have a large impact on climate and are

notable for their correlation

to glacial and interglacial periods,[7]their correlation

with the advance and retreat of the Sahara, and for

their appearance in thestratigraphic record.

The IPCC notes that Milankovitch cycles drove the

ice age cycles; CO2 followed temperature change "with a

lag of some hundreds of years"; and that as a feedback

amplified temperature change. The depths of the ocean

have a lag time in changing temperature (thermal

inertiaon such scale). Upon seawater temperature

change, the solubility of CO2 in the oceans changed, as

well as other factors impacting air-sea CO2 exchange.

Variations in solar activity during the last

several centuries based on observations

ofsunspots and beryllium isotopes. The period of

extraordinarily few sunspots in the late 17th century

was the Maunder minimum.

Solar output

The Sun is the predominant source for energy input

to the Earth. Both long- and short-term variations in

solar intensity are known to affect global climate.

Three to four billion years ago the sun emitted

only 70% as much power as it does today. If the

atmospheric composition had been the same as today,

liquid water should not have existed on Earth. However,

there is evidence for the presence of water on the

early Earth, in the Hadean and Archean eons, leading to

what is known as the faint young Sun

paradox. Hypothesized solutions to this paradox include

a vastly different atmosphere, with much higher

concentrations of greenhouse gases than currently

exist.Over the following approximately 4 billion years,

the energy output of the sun increased and atmospheric

composition changed. The Great Oxygenation Event –

oxygenation of the atmosphere around 2.4 billion years

ago – was the most notable alteration. Over the next

five billion years the sun's ultimate death as it

becomes a red giant and then a white dwarf will have

large effects on climate, with the red giant phase

possibly ending any life on Earth that survives until

that time.

Human influences

In the context of climate variation, anthropogenic

factors are human activities which affect the climate.

The scientific consensus on climate change is "that

climate is changing and that these changes are in large

part caused by human activities," and it "is largely

irreversible."

Climate change in india:

India has reason to be concerned about the effects of

climate change. Across its geography, India shows a

wide range of climatic conditions - from the high

altitude Himalayas to the marine climates of the

coastline and islands; from the arid deserts of the

north-west to the tropical forests of the north-east.

Owing to this complex geography, the consequences of

changes in climate would vary greatly across the

different climatic zones of the country.

Much of the climate and a large proportion of the

economy depend on the South West Monsoon - the short

three-month period over which nearly all the rainfall

occurs over the subcontinent.

Any changes in the monsoon will further stress

water availability and distribution across the

subcontinent.

Regional climate model simulations for India indicate

that a 0.4 °C rise in annual air surface temperature

has already taken place. Predicted increases in maximum

and minimum temperatures and increased frequency and

intensity of floods and drought are likely to adversely

affect agriculture, ecosystems, coastal zones, health

and infrastructure.

Projections of rainfall vary from model to model,

but it is projected climate change will affect water

balance in various parts of the country, and alter the

quality of ground water.

Reduced water availability - owing to glacier

retreat and decreased rainfall will increase water

stress. These and other impacts become significant in

light of projected water demands from a growing

population: estimated to rise to 980 billion cubic

metres by 2050.

River basins of west-flowing Mahi, Pennar,

Sabarmati and Tapati are likely to experience constant

water scarcities, while the river basins of the

Cauvery, Ganga, Narmada and Krishna are likely to

experience seasonal or regular water-stressed

conditions.

Agriculture

Sixty-eight percent of agriculture in India is rain-

fed, and depends heavily on the quantity and

distribution of rainfall. Predicted effects include a

drop in wheat production if the effects of climate

change are ‘pessimistic’

Ecosystems

Regional climate model predictions indicate shifts in

forest boundary, changes in species assemblages, and 70

percent of forest vegetation likely to be less

optimally adapted to their existing locations. These

are long-term and irreversible impacts, for which long-

term adaptation strategies need to be developed.

Mangroves submergence and increased wetland salinity

are likely to occur with sea level rise, as also

bleaching of degraded

Coastal Areas

India’s coastline is densely populated - with an

average population density of 455 persons per km2 as

opposed to the national average is 324. Adverse effects

are likely to be worsening of existing coastal zone

problems such as erosion, flooding, and the submergence

and deterioration of coastal ecosystems.

A one-meter sea level rise could displace about 7.1

million people, and result in the loss of 5674 sq. km

of land, damage coastal infrastructure and result in

the Stalinization of fertile agricultural soils.

Health

Similar to other tropical countries, India is

predicted to have increased susceptibility to vector-

borne diseases such as malaria – projected to move to

higher latitudes and altitudes, covering ten percent

more area in 2080.

References

1.Amarasinghe et al. India’s water supply and demand

from 2025-2050: Business as Usual Scenario and

Issues. IWMI

2.India National Communications. 2004

3.MSN Encarta Dictionary. Flood. Retrieved on 2006-12-

28.Archived 2009-10-31.

4.Directive 2007/60/EC Chapter 1 Article2. eur-

lex.europa.eu. Retrieved on 2012-06-12.

5.Glossary of Meteorology (June 2000). Flood. Retrieved

on 2009-01-09.

6. http://www.southasianfloods.org

7.Stephen Bratkovich, Lisa Burban, et al., "Flooding

and its Effects on Trees", USDA Forest Service,

Northeastern Area State and Private Forestry, St.

Paul, MN, September 1993, webpage: Na.fs.fed.us-

flood-cover.

8. Henry Petroski (2006). Levees and Other Raised

Ground. 94. American Scientist. pp. 7–11.

9. See Jeffrey H. Jackson, Paris Under Water: How the City of

Light Survived the Great Flood of 1910 (New York: Palgrave

Macmillan, 2010).

10. United States Department of Commerce (June

2006)."Hurricane Katrina Service Assessment

Report" (PDF). Retrieved 2006-07-14.

11. Amanda Ripley. "Floods, Tornadoes, Hurricanes,

Wildfires, Earthquakes... Why We Don't

Prepare." Time. August 28, 2006.