Environmental impacts of climate change

Greenhouse gas emissions from human activity are changing the Earth’s climate. The mid-range estimate for the next twenty years is an average global warming of 0.2ºC per decade, according to the Intergovernmental Panel on Climate Change (IPCC). This equates to a potential total increase of over 1.3ºC by 2040 compared to 1850-1900.

As a result, the frequency and intensity of storms is likely to increase, more areas will be affected by drought, and there will be hotter and more frequent heat waves in temperate zones. In some areas climate change will alter entire ecosystems (including agricultural systems), with grave consequences for biodiversity. Low lying coastal regions, deltas (which tend to hold large population concentrations and productive agricultural and natural systems) and coastal fisheries are particularly at risk. 

Although all regions of the world will be affected by climate change, the poor in tropical countries will suffer the brunt of its impact, as they tend to live in the most exposed and least protected areas. 

Action to mitigate climate change is also occurring more slowly than many people hoped it would, while the growth of greenhouse gas emissions is accelerating. If this trend continues the threshold for dangerous climate change – generally accepted to be 2 ºC – will be crossed, increasing the probability of severe, unpredictable and disruptive impacts. 1

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Current trajectory

  • The 2013 Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report warns that carbon emissions grew twice as fast during the past decade than over the 30 years before.1
  • In 2014, the atmospheric concentration of CO2 reached 400 ppm for the first time in human history, up from pre-industrial levels of 280ppm. 2
  • Fossil fuel combustion for energy is responsible for 69% of the world’s greenhouse gas emissions. Of this, coal accounted for 44% of the energy-related global CO2 emissions in 2012, while oil and gas accounted for 35% and 20% of emissions respectively. 3
  • Total net emissions from agriculture, forestry and other land uses decreased in developed nations (-20%) and increased in developing nations (+37%) between 2001 and 2011. In future global increases in carbon emissions are expected to mainly come from Asia and Africa. [5] 2014 was the hottest on record for the planet, with global temperatures 0.57 degrees Celsius higher than the 1961-1990 average. 414 of the 15 warmest years on record have occurred in the 21st century. 5
  • The annual mean Arctic sea-ice extent decreased from 1979 to 2012, approximately at a rate of 3.5-4.1% per decade. Arctic sea-ice extent has decreased in every season and in every successive decade since 1979. 6
  • Sea level is predicted to rise between 0.24 - 0.3 meters by 2065 compared to mean levels for 1986-2005, putting densely populated, low lying coastal areas and deltas at great risk. 7
  • Field trials of wheat, rice, maize and soybeans showed that higher CO2 levels significantly reduced the levels of essential nutrients like iron and zinc, as well as cutting protein levels. 8 About 2.4 billion people currently get at least 60% of their zinc and iron from these staples, a percentage that rises to over 75% in Bangladesh, Iraq and Algeria.9

Implications

  • Natural systems, including glaciers, coral reefs, mangroves, Arctic ecosystems, alpine ecosystems, Boreal forests, tropical forests, prairie wetlands and native grasslands are all severely threatened by climate change. This has serious consequences for people as well as nature, and will affect all human systems – changing climatic patterns and extreme weather events threaten our food security, for example.
  • Rapid and fundamental action is needed across society and the economy to prevent more extreme impacts and avoid passing tipping points that will change our climate unpredictably and irreversibly. The slow progress made in the global UNFCCC process has put more pressure on national governments, business and civil society to take the lead. Fortunately there are many signs of hope and progress, not least in the fields of energy generation and management.
  • The longer we wait for a global, radical decarbonisation agenda to become reality, the greater the likely impacts from climate change will be, and the greater the pressure to intervene directly in the climate system through major forest or soil-carbon projects, or even more experimental – and risky – geo-engineering approaches.

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