Climate Change

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Climate Change is one of the major challenges of our times and we are at a defining moment. From shifting weather patterns that threaten food production, to rising sea levels that increase the risk of catastrophic flooding, the impacts of climate change are global in scope and unprecedented in scale. Without drastic action today, adapting to these impacts in the future will be more difficult and costly.

As climate change is making a profound impact on the consciousness of humanity, so the world is working towards the Sustainable Development Goals. Climate action and sustainable development are intrinsically linked and both are vital to the present and future well-being of humanity.

Building a more sustainable global economy will help reduce the greenhouse gas emissions that cause climate change. It is, therefore, critically important that the international community meet the UN's Sustainable Development Goals and also the targets for reducing emissions set in the Paris Climate Agreement of 2015.

Every country is affected by climate change

No country in the world is safe from the effects of climate change, from cataclysmic weather events increasing in ferocity to polar ice caps melting and global sea levels rising.

Already we are facing ferocious storms, floods, droughts and wildfires and in the future there will be unliveable temperatures in vast swathes of the planet unless we take action to reduce emissions by weaning ourselves off fossil fuels and accelerating the transition to renewable energy.


  • Climate Dictionary

    Climate Dictionary


    Climate change is the defining issue of our times. Every day, more and more people are getting involved in climate action.

    That’s why the United Nations Development Programme prepared this resource of climate change terms and concepts. If you’re struggling to keep up with the climate conversation, the Climate Dictionary is for you.

The Human Fingerprint on Greenhouse Gases

Greenhouse gases occur naturally and are essential to the survival of humans and millions of other living things, by keeping some of the sun’s warmth from reflecting back into space and making Earth liveable. But after more than a century and a half of industrialization, deforestation, and large-scale agriculture, the quantities of greenhouse gases in the atmosphere have risen to record levels not seen in three million years. As populations, economies and standards of living grow, so does the cumulative level of greenhouse gas emissions.

There are some basic well-established scientific links:

  • The concentration of greenhouse gases in the Earth’s atmosphere is directly linked to the average global temperature on Earth;
  • This concentration has been rising steadily, and mean global temperatures along with it, since the time of the Industrial Revolution;
  • The most abundant greenhouse gas is carbon dioxide (CO2), which is largely the product of burning fossil fuels.
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What is the United Nations doing to tackle climate change?

The UN family is at the forefront of the effort to save our planet. Through the Intergovernmental Panel on Climate Change (IPCC), the United Nations provides policymakers with objective scientific data on climate change, its impacts and future risks, as well as options for adaptation, resilience and mitigation. The UN also provides a forum for bringing the world together to take collective action on climate change, through the UN Framework Convention on Climate Change (UNFCCC).

Around the world, the UN works to assist countries transition to climate-resilient and low emissions strategies while also helping those especially vulnerable to the effects of climate change to adapt to a more unstable climate.

Act Now for our common future

Oceans are filling with plastic, nature is disappearing and heat, wildfires and floods are affecting millions of people. Mother Earth is clearly sending us a message that things must change. The good news: we can all do our part and help our planet heal. Get inspired by the actions of these climate activists and be part of the movement #ActNow.

Why is combating climate change important?

There is alarming evidence from the IPCC's reports that important tipping points, leading to irreversible changes in major ecosystems and the planetary climate system, may already have been reached or passed. Ecosystems as diverse as the Amazon rainforest and the Arctic tundra, may be approaching thresholds of dramatic change through warming and drying. Mountain glaciers are in alarming retreat and the downstream effects of reduced water supply in the driest months will have repercussions that transcend generations.

The 2021 scientific report by the IPCC shows changes in the Earth’s climate in every region and across the whole climate system. It clearly states that the role of human influence on the climate system is undisputed. It also shows that human actions still have the potential to determine the future course of climate, pointing to strong and sustained reductions in emissions of carbon dioxide and other greenhouse gases to limit climate change. Benefits for air quality would come quickly, while global temperatures would take 20-30 years to stabilize.

Global agreements and cooperation

The 1992 "Earth Summit" led to the establishment of the United Nations Framework Convention on Climate Change (UNFCCC) as a first step in addressing the climate change problem. Today, it has near-universal membership with 197 countries having ratified the Convention. The ultimate aim of the Convention is to prevent “dangerous” human interference with the climate system. The Kyoto Protocol, adopted in 1997, legally binds developed countries which are party to the Protocol to emission reduction targets.

Paris Agreement

In 2015 at the 21st Conference of the Parties to the UNFCCC in Paris, a landmark agreement was reached to combat climate change and to accelerate and intensify the actions and investments needed for a sustainable low carbon future. The Paris Agreement builds upon the Convention and - for the first time - brings all nations into a common cause to undertake take ambitious efforts to combat climate change and adapt to its effects, with enhanced support to assist developing countries to do so. As such, it charts a new course in the global climate effort.

The Paris Agreement's central aim is to strengthen the global response to the threat of climate change by keeping the global temperature rise this century well below 2 degrees Celsius above pre-industrial levels, or even below 1.5 degrees Celsius.

On Earth Day, 22 April 2016, 175 world leaders signed the Paris Agreement at United Nations Headquarters in New York. This was by far the largest number of countries ever to sign an international agreement on a single day. There are now 191 countries that have ratified the Paris Agreement.

<p><sub>Former Secretary-General Ban Ki-moon (second left); Christiana Figueres (left), Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC); Laurent Fabius (second right), Minister for Foreign Affairs of France and President of the UN Climate Change Conference in Paris (COP21) and François Hollande (right), President of France celebrate after the historic adoption of Paris Agreement on climate change.</sub></p>
© UN Photo/Mark Garten

Former Secretary-General Ban Ki-moon (second left); Christiana Figueres (left), Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC); Laurent Fabius (second right), Minister for Foreign Affairs of France and President of the UN Climate Change Conference in Paris (COP21) and François Hollande (right), President of France celebrate after the historic adoption of Paris Agreement on climate change.

How the UN in Vienna works to support climate action

Many of the Vienna-based UN organizations are actively involved in achieving Sustainable Development Goal 13 on climate action.

The United Nations Industrial Development Organization (UNIDO) promotes green and innovative technology to transform industry, supports countries in environmental management including the provision of sustainable energy, helps improve industrial energy efficiency, assists with clean production, supports the sustainable use of water resources and promotes green jobs and green growth.

The United Nations Office for Outer Space Affairs (UNOOSA) supports the use of space technologies to monitor greenhouse gases related to deforestation and industrial processes, the changing of ice in polar caps and glaciers, sea-level rise and temperature.

The  UN Environment Programme Vienna provides support for climate change action and adaptation in developing counties with fragile mountainous ecosystems and protects endangered mountain species. UNEP Vienna also supports environmental protection projects in Central and South-Eastern European countries.

Data from the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is used for climate change studies by scientists and institutions in all its 183 Member States. The data from seismic, hydroacoustic, infrasound and radionuclide monitoring supports research into icebergs and movements of glaciers, hurricanes and tornadoes, landslides and avalanches, seasonal and yearly variations of specific radionuclides, ocean processes and marine life.

Similarly, the International Atomic Energy Agency (IAEA) helps countries use nuclear science and technology to monitor emissions and environmental changes to the ocean and ecosystems, mitigate sources of greenhouse gas emissions from energy production and land use, and adapt to new climate realities including food and water shortages and ecosystem losses.

The International Commission for the Protection of the Danube River ensures the sustainable use of waters in the Danube River basin

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