For the first time in human history the air that surrounds us on average contained 400 ppm (parts per million) CO2, and 475 ppm greenhouse gases. If we add the increased amount of water vapor due to global warming, we approach 500 ppm. 2013 is a special year in this respect. The 400 ppm mark only lasted some weeks. Next year the duration will be longer. From 2016 onwards, it will probably be permanent. We have now crossed a border we should not have crossed and are venturing into the unknown.
The last one hundred years the world has become + 0.8°C warmer. In spite of unusually low solar activity and long periods of La Ninas in the Pacific, the last decades have become warmer. Not so much yet maybe, but below are examples of consequences that probably are caused by anthropogenic climate change. The summer of 2012 included the following:
- The worst heat and drought in living memory in the United States. Agriculture and food production were greatly affected in more than half the country
- Droughts in many parts of Eastern and Southern Europe, Australia and India
- More rain than ever measured in southern Norway in June and July
- Extreme rain worse than ever in Buskerud, Norway, August 2012
- The tropical storm Sandy, and others.
The summer of 2011 included the following disasters likely due to anthropogenic global warming:
- 2011 one of the warmest years measured despite the low solar radiation and a strong and cooling La Nina ocean current in the Pacific.
- Large forest fires in New Mexico, USA, dangerously close to the nuclear facility Los Alamos. 12,000 people evacuated.
- Floods in neighbouring Nebraska threatening the safety of two nuclear power plants.
- The worst flooding ever in North Dakota, USA
- Unusually early tornado season in the United States and 8 states ravaged by monster tornado. The city of Joplin partially destroyed.
- 34 million people were affected by drought in May around the Yangtze River in China, when normally there should have been rainy season. The rain arrived later and caused flooding. Over half a million people were evacuated. Food prices have risen sharply in the area.
- March to May was extremely dry and hot. Extreme drought expected in 16 European countries.
- Norwegian production of wheat for consumption decreased from self-sufficiency to 15% of the population’s needs
Otherwise, the last few years:
- Floods like the one in Pakistan in summer 2010, China and the United States in 2011.
- Heat wave in Europe in 2003 killed between 22,000 and 35,000 people. The probability of such heat waves is now twice as large as before.
- More forest fires, such as those we have seen in recent years in California, Canada, Australia, Greece and Russia
- Canada: Twice as much forest as the total of forests in Norway is attacked by the mountain pine beetle. Dead trees provide a discharge of a billion tonnes of CO2 between 2013 and 2020.
- Extreme droughts in the Amazon in 2005 damaged the forest and gave 3 billion tons of CO2 emissions.
- The area covered by sea ice in the Arctic at the end of the melt season has decreased by approx. 30% since records began in the 70′s.
- The area of Greenland where the ice melts in summer has increased by 50% over the last ten years. Greenland glaciers now decrease by more than 200 cubic kilometres per year.
- The low-lying glaciers decrease in Norway, in the Rocky Mountains, the Andes, the Alps and the Himalayas. Some of the highest glaciers may be growing in some places due to increased precipitation and still sufficiently cold weather.
- Increasing damages from extreme weather. Tornadoes are increasing in number and strength. Tornadoes now appear in areas they have not occurred before.
- Prerequisite for the formation of hurricanes is surface temperature of more than 26.5 degrees. This will occur more frequently.
+ 1-2 degrees warmer world. Examples of likely consequences: Well in time before the average global temperature has risen by 2°C, Europe will find that half of all summers are hotter than the summer of 2003. The extreme summers will be much warmer than the summer of 2003.
- Increasing damage from extreme weather, floods or droughts worldwide
- Reduced agricultural yields in tropical areas (5-10% in Africa)
- Rising prices of food
- Less water (20-30%) in vulnerable regions such as southern Africa and the Mediterranean.
- More people are exposed to malaria (60 million)
- Melting of the Greenland ice sheet can no longer be stopped
+ 2 °C warmer world. May occur before 2050. Examples of likely consequences:
- Severe droughts in southern Europe.
- Hurricanes can occur around the Mediterranean Sea and other coastal areas where the water in the sea has become sufficiently warm.
- 1-4 billion people vulnerable to water shortages. 1-5 billion prone to flooding.
- The glaciers in mountain areas decrease drastically. Large parts of Asia and other areas that receive water from glaciers will experience growing water shortages and flooding periods.
- 25% of all wild species of plants and animals are exposed to high risk of extinction
- Increasing damage and high costs of extreme weather, floods or droughts worldwide
- Drought, extreme precipitation and extreme weather damage livelihoods in Africa, Asia and South America.
- 25% lower food production in China and in many other countries.
- High corn prices and other basic foods. Rising sea levels cause problems in more areas.
- More people risk starvation (150-550 million)
- Malaria is spreading to new regions
Now the great feedback effects begin in earnest. It may be possible to prevent the global average temperature from rising more than 2 degrees, on condition that we manage to reduce greenhouse gas emissions by 10% every year from 2015.
+ 3 degrees warmer world. Examples of likely consequences:
- 30-50% less water in southern Africa and the Mediterranean
- The Amazon Rainforest may collapse because of increased temperature and the absence of rain. This means that the world will lose 10% of its photosynthesis and huge extra emissions of CO2 are unavoidable.
- 50% of the arctic tundra melts and gives huge additional emissions of greenhouse gases.
- Accelerating glacier melting on Greenland and the Antarctica will be impossible to stop in this situation. By 2100, sea levels will have risen by a meter or more.
- Dangerous heat waves in southern Europe.
- The Asian summer monsoon is no longer stable. Food production in this area, where 60% of the world population lives, is severely hampered.
- Himalayan glaciers melting – this affects billions of people in Asia.
- Western and central parts of Africa become uninhabitable due to droughts. The east side of Africa will experience periods of immense precipitation.
- Global food production will most probably be reduced by 15-35%.
- Rising sea levels threaten small island states and low-lying areas such as Florida and cities like London, New York and Tokyo.
- Many states will be destabilized by rebellion. The world will see millions of climate refugees. In some regions, the number of climate nomads – the landless and lawless people on the move for food and water, will increase dramatically.
- Wars over water, habitats and natural resources
If global average temperature rises by more than 3 degrees it will be extremely difficult to prevent a rapid continued rise of temperatures to both 4 and 5 centigrades.
+ 6 degrees warmer world. Examples of likely consequences:
- Most natural ecosystems will break down and their production capacity substantially reduced.
- The civilized society no longer functions. Very few people manage to survive.
A +2 To +3 degrees warmer Norway. Likely consequences:
- This dramatic warming may occur as soon as 2040. The average global temperature has now increased by 1.5-2 °C above pre-industrial times.
- Increased plant growth destruction due to more rain in the west; flooding and occasional drought in eastern Norway.
- New pests and diseases harmful to plants, people and animals.
- Ski tourism is not possible except in the highest mountains.
- Norway passes 8 million inhabitants because of climate refugees.
- Apathy in the population when the “tipping points” are passed.
4 degrees warming in Norway. Likely consequences:
- May occur by 2060. The global average temperature has now risen by about 2.5-3 ° C above pre-industrial times.
- Decline in crop production due to extreme weather, too much or too little water.
- Millions will move to Norway because of the temperature rise and heat waves in southern Europe and even greater problems in Africa and Asia.
- Dramatic changes in fish populations.
- Our forests are vulnerable to forest fires and insect attacks. The forests in Norway emit more carbon by rotting, fire and breathing than it binds through photosynthesis. There are more deciduous forests and less spruce and pine.
- Major damages from extreme weather must be expected.
- Life conditions in Norway depend mainly on what happens in other countries.
The large feedback links. These large natural processes all contribute to higher emissions of greenhouse gases or directly increase the average temperature of the globe.
- There will be increasing amounts of water vapour in the atmosphere at elevated temperature. Water vapour is the main greenhouse gas and have the greatest effect on the temperature.
- There will be large emissions of the greenhouse gases methane and CO2 from the melting tundra.
- There will be additional rapid heating due to surfaces of ice and snow that are replaced by darker, heat-absorbing surfaces.
- There is an increased and accelerating release of CO2 from soil and organic matter at elevated temperatures.
- There is a lower uptake of CO2 in the oceans by increased temperatures, which will lead to that an increasing proportion of our emissions of CO2 will remain in the atmosphere. The sea has until now taken up half of all CO2 emissions emitted from the burning of fossil fuels.
- There will be accelerating emissions from the collapse of major habitats such as the Amazon rainforest or large forest areas elsewhere as a result of reduced precipitation and increased temperatures or pests, diseases and forest fires.
This article is written with the help of Thomas Cottis and Svein Tveitdal in the Climate Election campaign 2013 in collaboration with climate scientist Steffen Kalbekken at Cicero
- Keeling curve update
- 400 ppm – now what?
- Climate change in facts and figures
- CICERO climate change fact sheets
- Lecture on U-tube
- Unburnable fuel and mispricing (Economist 2013)
- What Will It Take for Us to Recognize That the Way We Live Could Be Destroying Life as We Know It?
- 400 ppm – a tipping point?
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- Hansen et al (2013) ’Assessing “Dangerous Climate Change”: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature’
- What Happens if We Don’t Prevent Average Global Temperatures from Rising?
- Italian Island Hit By ‘Apocalyptic’ Storm As 17 Inches Of Rain Fall In 90 Minutes
- Flooding threatens one in four London properties
- Alaska on the edge. USAs first climate refugees
- The effects of climate change: Storm damage in Europe on the rise (Swiss re)
- As Glaciers Melt, Alpine Mountains Lose Their Glue, Threatening Swiss Village
- Flooding in Hungary 2013
- Flooding in Hungary and Central Europe 2010
- Floods in Pakistan
- Floods in India 2013
- Floods in Canada 2013
- Floods in Canada 2011
- 2013 Alberta Floods Were Costliest Natural Disaster In Canadian History, Insurers Estimate
- Deadly floods in Sri Lanka 2012
- Deadly floods in Sri Lanka 2011 (BBC)
- Floods in Sri Lanka 2013
- Floods in Mexico 2013
- Floods in Russia 2013
- Floods in China 2013
- Typhoon Fitow Hits China: Half A Million People Forced To Evacuate
- Super-Typhoon Haiyan is almost like Katrina and Sandy combined (Nov 2013)
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- Typhoon Haiyan - Was That Huge Storm Caused by Climate Change?
- Extreme Weather Events in Europe: preparing for climate change adaptation
- CT, NY, NJ Should Expect Unprecedented Flooding by Mid-Century, Scientists Predict
- Extreme heat forecasted for the USA June 2013
- Deadly Heat Wave in the West Brings Fires and Travel Delays (NYT, June 2013)
- Record heat over Alaska 2013
- Dust bowl blues – the US South West drying out
- Extreme heat waves to quadruple by 2040, study says
- Heat waves in China 2013
- Typhoon in China 2013
- Flooding due to rising seas could cost $1 trillion by 2050
- Deadly 1,000-year floods strike Colorado
- Colorado floods: 3 dead, 1 missing, rescue efforts continue amid rain
- Colorado Flooding: Did Climate Change Play A Role In Recent Disaster?
- 5 Things You Should Know About Colorado’s ’1,000 Year Flood’
- President of Marshall islands: Climate Change Has Reached Our Shores
- The Amazon Rain Forest Is Drying Out, Probably Because Of Climate Change
- Climate Change Report Predicts Warming Will Only Make Human Ills Worse
- Extreme weather patterns and the possible role of climate change (Face the nation)
- Arctic sea ice melts at alarming rate
- Arctic sea ice loss (video)
- Vast costs of Arctic change (Nature)
- Top 20 cities with billions at risk from climate change