Climate change summary
Climate change represents one of the greatest environmental, social and economic threats facing the planet. Climate change is the long-term change in average weather conditions, including temperature, precipitation and wind.
What is climate change?
Climate change is the long-term change in average weather conditions, including temperature, precipitation and wind.
According to the United Nations Intergovernmental Panel on Climate Change (IPCC), which is comprised of the world’s leading scientific experts in the field of climate change, the global climate is changing as the direct result of greenhouse gas emissions from human activity. Climate change is already apparent as evidenced by higher temperatures, rising sea levels, increased ocean acidity and ice melt. Global surface temperatures, alone, have increased by roughly 0.74 °C (1.33 °F) between the start and the end of the 20th century. According to the IPCC these trends are set to continue to accelerate into the 21st century and will be accompanied by new changes such as increases in extreme weather events like hurricanes. In fact, according to the IPCC’s most recent Synthesis Report released in 2007, global average temperatures will probably rise a further 1.1 to 6.4 ºC (2.0 to 11.5 ºF) this century, depending on the extent of continued greenhouse gas emissions.
In September 2013, the IPCC will publish a new Synthesis Report with revised climate scenarios based on an analysis of the most recent data sources. Some of the findings of this report were leaked in 2012, although the IPCC has cautioned that its panel of 800 experts had not completed their review of the findings. Scientific and industry bodies expect our understanding of the long term effects of climate change to increase as a result of the latest study, but do not expect temperature scenarios to be revised downwards.
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What are greenhouse gases (GHGs)?
Greenhouse gases are those that affect the atmosphere. They act like a blanket or glass roof around the earth, trapping in heat that would otherwise escape to space – this is commonly referred to as the “greenhouse effect”. From the end of the last Ice Age about 10,000 years ago to the end of the 18th century, the levels of greenhouse gases in the atmosphere remained fairly constant and at a level sufficient to sustain life as we know it today. Since the Industrial Revolution 200 years ago, mankind has been releasing unprecedented amounts of greenhouse gases into the atmosphere, which trap more heat, amplifying the natural greenhouse effect.Carbon dioxide (CO2) is the most significant greenhouse gas released by human activities and is emitted mostly from the burning of fossil fuels like coal, oil and natural gas. Other greenhouse gases include methane and nitrous oxide.
Carbon dioxide (CO2) is the most significant and prevalent greenhouse gas released by human activities and is emitted mostly from the burning of fossil fuels like coal, oil and natural gas. The Kyoto Protocol identified five other gases that signatories pledged to reduce in order to limit anthropogenic climate change: methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). A seventh gas, nitrogen trifluoride (NF3), was later added to the list.
Chlorofluorocarbons (CFCs) are also anthropogenic greenhouse gases. Their production is being phased out under requirements of the Montreal Protocol.
How do we know that climate change is real?
As early as 1995, the IPCC had strong scientific evidence that climate change was occurring and that human activities were a primary cause. Since then, the IPCC has conducted four detailed assessments of climate change which on each occasion has reported greater confidence in the case for human-induced climate change. The fifth IPCC report will be published in sections from September 2013.
By 2007, the IPCC concluded that it is ‘‘extremely unlikely that the global climate changes of the past fifty years can be explained without invoking human activities’’. Prominent scientists and major scientific organisations have all ratified the IPCC conclusion. Today, all but a very small percentage of climate scientists are convinced that the Earth’s climate is heating up and that humanactivities are a significant cause.
The scientific consensus regarding climate change is based on the work of thousands of experts from hundreds of research institutions located across the globe. Scientists worldwide have considered all the possible natural factors that affect climate on Earth, from the output of the sun to the effects of volcanoes. After analysing the possible impacts on both warming and cooling of each of the factors, along with man-made factors, the IPCC concluded that most of the observed increase in globally averaged temperatures since the 1950s is very likely (more than 90% certainty) due to the observed increase in man-made greenhouse gas concentrations over the same period.
What are the potential consequences of climate change?
Without effective action to halt the rise and then reduce the levels of greenhouse gases released by human activity, countries worldwide and their citizens face significant changes in food and water resources, health and living standards as they are forced to adapt to a changing climate. The widely quoted Stern Review on the Economics of Climate Change, published by economist Nick Stern in 2006 at the request of the British Government, concluded that failure to act on climate change will cost the world the equivalent on 5% of GDP a year, raising as high as 20% of GDP if a wider range of risks are incorporated. In a 2013 interview at the World Economic Forum, Nick Stern said he now believed he had underestimated the impact of climate change.
The World Bank’s paper "Turn Down the Heat: Why a 4°C Warmer World Must be Avoided", was intended to address the realities of the world’s current emissions trajectory until the IPCC reports in 2013. It predicts society will face disruption from extreme weather, with more frequent storms and flooding, more severe droughts and heat waves, which will result in a loss of agricultural land and biodiversity, including a severe impact on the Amazon basin. Rising sea levels and thawing permafrost will put essential infrastructure under pressure and the increased levels of carbon dioxide in sea water means coral reefs may stop growing as soon as 2030.
In many regions agriculture will be adversely affected by water shortages and extreme heat. The impacts of changing climate are often most felt in fragile and degraded regions in the developing world, adding an additional level of complexity to the challenges of sustainable development.
These impacts will be felt in economic terms and the pressure on already stressed world financial systems could be catastrophic. There will also be social consequences with large scale human migrations from lands affected by drought and famine and extreme heat stress in the urban areas of tropical and subtropical countries.
Can climate change be reversed?
Some changes to our climate are inevitable given the historic build up of emissions in the atmosphere, but further and immediate action is needed to avert the worst of these impacts.
The IPCC’s 2007 calculations estimated that greenhouse gas emissions would need to be cut by at least 80% by 2050 in order to avoid the worst impacts of climate change.
The Kyoto Protocol, the international agreement on emissions reductions, asked signatories to commit to this target in order to limit global warming to 2ºC. Some countries, like the UK, committed to reducing their greenhouse gas emissions in line with this target however most countries did not, or had missed their targets by 2012.
The more action is delayed the more the levels of greenhouse gases will rise before they are brought under control, exposing the Earth to greater levels of warming and making the required reductions even greater. The international climate negotiation process will not reach a new agreement until 2020, and in the mean time the signatories to a second phase cover only 15% of global emissions. In the absence of unilateral agreements, other groups such as investors and business are beginning to look beyond governments for solutions.
Fortunately, many technological solutions exist for reducing greenhouse gas emissions. While these technologies come with a price, it is far outweighed by the cost of inaction. Financing these technologies, however, remains a challenge. New sources of finance, such as the carbon markets, are required to mobilise the necessary investment and financial flows to address climate change.
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