At A Glance
The planet's temperature is rising at an accelerated pace that most scientists attribute to greenhouse gases produced by human activity. They predict global warming will lead to rising sea levels and more extreme weather, including droughts, heat waves and heavier rainfall.
Growing weather and climate hazards increase the risk of disasters, and threaten food and water supplies across the world - especially in the poorest countries. Some people will need to find new homes as their living environments are submerged or can no longer sustain them.
- Numbers affected by climate disasters expected to keep rising
- World's poor - the most vulnerable - need help to adapt
- Negotiations on a new global climate pact are slow and fractious
Statistics show a steep rise in climate and weather-related disasters since the middle of the 20th century, and the number of people affected is also increasing.
The U.N. climate panel says the world can expect more heat waves and droughts, heavier rains, stronger storms and higher sea levels as the planet is warmed by emissions of heat-trapping gases.
Africa, Latin America and parts of Asia - where the climate is already more extreme and arid regions are common - are likely to be most affected, as rainfall becomes less predictable and glaciers melt.
In coastal areas and small island states, tens of millions of people could be uprooted as rising seas swallow their land, or food and water become scarce. Human, plant and animal diseases are also expected to spread to new places.
There is growing concern about the potential impact of climate change on local, regional and global security. Experts warn there is a higher risk of violence in places where tensions sparked by the environmental impacts of climate change add to existing stresses.
There is intense debate and a wide range of competing ideas on how best to keep global warming in check and cope with its impacts.
Many developing countries believe richer nations should make bigger commitments to reduce their carbon emissions, while providing additional funding to help poor states adjust to the effects of climate change and find less carbon-intensive ways to develop. Wealthy countries want fast-developing nations to curb their rising emissions too.
More than 190 countries have agreed to negotiate a new global pact by 2015 to replace the Kyoto Protocol, which binds some rich nations to capping their emissions of greenhouse gases until 2020, when a successor agreement would come into force.
Humanitarian and development agencies are working to lessen the negative effects of climate change on their projects and the communities they support. Increasingly, they are helping local people become more resilient to weather-related disasters and shifting climate patterns.
But many aid groups and governments in developing states say they do not have the resources to move fast enough to protect people from floods or droughts, introduce more climate-tolerant crops and farming methods, and provide access to renewable energy on the scale needed.
The planet's temperature is rising at an accelerated pace most scientists attribute mainly to man-made factors. As the earth's climate changes, they predict it will lead to higher sea levels and more extreme weather, including droughts, heat waves and heavy rainfall.
Growing weather and climate hazards increase the risk of disasters and threaten food and water supplies across the world - especially in the poorest countries. Large numbers of people could be forced from their homes as their environments are submerged or can no longer sustain them.
Global temperatures have risen by about 0.8 degrees Celsius in the past 100 years, and the U.N. Intergovernmental Panel on Climate Change (IPCC) says they are probably going to increase by between 1.8 and 4 degrees (3.2-7.2F) before the end of the century.
There isn't complete agreement on why the planet is getting warmer. But after examining the scientific evidence, the IPCC concluded there was at least a 90 percent probability it was primarily due to man-made factors.
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic [human-produced] greenhouse gas concentrations," it said in a benchmark 2007 report.
Rising emissions of carbon dioxide, methane and other greenhouse gases in the atmosphere are trapping heat, warming the Earth. That is causing ice caps to melt and sea-levels to rise, as well as bringing wilder weather and longer-term variations in climate patterns.
Evidence suggests climate change has already led to shifts in climate extremes such as heat waves, record high temperatures and, in many regions, heavy precipitation in the past half century, the IPCC said in a report, whose main findings were released in 2011.
This century, many parts of the world are likely to experience heavier rainfall and cyclones with stronger winds, and there’s a 50 percent chance of more intense droughts, the report warned. Increases in warm daily temperature extremes are almost certain, while the globe is very likely to suffer fiercer heat waves more often, it said.
As the world heats up and polar ice and glaciers melt, oceans are rising too. The IPCC said in 2007 that sea levels would rise between 18 and 59 cm (7.2 to 23.6 inches) this century because of global warming. But a group of 26 scientists warned in 2009 that sea level could rise by 1 to 2 metres by 2100 as climate change accelerates faster than anticipated.
In 2012, Arctic sea ice, a key indicator of climate change, melted to its lowest level since satellite records began 33 years ago before beginning its autumnal freeze, according to the U.S. National Snow and Ice Data Center.
The IPCC says the regions most vulnerable to climate change are Africa, Asia's mega-deltas and small island states like Tuvalu, in the south Pacific.
From a humanitarian perspective, the key issue is how projected changes in climate and weather could impact on populations already made vulnerable by poverty, hunger, disease, conflict and poor governance.
Estimates of the number of people who could be affected remain speculative and hotly disputed.
Climate change contributed to 400,000 deaths in 2010 from hunger and communicable diseases, including diarrhoea and malaria, hitting children in developing countries the hardest, according to the 2012 Climate Vulnerability Monitor, a report backed by 20 governments. And carbon-intensive energy use was responsible for over 4.5 million deaths, most due to indoor smoke from dirty stoves and air pollution, the study said.
Aid agency Oxfam has predicted that climate-related disasters will hit more than 375 million people each year by 2015, up from nearly 250 million in 2009.
Most humanitarian experts agree that climate change is adding to the pressures on the world's poorest communities and poses a major challenge to the work of relief and development agencies.
The challenge of curbing emissions
A widely heard argument is that rich industrialised nations - which have played the biggest role in global warming through high emissions of greenhouse gases - have a responsibility to help less developed countries adjust to the coming changes and find a cleaner development path, as they are likely to suffer the most from climate change even though they have done the least to cause it.
And yet U.N. talks to craft a new global deal to tackle global warming – to extend and then replace the Kyoto Protocol, whose first phase expired at the end of 2012 - have inched forward at a snail's pace.
Only some developed nations have had targets to limit emissions under the Kyoto Protocol. Emissions of carbon dioxide, the main greenhouse gas, rose 3.1 percent in 2011 to a record high, while the decade ending in 2010 was the warmest since records began in the mid-19th century, according to U.N. data.
There had been high hopes the world's governments would reach a new, legally binding agreement at a 2009 U.N. climate summit in Copenhagen. But it produced only a voluntary accord to limit temperature rises to 2 degrees Celsius (3.6 F) above pre-industrial times and provide funding to help poorer nations cope with climate change.
An increase of 2 degrees is seen as a threshold to dangerous changes in the Earth's climate, but current targets and policies are insufficient to reach that goal, the United Nations says.
According to Climate Action Tracker, an independent science-based assessment, the world is headed for a rise of about 3.3 degrees Celsius by 2100, based on existing promises for curbs in planet-warming greenhouse gas emissions. Some scientists believe even that is a conservative estimate, and that the temperature increase could be significantly higher.
The 2011 U.N. climate conference in South Africa agreed that countries would reach a new global deal to cut greenhouse gas emissions by the end of 2015, to come into force by 2020.
In Doha, in 2012, the Kyoto Protocol was extended until 2020, albeit in a weakened form. The eight-year extension of the treaty beyond 2012 kept it alive as the sole legally binding plan for combating global warming. But it was sapped by the withdrawal of Russia, Japan and Canada, so its signatories now account for only 15 percent of global greenhouse emissions.
Under separate, voluntary climate goals, rich nations have promised to cut emissions by 2020, while developing nations led by China and India are seeking to slow the growth of their emissions.
But both sides fear carbon restraints will hamper their economic progress – one of the main factors putting the brakes on concerted international action to tackle climate change.
The difference between climate and weather
While climate statistics focus on averages, people tend to be most interested in extreme weather events, including super-strength storms and long spells of abnormal weather like severe winters and hot summers, according to the World Meteorological Organization (WMO).
Weather refers to what is happening to the atmosphere at a given time - usually on a daily or weekly basis. Climate is a measure of what to expect in any month, season or year, and is based on data built up over a longer period.
Scientists and weather experts often use the term "climate variability", which is different from "climate change".
According to the International Research Institute for Climate and Society (IRI), climate variability refers to "variations of the climate system, which includes oceans and the land surface as well as the atmosphere, over months, years and decades" - not all of which can be predicted.
Climate change, in comparison, refers to "longer-term trends in average temperature or rainfall or in climate variability itself, and often to trends resulting wholly or in part from human activities, notably global warming due to the burning of fossil fuels".
Until recently, climate scientists have shied away from attributing particular extreme weather events to climate change. But improvements in data and statistical techniques based on more refined models of the climate are gradually making the linkages clearer.
British and American scientists have said, for example, that climate change increased the odds for some of the extreme weather that prevailed in 2011, a year that saw severe drought in Texas, a very warm November in England, and was one of the 15 warmest years on record.
But they stressed, in the Bulletin of the American Meteorological Society, that attribution must be framed in terms of probability rather than certainty. So instead of saying climate change caused a heat wave, researchers could gauge how much more or less likely the heat wave was in a world where the climate is changing.
There's a high degree of uncertainty in long-term climate predictions. Yet many climate and development specialists believe that, by learning how to manage climate variability from season to season and year to year, communities will be better equipped to adapt to climate change in the future. This requires well-designed policies together with access to high-quality data and information about climate at the local level.
In Africa - which is highly vulnerable to climate change due to its dependency on rain-fed agriculture - farmers often lose crops because they can't get hold of accurate and timely forecasts, for example.
The WMO and its partners are now setting up a Global Framework for Climate Services, which aims to fill gaps in the provision of science-based climate information and forecasting in less developed countries, and integrate it with policy making.
Many projects have also started up at the local level, broadcasting daily and seasonal weather forecasts to farmers and fishermen through radio stations or cell-phone text messages.
More natural disasters
There has been a steep rise in climate-related and hydro-meteorological disasters - which include floods, wave surges, storms, droughts and landslides - since the middle of the 20th century, according to statistics from the International Disaster Database managed by the Centre for Research on the Epidemiology of Disasters (CRED) at Belgium's Louvain University.
Because the pattern of weather-related disasters varies sharply from year to year, it is best to look at longer-term trends.
In the period from 1900 to 1909, 28 disasters were recorded in this category. Between 1950 and 1959, there were 232. In the 1990s, there were 2,034, and in the first decade of the 21st century, there were 3,669.
CRED researchers caution, however, that the rise in natural disasters isn't all down to global warming. "Climate change is probably an actor in this increase but not the major one," says their report on statistics for 2007. Other factors contributing to the growing number of disasters are that information about them is more accurate and widely available than in the past, and populations have grown.
According to the 2011 Red Cross World Disasters Report, over the decade from 2001-2010, climate- and hydro-meteorological disasters killed more than 540,000 people – less than half the total disaster death toll of 1.3 million. But they accounted for the vast majority of the 2.7 billion people affected by disasters around the world in that period, with floods and drought-induced food insecurity hitting just over 1 billion each.
The growth in mega-cities is also increasing the risk of disasters in densely populated urban environments - a challenge for which many aid agencies are not well prepared.
For the first time in history, over half the world's 6.7 billion people live in urban areas, according to the United Nations. Six of the world's 10 most populous cities are on or near the coast, leaving millions vulnerable to flooding, storm surges and post-quake tsunamis.
Mumbai in India, Mexico City, Colombia's capital Bogota, China's Shanghai, Manila in the Philippines, Lagos in Nigeria and the Indonesian city of Jakarta are just some of the places of particular concern to disaster experts.
Around one tenth of the global population - 634 million people - live in coastal areas less than 10 metres above sea level, and that number is rising, according to a 2007 study by academics at the International Institute for Environment and Development (IIED) and New York's City and Columbia universities.
A 2011 report from the Intergovernmental Panel on Climate Change made clear that nations should act now to prevent disasters, because increasingly extreme weather is already a trend. The need for action has become more acute as a growing human population puts more people and more assets in the path of disaster, raising economic risk, it said.
The 2012 Climate Vulnerability Monitor, a study backed by 20 governments, calculated that climate impacts - including floods, droughts, sea-level rise and reduced labour productivity - are estimated to have cut the world's gross domestic product (GDP) by a net 0.8 percent in 2010, or close to $700 billion. It predicted losses would rise to 2.1 percent of GDP by 2030.
Food and water shortages
Aid agencies are concerned that a rise in climate-related disasters will tip a growing number of poor people into an emergency situation.
Oxfam warned in 2009 that the world's relief agencies will be overwhelmed by a sharp rise in the number of people affected by climate-related disasters by 2015 unless the quantity and quality of aid improves. In a report, it said the number of people affected by climate crises could rise from nearly 250 million each year to more than 375 million by 2015.
Scientists expect spreading deserts and the degradation of farm land linked to climate change and environmental exploitation to pose a serious threat to food supplies for the world's surging population in coming years.
Africa, Latin America and parts of Asia - where the climate is already more extreme and arid regions are common - are likely to be most affected as rainfall declines in some areas and its timing becomes less predictable, exacerbating water stress.
The expansion of deserts and salt intrusion into once-arable land is already well under way in some places. This phenomenon is likely to be most severe in drier areas of Latin America, including farming-giant Brazil, in future.
In Africa, increasing climate variability is expected to create major problems for poor rural farmers, who are likely to see their growing seasons get shorter and crop yields fall, especially near already arid and semi-arid regions.
The IPCC says that between 90 million and 220 million Africans could find their water sources at risk from climate change by 2020. Experts say climate risks are particularly high on that continent because of the additional challenges it faces, including conflicts and corruption.
In Asia, global warming is expected to cause large sections of glaciers in the Himalayas and surrounding highlands to disappear, threatening water supplies and livelihoods across much of the continent. Rising temperatures have already shrunk glaciers on the mountains dividing China and South Asia.
Accelerated melting could severely disrupt river flows, rainfall patterns and farming across Asia, because glaciers in the Himalayas and the Qinghai-Tibet Plateau are a major source of rivers, including the Yangtze in China, the Mekong in Indochina and the Ganges in India. Glacier-fed rivers could swell as the ice melts, then dry out as the ice disappears.
Warmer, wetter or drier conditions are also expected to expand the range of agricultural pests in some parts of the world, bringing new threats to crops.
Research and development institutions are working to develop new varieties of crops that are more tolerant to climate extremes and salty conditions, as well as identifying hardy indigenous crops that could be used in other parts of the world.
In addition, there are a growing number of projects that help smallholder farmers collect and use water more efficiently, including rainwater harvesting and drip irrigation. Some are also introducing climate-friendly techniques such as conservation agriculture, where the soil is left untilled, or the production of biogas from animal manure, human waste and crop residue.
The aim of most of these development programmes is to improve food and water security in poor rural societies - and increasingly urban areas - that are vulnerable to climate change.
Conflict and displacement
Aid agencies fear that food and water shortages stoked by climate change and environmental degradation could create or exacerbate tensions within and between communities, which may spill over into violent conflict.
The climate threat to world security grabbed attention in 2007, when U.N. Secretary-General Ban Ki-moon warned that environmental changes caused by global warming "are likely to become a major driver of war and conflict", and climate change was debated at the Security Council for the first time.
The Nobel Peace Prize was awarded jointly to the IPCC and former U.S. Vice President Al Gore that year "for their efforts to build up and disseminate greater knowledge about man-made climate change".
Most experts argue that climate change and its impacts alone are unlikely to spark conflict directly, but will increase tensions in already unstable areas.
Flooding, sea-level rise and land degradation could also force people from their homes, creating tens of millions of climate migrants. But there is no single authoritative prediction about the numbers of people who could be uprooted by global warming.
The U.N. refugee agency has warned that the impacts of climate change could displace around six million people each year, half of them due to weather disasters like floods and storms.
And UK-based development agency Christian Aid has said 250 million people could be uprooted by 2050, a figure based on an updated estimate from scientist Norman Myers, who suggested in 1995 that between 150 and 200 million people would have to leave their homes permanently because of climate change.
The U.N.'s State of the World's Cities 2008/2009 report noted that 3,351 of the world's cities are located less than 10 metres above sea level, putting nearly 400 million people at risk of displacement from rising sea levels.
Most experts argue that much of the migration linked with global warming is likely to be within countries and in some cases for short periods only. It is expected to follow existing migratory patterns, and may prove an effective way of adapting to climate pressures, particularly if those who leave send remittances home, experts say.
Climate-linked migration is unlikely to cause a major flow of climate refugees from poor to rich countries, they add.
For those who do cross national borders, however, it remains unclear who should help them. Climate refugees do not have the same protection under international law as people who flee their countries to escape violence or political persecution.
Norway and Switzerland, with the support of the U.N. refugee agency (UNHCR) and the Norwegian Refugee Council, launched the Nansen Initiative in 2012 to address the current legal and protection gap for people displaced across borders by environmental change and extreme weather events.
New health threats
Climate change is likely to lead to shifting patterns of disease and rising malnutrition, bringing new health hazards for millions, experts warn.
The World Health Organization (WHO) says public health depends on safe drinking water, sufficient food, secure shelter and good social conditions - all of which are likely to be negatively affected by global warming, especially in some of the world’s poorest places.
On the positive side, rising temperatures could bring limited local benefits, such as fewer winter deaths from the cold in temperate climates and increased food production in high-latitude regions.
Scientists and health experts are working to gather more evidence on how climate change affects diseases and other aspects of health. Statistics are hard to come by.
WHO research, published in 2003, concluded that the effects of climate change since the mid-1970s may have caused over 150,000 deaths in 2000, and a further 5.5 million healthy years of life were lost worldwide due to debilitating diseases caused by climate change.
The agency warned that the death toll could double in the next 30 years if trends were not reversed. One heat wave in 2003 killed 20,000 people in Europe alone, the WHO said.
A group of international experts is now working on updating the WHO figures on climate-related health burdens.
There is a growing view that hunger is likely to be the most serious health threat linked to climate shifts in the coming decades, as farmers struggle to cope with more unpredictable weather.
The two areas of the world likely to suffer the greatest health risks from climate change are sub-Saharan Africa and South Asia, IPCC studies suggest. Both are already grappling with undernutrition, in particular, and could see farm yields hit by climate extremes, health experts say.
Other expected impacts of climate change on human health include:
* Wetter, warmer weather could take malaria into previously cool areas like the highlands of Tanzania and Rwanda.
* Increased rainfall in hot areas could boost dengue and Rift Valley Fever, also carried by mosquitoes, as well as leishmaniasis, a parasitic disease that causes ulcers and facial disfigurement.
* Both floods and drought can boost the spread of waterborne diseases like cholera and diarrhoea as people resort to drinking sewage-contaminated or other dirty sources of water.
* Meningitis, passed through the air, could increase in hot, dusty regions such as the Sahel if climate change brings more arid conditions.
* More frequent and intense heat waves may lead to rising illness and death, particularly among young, elderly and frail people in large urban centres.
* Increased smog and air pollution could cause more respiratory disorders.
In 2008, the WHO warned that climate change would exacerbate health crises in many poor countries already strained by inadequate hospitals, too few medical staff and uneven access to drugs.
Combating the health challenges from global warming will require greater efforts to forecast changing weather patterns, fight disease-spreading insects like mosquitoes, distribute vaccinations and make health services available to more people.
International action on global warming
International, national and local-level activities to tackle climate change fall into two main categories: mitigation and adaptation.
Mitigation is concerned with curbing greenhouse gas emissions and finding cleaner ways of powering the world. Adaptation assesses the vulnerability of societies and natural systems to climate change, and helps people cope with the negative effects and benefit from any potential opportunities.
Greenhouse gas emissions have risen by 70 percent since 1970, and are expected to rise by between 25 percent and 90 percent over the next 25 years if the world continues with "business as usual".
The IPCC says rich nations need to cut emissions by 25 to 40 percent below 1990 levels by 2020 to keep temperatures below what many experts regard as a "dangerous" 2 degree Celsius (3.6 Fahrenheit) rise.
IPCC scientists said in 2007 that growth in greenhouse gas emissions could be curbed at reasonable cost to the world through policies like switching to renewable energy sources, reducing deforestation and improving energy efficiency.
But in 2012, the World Bank warned that the world is likely to warm by 3 to 4 degrees by the end of the century and extreme weather will become the "new normal", affecting every region.
The bank and many other international institutions have warned that progress by governments to tackle climate change has been far too slow.
At a 2007 U.N. climate conference in Bali, nearly 200 nations agreed to launch negotiations on a new pact to replace or extend the Kyoto Protocol, which in its first phase bound 37 rich nations to capping their emissions of greenhouse gases until the end of 2012.
It has never included the United States, the world's second-largest greenhouse gas emitter, after its Senate refused to approve the treaty.
The United States has consistently argued that major developing country emitters, including China and India, should also be subject to curbs. But they have been reluctant to make promises without seeing more decisive steps from wealthier industrialised nations first.
High expectations were dashed at the U.N. climate summit in December 2009. Instead of producing a new treaty, the talks ended with the "Copenhagen Accord", a last-minute agreement brokered by the United States with China, India, Brazil and South Africa, which set no binding targets for reducing emissions but called for cuts that would keep global temperature rise from climate change below 2 degrees Celsius.
The pact also committed rich countries to provide "fast start" climate funding for poorer nations of $30 billion between 2010 and 2012, rising to $100 billion per year from 2020.
At the U.N. climate conference in Durban in December 2011, member countries agreed they would reach a new worldwide deal to cut greenhouse gas emissions by the end of 2015, which could come into force by 2020.
The meeting in South Africa also agreed to set up a Green Climate Fund to channel finance to poorer nations to help them cope with the effects of climate change.
At the Doha conference, in 2012, the Kyoto Protocol was extended until 2020 in a weakened form. The eight-year extension of the treaty kept it alive as the only legally binding plan for combating global warming. But it was sapped by the withdrawal of Russia, Japan and Canada, so its signatories now account for only 15 percent of global greenhouse emissions.
Outside the U.N. process, large greenhouse gas emitters - including China, the European Union, Australia and South Korea - are moving forward with carbon trading schemes, clean technology investment and national legislation.
In mid-2009, G8 nations set a goal of cutting their overall emissions by 80 percent by 2050. But developing countries refused to sign up for a global target, calling for interim commitments for 2020 from the richer states.
So far the European Union has promised to reduce emissions by at least 20 percent by 2020 from 1990 levels, and U.S. President Barack Obama aims to cut U.S. emissions by 17 percent below 2005 levels by 2020.
But such goals, even if met, are unlikely to be enough to keep the planet’s temperature increase to a safe level.
Greenhouse gas emissions in 2020 could rise more than previously forecast to between 8 billion and 13 billion tonnes above what is needed to keep global warming to 2 degrees Celsius, according to a 2012 U.N. Environment Programme (UNEP) report.
In April 2013, a draft summary of a forthcoming IPCC report warned the 2 degree limit is slipping out of reach and governments may have to find ways to artificially suck greenhouse gases from the air if they fail to make deep cuts in rising emissions by 2030. Emissions of heat-trapping gases rose to record levels in the decade to 2010, led by Asian industrial growth, it added.
Adapting to climate change
While emissions cuts are essential to limit global warming in the future, aid workers say vulnerable communities need support now to adapt to extreme weather and climate shifts that are already happening.
Policies and programmes to cope with climate change can also offer new opportunities to alleviate poverty if managed in the right way.
Making people more resilient to the potentially harmful consequences of weather hazards and longer-term climate change includes sophisticated measures like future climate modelling and switching to more appropriate crops like drought-tolerant maize.
Or it can be as simple as alerting people to approaching storms, teaching them to swim, protecting water supplies from contamination, or storing food in safe places.
Governments are increasingly recognising the need to prepare for and manage climate-related risks, and are taking measures to help people adapt to climate change.
Adaptation policies include:
* Better use of data and forecasting to give the public early warning of extreme weather
* Physical barriers, like better flood defences
* Financial buffers, such as cash transfers and weather-related insurance
* Improved health and sanitation systems
* Helping communities find alternative livelihoods, or move to more hospitable environments if staying put is no longer an option
* Supporting a more pro-active international disaster response system
Disaster experts are also devising ways to get important weather and climate information to the people who are most exposed, as well as incorporating communities' own views of the hazards they face. Local knowledge is valuable in avoiding disasters, but has often been overlooked by scientists and aid agencies.
In recent years, it has become more common for relief and development agencies to address the potential impacts of climate change when planning their activities.
They try to identify and reduce the risks to their projects and other assets ("climate proofing"). Some are also encouraging the communities they assist to follow a low-carbon development path by adopting renewable energy and other strategies for greener growth.
Nonetheless, experts say efforts to protect people from weather disasters and longer-term climate shifts still aren’t moving fast enough - even though it is cheaper to invest in preventing emergencies than to pay to repair the damage afterwards.
One key barrier is that aid for climate adaptation programmes has been limited and slow to emerge, with only several hundred million dollars made available through international funding mechanisms so far. Bilateral aid is higher, but hard to track because there is no common reporting system for climate finance, outside of official development assistance.
There is a large gap between the amounts international institutions estimate are needed for developing countries to adapt to climate change - which run to tens of billions of dollars per year - and the amounts governments and communities are receiving to roll out adaptation measures on the ground.
Some environment and development groups now fear that loss and damage caused by climate change has become unavoidable due to inadequate efforts to curb global warming and scant support for poorer nations to cope with its impacts.
Loss and damage is widely understood as the adverse effects of climate change that result from failed efforts to protect people from disasters or to adapt. It includes the ramifications of slow-onset processes like sea-level rise and desertification, where adaptation may be impossible.
It has become a controversial issue within the U.N. climate talks. Around 100 developing countries are pushing for an international mechanism to guard against and help them recover from climate losses and damage. But some rich nations have tried to block progress on such a mechanism, fearing they will be held liable for the cost of climate change in poorer states.
Climate finance for developing states
It's widely recognised that developing countries need substantial financial support to cope with climate change and develop in a cleaner way than industrialised nations. But the issue of who should pay for the technology, infrastructure and new institutions required remains controversial.
Experts agree there is overlap between development activities and measures to help poor countries become more resilient to climate change. But adapting to climate change also requires large, additional interventions, such as building sea walls, protecting roads from flash floods, maintaining agricultural yields and bolstering health services.
International funds and schemes, like the U.N. Clean Development Mechanism (CDM), have been established to channel money to renewable energy initiatives in developing countries.
The CDM allocates carbon credits to projects that cut greenhouse gas emissions in developing countries, such as wind farms and hydro-power projects, which are then sold to investors or to companies and nations that want to offset their own pollution. In practice, China has won the vast majority of CDM funding, with little going to the world’s poorest nations.
A 2 percent levy on CDM transactions goes into the U.N. Adaptation Fund, which was set up to help poorer nations adapt to global warming. It had disbursed around $54 million, and approved further project contributions of nearly $180 million by early 2013.
The World Bank also runs two large climate investment funds, set up in 2008 to help developing countries introduce low carbon technologies and adapt to climate change.
In 2011, official development assistance that supported climate change adaptation was just over $8.3 billion, down slightly from almost $8.5 billion in 2010, although some of it had other purposes too, according to figures from the Organisation for Economic Cooperation and Development (OECD).
These sums are paltry compared with calls from developing countries, the United Nations and aid groups for tens of billions of dollars per year in new financing for climate change adaptation.
The 2009 Copenhagen Accord, backed by around two-thirds of the world's nations, committed wealthy nations to providing up to $30 billion for tackling climate change in developing countries by 2012, and $100 billion a year by 2020 in public and private funding, including "alternative sources of finance".
The amounts donors say they pledged in “fast start” finance, between 2010 and 2012, add up to nearly $34 billion, which includes $3 billion in leveraged private finance from Japan, according to a review from the World Resources Institute (WRI). But not all of that money had been budgeted or requested by late 2012, and the exact definition of what should count towards the total remained unclear, it added.
The International Institute for Environment and Development and Oxfam have both calculated that only around a fifth of this funding was allocated for adaptation – which they say is not in line with the promise that fast-start finance would be balanced between adaptation and mitigation.
Moreover, some campaigners argue that not all the money is new, with some coming from development aid budgets. And there are growing concerns about how climate finance will be scaled up from 2013-2019, as few firm commitments have yet to be made.
At the Doha conference in 2012, the least developed countries had demanded that donor governments set a firm target of providing $60 billion in climate finance in the next three years. But only some European countries and the European Union made new pledges, adding up to around $6 billion in climate aid for 2013. No interim goal for 2015 was agreed on.
It is generally accepted that rich governments cannot find the large sums they have promised to mobilise by 2020 from their public coffers alone, and new ways of raising money will have to be found, such as taxes on international emissions trading, aviation, shipping and even financial transactions.
Other market-based ideas to protect countries, communities and individuals against climate and disaster risk range from catastrophe bonds to micro-insurance and disaster derivatives.
All eyes are now on the fledgling U.N.-backed Green Climate Fund (GCF), which held its first board meeting in August 2012 and is still working out how it will operate.
It is regarded by many as one of the bright spots in fractious international climate negotiations, although it is unlikely to start disbursing money until the beginning of 2014.
A major sticking point is likely to be how much money the fund will receive, from which countries and alternative financing sources, with some richer developing countries arguing they should not be expected to contribute.
Civil society groups are also worried the fund won’t be transparent enough, with some fearing the private sector may be given too large a role in running projects the GCF finances.
Reducing emissions from deforestation
Deforestation and forest degradation contribute nearly 20 percent of total greenhouse gas emissions - more than all the world's cars, trucks, trains and airplanes put together, and second only to the energy sector.
Environmental groups say protecting tropical forests from being cut down and burned - "avoided deforestation" - is the quickest and most direct way to mitigate climate change.
Increased logging in the Amazon and parts of Asia and Africa is reducing the capacity of the world’s forests to store carbon.
Tropical forests and swamps release greenhouse gases when they are cleared for timber and fuel wood, to plant crops such as palm oil or soybeans, or to free up land for cattle ranching.
Trees also act as a natural defence against soil erosion, flooding and landslides, and cutting them down can increase the risk of disasters.
Moreover, opponents of commercial logging argue it is often carried out with little respect for the rights of indigenous and other minority groups who rely on forests for their livelihoods and survival. Organised crime groups are heavily involved in illegal logging.
Countries with large areas of rainforest - including Brazil, Cameroon, Democratic Republic of Congo, Costa Rica, Gabon, Indonesia, Malaysia and Papua New Guinea – are starting to receive financial compensation from richer nations to protect their forests from logging.
The majority of payments are being made under an international, U.N.-backed scheme called "reducing emissions from deforestation and forest degradation" (REDD), which aims to develop a global market in carbon credits derived from preserving and improving forests.
A more advanced version, known as "REDD+", also includes the role of conservation, sustainable management of forests and enhancement of forest carbon stocks.
REDD+ aims to reward developing countries that save, protect and rehabilitate forests through large-scale projects. It is intended to channel funds to communities that manage forests sustainably and provide forest services.
REDD+ is not yet formally part of a broader U.N. climate pact, and potential buyers of carbon credits generated by forest projects are waiting for an approved global standard to ensure emissions reductions are real and verifiable, and that local people also benefit.
The United Nations says financial flows for greenhouse gas emission reductions from REDD+ could reach up to $30 billion a year. So far, developed countries, particularly Norway, have promised several billion dollars to support REDD+ activities.
Other initiatives include a World Bank financing and capacity-building mechanism called the Forest Carbon Partnership Facility, which pays developing countries to protect and replant tropical forests.
By creating an economic value for forests, it aims to help developing countries generate new revenues for tackling poverty while maintaining forest resources such as fresh water, food and herbal medicines.
U.N. & international organisations
The Gateway to the U.N. System's Work on Climate Change provides links to various U.N. agencies that are concerned with climate change.
The website of the United Nations Framework Convention on Climate Change (UNFCCC) is the official source for the latest on U.N. climate change negotiations. It also hosts information about the U.N. Clean Development Mechanism (CDM).
The World Meteorological Organization provides information and resources on weather and climate change.
The U.N. Office for Disaster Risk Reduction (UNISDR) publishes information on high-level work to prevent disasters. It also backs a specialised site for disaster risk reduction, called PreventionWeb.
The U.N. Environment Programme (UNEP) website offers resources on climate change and other environmental issues that affect development.
The U.N.-REDD programme website has news and information on the international initiative to reduce emissions from deforestation and forest degradation in developing countries.
The World Bank has a web page presenting its approach to climate change and clean energy, with related research and links for more detailed information.
Science, data and forecasts
The United Nations Intergovernmental Panel on Climate Change (IPCC) assesses "scientific, technical and socio-economic information" relevant to understanding climate change, its potential effects and the options for curbing and adapting to its negative consequences. The IPCC's website carries summaries and full versions of all the body's key reports, as well as press releases and webcasts of important press conferences.
The Belgium-based Centre for Research on the Epidemiology of Disasters has a database of data and statistics on disasters.
The U.S. National Oceanic & Atmospheric Administration gives storm forecasts, and makes seasonal hurricane predictions. Tropical Storm Risk does the same on a global scale.
The Humanitarian Early Warning Service provides an overview of natural hazards around the globe, including storms, floods and droughts.
The International Research Institute for Climate and Society (IRI) works to promote climate risk management and help poorer countries improve their access to weather and climate information.
Climate change, disasters and development
The International Institute for Environment and Development produces briefings and reports that explore how climate change and climate policy impact on developing countries, including the poorest communities.
Advocacy group Germanwatch also issues papers on climate change policy, adaptation and development, and tracks U.N. negotiations closely.
The London-based Overseas Development Institute puts out regular research reports, policy briefings and blogs on climate change issues, from energy and forests to disaster risk reduction.
The Climate and Development Knowledge Network (CDKN) aims to help decision-makers in developing countries design and deliver climate compatible development, and issues regular reports and articles.
Britain's Institute of Development Studies has a Climate Change and Disasters Centre that publishes research on a range of issues, from helping cities adapt to how children are affected by climate change.
The Africa Adaptation Knowledge Network (AAK Net) gathers news, publications and success stories about climate adaptation efforts in Africa.
Among aid groups, CARE has a dedicated website with information about the work it is doing to help people in some of the most vulnerable places adapt to climate change.
The website of the Red Cross/Red Crescent Climate Centre explains what the organisation is doing to reduce the impact of climate change and extreme weather events on those it works with – including using games as an awareness tool.
Climate Funds Update, sponsored by the Overseas Development Institute and the Heinrich Boll Foundation among others, provides information on international funds to help developing countries address the challenges of climate change, including the amounts they have generated.
The UNFCCC's Adaptation Fund has a website with updates on its meetings and activities, as does the World Bank's set of Climate Investment Funds and the fledgling U.N. Green Climate Fund.
The World Resources Institute tracks climate finance, and has some useful analysis.