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The Changing Earth: Environmental Trends Since Rio
  How the World has Changed in 20 Years  
  Global Governance – Managing the Needs of Ten Billion People  
Earth Observations – Informing the Conventions
Future Challenges
spacer How the World has Changed in 20 years

Not so long ago, our planet seemed infinitely large in its extent and capacity to support human life and lifestyles. Distances seemed huge, news travelled slowly and our imaginations were fired by rare images of exotic peoples and unspoilt and remote countries, abundant in natural beauty and resources. These days, Earth seems like a much smaller place. Modern modes of communication and transportation have shrunk distances. The daily news is a global bulletin, and we communicate with, and consume and trade products and services supplied by, people and countries from around the globe without so much as a second thought.

Evidence compiled for the Rio+20 debates identifies key global trends of relevance to the Earth Summit, focusing on causes and effects and on the 20 years of change since 1992:

− increasingly, the world’s population are urban dwellers, with more than half now living in cities. These people account for 75% of global energy consumption and 80% of global carbon emissions;

− globally, CO2 emissions increased by 36% between 1992 and 2008, from around 22 billion tonnes to over 30 billion tonnes. Emissions have accelerated in the most recent years, due to economic growth and significant investments in infrastructure and manufacturing in the largest developing countries. Eighty percent of global CO2 emissions are generated by just 19 countries – mainly those with high levels of economic development and/or large populations. The energy, industry/manufacturing and forestry sectors together account for over 60% of all greenhouse gas emissions;

− aviation is estimated to be responsible for 5% of global emissions of greenhouse gases: 2.27 billion passenger trips were undertaken in 2009, up 100% since 1992, and air freight (tonne–km) is up 230% over the same period;

− since 1992, the world’s overall Gross Domestic Product (GDP) has increased by 75% (from US$36 trillion to US$63 trillion). Per capita GDP rose by 40%, and up to 80% in developing countries;

− the last two decades will be remembered as the era of globalisation of trade, during which internationally traded products have tripled from over US$9 trillion to US$28 trillion;

− global dietary patterns have changed enormously over the last two decades. Income growth and shifts in consumer preferences have altered dietary patterns, particularly in developing countries. Average meat consumption (which accounts for 18-25% of the world’s greenhouse gas emissions) grew from 34kg to 43kg per person per year.

The economic growth of recent decades has been accomplished mainly through the drawing down of natural resources, without allowing stocks to regenerate, and through allowing widespread ecosystem degradation and loss. Global use of natural resource materials increased by over 40% between 1992 and 2005, from approximately 42 billion tonnes to 60 billion tonnes – a per capita basis increase of 27%. More people are consuming more natural resources every year. Resource extraction and conversion is strongly linked to increasing population numbers and the need for shelter, food and an improved standard of living.

There is now strong evidence that human activities are affecting Earth’s environment at the global scale:

− in a few generations, humankind is likely to exhaust fossil fuel reserves that were formed over several hundred million years, resulting in atmospheric greenhouse gas concentrations to rise far beyond the maxima reached during at least the last 1 million years;

− human action has transformed almost half of Earth’s land surface, with significant consequences for biodiversity and climate. Land degradation and desertification are increasingly serious issues in relation to food security. The global community is estimated to lose 12 million hectares of productive land every year (equivalent to losing an area the size of South Africa over a decade);

− tropical forest areas have been reduced by 50%. Assessments by the UN Food and Agriculture Organization (FAO) indicate that around 13 million hectares of forest were converted to other uses or lost through natural causes each year between 2000 and 2010 (and 16 million hectares each year in the decade prior). This deforestation results in loss of biodiversity and is a significant contributor to CO2 emissions, estimated to amount to around 17% of the global total;

− more than half of all accessible freshwater is used directly or indirectly by humankind;

− nearly all mountain glaciers around the world are retreating and getting thinner, as measured by their annual mass balance. Approximately one-sixth of the world’s population depend on glacier ice and seasonal snow for their water resources;

− coastal and marine habitats are being dramatically altered. Fifty per cent of mangroves have been removed and wetlands have shrunk by half;

− extinction rates are increasing sharply in marine and terrestrial ecosystems around the world. The Living Planet Index reflects changes in the health of Earth’s ecosystems (monitoring almost 8000 populations of over 2500 vertebrate species). Biodiversity in the tropics is dramatically declining, by 30% since 1992, indicating the ecosystems’ severe degradation due to high deforestation rates of primary forest and transformation into agricultural land and pasture;

− humankind is responsible for 70% of the nitrogen cycle and 95% of the phosphorus cycle on Earth;

− over the past two decades, the number of reported natural disasters has doubled from around 200 to over 400 per year. In 2010, over 90% of disaster displacement within countries was attributed to climate-related hazards. Increased risk is resulting from population increase, climate change and ecosystem degradation. The World Bank predicts the human and financial impact of disasters to grow in the coming century. By 2100, even without climate change, damages from weather-related hazards may triple to US$185 billion annually, with a further US$28 billion to US$68 billion from increasing tropical cyclones alone.


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Increasingly strong evidence suggests that the functioning of the Earth System is changing in response. The facts are not easily accepted by a generation unaccustomed to associating environmental factors with lifestyle and consumer choices. But today it is a reality that humankind has begun to match and even exceed nature in terms of changes to the atmosphere and biosphere and impacts on other facets of Earth System functioning.

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 to bring together leading scientists from all over the world to conduct rigorous surveys of the latest technical and scientific literature on climate change. The main activity of the IPCC is to provide regular Assessment Reports of the state of knowledge on climate change. The latest of these is Climate Change 2007, the Fourth IPCC Assessment Report; the key conclusions are summarised below. This report has been described as a historic landmark in the debate about whether humans are affecting the state of the atmosphere.

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1.Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

Eleven of the last twelve years (1995–2006) rank among the twelve warmest years in the instrumental record of global surface temperature (since 1850). The 100-year linear trend (1906–2005) is 0.74°C; temperature increase is widespread over the globe, and is greater at higher northern latitudes. Land regions have warmed faster than the oceans.

2.Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (over 90% probability) due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations.

3.Rising sea level is consistent with warming. Global average sea level has risen since 1961 at an average rate of 1.8 mm/yr and since 1993 at 3.1 mm/yr, with contributions from thermal expansion, melting glaciers and ice caps, and the polar ice sheets. Whether the faster rate for 1993 to 2003 reflects decadal variation or an increase in the longer-term trend is unclear.

4.Observed decreases in snow and ice extent are also consistent with warming. Satellite data since 1978 show that annual average Arctic sea ice extent has shrunk by 2.7% per decade, with larger decreases in summer of 7.4% per decade. Mountain glaciers and snow cover on average have declined in both hemispheres.

5.There is observational evidence of an increase in intense tropical cyclone activity in the North Atlantic since about 1970, with limited evidence of increases elsewhere.

Source: Fourth IPCC Assessment Report, “Climate Change 2007”