causes and consequences of climate change pdf

Causes And Consequences Of Climate Change Pdf

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Climate change

Climate change includes both global warming driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change , since the midth century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires. These impacts have led the World Health Organization to call climate change the greatest threat to global health in the 21st century. Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali.

Storm intensification. Bangladesh after Cyclone Sidr is an example of catastrophic flooding from increased rainfall. Pest propagation. Mild winters allow more pine beetles to survive to kill large swaths of forest. Heat wave intensification. Events like the June European heat wave are becoming more common. Ecological collapse. Bleaching has damaged the Great Barrier Reef and threatens reefs worldwide. Arctic warming. Permafrost thaws undermine infrastructure and release methane , a greenhouse gas.

Habitat destruction. Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic. Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy.

Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US. Extreme weather. Drought and high temperatures worsened the bushfires in Australia. Many of these impacts are already felt at the current level of warming, which is about 1. Adaptation consists of adjusting to actual or expected climate, [16] such as through improved coastline protection , better disaster management , assisted colonization , and the development of more resistant crops.

Adaptation alone cannot avert the risk of "severe, widespread and irreversible" impacts. Under the Paris Agreement , nations collectively agreed to keep warming "well under 2. However, with pledges made under the Agreement, global warming would still reach about 2.

Before the s, when it was unclear whether warming by greenhouse gases would dominate aerosol-induced cooling, scientists often used the term inadvertent climate modification to refer to humankind's impact on the climate. In the s, the terms global warming and climate change were introduced, the former referring only to increased surface warming, while the latter describes the full effect of greenhouse gases on the climate.

Various scientists, politicians and media figures have adopted the terms climate crisis or climate emergency to talk about climate change, while using global heating instead of global warming.

Multiple independently produced instrumental datasets show that the climate system is warming, [30] with the — decade being 0. There was little net warming between the 18th century and the midth century.

Climate proxies , sources of climate information from natural archives such as trees and ice cores , show that natural variations offset the early effects of the Industrial Revolution. Evidence of warming from air temperature measurements are reinforced with a wide range of other observations. Patterns of warming are independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet; however, localized black carbon deposits on snow and ice do contribute to Arctic warming.

The Northern Hemisphere not only has much more land, but also more snow area and sea ice, because of how the land masses are arranged around the Arctic Ocean. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat.

The Southern Hemisphere already had little sea ice in summer before it started warming. The attribution of climate change is the effort to scientifically show which mechanisms are responsible for observed changes in Earth's climate. To determine the human contribution, known internal climate variability and natural external forcings need to be ruled out.

A key approach is to use computer modelling of the climate system to determine unique "fingerprints" for all potential causes. By comparing these fingerprints with observed patterns and evolution of climate change, and the observed history of the forcings, the causes of the changes can be determined.

The Earth absorbs sunlight , then radiates it as heat. Some of this infrared radiation is absorbed by greenhouse gases in the atmosphere, and is trapped on Earth instead of escaping into space. Furthermore, ozone is highly reactive and interacts with other greenhouse gases and aerosols.

Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels coal , oil , and natural gas , [62] has increased the amount of greenhouse gases in the atmosphere. These elevated levels of gases such as CO 2 , methane, tropospheric ozone , CFCs , and nitrous oxide drive up temperatures via radiative forcing. Despite the contribution of deforestation to greenhouse gas emissions, the Earth's land surface, particularly its forests, remain a significant carbon sink for CO 2.

Natural processes, such as carbon fixation in the soil and photosynthesis, more than offset the greenhouse gas contributions from deforestation. First, CO 2 dissolves in the surface water. Afterwards, the ocean's overturning circulation distributes it deep into the ocean's interior, where it accumulates over time as part of the carbon cycle.

Air pollution , in the form of aerosols , not only puts a large burden on human health, but also affects the climate on a large scale. In addition to their direct effects scattering and absorbing solar radiation , aerosols have indirect effects on the Earth's radiation budget.

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. While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming.

Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise. Humans change the Earth's surface mainly to create more agricultural land. In addition to affecting greenhouse gas concentrations, land-use changes affect global warming through a variety of other chemical and physical mechanisms. Changing the type of vegetation in a region affects the local temperature, by changing how much of the sunlight gets reflected back into space albedo , and how much heat is lost by evaporation.

For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also contribute to changing temperatures by affecting the release of aerosols and other chemical compounds that influence clouds, and by changing wind patterns. Physical climate models are unable to reproduce the rapid warming observed in recent decades when taking into account only variations in solar output and volcanic activity.

Explosive volcanic eruptions represent the largest natural forcing over the industrial era. When the eruption is sufficiently strong with sulfur dioxide reaching the stratosphere sunlight can be partially blocked for a couple of years, with a temperature signal lasting about twice as long.

In the industrial era, volcanic activity has had negligible impacts on global temperature trends. The response of the climate system to an initial forcing is modified by feedbacks : increased by self-reinforcing feedbacks and reduced by balancing feedbacks. As air gets warmer, it can hold more moisture. After an initial warming due to emissions of greenhouse gases, the atmosphere will hold more water. As water vapour is a potent greenhouse gas, this further heats the atmosphere.

If clouds become more high and thin, they act as an insulator, reflecting heat from below back downwards and warming the planet. Around half of human-caused CO 2 emissions have been absorbed by land plants and by the oceans. Climate change also increases droughts and heat waves that inhibit plant growth, which makes it uncertain that this carbon sink will persist in the future.

Future warming depends on the strengths of climate feedbacks and on emissions of greenhouse gases. The physical realism of models is tested by examining their ability to simulate contemporary or past climates. A subset of climate models add societal factors to a simple physical climate model.

With this information, these models can produce scenarios of how greenhouse gas emissions may vary in the future. This output is then used as input for physical climate models to generate climate change projections. The remaining carbon emissions budget is determined by modelling the carbon cycle and the climate sensitivity to greenhouse gases.

This amount corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget; for instance, it may be gigatonnes of CO 2 smaller due to methane release from permafrost and wetlands.

The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations. Global sea level is rising as a consequence of glacial melt , melt of the ice sheets in Greenland and Antarctica , and thermal expansion. Between and , the rise increased over time, averaging 3.

Climate change has led to decades of shrinking and thinning of the Arctic sea ice , making it vulnerable to atmospheric anomalies. An increase in dissolved CO 2 is causing oceans to acidify. The long-term effects of climate change include further ice melt, ocean warming, sea level rise, and ocean acidification.

On the timescale of centuries to millennia, the magnitude of climate change will be determined primarily by anthropogenic CO 2 emissions. Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes. The future balance of these opposing effects is unclear. The oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. The effects of climate change on humans , mostly due to warming and shifts in precipitation , have been detected worldwide.

Climate change

The potential future effects of global climate change include more frequent wildfires, longer periods of drought in some regions and an increase in the number, duration and intensity of tropical storms. Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner. Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves. Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities.

This study reviews the causes and effects of climate change on agriculture in Africa. The main interests are findings concerning the present and potential impacts.

Global warming

During the course of global warming, the energy balance and thus the temperature of the earth change, due to the increased concentration of greenhouse gases, which has a significant impact on humans and the environment. It is not scientifically possible to assign individual weather events to the current climate change, however, it can be statistically proven that global warming will increase the probability of extreme weather events. The indirect consequences of climate change, which directly affect us humans and our environment, include:. As the global climate is a highly interconnected system that is influenced by many different factors, the consequences usually result in positive or negative feedback effects. This refers to developments that are self-enhancing due to the occurrence of certain conditions.

Climate change includes both global warming driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change , since the midth century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale. Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires.

Global warming , the phenomenon of increasing average air temperatures near the surface of Earth over the past one to two centuries. Increases in greenhouse gases —i. Continued global warming is expected to impact everything from energy use to water availability to crop productivity throughout the world.

Jump to navigation. And yes, it's really happening. Over the past 50 years, the average global temperature has increased at the fastest rate in recorded history.

What is climate change? Is it the same as global warming? What are its main causes and consequences? Is it a lie? Find everything about climate change bel ow!

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