If nothing is done about climate change and we keep on, among others, burning fossil fuels and chopping down our forests at current rates, potentially devastating impacts will result. It is estimated that South Africa’s coastal regions will warm by 1-2oC by 2050 and 3-4oC by 2100, whilst the country’s interior regions will warm by 3-4oC by 2050 and 6-7oC by 2100.
Significant changes in weather are predicted. Rainfall patterns, coupled with increased evaporation, are associated with changes in water availability. The western side of the country is likely to experience significant reductions in the flow of streams in the region
There will be an increase in the frequency and severity of extreme weather events. Damage costs due to extreme weather-related events (flooding, fire, storms and drought) have already been conservatively estimated at being roughly 1 billion rand per year between 2000 and 2009.
Because of our already poor health profile, South Africans are specifically vulnerable to new or exacerbated health threats resulting from climate change. For example, some effects of climate change may already be occurring, such as due to rainfall (drought and flood) and temperature extremes and Cholera outbreaks have been associated with extreme weather events, especially in poor, high density settlements
Small scale and homestead farmers in dry lands are most vulnerable to climate change and although intensive irrigated agriculture is better off than these farmers, irrigated lands remain vulnerable to reductions in available water. In addition, some predictions suggest that maize production in summer rainfall areas and fruit and cereal production in winter rainfall areas may be badly affected.
Our biodiversity will be severely impacted, especially the grasslands, fynbos and succulent karoo, where significant extinctions are predicted. Furthermore, alien invasive plant species are likely to spread more and have an ever-increasing negative impact on water resources.
When we hear the word climate change we often think it’s something that international organisations or governments need to deal with, and yes they must but YOU can also make changes to your lifestyle which can make a difference, even if it’s small, to prevent the worst of climate change. Here are a few ideas:
Waste
Waste is the result of our lifestyle. The hierarchy of waste minimisation options, starting with the most important:
Energy
Water
Others
City of Cape Town, May 2011, Smart Living Handbook: Making sustainable living a reality in Cape Town homes: Fourth Edition (available free for download).
You can help combat climate change locally by making simple changes to your daily routine. Transport accounts for 27% of Cape Town’s carbon emissions, so consider walking, cycling, carpooling or using public transport. Install a solar water heater. This will not only cut down your carbon emissions, but will save money in the long-term. Reduce, or better still eliminate the amount of waste you produce. And recycle the waste that you do create. Use energy efficient lighting in your home, and turn the lights off when they are not in use. Use heating and air conditioning only when necessary.
We would love for you to become involved in the Climate Smart Campaign! To keep up-to-date with the latest news and happenings of Climate Smart, follow us on Facebook at facebook.com/
We will also be regularly updating our blog to ensure you are up to speed with the latest info of what’s happening in Cape Town and internationally with regard to climate change. Feel free to comment on these – your feedback is valued!
We want everyone in Cape Town to “take action” so we invite you to write your own “take action” slogan and send it to us or post it on our Facebook page.
If you’ve found any of the tips we give useful, and you’ve made a change to your life and been amazed at the impact that one small change has made please let us know! Post it on our Facebook wall!
Spread the love: if you’ve been inspired and feel passionate about one of the causes that we are promoting, then get in contact directly with the organisation or team in that particular field.
Most modern, urban activities contribute to our individual carbon footprints. Every choice we make from switching on our lights, driving a car, washing our clothes, flying increases our carbon footprint and depletes the natural resources we rely on whilst affecting climate stability. Each person living day to day on earth has a carbon footprint, producing carbon emissions directly or indirectly, which have a combined negative long term effect on the environment. Yet each of us can make a difference. Every kilowatt-hour (kWh) of electricity we save through our daily choices, we prevent 1 kilogram carbon dioxide (CO2) from polluting our atmosphere. But before we can make changes to our behaviour, we need to know the negative impacts of our habits.
Here are some carbon calculator links below which will help you acquire the knowledge to make the necessary changes:
Project 90×2030 calculator – a comprehensive calculator intended to give a high level of accuracy (requires some detail regarding your mode of travel, waste management, energy & water consumption)
Food & Trees For Africa Carbon Calculator – using Global Greenhouse Gas Reporting Protocols
CO2balance calculator – carbon dioxide emission calculators
BP calculator – non-flash carbon footprint calculator
Forum for Economics & Environment calculator – CO2 calculator
It is important to foster and preserve biodiversity in our homes and urban environments. There are many ways to do this, and cultivating an indigenous garden is one fun, active way to make a difference right where you live:
Indigenous Gardening:
It is important for Capetonians to plant indigenous and endemic species (e.g., fynbos and strandveld). Cape Town’s soil, rain patterns and temperature are perfectly suited to these plants. Fynbos requires acidic and sandy soils, which require very little preparation. Trees, on the other hand, require nutrient rich soils and larger spaces, thus tree planting is well suited for urban greening projects. For the first two years of a plant’s growth it is important to water well.
Planting an indigenous garden will help stabilise your soils, provide shade, bring animals into your life and prevent dust. Below are a few species perfectly suited for Cape Flats Gardens.
Shrubs
Herbs and ground covers
Easily propagated plants (simply cut a side branch and stick it in damp ground)
If space is a problem, container gardening is a perfect option for indigenous planting. To be an eco-conscious gardener it is also necessary to reduce lawn space.
That’s great! Here are some other high-quality websites which can help you learn more:
Although there is always a degree of uncertainty, there are projected changes which have been given with a reasonable degree of certainty. These projections are available as a result of climate modelling and forecasting techniques which start off at a large scale and are downscaled to fit each smaller region, thereby enabling us to make projections on what the future climate will look like. For the Western Cape the following changes are projected: It is expected that temperatures will increase, and there will be a general drying for the Western Cape but the intensity of rainfall events is expected to increase. There are also projected changes in wind with the suggestion being that there will be an increase in wind speeds.
Whilst the projections can give us a rough idea of what to expect the downscaling of these projections has some limitations. There are also challenges of the local topography of Cape Town which can affect climatic conditions to potentially deviate from the projections. What Cape Town needs to do is prepare in such a way that we are resilient and can adapt to the changes that come our way, whether they are very close to what the projections say, of if in fact they differ.
There is always some degree of uncertainty with regard to projections and the changes in the state of the climate that can be expected. Although there may never be complete certainty there are very useful models and projections given by reputable sources which provide information on the general trend which can be expected. These projections and trend can and must be taken into account by both strategic decision makers and all citizens in order to affect changes that result in our City becoming one which is contributing less to the problem of climate change, and one which is resilient and ready to adapt to a future which is indeed uncertain.
Although the effects of climate change will be wide spread, with all industry’s, peoples groups and organisations being affected to some degree, which may vary drastically, these are 5 of the most pertinent challenges that will arise as a result of climate change :
Firstly the risk of flooding throughout the city will increase as rain is likely to fall in heavy showers over shorter lengths of times. This will increase the vulnerability of those living in informal settlements throughout the City, as well as place heavy strain on disaster management and emergency capacities during the winter months. This will also put pressure on systems controlling water such as the storm-water system
Secondly the management of coastal areas will prove challenging as the coast line in Cape Town is extremely long and will be at the coal face with regard to storm surges and increased swell, which are expected as weather patterns change.
Thirdly, the city’s transport networks will be significantly stressed in instances of extreme weather events like flooding. This will create numerous challenges, one which is of particular importance is the challenge of food security, as the large majority of the city’s food supply is brought into the city from surrounding areas.
Fourthly, the hotter, drier climatic conditions will make it difficult for the globally significant and economically valuable biodiversity to survive as we know it, which could threaten the city’s resilience – its ability to cope with natural disasters. Ecosystem services are often undervalued and poorly conserved, and there is a strong argument for building up ecosystem services as a means to adapting to climate change.
Finally, all these challenges are set in a development context, where poverty, limited access to services and poor provision of housing will only further exacerbate challenges associated with expected extreme weather events.
The South African government accepted the UNFCCC in 1997 and the Kyoto Protocol in 2002.
The need for a national climate change policy for South Africa was identified as an urgent requirement upon UNFCCC. Therefore, a process to develop such a policy was created with the support of the National Committee for Climate Change (NCCC), a nonstatutory stakeholder body set up in 1994 to advise the Minister on climate change issues and chaired by the Department of Environmental Affairs and Tourism (DEAT).
Department of Environmental Affairs and Tourism has developed a national climate change response strategy. The Department of Minerals and Energy has developed a white paper on renewable energy and clean energy development, together with an energy efficiency programme, to support change towards a less carbon intensive energy economy.
The Government’s chief objectives in combatting climate change include:
South Africa’s position is to view climate change response as an opportunity for achieving the national priorities, which include the creation of employment, the alleviation of poverty and the provision of housing, which implies a commitment to the process of sustainable development and advancement.
Source: Department of Environmental Affairs and Tourism, September 2004, A National Climate Change Response Strategy for South Africa (pdf)
The City’s Energy and Climate Change Strategy of 2006 sets out the vision, objectives, targets, measures and projects for all of its energy activities. It is based on the State of Energy Report, which maps out Cape Town’s energy profile, and issues such as the city’s energy security, resident’s access to energy services and vulnerability to climate change impacts.
Alongside this the City developed the Framework for Adaptation to Climate Change in the City of Cape Town (FAC4T). This sets a number of goals, including:
By following FAC4T, a City Adaptation Plan of Action (CAPA) for the City of Cape Town will be developed and the necessary resources mobilised for its mobilisation. The City currently has a large number of programmes and projects underway, which address energy efficiency or renewable energy. Some of the current projects include:
Source: City of Cape Town, August 2006, Framework for Adaptation to Climate Change in the City of Cape Town (FAC4T)
A number of key projects being implemented by the City are highlighted below:
Cape Town’s BRT Phase 1, the MyCiti service, commenced operations in May 2010. This uses a fleet of modern, comfortable buses moving in their own dedicated lanes on trunk routes, with special stations, often in the middle of the roads. Feeder routes run through suburbs and industrial areas with smaller buses to bring passengers to the main trunk routes. The service has links to other forms of transport – at rail stations, long-distance bus services and airports. They include a network of convenient, well-lit cycling and walking paths to and from the bus stops and stations to encourage people to ‘park and ride’.
For further information on routes, fares and schedules, please visit: www.capetown.gov.za/MyCiti
The Energy and Climate Action Plan is aimed at reducing the City’s carbon footprint and ensuring energy security by increasing energy efficiency, reducing demand and examining energy supply options. The Energy and Climate Action Plan was adopted by the Cape Town City Council in May 2010. It has eleven clear objectives, with targets and detailed implementation plans involving 40 programmes and more than 130 projects.
For further information on the Energy and Climate Action Plan please visit the City of Cape Town website: www.capetown.gov.za/en/EnvironmentalResourceManagement/projects/ClimateChange
The City has embarked on the development of the Climate Adaptation Plan of Action, which outlines sector-based adaptation interventions – some of which are already taking place, others that are planned and some which require further investigation and research. The approach has been two-fold; on one hand to examine significant climate-related vulnerability within the city and develop adaptation programmes around these. On the other hand, climate projections have been work shopped with specific sectors within the city in order to establish a range of potential impacts to the projected climate changes and identify areas of vulnerability and possible adaptation interventions aimed at building resilience to and mitigating climate change risk.
This intensive campaign is aimed at reducing the amount of electricity consumed by the groups in Cape Town which studies have shown to consume a large proportion of electricity and have the most scope to improve efficiencies, such as middle-to-high income residential consumers. The Campaign target is to reduce electricity consumption per annum but approximately 2,5% or 120 GWh (120,000 tons CO2) per year. The campaign is directly in line with the aims and objectives of the Energy and Climate Action Plan as the outcome will be a decreased use of electricity which is made in coal fired power stations which use a non-renewable resource and emit a substantial amount of CO2 into the atmosphere.
For further information on the Electricity Savings Campaign please visit www.SavingElectricity.org.za
The City has developed a Local Biodiversity Strategy and Action Plan with six strategic objectives that promote implementation and ensure that priority biodiversity sites are secured and well managed for the benefit of future generations. Proactive management of biodiversity is essential in an urban context in order to ensure resilience to climate change and the on-going delivery of ecosystem services.
The City of Cape Town has a 240km long coastline, which is arguably our greatest socio-economic and environmental asset. In order to protect this valuable asset the City has done a Sea-level Rise study to assess the potential impacts on the coast line which could occur as a result of climate change. Accordingly a Coastal Protection Zone is being developed with the intent to shape decisions relating to coastal planning and infrastructure development. This will not only enhance the coast as a shared and common asset, but it will also promote a risk averse approach which is critical in the context of climate change.
The Smart Living Campaign is a comprehensive, on-going sustainable lifestyle campaign, aimed at households, council staff, communities, businesses and schools in Cape Town. The campaign is based on the City’s Smart Living Handbook series. The detailed and user-friendly 160-page Smart Living Handbook and campaign guide people on how to be resource efficient and sustainable in their daily lives and practices. The themes covered in the handbook include energy, water, waste and biodiversity, and it contains a series of practical steps that households in Cape Town can take to protect the environment, save them money and make their homes safer to live in.
For further information on the Smart Living Campaign please visit the City of Cape Town official website: www.capetown.gov.za/en/EnvironmentalResourceManagement/Pages/SmartLivingHandbook.aspx
The City of Cape Town in partnership with Sustainable Energy Africa (SEA) and the African Centre for Cities (ACC) received funding from the Royal Danish Embassy to finance climate change research for the city of Cape Town, investigating both mitigation and adaptation aspects. A group consisting of academics, specialists and City officials was subsequently convened under the title “City of Cape Town’s Climate Change Think Tank”. This group ensures collaboration, integration and communication between various specialists in the field of climate change with the aim of producing research that is relevant and informative to ensure proactive management of climate change in the City of Cape Town.
For further information on the City of Cape Town’s Climate Change Think Tank please visit the City of Cape Town official website: www.capetown.gov.za/en/Pages/CitysnewClimateChangeThinkTanktoleadlocalinterventions.aspx
The Climate Smart Cape Town (CSCT) campaign aims to take advantage of the hosting of the Climate Change COP 17 in Durban in December both in profiling and marketing the city of Cape Town as a leading city in addressing the problems of climate change as well as to promote climate change literacy and awareness among Cape Town citizens. The campaign vision is for Cape Town to become more compact and resource efficient; a lower carbon city adapting well to the impacts of climate change, protecting its most vulnerable citizens and building an economic future based on clean development, localisation and jobs for all. Cape Town aims to inspire and assist other regional, national and continental cities to achieve similar ends.
The United Nations Framework Convention on Climate Change (UNFCCC) was formed in 1992 at the UN Conference on Environment and Development. With 194 Parties, the Convention enjoys near-universal membership. The ultimate objective of the Convention is to stabilise greenhouse gas concentrations in the atmosphere at a level that will prevent dangerous human interference with the climate system.
See also:
UNFCCC website: unfccc.int/2860.php
United Nations Framework Convention on Climate Change (UNFCCC), February 2011, Fact Sheet: An introduction to the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol
The Conference of the Parties (COP) is an annual conference hosted by the United Nations Framework Convention on Climate Change (UNFCCC). The 17th conference will be held in Durban from 28th November to 9 December 2011. There are 192 countries that are currently signed up, including all of the major economies and greenhouse gas emitters. A primary focus of the conference will be to secure a global climate agreement because the Kyoto Protocol’s commitment period will end in 2012. Other key questions that will need to be answered are:
See also:
COP17-CMP7 official website: www.cop17durban.com
Dane, A., Incite, August 2011, What South Africa hopes will come out of COP17
The Conference of the Meeting of the Parties to the Kyoto Protocol (CMP) is an annual meeting of the countries signed up to the Kyoto Protocol. There are 37 countries signed up to the Protocol, much less than the number signed up to the UNFCCC. The first CMP was held in Montreal, Canada, in 2005. This year is the 7th meeting, which is also being held in Durban in November-December.
See also:
COP17-CMP7 official website: www.cop17durban.com
The Kyoto Protocol is the only legally binding treaty on climate change, but expires in 2012. It was adopted at the third Conference of the Parties (COP 3) in Kyoto, Japan in December 1997. The Protocol is similar to the UNFCCC in terms of objectives, but the difference is that the Protocol is a commitment to stabilise greenhouse gas emissions, whereas the UNFCCC is an encouragement.
See also:
United Nations Framework Convention on Climate Change (UNFCCC), February 2011, Fact Sheet: The Kyoto Protocol
The Kyoto Protocol is the only legally binding treaty on climate change, but expires in 2012. Therefore, the conference in Durban will be the last decent chance to agree on a replacement. However, not all the major carbon emitters are on board. Japan caused upset at the 2010 conference in Cancun by announcing it would not back a second phase of the Kyoto Protocol, and was backed by Russia and Canada. Furthermore, the US and China – by far the world’s two largest greenhouse gas emitters – never ratified Kyoto. Talks in Cancun overlooked the issue, but negotiators in Durban will not have this option.
See also:
Carrington, D., The Guardian, December 2010, Cancun deal leaves hard climate tasks to Durban summit in 2011
COP17 will be an important climate change conference. It is the last chance to agree on a replacement for the Kyoto Protocol, the only international, legally binding commitment for countries to cut greenhouse gas emissions. If a replacement is not agreed upon, it is likely that countries’ emissions will continue to rise unabated, unless national commitments are enforced. This will have potentially devastating effects as runaway climate change ensues.
The term climate change is used to describe the dramatic increase in the planet’s atmospheric temperatures observed since the Industrial Revolution. It is almost certain that this is due to human influence.
Guy Midgley, Chief Director, Climate Change and BioAdaptation Division, South African National Biodiversity Institute. Climate Change – an Introduction
Increases in the atmospheric concentrations of gases known as greenhouse gases are largely to blame for a steady increase in average global temperatures and this, in turn, is starting to change our climate.
In the main, greenhouse gases are emitted when fossil fuels like coal, oil, petrol, diesel and natural gas are burned. We are 90% certain that the current warming is due to human activities like the burning of fossil fuels. Human activities, such as deforestation, are also reducing the earth’s natural ability to absorb greenhouses gases such as carbon dioxide (CO2).
Increased industrial activity since the mid eighteenth century has meant a rapid build-up of greenhouses gases such as carbon dioxide (CO2), methane and nitrous oxide. These gases combine to form a layer in the atmosphere that stops heat escaping. Instead, warmth is reflected back to earth causing the temperature to rise.
More frequent and intense extreme weather events, such as cyclones, droughts (means water and crop shortages), storms and heatwaves (leads to greater chance of bushfires). Melting of the world’s ice (i.e. polar ice caps, glaciers and permafrost), which causes sea level rise and increased absorption of sunlight.
Effect on the oceans:
Furthermore, an irreversible tipping point will be reached if greenhouse gas levels reach a certain concentration. This will mean various impacts of climate change will continue even if greenhouse gas emissions are cut.
There are many factors that work to control the Earth’s climate in a complex, interactive system. Solar radiation powers the climate system.The position and angle of the planet relative to the Sun dictates the seasons and the temperature variations that are characteristic of each.
The Earth’s atmosphere regulates the solar radiation entering and leaving the planet’s surface, ensuring temperatures are kept at an average 14oC. Natural greenhouse gases (water vapour and carbon dioxide), which regulate the amount of longwave radiation leaving the earth’s surface, therefore sustaining the earth’s average temperature of 14oC. Volcanic eruptions and anthropogenic aerosols and particles also influence the Earth’s climate.
Variation in wind and the water cycle is another factor which determines global climate. Air masses adopt the characteristics of the surface below them, and their movement has a big impact on climate.
Intergovernmental Panel on Climate Change (IPCC), 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Weather is the day-to-day climate in a given area, whereas climate is defined as the average weather over a given period (usually 30 years), either globally or in a given region. A common confusion between weather and climate is how scientists can predict the climate 50 years from now, but cannot forecast the weather a few weeks from now. This is because the chaotic nature of weather makes it unpredictable beyond a few days, whereas projecting climate is much easier as it is projecting the average weather over a long period of time. Another common misconception is thinking that an exceptionally cold winter is evidence against global warming. The fact is that there are always extremes of temperature and weather, but the long-term weather averaged throughout the Earth’s atmosphere indicates a clear warming trend.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Solar radiation reaches the Earth’s atmosphere. Two-thirds enters the atmosphere and most of this is absorbed by the Earth’s surface. Longwave, infrared radiation is emitted from the Earth’s surface, much of which is absorbed in the atmosphere and re-radiated back to Earth. This is known as the greenhouse effect. This gives us the liveable temperature we have today. Without this the Earth’s average temperature would be well below freezing.
Figure 1: The above diagram shows how the greenhouse effect is caused (source: globalconnections09.pbworks.com/f/06-07_greenhouse_effect.jpg)
However, since the mid-18th century, humans have intensified the natural greenhouse effect through deforestation and release of greenhouse gases, leading to an increase in global temperatures.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Human activities contribute to climate change due to the release of greenhouse gases and aerosols, which leads to changes in the Earth’s atmosphere. These emissions affect the amount of incoming solar radiation and outgoing infrared radiation from the Earth’s surface, therefore intensifying the greenhouse effect and warming the atmosphere. The chief contributor is the burning of fossil fuels, which releases carbon dioxide into the atmosphere. Deforestation is another major source of carbon dioxide. The human impact on the climate since the beginning of the industrial era greatly exceeds that due to changes in natural processes, such as solar changes or volcanic eruptions. However, it is true that solar output has gradually increased during the industrial era. Solar energy directly heats the atmosphere and can affect the abundance of atmospheric greenhouse gases, such as ozone. Major volcanic eruptions release aerosols into the stratosphere, which can create a short-lived (2 or 3 year) negative forcing. The stratosphere is currently free of aerosols, as the last major eruption was Mt Pinotubo in 1991.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Instrumental records over the past 157 years show that temperatures at the Earth’s surface have risen globally. Since the 1970s, the increase has been more extreme, with temperatures having risen by 0.55oC. 11 of the 12 warmest years on record have occurred in the past 12 years.
Warming has been greater over land than over the oceans. Seasonally, warming has been slightly greater in the winter. Since the 1950s, analysis of long-term changes in daily temperatures has become possible. These records show a decrease in the number of very cold days and nights and an increase in the number of very hot days and nights. The length of the frost-free season has increased in many mid- and high-latitude regions of both hemispheres. In the Northern Hemisphere, this means an earlier start to spring.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Observations show that changes are occurring in the amount, intensity, frequency and type of precipitation. These aspects of precipitation exhibit great natural variability, with substantial influence from phenomena such as El Nino and the North Atlantic Oscillation. Precipitation in a given region depends largely on the current weather in that region. Changes in cloud and wind patterns have a direct influence on precipitation.
Long-term trends from 1900 to 2005 display a greater amount of rainfall in regions such as eastern North and South America, northern Europe and northern and central Asia, whereas a decrease in rainfall has been observed in the Sahel, southern Africa, the Mediterranean and southern Asia. More precipitation now falls as rain rather than snow in northern regions. Increases in heavy precipitation events have been observed globally. These events are associated with an increase in water vapour in the atmosphere arising from warming the world’s oceans.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Heat wave frequency has increased since 1950. The extent of regions affected by droughts has also increased since this time, specifically in southern Asia, northern Africa, and northern North America. However, an opposite trend is observed in eastern North and South America, and no significant trend is apparent for Europe. Generally, the frequency and intensity of heavy precipitation that leads to flooding has increased, but not globally. Tropical storm and cyclone frequency varies substantially from year to year, and are greatly affected by natural phenomena such as the El Nino Southern oscillation. However, increases in intensity and duration have been observed since the 1970s, correlating strongly with increased tropical sea surface temperature.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Yes. Observations show a global-scale decline of snow and ice, particularly since 1980 and increasingly since the late 1990s. Most mountain glaciers are retreating. Snow cover is disappearing earlier in the spring in many regions. Arctic sea ice is retreating in all seasons, most dramatically in the summer. Reductions in permafrost and river and lake ice are evident, as well as thinning of polar ice off the coasts on Greenland and Antarctica.
Satellite measurements show that total snow cover in the Northern Hemisphere has decreased by 2% per decade since 1966. However this is predominantly due to summer changes, there has been little change in winter or early autumn. Since 1978, average annual sea ice extent in the Arctic has decreased by approximately 2.7% per decade, while summer sea ice extent has decreased by approximately 7.4%. Antarctic sea ice extent shows no significant trend.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
It is estimated that sea levels have been stable from between 2000 and 1000BC up until the late 19th century. During the 20th century, sea levels have risen globally at an average of 1.7mm per year. Since 1993, global sea level has risen by an average of 3mm per year. However, sea levels are not rising uniformly around the world. In some regions rates are several times the global average, while in other regions sea level is falling. This is due to non-uniform temperature changes globally and related to alterations of the ocean circulation. Over the period 1961-2003, thermal expansion accounted for about a quarter of sea level rise and melting ice accounted for almost half. However, more recently (1993-2003), each account for approximately half of observed sea level rise.
The Intergovernmental Panel on Climate Change (IPCC) projects that global sea level will increase at a greater rate than during 1961-2003.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Global climate is determined by the radiation balance of the Earth. This is influenced by three different factors: a change in the incoming solar radiation, an alteration in the amount of solar radiation reflected, and a change in the amount of infrared radiation emitted from the Earth’s surface (eg. Changes in greenhouse gas concentrations). There is strong evidence that ice ages occurring over the last 3 million years are related to regular variations in the Earth’s orbit around the Sun, known as Milankovitch Cycles. These cycles alter the amount of incoming solar radiation at a given latitude during a given season. It is thought that a lower level of summer sunshine means the snow from the previous winter does not melt away in the summer, leading to the formation of ice sheets.
Carbon dioxide is also linked to the development of ice ages. Ice core data shows that carbon dioxide concentrations were very low (~190ppm) during past ice ages, and high in the warm interglacial periods (~280ppm). An initial cooling due to the Milankovitch Cycle is subsequently amplified as CO2 concentrations fall, therefore increasing the speed and intensity of a developing ice age.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Some aspects of current climate change are not unusual, but others are. Carbon dioxide concentrations in the atmosphere are the highest they have been for an estimated half a million years, and have risen at an exceptionally high rate. Average global temperatures are the highest they have been for at least 500 years, probably even a millennium. Another unusual feature of current climate change is that it is caused by human activities, whereas past climatic changes where due to natural causes.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Yes. Concentrations of carbon dioxide and methane in the atmosphere are currently higher than at any time in the last 650,000 years. The dramatic increase in carbon dioxide is unprecedented. Increases in carbon dioxide have never exceeded 30ppm in 1000 years, but in the last 17 years concentrations have increased by 30ppm. Fossil fuel combustion and deforestation account for 75% and 25% of human-induced CO2 respectively. In addition, some greenhouse gases (such as chlorofluorocarbons, or CFCs) are manufactured by humans, and were not present in the atmosphere before the industrial era. Human activities emit more methane into the atmosphere than natural processes do. Between 1960 and 2000, methane concentrations grew six times faster than during any 40 year period of the 2000 years prior to the industrial era.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
There is confidence that climate models provide reliable evidence of future climate change. This is due to their foundation in accepted physical principles and from their ability to reproduce observed features of current and past climate change. Models have been used to accurately simulate ancient climates such as the last ice age 21,000 years ago. Confidence in models is higher for some factors (e.g. temperature) than others (e.g. precipitation). However, there are still some problems that remain with the construction of climate models. For example, it is still not yet possible to accurately simulate the El Nino Southern Oscillation.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
This depends on the chemical and physical processes that remove each gas from the atmosphere. Concentrations of some greenhouse gases decrease almost immediately if emissions are reduced, whereas others can continue to increase for centuries even if emissions are reduced. The concentration of a greenhouse gas in the atmosphere depends on the rate of emission into the atmosphere and the rate of removal from the atmosphere. For example, carbon dioxide is exchanged between the land, atmosphere and oceans through various processes. Currently more than half of the carbon dioxide emitted is removed from the atmosphere within a century, but about 20% remains for several millennia. Because of this, carbon dioxide will continue to increase in the long term, even with decreased emissions.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Yes, changes in climate will vary between different regions of the world. Climate varies from region to region, driven by the uneven distribution of solar heating, the interactions between the land, atmosphere and oceans and the physical characteristics of the regions. Changes in global climate will affect certain aspects of these complex interactions. Warming is expected worldwide, but the amount of projected warming is generally higher at the poles than at the tropics. Precipitation projection is more complex, but it is expected to increase at polar latitudes, but decrease near the equator. Increases in tropical precipitation are projected during rainy seasons, and over the tropical Pacific in particular.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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