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Home > Environmental issues > Global warming > Article

UN stark predictions of impact of climate change

7 April 2007

The latest report from the Intergovernmental Panel on Climate Change (IPCC) released in Brussels, describes divisions between rich and poor countries by the impacts of climate change.

The environmental catastrophe from climate change is being expressed in humanitarium terms, with the world's poor the victims.

People in Africa, Asia and South America are predicted to suffer more from drought, food and water shortages, disease, extreme weather and coastal destruction, than affluent people in the regions of Europe, North America and Australia.

It is now more than ever a global problem, requiring a global solution, lead by the countries who have been the major cause of global warming, and who have the resources to bring about massive counter measures.

Rajendra Pachauri, the IPCC chairman said "The poorest of the poor in the world, and this includes poor people in prosperous societies, are going to be the worst hit.  People who are poor are least able to adapt to climate change."

The IPCC study is endorsed by all major United Nations member states.  It is the second part of the Fourth Assessment Report released this year.  Two months ago, the first report dealt with the science of climate change and future temperature rises.  The latest report provides predictions of potential impacts.

A global assessment of data since 1970 has shown it is likely that anthropogenic warming has had a discernible influence on many physical and biological systems.

The current assessment concludes that evidence from all continents and most oceans show many natural systems affected by regional climate changes, particularly temperature increases.

Changes in snow, ice and frozen ground include more and larger glacial lakes, increasing ground instability in permafrost regions, rock avalanches in mountain regions, and changes in Arctic and Antarctic ecosystems including sea-ice biomes and predators high in the food chain.

There is increased run-off and earlier spring peak discharge in many glacier and snow-fed rivers, and warming of lakes and rivers, with effects on thermal structure and water quality.

Based on satellite observations since the early 1980s, there has been a trend in many regions towards earlier ‘greening’ of vegetation in the spring linked to longer thermal growing seasons.

New evidence shows that changes in marine and freshwater biological systems are associated with rising water temperatures, and related changes in ice cover, salinity, oxygen and circulation.

There are shifts in ranges and changes in algal, plankton and fish abundance in high-latitude oceans, increases in algal and zooplankton abundance in high-latitude and high-altitude lakes, and range changes and earlier migrations of fish in rivers.

The uptake of anthropogenic carbon since 1750 has led to the ocean becoming more acidic with an average decrease in pH of 0.1 units. However, the effects of ocean acidification on the marine biosphere are as yet undocumented.

Most of the observed increase in the globally averaged temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

Warming is affecting biological systems, including earlier spring leaf-unfolding, bird migration and egg-laying, and shifts upward toward the pole of plants and animals.

Of 29,000 observational data series, from 75 studies that show significant change in many physical and biological systems, more than 89 percent are consistent with the direction of change expected as a response to warming.

Warming is very unlikely to be due solely to natural variability of temperatures or natural variability of the systems.

The IPCC has concluded with high confidence that anthropogenic warming over the last three decades has had a discernible influence on many physical and biological systems.

It has been determined with medium confidence that temperature increases have had an effect on agriculture and forestry in Northern Hemisphere higher latitudes, with earlier spring planting of crops, and alterations in disturbance of forests from fires and pests.

Some aspects of human health, such as heat-related death in Europe, infectious disease, and allergenic pollen in Northern Hemisphere high and mid-latitudes have worsened.

Warming has impacted hunting and travel over snow and ice in the Arctic, and mountain sports in lower elevation alpine areas.

Recent climate changes and variations are beginning to have effects on many other natural and human systems.  Settlements in mountain regions are at enhanced risk to glacier lake outburst floods caused by melting glaciers.  Governments in some places have begun to respond by building dams and drainage works.

In the Sahelian region of Africa, warmer and drier conditions have led to a reduced length of the growing season with detrimental effects on crops. In southern Africa, longer dry seasons and more uncertain rainfall are prompting adaptation measures.

Sea-level rise and human development are contributing to losses of coastal wetlands and mangroves and increasing damage from coastal flooding in many areas.

Current knowledge about future impacts

The following is a selection of key findings of projected impacts, for unmitigated climate changes projected by the IPCC over this century.

Fresh water resources and their management

By 2050, annual average river runoff and water availability are projected to increase by 10-40% at high latitudes and in some wet tropical areas, and decrease by 10-30% over some dry regions at mid-latitudes and in the dry tropics.

Drought-affected areas will likely increase in extent. Heavy precipitation, which is very likely to increase in frequency, will augment flood risk.

In the course of the century, water supplies stored in glaciers and snow cover are projected to decline, reducing water availability in regions supplied by meltwater from major mountain ranges, where more than one-sixth of the world population currently lives.


The resilience of many ecosystems is likely to be exceeded t by an unprecedented combination of climate change, associated disturbances (flooding, drought, wildfire, insects, ocean acidification), and other global changes (land use change, pollution, resource over-exploitation).

Over the course of this century net carbon uptake by terrestrial ecosystems is likely to peak before 2050, and then weaken or even reverse, thus amplifying climate change.

About 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5°C.

For increases in global average temperature exceeding 1.5-2.5°C, and in concomitant atmospheric CO2 concentrations, there will be major changes in ecosystem structure and function, species’ ecological interactions, and species’ geographic ranges, with negative consequences for biodiversity, and ecosystem goods and services e.g., water and food supply.

The progressive acidification of oceans due to increasing atmospheric carbon dioxide is expected to have negative impacts on marine shell forming organisms (e.g., corals) and their dependent species.

Food, fibre and forest products

Crop productivity is projected to increase slightly at mid to high latitudes for local mean temperature increases of up to 1°C to 3°C depending on the crop, and then decrease beyond that in some regions.

At lower latitudes, crop productivity is projected to decrease for even small local temperature increases (1-2°C).

Globally, the potential for food production is projected to increase with increases in local average temperature over a range of 1°C to 3°C, but above this it is projected to decrease.

Adaptations such as altered cultivars and planting times allow low and mid- to high latitude cereal yields to be maintained at or above baseline yields for modest warming.

Increases in the frequency of droughts and floods are projected to lower local production, especially in subsistence areas at low latitudes.

Globally, commercial timber productivity rises modestly with climate change in the short- to medium-term, with large regional variability around the global trend.

Regional changes in the distribution of fish species are expected, with adverse effects projected for aquaculture and fisheries.

Coastal systems and low-lying areas

Coasts are projected to be exposed to coastal erosion, due to climate change and sea-level rise and the effect will be exacerbated by increasing human-induced pressures on coastal areas.

Corals are vulnerable to thermal stress and have low adaptive capacity. Increases in sea surface temperature of about 1 to 3°C are projected to result in more frequent coral bleaching and widespread mortality, unless there is thermal adaptation or acclimatisation by corals.

Coastal wetlands including salt marshes and mangroves are projected to be negatively affected by sea-level rise especially where they are constrained on their landward side, or starved of sediment.

Many millions more people are projected to be flooded every year due to sea-level rise by the 2080s. The numbers affected will be largest in the mega-deltas of Asia and Africa while small islands are especially vulnerable.

Industry, Settlement and Society

Costs and benefits of climate change for industry, settlement, and society will vary widely by location and scale.

The most vulnerable industries, settlements and societies are generally in coastal and river flood plains, have economies are closely linked with climate-sensitive resources, or are in areas prone to extreme weather, especially where rapid urbanisation is occurring.

Poor communities can be especially vulnerable, particularly those concentrated in high-risk areas. They tend to have more limited adaptive capacity, and are more dependent on climate-sensitive resources such as local water and food.

Where extreme weather events become more intense and frequent, the economic and social costs will increase, more substantially in areas directly affected. Climate change impacts spread from directly impacted areas to other areas through extensive and complex linkages.


Climate change-related exposures are likely to affect the health of millions of people, particularly those with low adaptive capacity, through increases in malnutrition and consequent disorders, with implications for child growth and development.

There will be increased deaths, disease and injury from heat waves, floods, storms, fires and droughts.  There will also be an increase of diarrhoeal disease, and the frequency of cardio-respiratory diseases due to higher concentrations of ground level ozone.

Studies in temperate areas have shown that climate change is projected to bring some benefits, such as fewer deaths from cold exposure.  Overall it is expected that benefits will be outweighed by the negative health effects of rising temperatures world-wide, especially in developing countries.

A pair of Auckland Island teal Anas aucklandicus amongst kelp on Rose Island, in the New Zealand subantarctic Auckland Islands.  The IPCC predicts that by 2020, significant loss of biodiversity will occur in some ecologically rich sites in New Zealand, including the subantarctic islands and alpine areas.
Image Rod Morris, Crown Copyright © Department of Conservation 1973.

View larger image
See Climate Change 2007: The Physical Science Basis - Summary for Policymakers (PDF 18p)
See Climate Change 2007: Impacts, Adaptation and Vulnerability - Summary for Policymakers (PDF 23p)

New Zealand biodiversity loss from drought, more agricultural production from high rainfall & coastal destruction

The IPCC report predicts that as a result of less rainfall and increased evaporation, water security problems will intensify by 2030 in Northland and some eastern regions.

Coastal development and population growth in Northland and the Bay of Plenty are projected to exacerbate risks from sea-level rise, and increases in the severity and frequency of storms and coastal flooding by 2050.

By 2030, agriculture and forestry will decline in parts of eastern New Zealand, due to drought and fire.  Initial benefits to agriculture and forestry are projected in western and southern areas and close to major rivers due to a longer growing season, less frost and more rain.

New Zealand has adaptive capacity with a well-developed economy and scientific and technical capability, but there are significant constraints on implementation and big challenges from extreme events.  Natural systems have limited adaptive capacity.

Half the agricultural yield in Africa

By 2020, between 75 and 250 million people are projected to be exposed to an increase of water stress.

The area suitable for agriculture, the length of growing seasons and yield potential, particularly along the margins of semi-arid and arid areas, are expected to decrease.

In some countries in Africa, yields from rain-fed agriculture could be reduced by up to 50 percent by 2020.

Local food supplies will be negatively affected by decreasing fisheries in lakes due to rising water temperatures, which may be worsened by over-fishing.

Towards the end of the 21st century, projected sea-level rise will affect low-lying coastal areas with large populations. The cost of adaptation could amount to at least 5-10 percent of GDP.

Africa is one of the most vulnerable continents to climate variability and change because of multiple stresses and low adaptive capacity. Some adaptation is taking place, however, this may be insufficient.

Asian flooding, water supply problems, hunger & disease .....

Glacier melt in the Himalayas is projected to increase flooding and rock avalanches, and affect water resources within the next 2 to 3 decades. This will be followed by decreased river flows as the glaciers recede.

There will be less freshwater in Central, South, East and Southeast Asia, which along with population growth and higher demand from higher living standards, could adversely affect more than a billion people by the 2050s.

Coastal areas, especially heavily-populated mega-delta regions in South, East and Southeast Asia, will be at greatest risk due to flooding from the sea and the rivers.

Climate change will impinge on sustainable development of most developing countries of Asia as it compounds the pressures on natural resources and the environment from development.

It is projected that crop yields could increase up to 20 percent in East and Southeast Asia, but decrease 30 percent in Central and South Asia by 2050. The risk of hunger is projected to remain very high in several countries.

Endemic morbidity and mortality due to diarrhoeal disease associated with floods and droughts are expected to rise in East, South and Southeast Asia due to changes in the hydrological cycle. Increases in coastal water temperature would exacerbate the abundance and toxicity of cholera in South Asia.

Drought and fire in Australia .....

Less precipitation and increased evaporation will cause water security problems to intensify by 2030 in southern and eastern Australia.

Significant loss of biodiversity is projected by 2020 in ecologically-rich sites, including the Great Barrier Reef, Queensland Wet Tropics, and Kakadu wetlands in southwest Australia.

Ongoing coastal development in areas such as Cairns and Southeast Queensland are projected to exacerbate risks from sea-level rise and increases in the severity and frequency of storms and coastal flooding by 2050.

Production from agriculture and forestry by 2030 is projected to decline over much of southern and eastern Australia due to increased drought and fire.

Current changes to continue in Europe

Changes associated with climate have been documented for retreating glaciers, longer growing seasons, a shift of the range of species, and health impacts due to a heat wave of unprecedented magnitude. These changes are consistent with projected future changes.

Nearly all European regions are anticipated to be negatively affected by future impacts of climate change, posing challenges to many economic sectors.  Climate change is expected to magnify regional differences in natural resources and assets.

There will be more risk of inland flash floods, frequent coastal flooding, and erosion from storms and sea level rise. The majority of organisms and ecosystems will have difficulty adapting to climate change.

Alpine areas will face glacier retreat, less snow cover and winter tourism, and the loss of up to 60 percent of species in some areas by 2080.

In Southern Europe, climate change is projected to worsen high temperatures and drought in a region already vulnerable to climate variability. There will be less water, hydropower potential, summer tourism, and crop production; and more health risks due to heat waves and wildfires.

In Central and Eastern Europe, summer rain will decrease, causing higher water stress, and health risks due to heat waves will increase.  Forest productivity is expected to decline and the frequency of peatland fires to increase.

There will initially be mixed effects in Northern Europe, including benefits such as reduced heating demand, and increased crop yields and forest growth. However, as climate change continues, its negative impacts, including more frequent winter floods, endangered ecosystems and greater ground instability are likely to outweigh any benefit.

Dying rainforest and species extinctions in Latin America .....

By 2050, increases in temperature and decreases in soil water are projected to lead to replacement of tropical forest by savanna in eastern Amazonia.

Semi-arid vegetation will tend to be replaced by arid vegetation. There is a risk of significant biodiversity loss through species extinction.

In drier areas, climate change is expected to lead to salinisation and desertification of agricultural land.  Productivity of some important crops are projected to decrease and livestock productivity to decline. In temperate zones soybean yields are projected to increase.

Sea-level rise is predicted to cause increased risk of flooding in low-lying areas.

Increases in sea surface temperature are projected to have adverse effects on Mesoamerican coral reefs, and cause shifts in the location of south-east Pacific fish stocks.

Changes in precipitation and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation.

More agricultutal yield, but less water allocations in North America .....

Moderate climate change in the early decades of the century is projected to increase aggregate yields of rain-fed agriculture by 5-20 percent, but with regional variability.  Major challenges are projected for crops that are near the warm end of their range or depend on highly utilised water resources.

Warming in western mountains will cause reduced snowpack, more winter flooding, and less summer flow, exacerbating competition for over-allocated water resources.

Disturbances from pests, diseases, and fire are projected to have increasing impacts on forests, with an extended period of high fire risk and large increases in area burned.

Health will be further challenged in cities that now experience heat waves, by more of them and a greater intensity and duration.

Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution. Growth in population and rising infrastructure value will increase vulnerability, with losses projected to increase if the intensity of tropical storms increase.

Melting ice and rebuilding communities in polar regions .....

In the Polar Regions, the main projected biophysical effects are reductions in thickness and extent of glaciers and ice sheets, and changes in natural ecosystems with detrimental effects on many organisms including migratory birds, mammals and higher predators.

Impacts in the Arctic also include reduction in the extent of sea ice and permafrost, increased coastal erosion, and an increase in the depth of permafrost seasonal thawing.

Impacts on Arctic communities from changing snow and ice conditions, are projected to be mixed. There would be a detrimental impact on infrastructure and indigenous lifestyles.

In both polar regions, ecosystems and habitats are projected to be vulnerable, as climatic barriers to species’ invasions are lowered.

Arctic human communities are already adapting to climate change, but both external and internal stresses challenge their capacities. Despite the resilience shown historically by Arctic indigenous communities, some traditional ways of life are being threatened and substantial investments are needed to adapt of relocate communities.

Sea inundation and reduced water supply of small islands .....

All small islands are especially vulnerable to the effects of climate change, sea level rise and extreme events. Deterioration in coastal conditions through erosion of beaches and coral bleaching, is projected to affect fisheries, and reduce tourism.

Sea-level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.

By 2050, climate change is predicted to reduce water resources in many small islands in the Caribbean and the Pacific, to where they cannot meet demand during low rainfall periods.

With higher temperatures, increased invasion by non-native species is expected to occur, particularly on middle and high-latitude islands.

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