Climate change impacts

Introduction

The Intergovernmental Panel on Climate Change won the 2007 Nobel Peace Prize for its reports on climate change collated from the work of thousands of scientists. Here is an overview of their report Impacts, Adaptation and Vulnerability (April 2007) which describes the likely impacts of climate change. Download the report for free. A summary is also available. 

Key finding

The poorest people in the world will be hit first and worst by climate change, even though they have not caused it. Africa will be worst affected.

Impacts report overview

Fresh water
Ecosystems
Food
Coasts
Society and industry
Health
Climate impact headlines for Africa

Fresh water

• Water availability will increase at high latitudes and in some wet tropical areas.
• Water will decrease over some dry regions at mid-latitudes and in the dry tropics, some of which are already water-stressed.
• Drought will affect more areas. Heavy rain will be increase leading to more floods.
• Water stored in glaciers and snow will decline, reducing water availability to more than one-sixth of the world population.

Ecosystems

• Many ecosystems will be overcome by an unprecedented combination of climate change and linked events, such as flooding, drought, wildfire, insects, ocean acidification, land-use change, pollution, over-exploitation of resources.
• Net carbon uptake by land-based ecosystems will peak before mid-century and then weaken or reverse, thus amplifying climate change.
• If global temperature rise exceeds 1.5-2.5°C, 20-30% of plants and animals assessed so far will be at increased risk of extinction. There will be major changes in ecosystems with mainly negative consequences for biodiversity and ecosystem services eg, water and food.
• The acidification of oceans will have negative impacts on marine shell-forming organisms (eg, corals) and the species that depend on them.

Food

• Crop productivity away from the equator will go up slightly if the temperature rise is less than 1-3°C, then decrease if it gets hotter.
• Near the equator, especially dry and tropical regions, crop productivity will decrease for even small local temperature increases (1-2°C). This will increase the risk of hunger.
• Globally, food production may increase with temperature rises of 1-3°C, but above this it will decrease.
• More droughts and floods reduce crop production, especially for subsistence farmers near at low latitudes.
• Continued warming will change the distribution of some fish species, which will reduce fishing.

Coasts and low-lying areas

• Coasts will be at risk from erosion and sea-level rise.
• Corals are vulnerable to small changes in temperature. Sea temperature rise of 1-3°C will cause coral bleaching and widespread mortality.
• Coastal wetlands including salt marshes and mangroves will be damaged by sea-level rise.
• Many millions more people will be flooded every year due to sea-level rise by 2080. Densely-populated low-lying areas which face tropical storms or coastal subsidence (eg, small islands and the mega-deltas of Asia and Africa) are especially vulnerable.

Society and industry

• Impacts of climate change for industry and society will vary widely by location and scale. Overall, net effects will be more negative the bigger the change.
• The most vulnerable industries and societies are those in coastal and river flood plains, those who rely on climate-sensitive resources, and those in areas prone to extreme weather events. Particularly  where there is rapid urbanisation.
• Poor communities will be especially vulnerable. They have limited capacity to adapt, and are dependent on climate-sensitive resources such as local water and food supplies.
• More extreme weather events will have substantial economic and social costs in the areas directly affected. These impacts will spread to other areas too.

Health

• Climate change will impact the health of millions of people.
• Malnutrition and linked disorders will increase, with particular implications for children.
• There will be more deaths and disease from heatwaves, floods, storms, fires and droughts.
• Diarrhoea (water-related) and cardio-respiratory diseases (due to ground-level ozone) will rise.
• Insects that carry infectious diseases may change their range.
• It is difficult to predict some impacts, eg on the range and transmission of malaria in Africa.
• Changes will bring some benefits (eg, fewer deaths from the cold), but overall the impact on health will be negative worldwide, especially in developing countries.

Climate impact headlines for Africa

• 75-250 million people will be exposed to increased water stress by 2020. This will cause problems for health, food production and conflict.
• Agricultural production in many African countries will be severely compromised. This will reduce food security and increase malnutrition.
• In some places yields from rain-fed agriculture could reduce by 50% by 2020.
• Fishing resources in large lakes will reduce due to rising water temperatures, made worse by over-fishing.
• Towards 2100, sea-level rise will affect low-lying coastal areas with large populations. Mangroves and coral reefs will be further degraded, with consequences for fisheries and tourism [Editor: they should have mentioned reduced defences against tsunamis].
• Africa is particularly vulnerable to climate change because of multiple stresses and few resources to adapt.